} dispatchers Dispatchers to register\n\t * under the given name.\n\t */\n\tregister( groupName, dispatchers ) {\n\t\tif ( this._dispatchersGroups.has( groupName ) ) {\n\t\t\t/**\n\t\t\t * Trying to register a group name that was already registered.\n\t\t\t *\n\t\t\t * @error conversion-register-group-exists\n\t\t\t */\n\t\t\tthrow new CKEditorError( 'conversion-register-group-exists: Trying to register a group name that was already registered.' );\n\t\t}\n\n\t\tthis._dispatchersGroups.set( groupName, dispatchers );\n\t}\n\n\t/**\n\t * Provides chainable API to assign converters to dispatchers registered under a given group name. Converters are added\n\t * by calling the `.add()` method of an object returned by this function.\n\t *\n\t *\t\tconversion.for( 'downcast' )\n\t *\t\t\t.add( conversionHelperA )\n\t *\t\t\t.add( conversionHelperB );\n\t *\n\t * In this example `conversionHelperA` and `conversionHelperB` will be called for all dispatchers from the `'model'` group.\n\t *\n\t * The `.add()` method takes exactly one parameter, which is a function. This function should accept one parameter that\n\t * is a dispatcher instance. The function should add an actual converter to the passed dispatcher instance.\n\t *\n\t * Conversion helpers for most common cases are already provided. They are flexible enough to cover most use cases.\n\t * See the documentation to learn how they can be configured.\n\t *\n\t * For downcast (model-to-view conversion), these are:\n\t *\n\t * * {@link module:engine/conversion/downcast-converters~downcastElementToElement Downcast element-to-element converter},\n\t * * {@link module:engine/conversion/downcast-converters~downcastAttributeToElement Downcast attribute-to-element converter},\n\t * * {@link module:engine/conversion/downcast-converters~downcastAttributeToAttribute Downcast attribute-to-attribute converter}.\n\t *\n\t * For upcast (view-to-model conversion), these are:\n\t *\n\t * * {@link module:engine/conversion/upcast-converters~upcastElementToElement Upcast element-to-element converter},\n\t * * {@link module:engine/conversion/upcast-converters~upcastElementToAttribute Upcast attribute-to-element converter},\n\t * * {@link module:engine/conversion/upcast-converters~upcastAttributeToAttribute Upcast attribute-to-attribute converter}.\n\t *\n\t * An example of using conversion helpers to convert the `paragraph` model element to the `p` view element (and back):\n\t *\n\t *\t\t// Define conversion configuration - model element 'paragraph' should be converted to view element 'p'.\n\t *\t\tconst config = { model: 'paragraph', view: 'p' };\n\t *\n\t *\t\t// Add converters to proper dispatchers using conversion helpers.\n\t *\t\tconversion.for( 'downcast' ).add( downcastElementToElement( config ) );\n\t *\t\tconversion.for( 'upcast' ).add( upcastElementToElement( config ) );\n\t *\n\t * An example of providing a custom conversion helper that uses a custom converter function:\n\t *\n\t *\t\t// Adding a custom `myConverter` converter for 'paragraph' element insertion, with the default priority ('normal').\n\t *\t\tconversion.for( 'downcast' ).add( conversion.customConverter( 'insert:paragraph', myConverter ) );\n\t *\n\t * @param {String} groupName The name of dispatchers group to add the converters to.\n\t * @returns {Object} An object with the `.add()` method, providing a way to add converters.\n\t */\n\tfor( groupName ) {\n\t\tconst dispatchers = this._getDispatchers( groupName );\n\n\t\treturn {\n\t\t\tadd( conversionHelper ) {\n\t\t\t\t_addToDispatchers( dispatchers, conversionHelper );\n\n\t\t\t\treturn this;\n\t\t\t}\n\t\t};\n\t}\n\n\t/**\n\t * Sets up converters between the model and the view that convert a model element to a view element (and vice versa).\n\t * For example, the model `Foo` is `Foo
` in the view.\n\t *\n\t *\t\t// A simple conversion from the `paragraph` model element to the `` view element (and vice versa).\n\t *\t\tconversion.elementToElement( { model: 'paragraph', view: 'p' } );\n\t *\n\t *\t\t// Override other converters by specifying a converter definition with a higher priority.\n\t *\t\tconversion.elementToElement( { model: 'paragraph', view: 'div', converterPriority: 'high' } );\n\t *\n\t *\t\t// View specified as an object instead of a string.\n\t *\t\tconversion.elementToElement( {\n\t *\t\t\tmodel: 'fancyParagraph',\n\t *\t\t\tview: {\n\t *\t\t\t\tname: 'p',\n\t *\t\t\t\tclasses: 'fancy'\n\t *\t\t\t}\n\t *\t\t} );\n\t *\n\t *\t\t// Use `upcastAlso` to define other view elements that should also be converted to a `paragraph` element.\n\t *\t\tconversion.elementToElement( {\n\t *\t\t\tmodel: 'paragraph',\n\t *\t\t\tview: 'p',\n\t *\t\t\tupcastAlso: [\n\t *\t\t\t\t'div',\n\t *\t\t\t\t{\n\t *\t\t\t\t\t// Any element with the `display: block` style.\n\t *\t\t\t\t\tstyles: {\n\t *\t\t\t\t\t\tdisplay: 'block'\n\t *\t\t\t\t\t}\n\t *\t\t\t\t}\n\t *\t\t\t]\n\t *\t\t} );\n\t *\n\t *\t\t// `upcastAlso` set as callback enables a conversion of a wide range of different view elements.\n\t *\t\tconversion.elementToElement( {\n\t *\t\t\tmodel: 'heading',\n\t *\t\t\tview: 'h2',\n\t *\t\t\t// Convert \"headling-like\" paragraphs to headings.\n\t *\t\t\tupcastAlso: viewElement => {\n\t *\t\t\t\tconst fontSize = viewElement.getStyle( 'font-size' );\n\t *\n\t *\t\t\t\tif ( !fontSize ) {\n\t *\t\t\t\t\treturn null;\n\t *\t\t\t\t}\n\t *\n\t *\t\t\t\tconst match = fontSize.match( /(\\d+)\\s*px/ );\n\t *\n\t *\t\t\t\tif ( !match ) {\n\t *\t\t\t\t\treturn null;\n\t *\t\t\t\t}\n\t *\n\t *\t\t\t\tconst size = Number( match[ 1 ] );\n\t *\n\t *\t\t\t\tif ( size > 26 ) {\n\t *\t\t\t\t\t// Returned value can be an object with the matched properties.\n\t *\t\t\t\t\t// These properties will be \"consumed\" during the conversion.\n\t *\t\t\t\t\t// See `engine.view.Matcher~MatcherPattern` and `engine.view.Matcher#match` for more details.\n\t *\n\t *\t\t\t\t\treturn { name: true, styles: [ 'font-size' ] };\n\t *\t\t\t\t}\n\t *\n\t *\t\t\t\treturn null;\n\t *\t\t\t}\n\t *\t\t} );\n\t *\n\t * `definition.model` is a `String` with a model element name to convert from or to.\n\t * See {@link module:engine/conversion/conversion~ConverterDefinition} to learn about other parameters.\n\t *\n\t * @param {module:engine/conversion/conversion~ConverterDefinition} definition The converter definition.\n\t */\n\telementToElement( definition ) {\n\t\t// Set up downcast converter.\n\t\tthis.for( 'downcast' ).add( downcastElementToElement( definition ) );\n\n\t\t// Set up upcast converter.\n\t\tfor ( const { model, view } of _getAllUpcastDefinitions( definition ) ) {\n\t\t\tthis.for( 'upcast' ).add(\n\t\t\t\tupcastElementToElement( {\n\t\t\t\t\tmodel,\n\t\t\t\t\tview,\n\t\t\t\t\tconverterPriority: definition.converterPriority\n\t\t\t\t} )\n\t\t\t);\n\t\t}\n\t}\n\n\t/**\n\t * Sets up converters between the model and the view that convert a model attribute to a view element (and vice versa).\n\t * For example, a model text node with `\"Foo\"` as data and the `bold` attribute is `Foo` in the view.\n\t *\n\t *\t\t// A simple conversion from the `bold=true` attribute to the `` view element (and vice versa).\n\t *\t\tconversion.attributeToElement( { model: 'bold', view: 'strong' } );\n\t *\n\t *\t\t// Override other converters by specifying a converter definition with a higher priority.\n\t *\t\tconversion.attributeToElement( { model: 'bold', view: 'b', converterPriority: 'high' } );\n\t *\n\t *\t\t// View specified as an object instead of a string.\n\t *\t\tconversion.attributeToElement( {\n\t *\t\t\tmodel: 'bold',\n\t *\t\t\tview: {\n\t *\t\t\t\tname: 'span',\n\t *\t\t\t\tclasses: 'bold'\n\t *\t\t\t}\n\t *\t\t} );\n\t *\n\t *\t\t// Use `config.model.name` to define the conversion only from a given node type, `$text` in this case.\n\t *\t\t// The same attribute on different elements may then be handled by a different converter.\n\t *\t\tconversion.attributeToElement( {\n\t *\t\t\tmodel: {\n\t *\t\t\t\tkey: 'textDecoration',\n\t *\t\t\t\tvalues: [ 'underline', 'lineThrough' ],\n\t *\t\t\t\tname: '$text'\n\t *\t\t\t},\n\t *\t\t\tview: {\n\t *\t\t\t\tunderline: {\n\t *\t\t\t\t\tname: 'span',\n\t *\t\t\t\t\tstyles: {\n\t *\t\t\t\t\t\t'text-decoration': 'underline'\n\t *\t\t\t\t\t}\n\t *\t\t\t\t},\n\t *\t\t\t\tlineThrough: {\n\t *\t\t\t\t\tname: 'span',\n\t *\t\t\t\t\tstyles: {\n\t *\t\t\t\t\t\t'text-decoration': 'line-through'\n\t *\t\t\t\t\t}\n\t *\t\t\t\t}\n\t *\t\t\t}\n\t *\t\t} );\n\t *\n\t *\t\t// Use `upcastAlso` to define other view elements that should also be converted to the `bold` attribute.\n\t *\t\tconversion.attributeToElement( {\n\t *\t\t\tmodel: 'bold',\n\t *\t\t\tview: 'strong',\n\t *\t\t\tupcastAlso: [\n\t *\t\t\t\t'b',\n\t *\t\t\t\t{\n\t *\t\t\t\t\tname: 'span',\n\t *\t\t\t\t\tclasses: 'bold'\n\t *\t\t\t\t},\n\t *\t\t\t\t{\n\t *\t\t\t\t\tname: 'span',\n\t *\t\t\t\t\tstyles: {\n\t *\t\t\t\t\t\t'font-weight': 'bold'\n\t *\t\t\t\t\t}\n\t *\t\t\t\t},\n\t *\t\t\t\tviewElement => {\n\t *\t\t\t\t\tconst fontWeight = viewElement.getStyle( 'font-weight' );\n\t *\n\t *\t\t\t\t\tif ( viewElement.is( 'span' ) && fontWeight && /\\d+/.test() && Number( fontWeight ) > 500 ) {\n\t *\t\t\t\t\t\t// Returned value can be an object with the matched properties.\n\t *\t\t\t\t\t\t// These properties will be \"consumed\" during the conversion.\n\t *\t\t\t\t\t\t// See `engine.view.Matcher~MatcherPattern` and `engine.view.Matcher#match` for more details.\n\t *\n\t *\t\t\t\t\t\treturn {\n\t *\t\t\t\t\t\t\tname: true,\n\t *\t\t\t\t\t\t\tstyles: [ 'font-weight' ]\n\t *\t\t\t\t\t\t};\n\t *\t\t\t\t\t}\n\t *\t\t\t\t}\n\t *\t\t\t]\n\t *\t\t} );\n\t *\n\t *\t\t// Conversion from and to a model attribute key whose value is an enum (`fontSize=big|small`).\n\t *\t\t// `upcastAlso` set as callback enables a conversion of a wide range of different view elements.\n\t *\t\tconversion.attributeToElement( {\n\t *\t\t\tmodel: {\n\t *\t\t\t\tkey: 'fontSize',\n\t *\t\t\t\tvalues: [ 'big', 'small' ]\n\t *\t\t\t},\n\t *\t\t\tview: {\n\t *\t\t\t\tbig: {\n\t *\t\t\t\t\tname: 'span',\n\t *\t\t\t\t\tstyles: {\n\t *\t\t\t\t\t\t'font-size': '1.2em'\n\t *\t\t\t\t\t}\n\t *\t\t\t\t},\n\t *\t\t\t\tsmall: {\n\t *\t\t\t\t\tname: 'span',\n\t *\t\t\t\t\tstyles: {\n\t *\t\t\t\t\t\t'font-size': '0.8em'\n\t *\t\t\t\t\t}\n\t *\t\t\t\t}\n\t *\t\t\t},\n\t *\t\t\tupcastAlso: {\n\t *\t\t\t\tbig: viewElement => {\n\t *\t\t\t\t\tconst fontSize = viewElement.getStyle( 'font-size' );\n\t *\n\t *\t\t\t\t\tif ( !fontSize ) {\n\t *\t\t\t\t\t\treturn null;\n\t *\t\t\t\t\t}\n\t *\n\t *\t\t\t\t\tconst match = fontSize.match( /(\\d+)\\s*px/ );\n\t *\n\t *\t\t\t\t\tif ( !match ) {\n\t *\t\t\t\t\t\treturn null;\n\t *\t\t\t\t\t}\n\t *\n\t *\t\t\t\t\tconst size = Number( match[ 1 ] );\n\t *\n\t *\t\t\t\t\tif ( viewElement.is( 'span' ) && size > 10 ) {\n\t *\t\t\t\t\t\t// Returned value can be an object with the matched properties.\n\t *\t\t\t\t\t\t// These properties will be \"consumed\" during the conversion.\n\t *\t\t\t\t\t\t// See `engine.view.Matcher~MatcherPattern` and `engine.view.Matcher#match` for more details.\n\t *\n\t *\t\t\t\t\t\treturn { name: true, styles: [ 'font-size' ] };\n\t *\t\t\t\t\t}\n\t *\n\t *\t\t\t\t\treturn null;\n\t *\t\t\t\t},\n\t *\t\t\t\tsmall: viewElement => {\n\t *\t\t\t\t\tconst fontSize = viewElement.getStyle( 'font-size' );\n\t *\n\t *\t\t\t\t\tif ( !fontSize ) {\n\t *\t\t\t\t\t\treturn null;\n\t *\t\t\t\t\t}\n\t *\n\t *\t\t\t\t\tconst match = fontSize.match( /(\\d+)\\s*px/ );\n\t *\n\t *\t\t\t\t\tif ( !match ) {\n\t *\t\t\t\t\t\treturn null;\n\t *\t\t\t\t\t}\n\t *\n\t *\t\t\t\t\tconst size = Number( match[ 1 ] );\n\t *\n\t *\t\t\t\t\tif ( viewElement.is( 'span' ) && size < 10 ) {\n\t *\t\t\t\t\t\t// Returned value can be an object with the matched properties.\n\t *\t\t\t\t\t\t// These properties will be \"consumed\" during the conversion.\n\t *\t\t\t\t\t\t// See `engine.view.Matcher~MatcherPattern` and `engine.view.Matcher#match` for more details.\n\t *\n\t *\t\t\t\t\t\treturn { name: true, styles: [ 'font-size' ] };\n\t *\t\t\t\t\t}\n\t *\n\t *\t\t\t\t\treturn null;\n\t *\t\t\t\t}\n\t *\t\t\t}\n\t *\t\t} );\n\t *\n\t * The `definition.model` parameter specifies which model attribute should be converted from or to. It can be a `{ key, value }` object\n\t * describing the attribute key and value to convert or a `String` specifying just the attribute key (then `value` is set to `true`).\n\t * See {@link module:engine/conversion/conversion~ConverterDefinition} to learn about other parameters.\n\t *\n\t * @param {module:engine/conversion/conversion~ConverterDefinition} definition The converter definition.\n\t */\n\tattributeToElement( definition ) {\n\t\t// Set up downcast converter.\n\t\tthis.for( 'downcast' ).add( downcastAttributeToElement( definition ) );\n\n\t\t// Set up upcast converter.\n\t\tfor ( const { model, view } of _getAllUpcastDefinitions( definition ) ) {\n\t\t\tthis.for( 'upcast' ).add(\n\t\t\t\tupcastElementToAttribute( {\n\t\t\t\t\tview,\n\t\t\t\t\tmodel,\n\t\t\t\t\tpriority: definition.priority\n\t\t\t\t} )\n\t\t\t);\n\t\t}\n\t}\n\n\t/**\n\t * Sets up converters between the model and the view that convert a model attribute to a view attribute (and vice versa).\n\t * For example, `` is converted to `` (the same attribute key and value).\n\t *\n\t *\t\t// A simple conversion from the `source` model attribute to the `src` view attribute (and vice versa).\n\t *\t\tconversion.attributeToAttribute( { model: 'source', view: 'src' } );\n\t *\n\t *\t\t// Attribute values are strictly specified.\n\t *\t\tconversion.attributeToAttribute( {\n\t *\t\t\tmodel: {\n\t *\t\t\t\tname: 'image',\n\t *\t\t\t\tkey: 'aside',\n\t *\t\t\t\tvalues: [ 'aside' ]\n\t *\t\t\t},\n\t *\t\t\tview: {\n\t *\t\t\t\taside: {\n\t *\t\t\t\t\tname: 'img',\n\t *\t\t\t\t\tkey: 'class',\n\t *\t\t\t\t\tvalue: [ 'aside', 'half-size' ]\n\t *\t\t\t\t}\n\t *\t\t\t}\n\t *\t\t} );\n\t *\n\t *\t\t// Set the style attribute.\n\t *\t\tconversion.attributeToAttribute( {\n\t *\t\t\tmodel: {\n\t *\t\t\t\tname: 'image',\n\t *\t\t\t\tkey: 'aside',\n\t *\t\t\t\tvalues: [ 'aside' ]\n\t *\t\t\t},\n\t *\t\t\tview: {\n\t *\t\t\t\taside: {\n\t *\t\t\t\t\tname: 'img',\n\t *\t\t\t\t\tkey: 'style',\n\t *\t\t\t\t\tvalue: {\n\t *\t\t\t\t\t\tfloat: 'right',\n\t *\t\t\t\t\t\twidth: '50%',\n\t *\t\t\t\t\t\tmargin: '5px'\n\t *\t\t\t\t\t}\n\t *\t\t\t\t}\n\t *\t\t\t}\n\t *\t\t} );\n\t *\n\t *\t\t// Conversion from and to a model attribute key whose value is an enum (`align=right|center`).\n\t *\t\t// Use `upcastAlso` to define other view elements that should also be converted to the `align=right` attribute.\n\t *\t\tconversion.attributeToAttribute( {\n\t *\t\t\tmodel: {\n\t *\t\t\t\tkey: 'align',\n\t *\t\t\t\tvalues: [ 'right', 'center' ]\n\t *\t\t\t},\n\t *\t\t\tview: {\n\t *\t\t\t\tright: {\n\t *\t\t\t\t\tkey: 'class',\n\t *\t\t\t\t\tvalue: 'align-right'\n\t *\t\t\t\t},\n\t *\t\t\t\tcenter: {\n\t *\t\t\t\t\tkey: 'class',\n\t *\t\t\t\t\tvalue: 'align-center'\n\t *\t\t\t\t}\n\t *\t\t\t},\n\t *\t\t\tupcastAlso: {\n\t *\t\t\t\tright: {\n\t *\t\t\t\t\tstyles: {\n\t *\t\t\t\t\t\t'text-align': 'right'\n\t *\t\t\t\t\t}\n\t *\t\t\t\t},\n\t *\t\t\t\tcenter: {\n\t *\t\t\t\t\tstyles: {\n\t *\t\t\t\t\t\t'text-align': 'center'\n\t *\t\t\t\t\t}\n\t *\t\t\t\t}\n\t *\t\t\t}\n\t *\t\t} );\n\t *\n\t * The `definition.model` parameter specifies which model attribute should be converted from and to.\n\t * It can be a `{ key, [ values ], [ name ] }` object or a `String`, which will be treated like `{ key: definition.model }`.\n\t * The `key` property is the model attribute key to convert from and to.\n\t * The `values` are the possible model attribute values. If `values` is not set, the model attribute value will be the same as the\n\t * view attribute value.\n\t * If `name` is set, the conversion will be set up only for model elements with the given name.\n\t *\n\t * The `definition.view` parameter specifies which view attribute should be converted from and to.\n\t * It can be a `{ key, value, [ name ] }` object or a `String`, which will be treated like `{ key: definition.view }`.\n\t * The `key` property is the view attribute key to convert from and to.\n\t * The `value` is the view attribute value to convert from and to. If `definition.value` is not set, the view attribute value will be\n\t * the same as the model attribute value.\n\t * If `key` is `'class'`, `value` can be a `String` or an array of `String`s.\n\t * If `key` is `'style'`, `value` is an object with key-value pairs.\n\t * In other cases, `value` is a `String`.\n\t * If `name` is set, the conversion will be set up only for model elements with the given name.\n\t * If `definition.model.values` is set, `definition.view` is an object that assigns values from `definition.model.values`\n\t * to `{ key, value, [ name ] }` objects.\n\t *\n\t * `definition.upcastAlso` specifies which other matching view elements should also be upcast to the given model configuration.\n\t * If `definition.model.values` is set, `definition.upcastAlso` should be an object assigning values from `definition.model.values`\n\t * to {@link module:engine/view/matcher~MatcherPattern}s or arrays of {@link module:engine/view/matcher~MatcherPattern}s.\n\t *\n\t * **Note:** `definition.model` and `definition.view` form should be mirrored, so the same types of parameters should\n\t * be given in both parameters.\n\t *\n\t * @param {Object} definition The converter definition.\n\t * @param {String|Object} definition.model The model attribute to convert from and to.\n\t * @param {String|Object} definition.view The view attribute to convert from and to.\n\t * @param {module:engine/view/matcher~MatcherPattern|Array.} [definition.upcastAlso]\n\t * Any view element matching `definition.upcastAlso` will also be converted to the given model attribute. `definition.upcastAlso`\n\t * is used only if `config.model.values` is specified.\n\t */\n\tattributeToAttribute( definition ) {\n\t\t// Set up downcast converter.\n\t\tthis.for( 'downcast' ).add( downcastAttributeToAttribute( definition ) );\n\n\t\t// Set up upcast converter.\n\t\tfor ( const { model, view } of _getAllUpcastDefinitions( definition ) ) {\n\t\t\tthis.for( 'upcast' ).add(\n\t\t\t\tupcastAttributeToAttribute( {\n\t\t\t\t\tview,\n\t\t\t\t\tmodel\n\t\t\t\t} )\n\t\t\t);\n\t\t}\n\t}\n\n\t/**\n\t * Returns dispatchers registered under a given group name.\n\t *\n\t * If the given group name has not been registered, the\n\t * {@link module:utils/ckeditorerror~CKEditorError `conversion-for-unknown-group` error} is thrown.\n\t *\n\t * @private\n\t * @param {String} groupName\n\t * @returns {Array.}\n\t */\n\t_getDispatchers( groupName ) {\n\t\tconst dispatchers = this._dispatchersGroups.get( groupName );\n\n\t\tif ( !dispatchers ) {\n\t\t\t/**\n\t\t\t * Trying to add a converter to an unknown dispatchers group.\n\t\t\t *\n\t\t\t * @error conversion-for-unknown-group\n\t\t\t */\n\t\t\tthrow new CKEditorError( 'conversion-for-unknown-group: Trying to add a converter to an unknown dispatchers group.' );\n\t\t}\n\n\t\treturn dispatchers;\n\t}\n}\n\n/**\n * Defines how the model should be converted from and to the view.\n *\n * @typedef {Object} module:engine/conversion/conversion~ConverterDefinition\n *\n * @property {*} [model] The model conversion definition. Describes the model element or model attribute to convert. This parameter differs\n * for different functions that accept `ConverterDefinition`. See the description of the function to learn how to set it.\n * @property {module:engine/view/elementdefinition~ElementDefinition|Object} view The definition of the view element to convert from and\n * to. If `model` describes multiple values, `view` is an object that assigns these values (`view` object keys) to view element definitions\n * (`view` object values).\n * @property {module:engine/view/matcher~MatcherPattern|Array.} [upcastAlso]\n * Any view element matching `upcastAlso` will also be converted to the model. If `model` describes multiple values, `upcastAlso`\n * is an object that assigns these values (`upcastAlso` object keys) to {@link module:engine/view/matcher~MatcherPattern}s\n * (`upcastAlso` object values).\n * @property {module:utils/priorities~PriorityString} [converterPriority] The converter priority.\n */\n\n// Helper function for the `Conversion` `.add()` method.\n//\n// Calls `conversionHelper` on each dispatcher from the group specified earlier in the `.for()` call, effectively\n// adding converters to all specified dispatchers.\n//\n// @private\n// @param {Array.} dispatchers\n// @param {Function} conversionHelper\nfunction _addToDispatchers( dispatchers, conversionHelper ) {\n\tfor ( const dispatcher of dispatchers ) {\n\t\tconversionHelper( dispatcher );\n\t}\n}\n\n// Helper function that creates a joint array out of an item passed in `definition.view` and items passed in\n// `definition.upcastAlso`.\n//\n// @param {module:engine/conversion/conversion~ConverterDefinition} definition\n// @returns {Array} Array containing view definitions.\nfunction* _getAllUpcastDefinitions( definition ) {\n\tif ( definition.model.values ) {\n\t\tfor ( const value of definition.model.values ) {\n\t\t\tconst model = { key: definition.model.key, value };\n\t\t\tconst view = definition.view[ value ];\n\t\t\tconst upcastAlso = definition.upcastAlso ? definition.upcastAlso[ value ] : undefined;\n\n\t\t\tyield* _getUpcastDefinition( model, view, upcastAlso );\n\t\t}\n\t} else {\n\t\tyield* _getUpcastDefinition( definition.model, definition.view, definition.upcastAlso );\n\t}\n}\n\nfunction* _getUpcastDefinition( model, view, upcastAlso ) {\n\tyield { model, view };\n\n\tif ( upcastAlso ) {\n\t\tupcastAlso = Array.isArray( upcastAlso ) ? upcastAlso : [ upcastAlso ];\n\n\t\tfor ( const upcastAlsoItem of upcastAlso ) {\n\t\t\tyield { model, view: upcastAlsoItem };\n\t\t}\n\t}\n}\n","/**\n * @license Copyright (c) 2003-2018, CKSource - Frederico Knabben. All rights reserved.\n * For licensing, see LICENSE.md.\n */\n\n/**\n * @module engine/model/batch\n */\n\n/**\n * A batch instance groups model changes ({@link module:engine/model/operation/operation~Operation operations}). All operations\n * grouped in a single batch can be reverted together, so you can also think about a batch as of a single undo step. If you want\n * to extend a given undo step, you can add more changes to the batch using {@link module:engine/model/model~Model#enqueueChange}:\n *\n *\t\tmodel.enqueueChange( batch, writer => {\n *\t\t\twriter.insertText( 'foo', paragraph, 'end' );\n *\t\t} );\n *\n * @see module:engine/model/model~Model#enqueueChange\n * @see module:engine/model/model~Model#change\n */\nexport default class Batch {\n\t/**\n\t * Creates a batch instance.\n\t *\n\t * @see module:engine/model/model~Model#enqueueChange\n\t * @see module:engine/model/model~Model#change\n\t * @param {'transparent'|'default'} [type='default'] The type of the batch.\n\t */\n\tconstructor( type = 'default' ) {\n\t\t/**\n\t\t * An array of operations that compose this batch.\n\t\t *\n\t\t * @readonly\n\t\t * @type {Array.}\n\t\t */\n\t\tthis.operations = [];\n\n\t\t/**\n\t\t * The type of the batch.\n\t\t *\n\t\t * It can be one of the following values:\n\t\t * * `'default'` – All \"normal\" batches. This is the most commonly used type.\n\t\t * * `'transparent'` – A batch that should be ignored by other features, i.e. an initial batch or collaborative editing\n\t\t * changes.\n\t\t *\n\t\t * @readonly\n\t\t * @type {'transparent'|'default'}\n\t\t */\n\t\tthis.type = type;\n\t}\n\n\t/**\n\t * Returns the base version of this batch, which is equal to the base version of the first operation in the batch.\n\t * If there are no operations in the batch or neither operation has the base version set, it returns `null`.\n\t *\n\t * @readonly\n\t * @type {Number|null}\n\t */\n\tget baseVersion() {\n\t\tfor ( const op of this.operations ) {\n\t\t\tif ( op.baseVersion !== null ) {\n\t\t\t\treturn op.baseVersion;\n\t\t\t}\n\t\t}\n\n\t\treturn null;\n\t}\n\n\t/**\n\t * Adds an operation to the batch instance.\n\t *\n\t * @param {module:engine/model/operation/operation~Operation} operation An operation to add.\n\t * @returns {module:engine/model/operation/operation~Operation} The added operation.\n\t */\n\taddOperation( operation ) {\n\t\toperation.batch = this;\n\t\tthis.operations.push( operation );\n\n\t\treturn operation;\n\t}\n}\n","/**\n * @license Copyright (c) 2003-2018, CKSource - Frederico Knabben. All rights reserved.\n * For licensing, see LICENSE.md.\n */\n\n/**\n * @module engine/model/operation/operation\n */\n\n/**\n * Abstract base operation class.\n *\n * @abstract\n */\nexport default class Operation {\n\t/**\n\t * Base operation constructor.\n\t *\n\t * @param {Number|null} baseVersion Document {@link module:engine/model/document~Document#version} on which operation\n\t * can be applied or `null` if the operation operates on detached (non-document) tree.\n\t */\n\tconstructor( baseVersion ) {\n\t\t/**\n\t\t * {@link module:engine/model/document~Document#version} on which operation can be applied. If you try to\n\t\t * {@link module:engine/model/model~Model#applyOperation apply} operation with different base version than the\n\t\t * {@link module:engine/model/document~Document#version document version} the\n\t\t * {@link module:utils/ckeditorerror~CKEditorError model-document-applyOperation-wrong-version} error is thrown.\n\t\t *\n\t\t * @member {Number}\n\t\t */\n\t\tthis.baseVersion = baseVersion;\n\n\t\t/**\n\t\t * Defines whether operation is executed on attached or detached {@link module:engine/model/item~Item items}.\n\t\t *\n\t\t * @readonly\n\t\t * @member {Boolean} #isDocumentOperation\n\t\t */\n\t\tthis.isDocumentOperation = this.baseVersion !== null;\n\n\t\t/**\n\t\t * {@link module:engine/model/batch~Batch Batch} to which the operation is added or `null` if the operation is not\n\t\t * added to any batch yet.\n\t\t *\n\t\t * @member {module:engine/model/batch~Batch|null} #batch\n\t\t */\n\t\tthis.batch = null;\n\n\t\t/**\n\t\t * Operation type.\n\t\t *\n\t\t * @readonly\n\t\t * @member {String} #type\n\t\t */\n\n\t\t/**\n\t\t * Creates and returns an operation that has the same parameters as this operation.\n\t\t *\n\t\t * @method #clone\n\t\t * @returns {module:engine/model/operation/operation~Operation} Clone of this operation.\n\t\t */\n\n\t\t/**\n\t\t * Creates and returns a reverse operation. Reverse operation when executed right after\n\t\t * the original operation will bring back tree model state to the point before the original\n\t\t * operation execution. In other words, it reverses changes done by the original operation.\n\t\t *\n\t\t * Keep in mind that tree model state may change since executing the original operation,\n\t\t * so reverse operation will be \"outdated\". In that case you will need to transform it by\n\t\t * all operations that were executed after the original operation.\n\t\t *\n\t\t * @method #getReversed\n\t\t * @returns {module:engine/model/operation/operation~Operation} Reversed operation.\n\t\t */\n\n\t\t/**\n\t\t * Executes the operation - modifications described by the operation properties will be applied to the model tree.\n\t\t *\n\t\t * @protected\n\t\t * @method #_execute\n\t\t */\n\t}\n\n\t/**\n\t * Checks whether the operation's parameters are correct and the operation can be correctly executed. Throws\n\t * an error if operation is not valid.\n\t *\n\t * @protected\n\t * @method #_validate\n\t */\n\t_validate() {\n\t}\n\n\t/**\n\t * Custom toJSON method to solve child-parent circular dependencies.\n\t *\n\t * @method #toJSON\n\t * @returns {Object} Clone of this object with the operation property replaced with string.\n\t */\n\ttoJSON() {\n\t\t// This method creates only a shallow copy, all nested objects should be defined separately.\n\t\t// See https://github.com/ckeditor/ckeditor5-engine/issues/1477.\n\t\tconst json = Object.assign( {}, this );\n\n\t\tjson.__className = this.constructor.className;\n\n\t\t// Remove reference to the parent `Batch` to avoid circular dependencies.\n\t\tdelete json.batch;\n\n\t\t// Only document operations are shared with other clients so it is not necessary to keep this information.\n\t\tdelete json.isDocumentOperation;\n\n\t\treturn json;\n\t}\n\n\t/**\n\t * Name of the operation class used for serialization.\n\t *\n\t * @type {String}\n\t */\n\tstatic get className() {\n\t\treturn 'Operation';\n\t}\n\n\t/**\n\t * Creates Operation object from deserilized object, i.e. from parsed JSON string.\n\t *\n\t * @param {Object} json Deserialized JSON object.\n\t * @param {module:engine/model/document~Document} doc Document on which this operation will be applied.\n\t * @returns {module:engine/model/operation/operation~Operation}\n\t */\n\tstatic fromJSON( json ) {\n\t\treturn new this( json.baseVersion );\n\t}\n}\n","/**\n * @license Copyright (c) 2003-2018, CKSource - Frederico Knabben. All rights reserved.\n * For licensing, see LICENSE.md.\n */\n\n/**\n * @module module:engine/model/documentfragment\n */\n\nimport NodeList from './nodelist';\nimport Element from './element';\nimport Text from './text';\nimport TextProxy from './textproxy';\nimport isIterable from '@ckeditor/ckeditor5-utils/src/isiterable';\n\n/**\n * DocumentFragment represents a part of model which does not have a common root but it's top-level nodes\n * can be seen as siblings. In other words, it is a detached part of model tree, without a root.\n *\n * DocumentFragment has own {@link module:engine/model/markercollection~MarkerCollection}. Markers from this collection\n * will be set to the {@link module:engine/model/model~Model#markers model markers} by a\n * {@link module:engine/model/writer~Writer#insert} function.\n */\nexport default class DocumentFragment {\n\t/**\n\t * Creates an empty `DocumentFragment`.\n\t *\n\t * **Note:** Constructor of this class shouldn't be used directly in the code.\n\t * Use the {@link module:engine/model/writer~Writer#createDocumentFragment} method instead.\n\t *\n\t * @protected\n\t * @param {module:engine/model/node~Node|Iterable.} [children]\n\t * Nodes to be contained inside the `DocumentFragment`.\n\t */\n\tconstructor( children ) {\n\t\t/**\n\t\t * DocumentFragment static markers map. This is a list of names and {@link module:engine/model/range~Range ranges}\n\t\t * which will be set as Markers to {@link module:engine/model/model~Model#markers model markers collection}\n\t\t * when DocumentFragment will be inserted to the document.\n\t\t *\n\t\t * @readonly\n\t\t * @member {Map} module:engine/model/documentfragment~DocumentFragment#markers\n\t\t */\n\t\tthis.markers = new Map();\n\n\t\t/**\n\t\t * List of nodes contained inside the document fragment.\n\t\t *\n\t\t * @private\n\t\t * @member {module:engine/model/nodelist~NodeList} module:engine/model/documentfragment~DocumentFragment#_children\n\t\t */\n\t\tthis._children = new NodeList();\n\n\t\tif ( children ) {\n\t\t\tthis._insertChild( 0, children );\n\t\t}\n\t}\n\n\t/**\n\t * Returns an iterator that iterates over all nodes contained inside this document fragment.\n\t *\n\t * @returns {Iterable.}\n\t */\n\t[ Symbol.iterator ]() {\n\t\treturn this.getChildren();\n\t}\n\n\t/**\n\t * Number of this document fragment's children.\n\t *\n\t * @readonly\n\t * @type {Number}\n\t */\n\tget childCount() {\n\t\treturn this._children.length;\n\t}\n\n\t/**\n\t * Sum of {@link module:engine/model/node~Node#offsetSize offset sizes} of all of this document fragment's children.\n\t *\n\t * @readonly\n\t * @type {Number}\n\t */\n\tget maxOffset() {\n\t\treturn this._children.maxOffset;\n\t}\n\n\t/**\n\t * Is `true` if there are no nodes inside this document fragment, `false` otherwise.\n\t *\n\t * @readonly\n\t * @type {Boolean}\n\t */\n\tget isEmpty() {\n\t\treturn this.childCount === 0;\n\t}\n\n\t/**\n\t * Artificial root of `DocumentFragment`. Returns itself. Added for compatibility reasons.\n\t *\n\t * @readonly\n\t * @type {module:engine/model/documentfragment~DocumentFragment}\n\t */\n\tget root() {\n\t\treturn this;\n\t}\n\n\t/**\n\t * Artificial parent of `DocumentFragment`. Returns `null`. Added for compatibility reasons.\n\t *\n\t * @readonly\n\t * @type {null}\n\t */\n\tget parent() {\n\t\treturn null;\n\t}\n\n\t/**\n\t * Checks whether given model tree object is of given type.\n\t *\n\t * Read more in {@link module:engine/model/node~Node#is}.\n\t *\n\t * @param {String} type\n\t * @returns {Boolean}\n\t */\n\tis( type ) {\n\t\treturn type == 'documentFragment';\n\t}\n\n\t/**\n\t * Gets the child at the given index. Returns `null` if incorrect index was passed.\n\t *\n\t * @param {Number} index Index of child.\n\t * @returns {module:engine/model/node~Node|null} Child node.\n\t */\n\tgetChild( index ) {\n\t\treturn this._children.getNode( index );\n\t}\n\n\t/**\n\t * Returns an iterator that iterates over all of this document fragment's children.\n\t *\n\t * @returns {Iterable.}\n\t */\n\tgetChildren() {\n\t\treturn this._children[ Symbol.iterator ]();\n\t}\n\n\t/**\n\t * Returns an index of the given child node. Returns `null` if given node is not a child of this document fragment.\n\t *\n\t * @param {module:engine/model/node~Node} node Child node to look for.\n\t * @returns {Number|null} Child node's index.\n\t */\n\tgetChildIndex( node ) {\n\t\treturn this._children.getNodeIndex( node );\n\t}\n\n\t/**\n\t * Returns the starting offset of given child. Starting offset is equal to the sum of\n\t * {@link module:engine/model/node~Node#offsetSize offset sizes} of all node's siblings that are before it. Returns `null` if\n\t * given node is not a child of this document fragment.\n\t *\n\t * @param {module:engine/model/node~Node} node Child node to look for.\n\t * @returns {Number|null} Child node's starting offset.\n\t */\n\tgetChildStartOffset( node ) {\n\t\treturn this._children.getNodeStartOffset( node );\n\t}\n\n\t/**\n\t * Returns path to a `DocumentFragment`, which is an empty array. Added for compatibility reasons.\n\t *\n\t * @returns {Array}\n\t */\n\tgetPath() {\n\t\treturn [];\n\t}\n\n\t/**\n\t * Returns a descendant node by its path relative to this element.\n\t *\n\t *\t\t// ac\n\t *\t\tthis.getNodeByPath( [ 0 ] ); // -> \"a\"\n\t *\t\tthis.getNodeByPath( [ 1 ] ); // -> \n\t *\t\tthis.getNodeByPath( [ 1, 0 ] ); // -> \"c\"\n\t *\n\t * @param {Array.} relativePath Path of the node to find, relative to this element.\n\t * @returns {module:engine/model/node~Node|module:engine/model/documentfragment~DocumentFragment}\n\t */\n\tgetNodeByPath( relativePath ) {\n\t\tlet node = this; // eslint-disable-line consistent-this\n\n\t\tfor ( const index of relativePath ) {\n\t\t\tnode = node.getChild( node.offsetToIndex( index ) );\n\t\t}\n\n\t\treturn node;\n\t}\n\n\t/**\n\t * Converts offset \"position\" to index \"position\".\n\t *\n\t * Returns index of a node that occupies given offset. If given offset is too low, returns `0`. If given offset is\n\t * too high, returns index after last child}.\n\t *\n\t *\t\tconst textNode = new Text( 'foo' );\n\t *\t\tconst pElement = new Element( 'p' );\n\t *\t\tconst docFrag = new DocumentFragment( [ textNode, pElement ] );\n\t *\t\tdocFrag.offsetToIndex( -1 ); // Returns 0, because offset is too low.\n\t *\t\tdocFrag.offsetToIndex( 0 ); // Returns 0, because offset 0 is taken by `textNode` which is at index 0.\n\t *\t\tdocFrag.offsetToIndex( 1 ); // Returns 0, because `textNode` has `offsetSize` equal to 3, so it occupies offset 1 too.\n\t *\t\tdocFrag.offsetToIndex( 2 ); // Returns 0.\n\t *\t\tdocFrag.offsetToIndex( 3 ); // Returns 1.\n\t *\t\tdocFrag.offsetToIndex( 4 ); // Returns 2. There are no nodes at offset 4, so last available index is returned.\n\t *\n\t * @param {Number} offset Offset to look for.\n\t * @returns {Number} Index of a node that occupies given offset.\n\t */\n\toffsetToIndex( offset ) {\n\t\treturn this._children.offsetToIndex( offset );\n\t}\n\n\t/**\n\t * Converts `DocumentFragment` instance to plain object and returns it.\n\t * Takes care of converting all of this document fragment's children.\n\t *\n\t * @returns {Object} `DocumentFragment` instance converted to plain object.\n\t */\n\ttoJSON() {\n\t\tconst json = [];\n\n\t\tfor ( const node of this._children ) {\n\t\t\tjson.push( node.toJSON() );\n\t\t}\n\n\t\treturn json;\n\t}\n\n\t/**\n\t * Creates a `DocumentFragment` instance from given plain object (i.e. parsed JSON string).\n\t * Converts `DocumentFragment` children to proper nodes.\n\t *\n\t * @param {Object} json Plain object to be converted to `DocumentFragment`.\n\t * @returns {module:engine/model/documentfragment~DocumentFragment} `DocumentFragment` instance created using given plain object.\n\t */\n\tstatic fromJSON( json ) {\n\t\tconst children = [];\n\n\t\tfor ( const child of json ) {\n\t\t\tif ( child.name ) {\n\t\t\t\t// If child has name property, it is an Element.\n\t\t\t\tchildren.push( Element.fromJSON( child ) );\n\t\t\t} else {\n\t\t\t\t// Otherwise, it is a Text node.\n\t\t\t\tchildren.push( Text.fromJSON( child ) );\n\t\t\t}\n\t\t}\n\n\t\treturn new DocumentFragment( children );\n\t}\n\n\t/**\n\t * {@link #_insertChild Inserts} one or more nodes at the end of this document fragment.\n\t *\n\t * @protected\n\t * @param {module:engine/model/item~Item|Iterable.} items Items to be inserted.\n\t */\n\t_appendChild( items ) {\n\t\tthis._insertChild( this.childCount, items );\n\t}\n\n\t/**\n\t * Inserts one or more nodes at the given index and sets {@link module:engine/model/node~Node#parent parent} of these nodes\n\t * to this document fragment.\n\t *\n\t * @protected\n\t * @param {Number} index Index at which nodes should be inserted.\n\t * @param {module:engine/model/item~Item|Iterable.} items Items to be inserted.\n\t */\n\t_insertChild( index, items ) {\n\t\tconst nodes = normalize( items );\n\n\t\tfor ( const node of nodes ) {\n\t\t\t// If node that is being added to this element is already inside another element, first remove it from the old parent.\n\t\t\tif ( node.parent !== null ) {\n\t\t\t\tnode._remove();\n\t\t\t}\n\n\t\t\tnode.parent = this;\n\t\t}\n\n\t\tthis._children._insertNodes( index, nodes );\n\t}\n\n\t/**\n\t * Removes one or more nodes starting at the given index\n\t * and sets {@link module:engine/model/node~Node#parent parent} of these nodes to `null`.\n\t *\n\t * @protected\n\t * @param {Number} index Index of the first node to remove.\n\t * @param {Number} [howMany=1] Number of nodes to remove.\n\t * @returns {Array.} Array containing removed nodes.\n\t */\n\t_removeChildren( index, howMany = 1 ) {\n\t\tconst nodes = this._children._removeNodes( index, howMany );\n\n\t\tfor ( const node of nodes ) {\n\t\t\tnode.parent = null;\n\t\t}\n\n\t\treturn nodes;\n\t}\n}\n\n// Converts strings to Text and non-iterables to arrays.\n//\n// @param {String|module:engine/model/item~Item|Iterable.}\n// @returns {Iterable.}\nfunction normalize( nodes ) {\n\t// Separate condition because string is iterable.\n\tif ( typeof nodes == 'string' ) {\n\t\treturn [ new Text( nodes ) ];\n\t}\n\n\tif ( !isIterable( nodes ) ) {\n\t\tnodes = [ nodes ];\n\t}\n\n\t// Array.from to enable .map() on non-arrays.\n\treturn Array.from( nodes )\n\t\t.map( node => {\n\t\t\tif ( typeof node == 'string' ) {\n\t\t\t\treturn new Text( node );\n\t\t\t}\n\n\t\t\tif ( node instanceof TextProxy ) {\n\t\t\t\treturn new Text( node.data, node.getAttributes() );\n\t\t\t}\n\n\t\t\treturn node;\n\t\t} );\n}\n","/**\n * @license Copyright (c) 2003-2018, CKSource - Frederico Knabben. All rights reserved.\n * For licensing, see LICENSE.md.\n */\n\n/**\n * @module engine/model/operation/utils\n */\n\nimport Node from '../node';\nimport Text from '../text';\nimport TextProxy from '../textproxy';\nimport Range from '../range';\nimport DocumentFragment from '../documentfragment';\nimport NodeList from '../nodelist';\nimport CKEditorError from '@ckeditor/ckeditor5-utils/src/ckeditorerror';\n\n/**\n * Contains functions used for composing model tree by {@link module:engine/model/operation/operation~Operation operations}.\n * Those functions are built on top of {@link module:engine/model/node~Node node}, and it's child classes', APIs.\n *\n * @protected\n * @namespace utils\n */\n\n/**\n * Inserts given nodes at given position.\n *\n * @protected\n * @function module:engine/model/operation/utils~utils.insert\n * @param {module:engine/model/position~Position} position Position at which nodes should be inserted.\n * @param {module:engine/model/node~NodeSet} nodes Nodes to insert.\n * @returns {module:engine/model/range~Range} Range spanning over inserted elements.\n */\nexport function _insert( position, nodes ) {\n\tnodes = _normalizeNodes( nodes );\n\n\t// We have to count offset before inserting nodes because they can get merged and we would get wrong offsets.\n\tconst offset = nodes.reduce( ( sum, node ) => sum + node.offsetSize, 0 );\n\tconst parent = position.parent;\n\n\t// Insertion might be in a text node, we should split it if that's the case.\n\t_splitNodeAtPosition( position );\n\tconst index = position.index;\n\n\t// Insert nodes at given index. After splitting we have a proper index and insertion is between nodes,\n\t// using basic `Element` API.\n\tparent._insertChild( index, nodes );\n\n\t// Merge text nodes, if possible. Merging is needed only at points where inserted nodes \"touch\" \"old\" nodes.\n\t_mergeNodesAtIndex( parent, index + nodes.length );\n\t_mergeNodesAtIndex( parent, index );\n\n\treturn new Range( position, position.getShiftedBy( offset ) );\n}\n\n/**\n * Removed nodes in given range. Only {@link module:engine/model/range~Range#isFlat flat} ranges are accepted.\n *\n * @protected\n * @function module:engine/model/operation/utils~utils._remove\n * @param {module:engine/model/range~Range} range Range containing nodes to remove.\n * @returns {Array.}\n */\nexport function _remove( range ) {\n\tif ( !range.isFlat ) {\n\t\t/**\n\t\t * Trying to remove a range which starts and ends in different element.\n\t\t *\n\t\t * @error operation-utils-remove-range-not-flat\n\t\t */\n\t\tthrow new CKEditorError( 'operation-utils-remove-range-not-flat: ' +\n\t\t\t'Trying to remove a range which starts and ends in different element.' );\n\t}\n\n\tconst parent = range.start.parent;\n\n\t// Range may be inside text nodes, we have to split them if that's the case.\n\t_splitNodeAtPosition( range.start );\n\t_splitNodeAtPosition( range.end );\n\n\t// Remove the text nodes using basic `Element` API.\n\tconst removed = parent._removeChildren( range.start.index, range.end.index - range.start.index );\n\n\t// Merge text nodes, if possible. After some nodes were removed, node before and after removed range will be\n\t// touching at the position equal to the removed range beginning. We check merging possibility there.\n\t_mergeNodesAtIndex( parent, range.start.index );\n\n\treturn removed;\n}\n\n/**\n * Moves nodes in given range to given target position. Only {@link module:engine/model/range~Range#isFlat flat} ranges are accepted.\n *\n * @protected\n * @function module:engine/model/operation/utils~utils.move\n * @param {module:engine/model/range~Range} sourceRange Range containing nodes to move.\n * @param {module:engine/model/position~Position} targetPosition Position to which nodes should be moved.\n * @returns {module:engine/model/range~Range} Range containing moved nodes.\n */\nexport function _move( sourceRange, targetPosition ) {\n\tif ( !sourceRange.isFlat ) {\n\t\t/**\n\t\t * Trying to move a range which starts and ends in different element.\n\t\t *\n\t\t * @error operation-utils-move-range-not-flat\n\t\t */\n\t\tthrow new CKEditorError( 'operation-utils-move-range-not-flat: ' +\n\t\t\t'Trying to move a range which starts and ends in different element.' );\n\t}\n\n\tconst nodes = _remove( sourceRange );\n\n\t// We have to fix `targetPosition` because model changed after nodes from `sourceRange` got removed and\n\t// that change might have an impact on `targetPosition`.\n\ttargetPosition = targetPosition._getTransformedByDeletion( sourceRange.start, sourceRange.end.offset - sourceRange.start.offset );\n\n\treturn _insert( targetPosition, nodes );\n}\n\n/**\n * Sets given attribute on nodes in given range. The attributes are only set on top-level nodes of the range, not on its children.\n *\n * @protected\n * @function module:engine/model/operation/utils~utils._setAttribute\n * @param {module:engine/model/range~Range} range Range containing nodes that should have the attribute set. Must be a flat range.\n * @param {String} key Key of attribute to set.\n * @param {*} value Attribute value.\n */\nexport function _setAttribute( range, key, value ) {\n\t// Range might start or end in text nodes, so we have to split them.\n\t_splitNodeAtPosition( range.start );\n\t_splitNodeAtPosition( range.end );\n\n\t// Iterate over all items in the range.\n\tfor ( const item of range.getItems( { shallow: true } ) ) {\n\t\t// Iterator will return `TextProxy` instances but we know that those text proxies will\n\t\t// always represent full text nodes (this is guaranteed thanks to splitting we did before).\n\t\t// So, we can operate on those text proxies' text nodes.\n\t\tconst node = item.is( 'textProxy' ) ? item.textNode : item;\n\n\t\tif ( value !== null ) {\n\t\t\tnode._setAttribute( key, value );\n\t\t} else {\n\t\t\tnode._removeAttribute( key );\n\t\t}\n\n\t\t// After attributes changing it may happen that some text nodes can be merged. Try to merge with previous node.\n\t\t_mergeNodesAtIndex( node.parent, node.index );\n\t}\n\n\t// Try to merge last changed node with it's previous sibling (not covered by the loop above).\n\t_mergeNodesAtIndex( range.end.parent, range.end.index );\n}\n\n/**\n * Normalizes given object or an array of objects to an array of {@link module:engine/model/node~Node nodes}. See\n * {@link module:engine/model/node~NodeSet NodeSet} for details on how normalization is performed.\n *\n * @protected\n * @function module:engine/model/operation/utils~utils.normalizeNodes\n * @param {module:engine/model/node~NodeSet} nodes Objects to normalize.\n * @returns {Array.} Normalized nodes.\n */\nexport function _normalizeNodes( nodes ) {\n\tconst normalized = [];\n\n\tif ( !( nodes instanceof Array ) ) {\n\t\tnodes = [ nodes ];\n\t}\n\n\t// Convert instances of classes other than Node.\n\tfor ( let i = 0; i < nodes.length; i++ ) {\n\t\tif ( typeof nodes[ i ] == 'string' ) {\n\t\t\tnormalized.push( new Text( nodes[ i ] ) );\n\t\t} else if ( nodes[ i ] instanceof TextProxy ) {\n\t\t\tnormalized.push( new Text( nodes[ i ].data, nodes[ i ].getAttributes() ) );\n\t\t} else if ( nodes[ i ] instanceof DocumentFragment || nodes[ i ] instanceof NodeList ) {\n\t\t\tfor ( const child of nodes[ i ] ) {\n\t\t\t\tnormalized.push( child );\n\t\t\t}\n\t\t} else if ( nodes[ i ] instanceof Node ) {\n\t\t\tnormalized.push( nodes[ i ] );\n\t\t}\n\t\t// Skip unrecognized type.\n\t}\n\n\t// Merge text nodes.\n\tfor ( let i = 1; i < normalized.length; i++ ) {\n\t\tconst node = normalized[ i ];\n\t\tconst prev = normalized[ i - 1 ];\n\n\t\tif ( node instanceof Text && prev instanceof Text && _haveSameAttributes( node, prev ) ) {\n\t\t\t// Doing this instead changing `prev.data` because `data` is readonly.\n\t\t\tnormalized.splice( i - 1, 2, new Text( prev.data + node.data, prev.getAttributes() ) );\n\t\t\ti--;\n\t\t}\n\t}\n\n\treturn normalized;\n}\n\n// Checks if nodes before and after given index in given element are {@link module:engine/model/text~Text text nodes} and\n// merges them into one node if they have same attributes.\n//\n// Merging is done by removing two text nodes and inserting a new text node containing data from both merged text nodes.\n//\n// @private\n// @param {module:engine/model/element~Element} element Parent element of nodes to merge.\n// @param {Number} index Index between nodes to merge.\nfunction _mergeNodesAtIndex( element, index ) {\n\tconst nodeBefore = element.getChild( index - 1 );\n\tconst nodeAfter = element.getChild( index );\n\n\t// Check if both of those nodes are text objects with same attributes.\n\tif ( nodeBefore && nodeAfter && nodeBefore.is( 'text' ) && nodeAfter.is( 'text' ) && _haveSameAttributes( nodeBefore, nodeAfter ) ) {\n\t\t// Append text of text node after index to the before one.\n\t\tconst mergedNode = new Text( nodeBefore.data + nodeAfter.data, nodeBefore.getAttributes() );\n\n\t\t// Remove separate text nodes.\n\t\telement._removeChildren( index - 1, 2 );\n\n\t\t// Insert merged text node.\n\t\telement._insertChild( index - 1, mergedNode );\n\t}\n}\n\n// Checks if given position is in a text node, and if so, splits the text node in two text nodes, each of them\n// containing a part of original text node.\n//\n// @private\n// @param {module:engine/model/position~Position} position Position at which node should be split.\nfunction _splitNodeAtPosition( position ) {\n\tconst textNode = position.textNode;\n\tconst element = position.parent;\n\n\tif ( textNode ) {\n\t\tconst offsetDiff = position.offset - textNode.startOffset;\n\t\tconst index = textNode.index;\n\n\t\telement._removeChildren( index, 1 );\n\n\t\tconst firstPart = new Text( textNode.data.substr( 0, offsetDiff ), textNode.getAttributes() );\n\t\tconst secondPart = new Text( textNode.data.substr( offsetDiff ), textNode.getAttributes() );\n\n\t\telement._insertChild( index, [ firstPart, secondPart ] );\n\t}\n}\n\n// Checks whether two given nodes have same attributes.\n//\n// @private\n// @param {module:engine/model/node~Node} nodeA Node to check.\n// @param {module:engine/model/node~Node} nodeB Node to check.\n// @returns {Boolean} `true` if nodes have same attributes, `false` otherwise.\nfunction _haveSameAttributes( nodeA, nodeB ) {\n\tconst iteratorA = nodeA.getAttributes();\n\tconst iteratorB = nodeB.getAttributes();\n\n\tfor ( const attr of iteratorA ) {\n\t\tif ( attr[ 1 ] !== nodeB.getAttribute( attr[ 0 ] ) ) {\n\t\t\treturn false;\n\t\t}\n\n\t\titeratorB.next();\n\t}\n\n\treturn iteratorB.next().done;\n}\n\n/**\n * Value that can be normalized to an array of {@link module:engine/model/node~Node nodes}.\n *\n * Non-arrays are normalized as follows:\n * * {@link module:engine/model/node~Node Node} is left as is,\n * * {@link module:engine/model/textproxy~TextProxy TextProxy} and `String` are normalized to {@link module:engine/model/text~Text Text},\n * * {@link module:engine/model/nodelist~NodeList NodeList} is normalized to an array containing all nodes that are in that node list,\n * * {@link module:engine/model/documentfragment~DocumentFragment DocumentFragment} is normalized to an array containing all of it's\n * * children.\n *\n * Arrays are processed item by item like non-array values and flattened to one array. Normalization always results in\n * a flat array of {@link module:engine/model/node~Node nodes}. Consecutive text nodes (or items normalized to text nodes) will be\n * merged if they have same attributes.\n *\n * @typedef {module:engine/model/node~Node|module:engine/model/textproxy~TextProxy|String|\n * module:engine/model/nodelist~NodeList|module:engine/model/documentfragment~DocumentFragment|Iterable}\n * module:engine/model/node~NodeSet\n */\n","import baseIsEqual from './_baseIsEqual.js';\n\n/**\n * Performs a deep comparison between two values to determine if they are\n * equivalent.\n *\n * **Note:** This method supports comparing arrays, array buffers, booleans,\n * date objects, error objects, maps, numbers, `Object` objects, regexes,\n * sets, strings, symbols, and typed arrays. `Object` objects are compared\n * by their own, not inherited, enumerable properties. Functions and DOM\n * nodes are compared by strict equality, i.e. `===`.\n *\n * @static\n * @memberOf _\n * @since 0.1.0\n * @category Lang\n * @param {*} value The value to compare.\n * @param {*} other The other value to compare.\n * @returns {boolean} Returns `true` if the values are equivalent, else `false`.\n * @example\n *\n * var object = { 'a': 1 };\n * var other = { 'a': 1 };\n *\n * _.isEqual(object, other);\n * // => true\n *\n * object === other;\n * // => false\n */\nfunction isEqual(value, other) {\n return baseIsEqual(value, other);\n}\n\nexport default isEqual;\n","/**\n * @license Copyright (c) 2003-2018, CKSource - Frederico Knabben. All rights reserved.\n * For licensing, see LICENSE.md.\n */\n\n/**\n * @module engine/model/operation/attributeoperation\n */\n\nimport Operation from './operation';\nimport Range from '../range';\nimport CKEditorError from '@ckeditor/ckeditor5-utils/src/ckeditorerror';\nimport { _setAttribute } from './utils';\nimport { isEqual } from 'lodash-es';\n\n/**\n * Operation to change nodes' attribute.\n *\n * Using this class you can add, remove or change value of the attribute.\n *\n * @extends module:engine/model/operation/operation~Operation\n */\nexport default class AttributeOperation extends Operation {\n\t/**\n\t * Creates an operation that changes, removes or adds attributes.\n\t *\n\t * If only `newValue` is set, attribute will be added on a node. Note that all nodes in operation's range must not\n\t * have an attribute with the same key as the added attribute.\n\t *\n\t * If only `oldValue` is set, then attribute with given key will be removed. Note that all nodes in operation's range\n\t * must have an attribute with that key added.\n\t *\n\t * If both `newValue` and `oldValue` are set, then the operation will change the attribute value. Note that all nodes in\n\t * operation's ranges must already have an attribute with given key and `oldValue` as value\n\t *\n\t * @param {module:engine/model/range~Range} range Range on which the operation should be applied. Must be a flat range.\n\t * @param {String} key Key of an attribute to change or remove.\n\t * @param {*} oldValue Old value of the attribute with given key or `null`, if attribute was not set before.\n\t * @param {*} newValue New value of the attribute with given key or `null`, if operation should remove attribute.\n\t * @param {Number|null} baseVersion Document {@link module:engine/model/document~Document#version} on which operation\n\t * can be applied or `null` if the operation operates on detached (non-document) tree.\n\t */\n\tconstructor( range, key, oldValue, newValue, baseVersion ) {\n\t\tsuper( baseVersion );\n\n\t\t/**\n\t\t * Range on which operation should be applied.\n\t\t *\n\t\t * @readonly\n\t\t * @member {module:engine/model/range~Range}\n\t\t */\n\t\tthis.range = Range.createFromRange( range );\n\n\t\t/**\n\t\t * Key of an attribute to change or remove.\n\t\t *\n\t\t * @readonly\n\t\t * @member {String}\n\t\t */\n\t\tthis.key = key;\n\n\t\t/**\n\t\t * Old value of the attribute with given key or `null`, if attribute was not set before.\n\t\t *\n\t\t * @readonly\n\t\t * @member {*}\n\t\t */\n\t\tthis.oldValue = oldValue === undefined ? null : oldValue;\n\n\t\t/**\n\t\t * New value of the attribute with given key or `null`, if operation should remove attribute.\n\t\t *\n\t\t * @readonly\n\t\t * @member {*}\n\t\t */\n\t\tthis.newValue = newValue === undefined ? null : newValue;\n\t}\n\n\t/**\n\t * @inheritDoc\n\t */\n\tget type() {\n\t\tif ( this.oldValue === null ) {\n\t\t\treturn 'addAttribute';\n\t\t} else if ( this.newValue === null ) {\n\t\t\treturn 'removeAttribute';\n\t\t} else {\n\t\t\treturn 'changeAttribute';\n\t\t}\n\t}\n\n\t/**\n\t * Creates and returns an operation that has the same parameters as this operation.\n\t *\n\t * @returns {module:engine/model/operation/attributeoperation~AttributeOperation} Clone of this operation.\n\t */\n\tclone() {\n\t\treturn new AttributeOperation( this.range, this.key, this.oldValue, this.newValue, this.baseVersion );\n\t}\n\n\t/**\n\t * See {@link module:engine/model/operation/operation~Operation#getReversed `Operation#getReversed()`}.\n\t *\n\t * @returns {module:engine/model/operation/attributeoperation~AttributeOperation}\n\t */\n\tgetReversed() {\n\t\treturn new AttributeOperation( this.range, this.key, this.newValue, this.oldValue, this.baseVersion + 1 );\n\t}\n\n\t/**\n\t * @inheritDoc\n\t */\n\ttoJSON() {\n\t\tconst json = super.toJSON();\n\n\t\tjson.range = this.range.toJSON();\n\n\t\treturn json;\n\t}\n\n\t/**\n\t * @inheritDoc\n\t */\n\t_validate() {\n\t\tif ( !this.range.isFlat ) {\n\t\t\t/**\n\t\t\t * The range to change is not flat.\n\t\t\t *\n\t\t\t * @error attribute-operation-range-not-flat\n\t\t\t */\n\t\t\tthrow new CKEditorError( 'attribute-operation-range-not-flat: The range to change is not flat.' );\n\t\t}\n\n\t\tfor ( const item of this.range.getItems( { shallow: true } ) ) {\n\t\t\tif ( this.oldValue !== null && !isEqual( item.getAttribute( this.key ), this.oldValue ) ) {\n\t\t\t\t/**\n\t\t\t\t * Changed node has different attribute value than operation's old attribute value.\n\t\t\t\t *\n\t\t\t\t * @error attribute-operation-wrong-old-value\n\t\t\t\t * @param {module:engine/model/item~Item} item\n\t\t\t\t * @param {String} key\n\t\t\t\t * @param {*} value\n\t\t\t\t */\n\t\t\t\tthrow new CKEditorError(\n\t\t\t\t\t'attribute-operation-wrong-old-value: Changed node has different attribute value than operation\\'s ' +\n\t\t\t\t\t'old attribute value.',\n\t\t\t\t\t{ item, key: this.key, value: this.oldValue }\n\t\t\t\t);\n\t\t\t}\n\n\t\t\tif ( this.oldValue === null && this.newValue !== null && item.hasAttribute( this.key ) ) {\n\t\t\t\t/**\n\t\t\t\t * The attribute with given key already exists for the given node.\n\t\t\t\t *\n\t\t\t\t * @error attribute-operation-attribute-exists\n\t\t\t\t * @param {module:engine/model/node~Node} node\n\t\t\t\t * @param {String} key\n\t\t\t\t */\n\t\t\t\tthrow new CKEditorError(\n\t\t\t\t\t'attribute-operation-attribute-exists: The attribute with given key already exists.',\n\t\t\t\t\t{ node: item, key: this.key }\n\t\t\t\t);\n\t\t\t}\n\t\t}\n\t}\n\n\t/**\n\t * @inheritDoc\n\t */\n\t_execute() {\n\t\t// If value to set is same as old value, don't do anything.\n\t\tif ( !isEqual( this.oldValue, this.newValue ) ) {\n\t\t\t// Execution.\n\t\t\t_setAttribute( this.range, this.key, this.newValue );\n\t\t}\n\t}\n\n\t/**\n\t * @inheritDoc\n\t */\n\tstatic get className() {\n\t\treturn 'AttributeOperation';\n\t}\n\n\t/**\n\t * Creates `AttributeOperation` object from deserilized object, i.e. from parsed JSON string.\n\t *\n\t * @param {Object} json Deserialized JSON object.\n\t * @param {module:engine/model/document~Document} document Document on which this operation will be applied.\n\t * @returns {module:engine/model/operation/attributeoperation~AttributeOperation}\n\t */\n\tstatic fromJSON( json, document ) {\n\t\treturn new AttributeOperation( Range.fromJSON( json.range, document ), json.key, json.oldValue, json.newValue, json.baseVersion );\n\t}\n}\n","/**\n * @license Copyright (c) 2003-2018, CKSource - Frederico Knabben. All rights reserved.\n * For licensing, see LICENSE.md.\n */\n\n/**\n * @module engine/model/operation/detachoperation\n */\n\nimport Operation from './operation';\nimport Position from '../position';\nimport Range from '../range';\nimport { _remove } from './utils';\nimport CKEditorError from '@ckeditor/ckeditor5-utils/src/ckeditorerror';\n\n/**\n * Operation to permanently remove node from detached root.\n * Note this operation is only a local operation and won't be send to the other clients.\n *\n * @extends module:engine/model/operation/operation~Operation\n */\nexport default class DetachOperation extends Operation {\n\t/**\n\t * Creates an insert operation.\n\t *\n\t * @param {module:engine/model/position~Position} sourcePosition\n\t * Position before the first {@link module:engine/model/item~Item model item} to move.\n\t * @param {Number} howMany Offset size of moved range. Moved range will start from `sourcePosition` and end at\n\t * `sourcePosition` with offset shifted by `howMany`.\n\t */\n\tconstructor( sourcePosition, howMany ) {\n\t\tsuper( null );\n\n\t\t/**\n\t\t * Position before the first {@link module:engine/model/item~Item model item} to detach.\n\t\t *\n\t\t * @member {module:engine/model/position~Position} #sourcePosition\n\t\t */\n\t\tthis.sourcePosition = Position.createFromPosition( sourcePosition );\n\n\t\t/**\n\t\t * Offset size of moved range.\n\t\t *\n\t\t * @member {Number} #howMany\n\t\t */\n\t\tthis.howMany = howMany;\n\t}\n\n\t/**\n\t * @inheritDoc\n\t */\n\tget type() {\n\t\treturn 'detach';\n\t}\n\n\t/**\n\t * @inheritDoc\n\t */\n\ttoJSON() {\n\t\tconst json = super.toJSON();\n\n\t\tjson.sourcePosition = this.sourcePosition.toJSON();\n\n\t\treturn json;\n\t}\n\n\t/**\n\t * @inheritDoc\n\t */\n\t_validate() {\n\t\tif ( this.sourcePosition.root.document ) {\n\t\t\t/**\n\t\t\t * Cannot detach document node.\n\t\t\t *\n\t\t\t * @error detach-operation-on-document-node\n\t\t\t */\n\t\t\tthrow new CKEditorError( 'detach-operation-on-document-node: Cannot detach document node.' );\n\t\t}\n\t}\n\n\t/**\n\t * @inheritDoc\n\t */\n\t_execute() {\n\t\t_remove( Range.createFromPositionAndShift( this.sourcePosition, this.howMany ) );\n\t}\n\n\t/**\n\t * @inheritDoc\n\t */\n\tstatic get className() {\n\t\treturn 'DetachOperation';\n\t}\n}\n","/**\n * @license Copyright (c) 2003-2018, CKSource - Frederico Knabben. All rights reserved.\n * For licensing, see LICENSE.md.\n */\n\n/**\n * @module engine/model/operation/moveoperation\n */\n\nimport Operation from './operation';\nimport Position from '../position';\nimport Range from '../range';\nimport CKEditorError from '@ckeditor/ckeditor5-utils/src/ckeditorerror';\nimport compareArrays from '@ckeditor/ckeditor5-utils/src/comparearrays';\nimport { _move } from './utils';\n\n/**\n * Operation to move a range of {@link module:engine/model/item~Item model items}\n * to given {@link module:engine/model/position~Position target position}.\n *\n * @extends module:engine/model/operation/operation~Operation\n */\nexport default class MoveOperation extends Operation {\n\t/**\n\t * Creates a move operation.\n\t *\n\t * @param {module:engine/model/position~Position} sourcePosition\n\t * Position before the first {@link module:engine/model/item~Item model item} to move.\n\t * @param {Number} howMany Offset size of moved range. Moved range will start from `sourcePosition` and end at\n\t * `sourcePosition` with offset shifted by `howMany`.\n\t * @param {module:engine/model/position~Position} targetPosition Position at which moved nodes will be inserted.\n\t * @param {Number|null} baseVersion Document {@link module:engine/model/document~Document#version} on which operation\n\t * can be applied or `null` if the operation operates on detached (non-document) tree.\n\t */\n\tconstructor( sourcePosition, howMany, targetPosition, baseVersion ) {\n\t\tsuper( baseVersion );\n\n\t\t/**\n\t\t * Position before the first {@link module:engine/model/item~Item model item} to move.\n\t\t *\n\t\t * @member {module:engine/model/position~Position} module:engine/model/operation/moveoperation~MoveOperation#sourcePosition\n\t\t */\n\t\tthis.sourcePosition = Position.createFromPosition( sourcePosition );\n\t\t// `'toNext'` because `sourcePosition` is a bit like a start of the moved range.\n\t\tthis.sourcePosition.stickiness = 'toNext';\n\n\t\t/**\n\t\t * Offset size of moved range.\n\t\t *\n\t\t * @member {Number} module:engine/model/operation/moveoperation~MoveOperation#howMany\n\t\t */\n\t\tthis.howMany = howMany;\n\n\t\t/**\n\t\t * Position at which moved nodes will be inserted.\n\t\t *\n\t\t * @member {module:engine/model/position~Position} module:engine/model/operation/moveoperation~MoveOperation#targetPosition\n\t\t */\n\t\tthis.targetPosition = Position.createFromPosition( targetPosition );\n\t\tthis.targetPosition.stickiness = 'toNone';\n\t}\n\n\t/**\n\t * @inheritDoc\n\t */\n\tget type() {\n\t\tif ( this.targetPosition.root.rootName == '$graveyard' ) {\n\t\t\treturn 'remove';\n\t\t} else if ( this.sourcePosition.root.rootName == '$graveyard' ) {\n\t\t\treturn 'reinsert';\n\t\t}\n\n\t\treturn 'move';\n\t}\n\n\t/**\n\t * Creates and returns an operation that has the same parameters as this operation.\n\t *\n\t * @returns {module:engine/model/operation/moveoperation~MoveOperation} Clone of this operation.\n\t */\n\tclone() {\n\t\treturn new this.constructor( this.sourcePosition, this.howMany, this.targetPosition, this.baseVersion );\n\t}\n\n\t/**\n\t * Returns the start position of the moved range after it got moved. This may be different than\n\t * {@link module:engine/model/operation/moveoperation~MoveOperation#targetPosition} in some cases, i.e. when a range is moved\n\t * inside the same parent but {@link module:engine/model/operation/moveoperation~MoveOperation#targetPosition targetPosition}\n\t * is after {@link module:engine/model/operation/moveoperation~MoveOperation#sourcePosition sourcePosition}.\n\t *\n\t *\t\t vv vv\n\t *\t\tabcdefg ===> adefbcg\n\t *\t\t ^ ^\n\t *\t\t targetPos\tmovedRangeStart\n\t *\t\t offset 6\toffset 4\n\t *\n\t * @returns {module:engine/model/position~Position}\n\t */\n\tgetMovedRangeStart() {\n\t\treturn this.targetPosition._getTransformedByDeletion( this.sourcePosition, this.howMany );\n\t}\n\n\t/**\n\t * See {@link module:engine/model/operation/operation~Operation#getReversed `Operation#getReversed()`}.\n\t *\n\t * @returns {module:engine/model/operation/moveoperation~MoveOperation}\n\t */\n\tgetReversed() {\n\t\tconst newTargetPosition = this.sourcePosition._getTransformedByInsertion( this.targetPosition, this.howMany );\n\n\t\treturn new this.constructor( this.getMovedRangeStart(), this.howMany, newTargetPosition, this.baseVersion + 1 );\n\t}\n\n\t/**\n\t * @inheritDoc\n\t */\n\t_validate() {\n\t\tconst sourceElement = this.sourcePosition.parent;\n\t\tconst targetElement = this.targetPosition.parent;\n\t\tconst sourceOffset = this.sourcePosition.offset;\n\t\tconst targetOffset = this.targetPosition.offset;\n\n\t\t// Validate whether move operation has correct parameters.\n\t\t// Validation is pretty complex but move operation is one of the core ways to manipulate the document state.\n\t\t// We expect that many errors might be connected with one of scenarios described below.\n\t\tif ( !sourceElement || !targetElement ) {\n\t\t\t/**\n\t\t\t * Source position or target position is invalid.\n\t\t\t *\n\t\t\t * @error move-operation-position-invalid\n\t\t\t */\n\t\t\tthrow new CKEditorError(\n\t\t\t\t'move-operation-position-invalid: Source position or target position is invalid.'\n\t\t\t);\n\t\t} else if ( sourceOffset + this.howMany > sourceElement.maxOffset ) {\n\t\t\t/**\n\t\t\t * The nodes which should be moved do not exist.\n\t\t\t *\n\t\t\t * @error move-operation-nodes-do-not-exist\n\t\t\t */\n\t\t\tthrow new CKEditorError(\n\t\t\t\t'move-operation-nodes-do-not-exist: The nodes which should be moved do not exist.'\n\t\t\t);\n\t\t} else if ( sourceElement === targetElement && sourceOffset < targetOffset && targetOffset < sourceOffset + this.howMany ) {\n\t\t\t/**\n\t\t\t * Trying to move a range of nodes into the middle of that range.\n\t\t\t *\n\t\t\t * @error move-operation-range-into-itself\n\t\t\t */\n\t\t\tthrow new CKEditorError(\n\t\t\t\t'move-operation-range-into-itself: Trying to move a range of nodes to the inside of that range.'\n\t\t\t);\n\t\t} else if ( this.sourcePosition.root == this.targetPosition.root ) {\n\t\t\tif ( compareArrays( this.sourcePosition.getParentPath(), this.targetPosition.getParentPath() ) == 'prefix' ) {\n\t\t\t\tconst i = this.sourcePosition.path.length - 1;\n\n\t\t\t\tif ( this.targetPosition.path[ i ] >= sourceOffset && this.targetPosition.path[ i ] < sourceOffset + this.howMany ) {\n\t\t\t\t\t/**\n\t\t\t\t\t * Trying to move a range of nodes into one of nodes from that range.\n\t\t\t\t\t *\n\t\t\t\t\t * @error move-operation-node-into-itself\n\t\t\t\t\t */\n\t\t\t\t\tthrow new CKEditorError(\n\t\t\t\t\t\t'move-operation-node-into-itself: Trying to move a range of nodes into one of nodes from that range.'\n\t\t\t\t\t);\n\t\t\t\t}\n\t\t\t}\n\t\t}\n\t}\n\n\t/**\n\t * @inheritDoc\n\t */\n\t_execute() {\n\t\t_move( Range.createFromPositionAndShift( this.sourcePosition, this.howMany ), this.targetPosition );\n\t}\n\n\t/**\n\t * @inheritDoc\n\t */\n\ttoJSON() {\n\t\tconst json = super.toJSON();\n\n\t\tjson.sourcePosition = this.sourcePosition.toJSON();\n\t\tjson.targetPosition = this.targetPosition.toJSON();\n\n\t\treturn json;\n\t}\n\n\t/**\n\t * @inheritDoc\n\t */\n\tstatic get className() {\n\t\treturn 'MoveOperation';\n\t}\n\n\t/**\n\t * Creates `MoveOperation` object from deserilized object, i.e. from parsed JSON string.\n\t *\n\t * @param {Object} json Deserialized JSON object.\n\t * @param {module:engine/model/document~Document} document Document on which this operation will be applied.\n\t * @returns {module:engine/model/operation/moveoperation~MoveOperation}\n\t */\n\tstatic fromJSON( json, document ) {\n\t\tconst sourcePosition = Position.fromJSON( json.sourcePosition, document );\n\t\tconst targetPosition = Position.fromJSON( json.targetPosition, document );\n\n\t\treturn new this( sourcePosition, json.howMany, targetPosition, json.baseVersion );\n\t}\n}\n","/**\n * @license Copyright (c) 2003-2018, CKSource - Frederico Knabben. All rights reserved.\n * For licensing, see LICENSE.md.\n */\n\n/**\n * @module engine/model/operation/insertoperation\n */\n\nimport Operation from './operation';\nimport Position from '../position';\nimport NodeList from '../nodelist';\nimport MoveOperation from './moveoperation';\nimport { _insert, _normalizeNodes } from './utils';\nimport Text from '../text';\nimport Element from '../element';\nimport CKEditorError from '@ckeditor/ckeditor5-utils/src/ckeditorerror';\n\n/**\n * Operation to insert one or more nodes at given position in the model.\n *\n * @extends module:engine/model/operation/operation~Operation\n */\nexport default class InsertOperation extends Operation {\n\t/**\n\t * Creates an insert operation.\n\t *\n\t * @param {module:engine/model/position~Position} position Position of insertion.\n\t * @param {module:engine/model/node~NodeSet} nodes The list of nodes to be inserted.\n\t * @param {Number|null} baseVersion Document {@link module:engine/model/document~Document#version} on which operation\n\t * can be applied or `null` if the operation operates on detached (non-document) tree.\n\t */\n\tconstructor( position, nodes, baseVersion ) {\n\t\tsuper( baseVersion );\n\n\t\t/**\n\t\t * Position of insertion.\n\t\t *\n\t\t * @readonly\n\t\t * @member {module:engine/model/position~Position} module:engine/model/operation/insertoperation~InsertOperation#position\n\t\t */\n\t\tthis.position = Position.createFromPosition( position );\n\t\tthis.position.stickiness = 'toNone';\n\n\t\t/**\n\t\t * List of nodes to insert.\n\t\t *\n\t\t * @readonly\n\t\t * @member {module:engine/model/nodelist~NodeList} module:engine/model/operation/insertoperation~InsertOperation#nodeList\n\t\t */\n\t\tthis.nodes = new NodeList( _normalizeNodes( nodes ) );\n\n\t\t/**\n\t\t * Flag deciding how the operation should be transformed. If set to `true`, nodes might get additional attributes\n\t\t * during operational transformation. This happens when the operation insertion position is inside of a range\n\t\t * where attributes have changed.\n\t\t *\n\t\t * @member {Boolean} module:engine/model/operation/insertoperation~InsertOperation#shouldReceiveAttributes\n\t\t */\n\t\tthis.shouldReceiveAttributes = false;\n\t}\n\n\t/**\n\t * @inheritDoc\n\t */\n\tget type() {\n\t\treturn 'insert';\n\t}\n\n\t/**\n\t * Total offset size of inserted nodes.\n\t *\n\t * @returns {Number}\n\t */\n\tget howMany() {\n\t\treturn this.nodes.maxOffset;\n\t}\n\n\t/**\n\t * Creates and returns an operation that has the same parameters as this operation.\n\t *\n\t * @returns {module:engine/model/operation/insertoperation~InsertOperation} Clone of this operation.\n\t */\n\tclone() {\n\t\tconst nodes = new NodeList( [ ...this.nodes ].map( node => node._clone( true ) ) );\n\t\tconst insert = new InsertOperation( this.position, nodes, this.baseVersion );\n\n\t\tinsert.shouldReceiveAttributes = this.shouldReceiveAttributes;\n\n\t\treturn insert;\n\t}\n\n\t/**\n\t * See {@link module:engine/model/operation/operation~Operation#getReversed `Operation#getReversed()`}.\n\t *\n\t * @returns {module:engine/model/operation/moveoperation~MoveOperation}\n\t */\n\tgetReversed() {\n\t\tconst graveyard = this.position.root.document.graveyard;\n\t\tconst gyPosition = new Position( graveyard, [ 0 ] );\n\n\t\treturn new MoveOperation( this.position, this.nodes.maxOffset, gyPosition, this.baseVersion + 1 );\n\t}\n\n\t/**\n\t * @inheritDoc\n\t */\n\t_validate() {\n\t\tconst targetElement = this.position.parent;\n\n\t\tif ( !targetElement || targetElement.maxOffset < this.position.offset ) {\n\t\t\t/**\n\t\t\t * Insertion position is invalid.\n\t\t\t *\n\t\t\t * @error insert-operation-position-invalid\n\t\t\t */\n\t\t\tthrow new CKEditorError(\n\t\t\t\t'insert-operation-position-invalid: Insertion position is invalid.'\n\t\t\t);\n\t\t}\n\t}\n\n\t/**\n\t * @inheritDoc\n\t */\n\t_execute() {\n\t\t// What happens here is that we want original nodes be passed to writer because we want original nodes\n\t\t// to be inserted to the model. But in InsertOperation, we want to keep those nodes as they were added\n\t\t// to the operation, not modified. For example, text nodes can get merged or cropped while Elements can\n\t\t// get children. It is important that InsertOperation has the copy of original nodes in intact state.\n\t\tconst originalNodes = this.nodes;\n\t\tthis.nodes = new NodeList( [ ...originalNodes ].map( node => node._clone( true ) ) );\n\n\t\t_insert( this.position, originalNodes );\n\t}\n\n\t/**\n\t * @inheritDoc\n\t */\n\ttoJSON() {\n\t\tconst json = super.toJSON();\n\n\t\tjson.position = this.position.toJSON();\n\t\tjson.nodes = this.nodes.toJSON();\n\n\t\treturn json;\n\t}\n\n\t/**\n\t * @inheritDoc\n\t */\n\tstatic get className() {\n\t\treturn 'InsertOperation';\n\t}\n\n\t/**\n\t * Creates `InsertOperation` object from deserilized object, i.e. from parsed JSON string.\n\t *\n\t * @param {Object} json Deserialized JSON object.\n\t * @param {module:engine/model/document~Document} document Document on which this operation will be applied.\n\t * @returns {module:engine/model/operation/insertoperation~InsertOperation}\n\t */\n\tstatic fromJSON( json, document ) {\n\t\tconst children = [];\n\n\t\tfor ( const child of json.nodes ) {\n\t\t\tif ( child.name ) {\n\t\t\t\t// If child has name property, it is an Element.\n\t\t\t\tchildren.push( Element.fromJSON( child ) );\n\t\t\t} else {\n\t\t\t\t// Otherwise, it is a Text node.\n\t\t\t\tchildren.push( Text.fromJSON( child ) );\n\t\t\t}\n\t\t}\n\n\t\tconst insert = new InsertOperation( Position.fromJSON( json.position, document ), children, json.baseVersion );\n\t\tinsert.shouldReceiveAttributes = json.shouldReceiveAttributes;\n\n\t\treturn insert;\n\t}\n}\n","/**\n * @license Copyright (c) 2003-2018, CKSource - Frederico Knabben. All rights reserved.\n * For licensing, see LICENSE.md.\n */\n\n/**\n * @module engine/model/operation/markeroperation\n */\n\nimport Operation from './operation';\nimport Range from '../range';\n\n/**\n * @extends module:engine/model/operation/operation~Operation\n */\nexport default class MarkerOperation extends Operation {\n\t/**\n\t * @param {String} name Marker name.\n\t * @param {module:engine/model/range~Range} oldRange Marker range before the change.\n\t * @param {module:engine/model/range~Range} newRange Marker range after the change.\n\t * @param {module:engine/model/markercollection~MarkerCollection} markers Marker collection on which change should be executed.\n\t * @param {Boolean} affectsData Specifies whether the marker operation affects the data produced by the data pipeline\n\t * (is persisted in the editor's data).\n\t * @param {Number|null} baseVersion Document {@link module:engine/model/document~Document#version} on which operation\n\t * can be applied or `null` if the operation operates on detached (non-document) tree.\n\t */\n\tconstructor( name, oldRange, newRange, markers, affectsData, baseVersion ) {\n\t\tsuper( baseVersion );\n\n\t\t/**\n\t\t * Marker name.\n\t\t *\n\t\t * @readonly\n\t\t * @member {String}\n\t\t */\n\t\tthis.name = name;\n\n\t\t/**\n\t\t * Marker range before the change.\n\t\t *\n\t\t * @readonly\n\t\t * @member {module:engine/model/range~Range}\n\t\t */\n\t\tthis.oldRange = oldRange ? Range.createFromRange( oldRange ) : null;\n\n\t\t/**\n\t\t * Marker range after the change.\n\t\t *\n\t\t * @readonly\n\t\t * @member {module:engine/model/range~Range}\n\t\t */\n\t\tthis.newRange = newRange ? Range.createFromRange( newRange ) : null;\n\n\t\t/**\n\t\t * Specifies whether the marker operation affects the data produced by the data pipeline\n\t\t * (is persisted in the editor's data).\n\t\t *\n\t\t * @readonly\n\t\t * @member {Boolean}\n\t\t */\n\t\tthis.affectsData = affectsData;\n\n\t\t/**\n\t\t * Marker collection on which change should be executed.\n\t\t *\n\t\t * @private\n\t\t * @member {module:engine/model/markercollection~MarkerCollection}\n\t\t */\n\t\tthis._markers = markers;\n\t}\n\n\t/**\n\t * @inheritDoc\n\t */\n\tget type() {\n\t\treturn 'marker';\n\t}\n\n\t/**\n\t * Creates and returns an operation that has the same parameters as this operation.\n\t *\n\t * @returns {module:engine/model/operation/markeroperation~MarkerOperation} Clone of this operation.\n\t */\n\tclone() {\n\t\treturn new MarkerOperation( this.name, this.oldRange, this.newRange, this._markers, this.affectsData, this.baseVersion );\n\t}\n\n\t/**\n\t * See {@link module:engine/model/operation/operation~Operation#getReversed `Operation#getReversed()`}.\n\t *\n\t * @returns {module:engine/model/operation/markeroperation~MarkerOperation}\n\t */\n\tgetReversed() {\n\t\treturn new MarkerOperation( this.name, this.newRange, this.oldRange, this._markers, this.affectsData, this.baseVersion + 1 );\n\t}\n\n\t/**\n\t * @inheritDoc\n\t */\n\t_execute() {\n\t\tconst type = this.newRange ? '_set' : '_remove';\n\n\t\tthis._markers[ type ]( this.name, this.newRange, true, this.affectsData );\n\t}\n\n\t/**\n\t * @inheritDoc\n\t */\n\ttoJSON() {\n\t\tconst json = super.toJSON();\n\n\t\tif ( this.oldRange ) {\n\t\t\tjson.oldRange = this.oldRange.toJSON();\n\t\t}\n\n\t\tif ( this.newRange ) {\n\t\t\tjson.newRange = this.newRange.toJSON();\n\t\t}\n\n\t\tdelete json._markers;\n\n\t\treturn json;\n\t}\n\n\t/**\n\t * @inheritDoc\n\t */\n\tstatic get className() {\n\t\treturn 'MarkerOperation';\n\t}\n\n\t/**\n\t * Creates `MarkerOperation` object from deserialized object, i.e. from parsed JSON string.\n\t *\n\t * @param {Object} json Deserialized JSON object.\n\t * @param {module:engine/model/document~Document} document Document on which this operation will be applied.\n\t * @returns {module:engine/model/operation/markeroperation~MarkerOperation}\n\t */\n\tstatic fromJSON( json, document ) {\n\t\treturn new MarkerOperation(\n\t\t\tjson.name,\n\t\t\tjson.oldRange ? Range.fromJSON( json.oldRange, document ) : null,\n\t\t\tjson.newRange ? Range.fromJSON( json.newRange, document ) : null,\n\t\t\tdocument.model.markers,\n\t\t\tjson.affectsData,\n\t\t\tjson.baseVersion\n\t\t);\n\t}\n}\n","/**\n * @license Copyright (c) 2003-2018, CKSource - Frederico Knabben. All rights reserved.\n * For licensing, see LICENSE.md.\n */\n\n/**\n * @module engine/model/operation/renameoperation\n */\n\nimport Operation from './operation';\nimport Element from '../element';\nimport CKEditorError from '@ckeditor/ckeditor5-utils/src/ckeditorerror';\nimport Position from '../position';\n\n/**\n * Operation to change element's name.\n *\n * Using this class you can change element's name.\n *\n * @extends module:engine/model/operation/operation~Operation\n */\nexport default class RenameOperation extends Operation {\n\t/**\n\t * Creates an operation that changes element's name.\n\t *\n\t * @param {module:engine/model/position~Position} position Position before an element to change.\n\t * @param {String} oldName Current name of the element.\n\t * @param {String} newName New name for the element.\n\t * @param {Number|null} baseVersion Document {@link module:engine/model/document~Document#version} on which operation\n\t * can be applied or `null` if the operation operates on detached (non-document) tree.\n\t */\n\tconstructor( position, oldName, newName, baseVersion ) {\n\t\tsuper( baseVersion );\n\n\t\t/**\n\t\t * Position before an element to change.\n\t\t *\n\t\t * @member {module:engine/model/position~Position} module:engine/model/operation/renameoperation~RenameOperation#position\n\t\t */\n\t\tthis.position = position;\n\t\t// This position sticks to the next node because it is a position before the node that we want to change.\n\t\tthis.position.stickiness = 'toNext';\n\n\t\t/**\n\t\t * Current name of the element.\n\t\t *\n\t\t * @member {String} module:engine/model/operation/renameoperation~RenameOperation#oldName\n\t\t */\n\t\tthis.oldName = oldName;\n\n\t\t/**\n\t\t * New name for the element.\n\t\t *\n\t\t * @member {String} module:engine/model/operation/renameoperation~RenameOperation#newName\n\t\t */\n\t\tthis.newName = newName;\n\t}\n\n\t/**\n\t * @inheritDoc\n\t */\n\tget type() {\n\t\treturn 'rename';\n\t}\n\n\t/**\n\t * Creates and returns an operation that has the same parameters as this operation.\n\t *\n\t * @returns {module:engine/model/operation/renameoperation~RenameOperation} Clone of this operation.\n\t */\n\tclone() {\n\t\treturn new RenameOperation( Position.createFromPosition( this.position ), this.oldName, this.newName, this.baseVersion );\n\t}\n\n\t/**\n\t * See {@link module:engine/model/operation/operation~Operation#getReversed `Operation#getReversed()`}.\n\t *\n\t * @returns {module:engine/model/operation/renameoperation~RenameOperation}\n\t */\n\tgetReversed() {\n\t\treturn new RenameOperation( Position.createFromPosition( this.position ), this.newName, this.oldName, this.baseVersion + 1 );\n\t}\n\n\t/**\n\t * @inheritDoc\n\t */\n\t_validate() {\n\t\tconst element = this.position.nodeAfter;\n\n\t\tif ( !( element instanceof Element ) ) {\n\t\t\t/**\n\t\t\t * Given position is invalid or node after it is not instance of Element.\n\t\t\t *\n\t\t\t * @error rename-operation-wrong-position\n\t\t\t */\n\t\t\tthrow new CKEditorError(\n\t\t\t\t'rename-operation-wrong-position: Given position is invalid or node after it is not an instance of Element.'\n\t\t\t);\n\t\t} else if ( element.name !== this.oldName ) {\n\t\t\t/**\n\t\t\t * Element to change has different name than operation's old name.\n\t\t\t *\n\t\t\t * @error rename-operation-wrong-name\n\t\t\t */\n\t\t\tthrow new CKEditorError(\n\t\t\t\t'rename-operation-wrong-name: Element to change has different name than operation\\'s old name.'\n\t\t\t);\n\t\t}\n\t}\n\n\t/**\n\t * @inheritDoc\n\t */\n\t_execute() {\n\t\tconst element = this.position.nodeAfter;\n\n\t\telement.name = this.newName;\n\t}\n\n\t/**\n\t * @inheritDoc\n\t */\n\ttoJSON() {\n\t\tconst json = super.toJSON();\n\n\t\tjson.position = this.position.toJSON();\n\n\t\treturn json;\n\t}\n\n\t/**\n\t * @inheritDoc\n\t */\n\tstatic get className() {\n\t\treturn 'RenameOperation';\n\t}\n\n\t/**\n\t * Creates `RenameOperation` object from deserialized object, i.e. from parsed JSON string.\n\t *\n\t * @param {Object} json Deserialized JSON object.\n\t * @param {module:engine/model/document~Document} document Document on which this operation will be applied.\n\t * @returns {module:engine/model/operation/attributeoperation~AttributeOperation}\n\t */\n\tstatic fromJSON( json, document ) {\n\t\treturn new RenameOperation( Position.fromJSON( json.position, document ), json.oldName, json.newName, json.baseVersion );\n\t}\n}\n","/**\n * @license Copyright (c) 2003-2018, CKSource - Frederico Knabben. All rights reserved.\n * For licensing, see LICENSE.md.\n */\n\n/**\n * @module engine/model/operation/rootattributeoperation\n */\n\nimport Operation from './operation';\nimport CKEditorError from '@ckeditor/ckeditor5-utils/src/ckeditorerror';\n\n/**\n * Operation to change root element's attribute. Using this class you can add, remove or change value of the attribute.\n *\n * This operation is needed, because root elements can't be changed through\n * @link module:engine/model/operation/attributeoperation~AttributeOperation}.\n * It is because {@link module:engine/model/operation/attributeoperation~AttributeOperation}\n * requires a range to change and root element can't\n * be a part of range because every {@link module:engine/model/position~Position} has to be inside a root.\n * {@link module:engine/model/position~Position} can't be created before a root element.\n *\n * @extends module:engine/model/operation/operation~Operation\n */\nexport default class RootAttributeOperation extends Operation {\n\t/**\n\t * Creates an operation that changes, removes or adds attributes on root element.\n\t *\n\t * @see module:engine/model/operation/attributeoperation~AttributeOperation\n\t * @param {module:engine/model/rootelement~RootElement} root Root element to change.\n\t * @param {String} key Key of an attribute to change or remove.\n\t * @param {*} oldValue Old value of the attribute with given key or `null` if adding a new attribute.\n\t * @param {*} newValue New value to set for the attribute. If `null`, then the operation just removes the attribute.\n\t * @param {Number|null} baseVersion Document {@link module:engine/model/document~Document#version} on which operation\n\t * can be applied or `null` if the operation operates on detached (non-document) tree.\n\t */\n\tconstructor( root, key, oldValue, newValue, baseVersion ) {\n\t\tsuper( baseVersion );\n\n\t\t/**\n\t\t * Root element to change.\n\t\t *\n\t\t * @readonly\n\t\t * @member {module:engine/model/rootelement~RootElement}\n\t\t */\n\t\tthis.root = root;\n\n\t\t/**\n\t\t * Key of an attribute to change or remove.\n\t\t *\n\t\t * @readonly\n\t\t * @member {String}\n\t\t */\n\t\tthis.key = key;\n\n\t\t/**\n\t\t * Old value of the attribute with given key or `null` if adding a new attribute.\n\t\t *\n\t\t * @readonly\n\t\t * @member {*}\n\t\t */\n\t\tthis.oldValue = oldValue;\n\n\t\t/**\n\t\t * New value to set for the attribute. If `null`, then the operation just removes the attribute.\n\t\t *\n\t\t * @readonly\n\t\t * @member {*}\n\t\t */\n\t\tthis.newValue = newValue;\n\t}\n\n\t/**\n\t * @inheritDoc\n\t */\n\tget type() {\n\t\tif ( this.oldValue === null ) {\n\t\t\treturn 'addRootAttribute';\n\t\t} else if ( this.newValue === null ) {\n\t\t\treturn 'removeRootAttribute';\n\t\t} else {\n\t\t\treturn 'changeRootAttribute';\n\t\t}\n\t}\n\n\t/**\n\t * Creates and returns an operation that has the same parameters as this operation.\n\t *\n\t * @returns {module:engine/model/operation/rootattributeoperation~RootAttributeOperation} Clone of this operation.\n\t */\n\tclone() {\n\t\treturn new RootAttributeOperation( this.root, this.key, this.oldValue, this.newValue, this.baseVersion );\n\t}\n\n\t/**\n\t * See {@link module:engine/model/operation/operation~Operation#getReversed `Operation#getReversed()`}.\n\t *\n\t * @returns {module:engine/model/operation/rootattributeoperation~RootAttributeOperation}\n\t */\n\tgetReversed() {\n\t\treturn new RootAttributeOperation( this.root, this.key, this.newValue, this.oldValue, this.baseVersion + 1 );\n\t}\n\n\t/**\n\t * @inheritDoc\n\t */\n\t_validate() {\n\t\tif ( this.root != this.root.root || this.root.is( 'documentFragment' ) ) {\n\t\t\t/**\n\t\t\t * The element to change is not a root element.\n\t\t\t *\n\t\t\t * @error rootattribute-operation-not-a-root\n\t\t\t * @param {module:engine/model/rootelement~RootElement} root\n\t\t\t * @param {String} key\n\t\t\t * @param {*} value\n\t\t\t */\n\t\t\tthrow new CKEditorError(\n\t\t\t\t'rootattribute-operation-not-a-root: The element to change is not a root element.',\n\t\t\t\t{ root: this.root, key: this.key }\n\t\t\t);\n\t\t}\n\n\t\tif ( this.oldValue !== null && this.root.getAttribute( this.key ) !== this.oldValue ) {\n\t\t\t/**\n\t\t\t * The attribute which should be removed does not exists for the given node.\n\t\t\t *\n\t\t\t * @error rootattribute-operation-wrong-old-value\n\t\t\t * @param {module:engine/model/rootelement~RootElement} root\n\t\t\t * @param {String} key\n\t\t\t * @param {*} value\n\t\t\t */\n\t\t\tthrow new CKEditorError(\n\t\t\t\t'rootattribute-operation-wrong-old-value: Changed node has different attribute value than operation\\'s ' +\n\t\t\t\t'old attribute value.',\n\t\t\t\t{ root: this.root, key: this.key }\n\t\t\t);\n\t\t}\n\n\t\tif ( this.oldValue === null && this.newValue !== null && this.root.hasAttribute( this.key ) ) {\n\t\t\t/**\n\t\t\t * The attribute with given key already exists for the given node.\n\t\t\t *\n\t\t\t * @error rootattribute-operation-attribute-exists\n\t\t\t * @param {module:engine/model/rootelement~RootElement} root\n\t\t\t * @param {String} key\n\t\t\t */\n\t\t\tthrow new CKEditorError(\n\t\t\t\t'rootattribute-operation-attribute-exists: The attribute with given key already exists.',\n\t\t\t\t{ root: this.root, key: this.key }\n\t\t\t);\n\t\t}\n\t}\n\n\t/**\n\t * @inheritDoc\n\t */\n\t_execute() {\n\t\tif ( this.newValue !== null ) {\n\t\t\tthis.root._setAttribute( this.key, this.newValue );\n\t\t} else {\n\t\t\tthis.root._removeAttribute( this.key );\n\t\t}\n\t}\n\n\t/**\n\t * @inheritDoc\n\t */\n\ttoJSON() {\n\t\tconst json = super.toJSON();\n\n\t\tjson.root = this.root.toJSON();\n\n\t\treturn json;\n\t}\n\n\t/**\n\t * @inheritDoc\n\t */\n\tstatic get className() {\n\t\treturn 'RootAttributeOperation';\n\t}\n\n\t/**\n\t * Creates RootAttributeOperation object from deserilized object, i.e. from parsed JSON string.\n\t *\n\t * @param {Object} json Deserialized JSON object.\n\t * @param {module:engine/model/document~Document} document Document on which this operation will be applied.\n\t * @returns {module:engine/model/operation/rootattributeoperation~RootAttributeOperation}\n\t */\n\tstatic fromJSON( json, document ) {\n\t\tif ( !document.getRoot( json.root ) ) {\n\t\t\t/**\n\t\t\t * Cannot create RootAttributeOperation for document. Root with specified name does not exist.\n\t\t\t *\n\t\t\t * @error rootattributeoperation-fromjson-no-root\n\t\t\t * @param {String} rootName\n\t\t\t */\n\t\t\tthrow new CKEditorError(\n\t\t\t\t'rootattribute-operation-fromjson-no-root: Cannot create RootAttributeOperation. Root with specified name does not exist.',\n\t\t\t\t{ rootName: json.root }\n\t\t\t);\n\t\t}\n\n\t\treturn new RootAttributeOperation( document.getRoot( json.root ), json.key, json.oldValue, json.newValue, json.baseVersion );\n\t}\n}\n","/**\n * @license Copyright (c) 2003-2018, CKSource - Frederico Knabben. All rights reserved.\n * For licensing, see LICENSE.md.\n */\n\n/**\n * @module engine/model/operation/mergeoperation\n */\n\nimport Operation from './operation';\nimport SplitOperation from './splitoperation';\nimport Position from '../position';\nimport Range from '../range';\nimport { _move } from './utils';\n\nimport CKEditorError from '@ckeditor/ckeditor5-utils/src/ckeditorerror';\n\n/**\n * Operation to merge two {@link module:engine/model/element~Element elements}.\n *\n * The merged element is the parent of {@link ~MergeOperation#sourcePosition} and it is merged into the parent of\n * {@link ~MergeOperation#targetPosition}. All nodes from the merged element are moved to {@link ~MergeOperation#targetPosition}.\n *\n * The merged element is moved to the graveyard at {@link ~MergeOperation#graveyardPosition}.\n *\n * @extends module:engine/model/operation/operation~Operation\n */\nexport default class MergeOperation extends Operation {\n\t/**\n\t * Creates a merge operation.\n\t *\n\t * @param {module:engine/model/position~Position} sourcePosition Position inside the merged element. All nodes from that\n\t * element after that position will be moved to {@link ~#targetPosition}.\n\t * @param {Number} howMany Summary offset size of nodes which will be moved from the merged element to the new parent.\n\t * @param {module:engine/model/position~Position} targetPosition Position which the nodes from the merged elements will be moved to.\n\t * @param {module:engine/model/position~Position} graveyardPosition Position in graveyard to which the merged element will be moved.\n\t * @param {Number|null} baseVersion Document {@link module:engine/model/document~Document#version} on which operation\n\t * can be applied or `null` if the operation operates on detached (non-document) tree.\n\t */\n\tconstructor( sourcePosition, howMany, targetPosition, graveyardPosition, baseVersion ) {\n\t\tsuper( baseVersion );\n\n\t\t/**\n\t\t * Position inside the merged element. All nodes from that element after that position will be moved to {@link ~#targetPosition}.\n\t\t *\n\t\t * @member {module:engine/model/position~Position} module:engine/model/operation/mergeoperation~MergeOperation#sourcePosition\n\t\t */\n\t\tthis.sourcePosition = Position.createFromPosition( sourcePosition );\n\t\t// This is, and should always remain, the first position in its parent.\n\t\tthis.sourcePosition.stickiness = 'toPrevious';\n\n\t\t/**\n\t\t * Summary offset size of nodes which will be moved from the merged element to the new parent.\n\t\t *\n\t\t * @member {Number} module:engine/model/operation/mergeoperation~MergeOperation#howMany\n\t\t */\n\t\tthis.howMany = howMany;\n\n\t\t/**\n\t\t * Position which the nodes from the merged elements will be moved to.\n\t\t *\n\t\t * @member {module:engine/model/position~Position} module:engine/model/operation/mergeoperation~MergeOperation#targetPosition\n\t\t */\n\t\tthis.targetPosition = Position.createFromPosition( targetPosition );\n\t\t// Except of a rare scenario in `MergeOperation` x `MergeOperation` transformation,\n\t\t// this is, and should always remain, the last position in its parent.\n\t\tthis.targetPosition.stickiness = 'toNext';\n\n\t\t/**\n\t\t * Position in graveyard to which the merged element will be moved.\n\t\t *\n\t\t * @member {module:engine/model/position~Position} module:engine/model/operation/mergeoperation~MergeOperation#graveyardPosition\n\t\t */\n\t\tthis.graveyardPosition = Position.createFromPosition( graveyardPosition );\n\t}\n\n\t/**\n\t * @inheritDoc\n\t */\n\tget type() {\n\t\treturn 'merge';\n\t}\n\n\t/**\n\t * Position before the merged element (which will be deleted).\n\t *\n\t * @readonly\n\t * @type {module:engine/model/position~Position}\n\t */\n\tget deletionPosition() {\n\t\treturn new Position( this.sourcePosition.root, this.sourcePosition.path.slice( 0, -1 ) );\n\t}\n\n\t/**\n\t * Artificial range that contains all the nodes from the merged element that will be moved to {@link ~MergeOperation#sourcePosition}.\n\t * The range starts at {@link ~MergeOperation#sourcePosition} and ends in the same parent, at `POSITIVE_INFINITY` offset.\n\t *\n\t * @readonly\n\t * @type {module:engine/model/range~Range}\n\t */\n\tget movedRange() {\n\t\tconst end = this.sourcePosition.getShiftedBy( Number.POSITIVE_INFINITY );\n\n\t\treturn new Range( this.sourcePosition, end );\n\t}\n\n\t/**\n\t * Creates and returns an operation that has the same parameters as this operation.\n\t *\n\t * @returns {module:engine/model/operation/mergeoperation~MergeOperation} Clone of this operation.\n\t */\n\tclone() {\n\t\treturn new this.constructor( this.sourcePosition, this.howMany, this.targetPosition, this.graveyardPosition, this.baseVersion );\n\t}\n\n\t/**\n\t * See {@link module:engine/model/operation/operation~Operation#getReversed `Operation#getReversed()`}.\n\t *\n\t * @returns {module:engine/model/operation/splitoperation~SplitOperation}\n\t */\n\tgetReversed() {\n\t\t// Positions in this method are transformed by this merge operation because the split operation bases on\n\t\t// the context after this merge operation happened (because split operation reverses it).\n\t\t// So we need to acknowledge that the merge operation happened and those positions changed a little.\n\t\tconst targetPosition = this.targetPosition._getTransformedByMergeOperation( this );\n\n\t\tconst path = this.sourcePosition.path.slice( 0, -1 );\n\t\tconst insertionPosition = new Position( this.sourcePosition.root, path )._getTransformedByMergeOperation( this );\n\n\t\tconst split = new SplitOperation( targetPosition, this.howMany, this.graveyardPosition, this.baseVersion + 1 );\n\t\tsplit.insertionPosition = insertionPosition;\n\n\t\treturn split;\n\t}\n\n\t/**\n\t * @inheritDoc\n\t */\n\t_validate() {\n\t\tconst sourceElement = this.sourcePosition.parent;\n\t\tconst targetElement = this.targetPosition.parent;\n\n\t\t// Validate whether merge operation has correct parameters.\n\t\tif ( !sourceElement || !sourceElement.is( 'element' ) || !sourceElement.parent ) {\n\t\t\t/**\n\t\t\t * Merge source position is invalid.\n\t\t\t *\n\t\t\t * @error merge-operation-source-position-invalid\n\t\t\t */\n\t\t\tthrow new CKEditorError( 'merge-operation-source-position-invalid: Merge source position is invalid.' );\n\t\t} else if ( !targetElement || !targetElement.is( 'element' ) || !targetElement.parent ) {\n\t\t\t/**\n\t\t\t * Merge target position is invalid.\n\t\t\t *\n\t\t\t * @error merge-operation-target-position-invalid\n\t\t\t */\n\t\t\tthrow new CKEditorError( 'merge-operation-target-position-invalid: Merge target position is invalid.' );\n\t\t} else if ( this.howMany != sourceElement.maxOffset ) {\n\t\t\t/**\n\t\t\t * Merge operation specifies wrong number of nodes to move.\n\t\t\t *\n\t\t\t * @error merge-operation-how-many-invalid\n\t\t\t */\n\t\t\tthrow new CKEditorError( 'merge-operation-how-many-invalid: Merge operation specifies wrong number of nodes to move.' );\n\t\t}\n\t}\n\n\t/**\n\t * @inheritDoc\n\t */\n\t_execute() {\n\t\tconst mergedElement = this.sourcePosition.parent;\n\t\tconst sourceRange = Range.createIn( mergedElement );\n\n\t\t_move( sourceRange, this.targetPosition );\n\t\t_move( Range.createOn( mergedElement ), this.graveyardPosition );\n\t}\n\n\t/**\n\t * @inheritDoc\n\t */\n\ttoJSON() {\n\t\tconst json = super.toJSON();\n\n\t\tjson.sourcePosition = json.sourcePosition.toJSON();\n\t\tjson.targetPosition = json.targetPosition.toJSON();\n\t\tjson.graveyardPosition = json.graveyardPosition.toJSON();\n\n\t\treturn json;\n\t}\n\n\t/**\n\t * @inheritDoc\n\t */\n\tstatic get className() {\n\t\treturn 'MergeOperation';\n\t}\n\n\t/**\n\t * Creates `MergeOperation` object from deserilized object, i.e. from parsed JSON string.\n\t *\n\t * @param {Object} json Deserialized JSON object.\n\t * @param {module:engine/model/document~Document} document Document on which this operation will be applied.\n\t * @returns {module:engine/model/operation/mergeoperation~MergeOperation}\n\t */\n\tstatic fromJSON( json, document ) {\n\t\tconst sourcePosition = Position.fromJSON( json.sourcePosition, document );\n\t\tconst targetPosition = Position.fromJSON( json.targetPosition, document );\n\t\tconst graveyardPosition = Position.fromJSON( json.graveyardPosition, document );\n\n\t\treturn new this( sourcePosition, json.howMany, targetPosition, graveyardPosition, json.baseVersion );\n\t}\n}\n","/**\n * @license Copyright (c) 2003-2018, CKSource - Frederico Knabben. All rights reserved.\n * For licensing, see LICENSE.md.\n */\n\n/**\n * @module engine/model/operation/splitoperation\n */\n\nimport Operation from './operation';\nimport MergeOperation from './mergeoperation';\nimport Position from '../position';\nimport Range from '../range';\nimport { _insert, _move } from './utils';\n\nimport CKEditorError from '@ckeditor/ckeditor5-utils/src/ckeditorerror';\n\n/**\n * Operation to split {@link module:engine/model/element~Element an element} at given\n * {@link module:engine/model/operation/splitoperation~SplitOperation#splitPosition split position} into two elements,\n * both containing a part of the element's original content.\n *\n * @extends module:engine/model/operation/operation~Operation\n */\nexport default class SplitOperation extends Operation {\n\t/**\n\t * Creates a split operation.\n\t *\n\t * @param {module:engine/model/position~Position} splitPosition Position at which an element should be split.\n\t * @param {Number} howMany Total offset size of elements that are in the split element after `position`.\n\t * @param {module:engine/model/position~Position|null} graveyardPosition Position in the graveyard root before the element which\n\t * should be used as a parent of the nodes after `position`. If it is not set, a copy of the the `position` parent will be used.\n\t * @param {Number|null} baseVersion Document {@link module:engine/model/document~Document#version} on which operation\n\t * can be applied or `null` if the operation operates on detached (non-document) tree.\n\t */\n\tconstructor( splitPosition, howMany, graveyardPosition, baseVersion ) {\n\t\tsuper( baseVersion );\n\n\t\t/**\n\t\t * Position at which an element should be split.\n\t\t *\n\t\t * @member {module:engine/model/position~Position} module:engine/model/operation/splitoperation~SplitOperation#splitPosition\n\t\t */\n\t\tthis.splitPosition = Position.createFromPosition( splitPosition );\n\t\t// Keep position sticking to the next node. This way any new content added at the place where the element is split\n\t\t// will be left in the original element.\n\t\tthis.splitPosition.stickiness = 'toNext';\n\n\t\t/**\n\t\t * Total offset size of elements that are in the split element after `position`.\n\t\t *\n\t\t * @member {Number} module:engine/model/operation/splitoperation~SplitOperation#howMany\n\t\t */\n\t\tthis.howMany = howMany;\n\n\t\t/**\n\t\t * Position at which the clone of split element (or element from graveyard) will be inserted.\n\t\t *\n\t\t * @member {module:engine/model/position~Position} module:engine/model/operation/splitoperation~SplitOperation#insertionPosition\n\t\t */\n\t\tthis.insertionPosition = SplitOperation.getInsertionPosition( splitPosition );\n\t\tthis.insertionPosition.stickiness = 'toNone';\n\n\t\t/**\n\t\t * Position in the graveyard root before the element which should be used as a parent of the nodes after `position`.\n\t\t * If it is not set, a copy of the the `position` parent will be used.\n\t\t *\n\t\t * The default behavior is to clone the split element. Element from graveyard is used during undo.\n\t\t *\n\t\t * @member {module:engine/model/position~Position|null} #graveyardPosition\n\t\t */\n\t\tthis.graveyardPosition = graveyardPosition ? Position.createFromPosition( graveyardPosition ) : null;\n\n\t\tif ( this.graveyardPosition ) {\n\t\t\tthis.graveyardPosition.stickiness = 'toNext';\n\t\t}\n\t}\n\n\t/**\n\t * @inheritDoc\n\t */\n\tget type() {\n\t\treturn 'split';\n\t}\n\n\t/**\n\t * Position inside the new clone of a split element.\n\t *\n\t * This is a position where nodes that are after the split position will be moved to.\n\t *\n\t * @readonly\n\t * @type {module:engine/model/position~Position}\n\t */\n\tget moveTargetPosition() {\n\t\tconst path = this.insertionPosition.path.slice();\n\t\tpath.push( 0 );\n\n\t\treturn new Position( this.insertionPosition.root, path );\n\t}\n\n\t/**\n\t * Artificial range that contains all the nodes from the split element that will be moved to the new element.\n\t * The range starts at {@link ~#splitPosition} and ends in the same parent, at `POSITIVE_INFINITY` offset.\n\t *\n\t * @readonly\n\t * @type {module:engine/model/range~Range}\n\t */\n\tget movedRange() {\n\t\tconst end = this.splitPosition.getShiftedBy( Number.POSITIVE_INFINITY );\n\n\t\treturn new Range( this.splitPosition, end );\n\t}\n\n\t/**\n\t * Creates and returns an operation that has the same parameters as this operation.\n\t *\n\t * @returns {module:engine/model/operation/splitoperation~SplitOperation} Clone of this operation.\n\t */\n\tclone() {\n\t\tconst split = new this.constructor( this.splitPosition, this.howMany, this.graveyardPosition, this.baseVersion );\n\t\tsplit.insertionPosition = this.insertionPosition;\n\n\t\treturn split;\n\t}\n\n\t/**\n\t * See {@link module:engine/model/operation/operation~Operation#getReversed `Operation#getReversed()`}.\n\t *\n\t * @returns {module:engine/model/operation/mergeoperation~MergeOperation}\n\t */\n\tgetReversed() {\n\t\tconst graveyard = this.splitPosition.root.document.graveyard;\n\t\tconst graveyardPosition = new Position( graveyard, [ 0 ] );\n\n\t\treturn new MergeOperation( this.moveTargetPosition, this.howMany, this.splitPosition, graveyardPosition, this.baseVersion + 1 );\n\t}\n\n\t/**\n\t * @inheritDoc\n\t */\n\t_validate() {\n\t\tconst element = this.splitPosition.parent;\n\t\tconst offset = this.splitPosition.offset;\n\n\t\t// Validate whether split operation has correct parameters.\n\t\tif ( !element || element.maxOffset < offset ) {\n\t\t\t/**\n\t\t\t * Split position is invalid.\n\t\t\t *\n\t\t\t * @error split-operation-position-invalid\n\t\t\t */\n\t\t\tthrow new CKEditorError( 'split-operation-position-invalid: Split position is invalid.' );\n\t\t} else if ( !element.parent ) {\n\t\t\t/**\n\t\t\t * Cannot split root element.\n\t\t\t *\n\t\t\t * @error split-operation-split-in-root\n\t\t\t */\n\t\t\tthrow new CKEditorError( 'split-operation-split-in-root: Cannot split root element.' );\n\t\t} else if ( this.howMany != element.maxOffset - this.splitPosition.offset ) {\n\t\t\t/**\n\t\t\t * Split operation specifies wrong number of nodes to move.\n\t\t\t *\n\t\t\t * @error split-operation-how-many-invalid\n\t\t\t */\n\t\t\tthrow new CKEditorError( 'split-operation-how-many-invalid: Split operation specifies wrong number of nodes to move.' );\n\t\t} else if ( this.graveyardPosition && !this.graveyardPosition.nodeAfter ) {\n\t\t\t/**\n\t\t\t * Graveyard position invalid.\n\t\t\t *\n\t\t\t * @error split-operation-graveyard-position-invalid\n\t\t\t */\n\t\t\tthrow new CKEditorError( 'split-operation-graveyard-position-invalid: Graveyard position invalid.' );\n\t\t}\n\t}\n\n\t/**\n\t * @inheritDoc\n\t */\n\t_execute() {\n\t\tconst splitElement = this.splitPosition.parent;\n\n\t\tif ( this.graveyardPosition ) {\n\t\t\t_move( Range.createFromPositionAndShift( this.graveyardPosition, 1 ), this.insertionPosition );\n\t\t} else {\n\t\t\tconst newElement = splitElement._clone();\n\n\t\t\t_insert( this.insertionPosition, newElement );\n\t\t}\n\n\t\tconst sourceRange = Range.createFromParentsAndOffsets(\n\t\t\tsplitElement, this.splitPosition.offset, splitElement, splitElement.maxOffset\n\t\t);\n\n\t\t_move( sourceRange, this.moveTargetPosition );\n\t}\n\n\t/**\n\t * @inheritDoc\n\t */\n\ttoJSON() {\n\t\tconst json = super.toJSON();\n\n\t\tjson.splitPosition = this.splitPosition.toJSON();\n\t\tjson.insertionPosition = this.insertionPosition.toJSON();\n\n\t\tif ( this.graveyardPosition ) {\n\t\t\tjson.graveyardPosition = this.graveyardPosition.toJSON();\n\t\t}\n\n\t\treturn json;\n\t}\n\n\t/**\n\t * @inheritDoc\n\t */\n\tstatic get className() {\n\t\treturn 'SplitOperation';\n\t}\n\n\t/**\n\t * Helper function that returns a default insertion position basing on given `splitPosition`. The default insertion\n\t * position is after the split element.\n\t *\n\t * @param {module:engine/model/position~Position} splitPosition\n\t * @returns {module:engine/model/position~Position}\n\t */\n\tstatic getInsertionPosition( splitPosition ) {\n\t\tconst path = splitPosition.path.slice( 0, -1 );\n\t\tpath[ path.length - 1 ]++;\n\n\t\treturn new Position( splitPosition.root, path );\n\t}\n\n\t/**\n\t * Creates `SplitOperation` object from deserilized object, i.e. from parsed JSON string.\n\t *\n\t * @param {Object} json Deserialized JSON object.\n\t * @param {module:engine/model/document~Document} document Document on which this operation will be applied.\n\t * @returns {module:engine/model/operation/splitoperation~SplitOperation}\n\t */\n\tstatic fromJSON( json, document ) {\n\t\tconst splitPosition = Position.fromJSON( json.splitPosition, document );\n\t\tconst insertionPosition = Position.fromJSON( json.insertionPosition, document );\n\t\tconst graveyardPosition = json.graveyardPosition ? Position.fromJSON( json.graveyardPosition, document ) : null;\n\n\t\tconst split = new this( splitPosition, json.howMany, graveyardPosition, json.baseVersion );\n\t\tsplit.insertionPosition = insertionPosition;\n\n\t\treturn split;\n\t}\n}\n","/**\n * @license Copyright (c) 2003-2018, CKSource - Frederico Knabben. All rights reserved.\n * For licensing, see LICENSE.md.\n */\n\n/**\n * @module engine/model/rootelement\n */\n\nimport Element from './element';\n\n/**\n * Type of {@link module:engine/model/element~Element} that is a root of a model tree.\n * @extends module:engine/model/element~Element\n */\nexport default class RootElement extends Element {\n\t/**\n\t * Creates root element.\n\t *\n\t * @param {module:engine/model/document~Document} doc Document that is an owner of this root.\n\t * @param {String} name Node name.\n\t * @param {String} [rootName='main'] Unique root name used to identify this root\n\t * element by {@link module:engine/model/document~Document}.\n\t */\n\tconstructor( doc, name, rootName = 'main' ) {\n\t\tsuper( name );\n\n\t\t/**\n\t\t * Document that is an owner of this root.\n\t\t *\n\t\t * @private\n\t\t * @member {module:engine/model/document~Document}\n\t\t */\n\t\tthis._doc = doc;\n\n\t\t/**\n\t\t * Unique root name used to identify this root element by {@link module:engine/model/document~Document}.\n\t\t *\n\t\t * @readonly\n\t\t * @member {String}\n\t\t */\n\t\tthis.rootName = rootName;\n\t}\n\n\t/**\n\t * {@link module:engine/model/document~Document Document} that owns this root element.\n\t *\n\t * In contrary, to {@link module:engine/model/node~Node node}, root element always have a `document`.\n\t *\n\t * @readonly\n\t * @type {module:engine/model/document~Document|null}\n\t */\n\tget document() {\n\t\treturn this._doc;\n\t}\n\n\t/**\n\t * @inheritDoc\n\t */\n\tis( type, name ) {\n\t\tif ( !name ) {\n\t\t\treturn type == 'rootElement' || super.is( type );\n\t\t} else {\n\t\t\treturn ( type == 'rootElement' && name == this.name ) || super.is( type, name );\n\t\t}\n\t}\n\n\t/**\n\t * Converts `RootElement` instance to `String` containing it's name.\n\t *\n\t * @returns {String} `RootElement` instance converted to `String`.\n\t */\n\ttoJSON() {\n\t\treturn this.rootName;\n\t}\n}\n","/**\n * @license Copyright (c) 2003-2018, CKSource - Frederico Knabben. All rights reserved.\n * For licensing, see LICENSE.md.\n */\n\n/**\n * @module engine/model/writer\n */\n\nimport AttributeOperation from './operation/attributeoperation';\nimport DetachOperation from './operation/detachoperation';\nimport InsertOperation from './operation/insertoperation';\nimport MarkerOperation from './operation/markeroperation';\nimport MoveOperation from './operation/moveoperation';\nimport RenameOperation from './operation/renameoperation';\nimport RootAttributeOperation from './operation/rootattributeoperation';\nimport SplitOperation from './operation/splitoperation';\nimport MergeOperation from './operation/mergeoperation';\n\nimport DocumentFragment from './documentfragment';\nimport Text from './text';\nimport Element from './element';\nimport RootElement from './rootelement';\nimport Position from './position';\nimport Range from './range.js';\nimport DocumentSelection from './documentselection';\n\nimport toMap from '@ckeditor/ckeditor5-utils/src/tomap';\n\nimport CKEditorError from '@ckeditor/ckeditor5-utils/src/ckeditorerror';\n\n/**\n * The model can only be modified by using the writer. It should be used whenever you want to create a node, modify\n * child nodes, attributes or text, set the selection's position and its attributes.\n *\n * The instance of the writer is only available in the {@link module:engine/model/model~Model#change `change()`} or\n * {@link module:engine/model/model~Model#enqueueChange `enqueueChange()`}.\n *\n *\t\tmodel.change( writer => {\n *\t\t\twriter.insertText( 'foo', paragraph, 'end' );\n *\t\t} );\n *\n * Note that the writer should never be stored and used outside of the `change()` and\n * `enqueueChange()` blocks.\n *\n * Note that writer's methods do not check the {@link module:engine/model/schema~Schema}. It is possible\n * to create incorrect model structures by using the writer. Read more about in\n * {@glink framework/guides/deep-dive/schema#who-checks-the-schema \"Who checks the schema?\"}.\n *\n * @see module:engine/model/model~Model#change\n * @see module:engine/model/model~Model#enqueueChange\n */\nexport default class Writer {\n\t/**\n\t * Creates a writer instance.\n\t *\n\t * **Note:** It is not recommended to use it directly. Use {@link module:engine/model/model~Model#change `Model#change()`} or\n\t * {@link module:engine/model/model~Model#enqueueChange `Model#enqueueChange()`} instead.\n\t *\n\t * @protected\n\t * @param {module:engine/model/model~Model} model\n\t * @param {module:engine/model/batch~Batch} batch\n\t */\n\tconstructor( model, batch ) {\n\t\t/**\n\t\t * Instance of the model on which this writer operates.\n\t\t *\n\t\t * @readonly\n\t\t * @type {module:engine/model/model~Model}\n\t\t */\n\t\tthis.model = model;\n\n\t\t/**\n\t\t * The batch to which this writer will add changes.\n\t\t *\n\t\t * @readonly\n\t\t * @type {module:engine/model/batch~Batch}\n\t\t */\n\t\tthis.batch = batch;\n\t}\n\n\t/**\n\t * Creates a new {@link module:engine/model/text~Text text node}.\n\t *\n\t *\t\twriter.createText( 'foo' );\n\t *\t\twriter.createText( 'foo', { bold: true } );\n\t *\n\t * @param {String} data Text data.\n\t * @param {Object} [attributes] Text attributes.\n\t * @returns {module:engine/model/text~Text} Created text node.\n\t */\n\tcreateText( data, attributes ) {\n\t\treturn new Text( data, attributes );\n\t}\n\n\t/**\n\t * Creates a new {@link module:engine/model/element~Element element}.\n\t *\n\t *\t\twriter.createElement( 'paragraph' );\n\t *\t\twriter.createElement( 'paragraph', { alignment: 'center' } );\n\t *\n\t * @param {String} name Name of the element.\n\t * @param {Object} [attributes] Elements attributes.\n\t * @returns {module:engine/model/element~Element} Created element.\n\t */\n\tcreateElement( name, attributes ) {\n\t\treturn new Element( name, attributes );\n\t}\n\n\t/**\n\t * Creates a new {@link module:engine/model/documentfragment~DocumentFragment document fragment}.\n\t *\n\t * @returns {module:engine/model/documentfragment~DocumentFragment} Created document fragment.\n\t */\n\tcreateDocumentFragment() {\n\t\treturn new DocumentFragment();\n\t}\n\n\t/**\n\t * Inserts item on given position.\n\t *\n\t *\t\tconst paragraph = writer.createElement( 'paragraph' );\n\t *\t\twriter.insert( paragraph, position );\n\t *\n\t * Instead of using position you can use parent and offset:\n\t *\n\t *\t\tconst text = writer.createText( 'foo' );\n\t *\t\twriter.insert( text, paragraph, 5 );\n\t *\n\t * You can also use `end` instead of the offset to insert at the end:\n\t *\n\t *\t\tconst text = writer.createText( 'foo' );\n\t *\t\twriter.insert( text, paragraph, 'end' );\n\t *\n\t * Or insert before or after another element:\n\t *\n\t *\t\tconst paragraph = writer.createElement( 'paragraph' );\n\t *\t\twriter.insert( paragraph, anotherParagraph, 'after' );\n\t *\n\t * These parameters works the same way as {@link module:engine/model/position~Position.createAt `Position.createAt()`}.\n\t *\n\t * Note that if the item already has parent it will be removed from the previous parent.\n\t *\n\t * Note that you cannot re-insert a node from a document to a different document or a document fragment. In this case,\n\t * `model-writer-insert-forbidden-move` is thrown.\n\t *\n\t * If you want to move {@link module:engine/model/range~Range range} instead of an\n\t * {@link module:engine/model/item~Item item} use {@link module:engine/model/writer~Writer#move `Writer#move()`}.\n\t *\n\t * **Note:** For a paste-like content insertion mechanism see\n\t * {@link module:engine/model/model~Model#insertContent `model.insertContent()`}.\n\t *\n\t * @param {module:engine/model/item~Item|module:engine/model/documentfragment~DocumentFragment} item Item or document\n\t * fragment to insert.\n\t * @param {module:engine/model/item~Item|module:engine/model/position~Position} itemOrPosition\n\t * @param {Number|'end'|'before'|'after'} [offset=0] Offset or one of the flags. Used only when\n\t * second parameter is a {@link module:engine/model/item~Item model item}.\n\t */\n\tinsert( item, itemOrPosition, offset ) {\n\t\tthis._assertWriterUsedCorrectly();\n\n\t\tconst position = Position.createAt( itemOrPosition, offset );\n\n\t\t// If item has a parent already.\n\t\tif ( item.parent ) {\n\t\t\t// We need to check if item is going to be inserted within the same document.\n\t\t\tif ( isSameTree( item.root, position.root ) ) {\n\t\t\t\t// If it's we just need to move it.\n\t\t\t\tthis.move( Range.createOn( item ), position );\n\n\t\t\t\treturn;\n\t\t\t}\n\t\t\t// If it isn't the same root.\n\t\t\telse {\n\t\t\t\tif ( item.root.document ) {\n\t\t\t\t\t// It is forbidden to move a node that was already in a document outside of it.\n\t\t\t\t\tthrow new Error( 'model-writer-insert-forbidden-move: Cannot move a node from a document to a different tree.' );\n\t\t\t\t} else {\n\t\t\t\t\t// Move between two different document fragments or from document fragment to a document is possible.\n\t\t\t\t\t// In that case, remove the item from it's original parent.\n\t\t\t\t\tthis.remove( item );\n\t\t\t\t}\n\t\t\t}\n\t\t}\n\n\t\tconst version = position.root.document ? position.root.document.version : null;\n\n\t\tconst insert = new InsertOperation( position, item, version );\n\n\t\tif ( item instanceof Text ) {\n\t\t\tinsert.shouldReceiveAttributes = true;\n\t\t}\n\n\t\tthis.batch.addOperation( insert );\n\t\tthis.model.applyOperation( insert );\n\n\t\t// When element is a DocumentFragment we need to move its markers to Document#markers.\n\t\tif ( item instanceof DocumentFragment ) {\n\t\t\tfor ( const [ markerName, markerRange ] of item.markers ) {\n\t\t\t\t// We need to migrate marker range from DocumentFragment to Document.\n\t\t\t\tconst rangeRootPosition = Position.createAt( markerRange.root );\n\t\t\t\tconst range = new Range(\n\t\t\t\t\tmarkerRange.start._getCombined( rangeRootPosition, position ),\n\t\t\t\t\tmarkerRange.end._getCombined( rangeRootPosition, position )\n\t\t\t\t);\n\n\t\t\t\tthis.addMarker( markerName, { range, usingOperation: true } );\n\t\t\t}\n\t\t}\n\t}\n\n\t/**\n\t * Creates and inserts text on given position. You can optionally set text attributes:\n\t *\n\t *\t\twriter.insertText( 'foo', position );\n\t *\t\twriter.insertText( 'foo', { bold: true }, position );\n\t *\n\t * Instead of using position you can use parent and offset or define that text should be inserted at the end\n\t * or before or after other node:\n\t *\n\t *\t\t// Inserts 'foo' in paragraph, at offset 5:\n\t *\t\twriter.insertText( 'foo', paragraph, 5 );\n\t *\t\t// Inserts 'foo' at the end of a paragraph:\n\t *\t\twriter.insertText( 'foo', paragraph, 'end' );\n\t *\t\t// Inserts 'foo' after an image:\n\t *\t\twriter.insertText( 'foo', image, 'after' );\n\t *\n\t * These parameters work in the same way as {@link module:engine/model/position~Position.createAt `Position.createAt()`}.\n\t *\n\t * @param {String} data Text data.\n\t * @param {Object} [attributes] Text attributes.\n\t * @param {module:engine/model/item~Item|module:engine/model/position~Position} itemOrPosition\n\t * @param {Number|'end'|'before'|'after'} [offset=0] Offset or one of the flags. Used only when\n\t * third parameter is a {@link module:engine/model/item~Item model item}.\n\t */\n\tinsertText( text, attributes, itemOrPosition, offset ) {\n\t\tif ( attributes instanceof DocumentFragment || attributes instanceof Element || attributes instanceof Position ) {\n\t\t\tthis.insert( this.createText( text ), attributes, itemOrPosition );\n\t\t} else {\n\t\t\tthis.insert( this.createText( text, attributes ), itemOrPosition, offset );\n\t\t}\n\t}\n\n\t/**\n\t * Creates and inserts element on given position. You can optionally set attributes:\n\t *\n\t *\t\twriter.insertElement( 'paragraph', position );\n\t *\t\twriter.insertElement( 'paragraph', { alignment: 'center' }, position );\n\t *\n\t * Instead of using position you can use parent and offset or define that text should be inserted at the end\n\t * or before or after other node:\n\t *\n\t *\t\t// Inserts paragraph in the root at offset 5:\n\t *\t\twriter.insertElement( 'paragraph', root, 5 );\n\t *\t\t// Inserts paragraph at the end of a blockquote:\n\t *\t\twriter.insertElement( 'paragraph', blockquote, 'end' );\n\t *\t\t// Inserts after an image:\n\t *\t\twriter.insertElement( 'paragraph', image, 'after' );\n\t *\n\t * These parameters works the same way as {@link module:engine/model/position~Position.createAt `Position.createAt()`}.\n\t *\n\t * @param {String} name Name of the element.\n\t * @param {Object} [attributes] Elements attributes.\n\t * @param {module:engine/model/item~Item|module:engine/model/position~Position} itemOrPosition\n\t * @param {Number|'end'|'before'|'after'} [offset=0] Offset or one of the flags. Used only when\n\t * third parameter is a {@link module:engine/model/item~Item model item}.\n\t */\n\tinsertElement( name, attributes, itemOrPosition, offset ) {\n\t\tif ( attributes instanceof DocumentFragment || attributes instanceof Element || attributes instanceof Position ) {\n\t\t\tthis.insert( this.createElement( name ), attributes, itemOrPosition );\n\t\t} else {\n\t\t\tthis.insert( this.createElement( name, attributes ), itemOrPosition, offset );\n\t\t}\n\t}\n\n\t/**\n\t * Inserts item at the end of the given parent.\n\t *\n\t *\t\tconst paragraph = writer.createElement( 'paragraph' );\n\t *\t\twriter.append( paragraph, root );\n\t *\n\t * Note that if the item already has parent it will be removed from the previous parent.\n\t *\n\t * If you want to move {@link module:engine/model/range~Range range} instead of an\n\t * {@link module:engine/model/item~Item item} use {@link module:engine/model/writer~Writer#move `Writer#move()`}.\n\t *\n\t * @param {module:engine/model/item~Item|module:engine/model/documentfragment~DocumentFragment}\n\t * item Item or document fragment to insert.\n\t * @param {module:engine/model/element~Element|module:engine/model/documentfragment~DocumentFragment} parent\n\t */\n\tappend( item, parent ) {\n\t\tthis.insert( item, parent, 'end' );\n\t}\n\n\t/**\n\t * Creates text node and inserts it at the end of the parent. You can optionally set text attributes:\n\t *\n\t *\t\twriter.appendText( 'foo', paragraph );\n\t *\t\twriter.appendText( 'foo', { bold: true }, paragraph );\n\t *\n\t * @param {String} text Text data.\n\t * @param {Object} [attributes] Text attributes.\n\t * @param {module:engine/model/element~Element|module:engine/model/documentfragment~DocumentFragment} parent\n\t */\n\tappendText( text, attributes, parent ) {\n\t\tif ( attributes instanceof DocumentFragment || attributes instanceof Element ) {\n\t\t\tthis.insert( this.createText( text ), attributes, 'end' );\n\t\t} else {\n\t\t\tthis.insert( this.createText( text, attributes ), parent, 'end' );\n\t\t}\n\t}\n\n\t/**\n\t * Creates element and inserts it at the end of the parent. You can optionally set attributes:\n\t *\n\t *\t\twriter.appendElement( 'paragraph', root );\n\t *\t\twriter.appendElement( 'paragraph', { alignment: 'center' }, root );\n\t *\n\t * @param {String} name Name of the element.\n\t * @param {Object} [attributes] Elements attributes.\n\t * @param {module:engine/model/element~Element|module:engine/model/documentfragment~DocumentFragment} parent\n\t */\n\tappendElement( name, attributes, parent ) {\n\t\tif ( attributes instanceof DocumentFragment || attributes instanceof Element ) {\n\t\t\tthis.insert( this.createElement( name ), attributes, 'end' );\n\t\t} else {\n\t\t\tthis.insert( this.createElement( name, attributes ), parent, 'end' );\n\t\t}\n\t}\n\n\t/**\n\t * Sets value of the attribute with given key on a {@link module:engine/model/item~Item model item}\n\t * or on a {@link module:engine/model/range~Range range}.\n\t *\n\t * @param {String} key Attribute key.\n\t * @param {*} value Attribute new value.\n\t * @param {module:engine/model/item~Item|module:engine/model/range~Range} itemOrRange\n\t * Model item or range on which the attribute will be set.\n\t */\n\tsetAttribute( key, value, itemOrRange ) {\n\t\tthis._assertWriterUsedCorrectly();\n\n\t\tif ( itemOrRange instanceof Range ) {\n\t\t\tconst ranges = itemOrRange.getMinimalFlatRanges();\n\n\t\t\tfor ( const range of ranges ) {\n\t\t\t\tsetAttributeOnRange( this, key, value, range );\n\t\t\t}\n\t\t} else {\n\t\t\tsetAttributeOnItem( this, key, value, itemOrRange );\n\t\t}\n\t}\n\n\t/**\n\t * Sets values of attributes on a {@link module:engine/model/item~Item model item}\n\t * or on a {@link module:engine/model/range~Range range}.\n\t *\n\t *\t\twriter.setAttributes( {\n\t *\t\t\tbold: true,\n\t *\t\t\titalic: true\n\t *\t\t}, range );\n\t *\n\t * @param {Object} attributes Attributes keys and values.\n\t * @param {module:engine/model/item~Item|module:engine/model/range~Range} itemOrRange\n\t * Model item or range on which the attributes will be set.\n\t */\n\tsetAttributes( attributes, itemOrRange ) {\n\t\tfor ( const [ key, val ] of toMap( attributes ) ) {\n\t\t\tthis.setAttribute( key, val, itemOrRange );\n\t\t}\n\t}\n\n\t/**\n\t * Removes an attribute with given key from a {@link module:engine/model/item~Item model item}\n\t * or from a {@link module:engine/model/range~Range range}.\n\t *\n\t * @param {String} key Attribute key.\n\t * @param {module:engine/model/item~Item|module:engine/model/range~Range} itemOrRange\n\t * Model item or range from which the attribute will be removed.\n\t */\n\tremoveAttribute( key, itemOrRange ) {\n\t\tthis._assertWriterUsedCorrectly();\n\n\t\tif ( itemOrRange instanceof Range ) {\n\t\t\tconst ranges = itemOrRange.getMinimalFlatRanges();\n\n\t\t\tfor ( const range of ranges ) {\n\t\t\t\tsetAttributeOnRange( this, key, null, range );\n\t\t\t}\n\t\t} else {\n\t\t\tsetAttributeOnItem( this, key, null, itemOrRange );\n\t\t}\n\t}\n\n\t/**\n\t * Removes all attributes from all elements in the range or from the given item.\n\t *\n\t * @param {module:engine/model/item~Item|module:engine/model/range~Range} itemOrRange\n\t * Model item or range from which all attributes will be removed.\n\t */\n\tclearAttributes( itemOrRange ) {\n\t\tthis._assertWriterUsedCorrectly();\n\n\t\tconst removeAttributesFromItem = item => {\n\t\t\tfor ( const attribute of item.getAttributeKeys() ) {\n\t\t\t\tthis.removeAttribute( attribute, item );\n\t\t\t}\n\t\t};\n\n\t\tif ( !( itemOrRange instanceof Range ) ) {\n\t\t\tremoveAttributesFromItem( itemOrRange );\n\t\t} else {\n\t\t\tfor ( const item of itemOrRange.getItems() ) {\n\t\t\t\tremoveAttributesFromItem( item );\n\t\t\t}\n\t\t}\n\t}\n\n\t/**\n\t * Moves all items in the source range to the target position.\n\t *\n\t *\t\twriter.move( sourceRange, targetPosition );\n\t *\n\t * Instead of the target position you can use parent and offset or define that range should be moved to the end\n\t * or before or after chosen item:\n\t *\n\t *\t\t// Moves all items in the range to the paragraph at offset 5:\n\t *\t\twriter.move( sourceRange, paragraph, 5 );\n\t *\t\t// Moves all items in the range to the end of a blockquote:\n\t *\t\twriter.move( sourceRange, blockquote, 'end' );\n\t *\t\t// Moves all items in the range to a position after an image:\n\t *\t\twriter.move( sourceRange, image, 'after' );\n\t *\n\t * These parameters works the same way as {@link module:engine/model/position~Position.createAt `Position.createAt()`}.\n\t *\n\t * Note that items can be moved only within the same tree. It means that you can move items within the same root\n\t * (element or document fragment) or between {@link module:engine/model/document~Document#roots documents roots},\n\t * but you can not move items from document fragment to the document or from one detached element to another. Use\n\t * {@link module:engine/model/writer~Writer#insert} in such cases.\n\t *\n\t * @param {module:engine/model/range~Range} range Source range.\n\t * @param {module:engine/model/item~Item|module:engine/model/position~Position} itemOrPosition\n\t * @param {Number|'end'|'before'|'after'} [offset=0] Offset or one of the flags. Used only when\n\t * second parameter is a {@link module:engine/model/item~Item model item}.\n\t */\n\tmove( range, itemOrPosition, offset ) {\n\t\tthis._assertWriterUsedCorrectly();\n\n\t\tif ( !( range instanceof Range ) ) {\n\t\t\t/**\n\t\t\t * Invalid range to move.\n\t\t\t *\n\t\t\t * @error writer-move-invalid-range\n\t\t\t */\n\t\t\tthrow new CKEditorError( 'writer-move-invalid-range: Invalid range to move.' );\n\t\t}\n\n\t\tif ( !range.isFlat ) {\n\t\t\t/**\n\t\t\t * Range to move is not flat.\n\t\t\t *\n\t\t\t * @error writer-move-range-not-flat\n\t\t\t */\n\t\t\tthrow new CKEditorError( 'writer-move-range-not-flat: Range to move is not flat.' );\n\t\t}\n\n\t\tconst position = Position.createAt( itemOrPosition, offset );\n\n\t\tif ( !isSameTree( range.root, position.root ) ) {\n\t\t\t/**\n\t\t\t * Range is going to be moved within not the same document. Please use\n\t\t\t * {@link module:engine/model/writer~Writer#insert insert} instead.\n\t\t\t *\n\t\t\t * @error writer-move-different-document\n\t\t\t */\n\t\t\tthrow new CKEditorError( 'writer-move-different-document: Range is going to be moved between different documents.' );\n\t\t}\n\n\t\tconst version = range.root.document ? range.root.document.version : null;\n\t\tconst operation = new MoveOperation( range.start, range.end.offset - range.start.offset, position, version );\n\n\t\tthis.batch.addOperation( operation );\n\t\tthis.model.applyOperation( operation );\n\t}\n\n\t/**\n\t * Removes given model {@link module:engine/model/item~Item item} or {@link module:engine/model/range~Range range}.\n\t *\n\t * @param {module:engine/model/item~Item|module:engine/model/range~Range} itemOrRange Model item or range to remove.\n\t */\n\tremove( itemOrRange ) {\n\t\tthis._assertWriterUsedCorrectly();\n\n\t\tif ( itemOrRange instanceof Range ) {\n\t\t\t// The array is reversed, so the ranges to remove are in correct order and do not have to be updated.\n\t\t\tconst ranges = itemOrRange.getMinimalFlatRanges().reverse();\n\n\t\t\tfor ( const flat of ranges ) {\n\t\t\t\tapplyRemoveOperation( flat.start, flat.end.offset - flat.start.offset, this.batch, this.model );\n\t\t\t}\n\t\t} else {\n\t\t\tconst howMany = itemOrRange.is( 'text' ) ? itemOrRange.offsetSize : 1;\n\n\t\t\tapplyRemoveOperation( Position.createBefore( itemOrRange ), howMany, this.batch, this.model );\n\t\t}\n\t}\n\n\t/**\n\t * Merges two siblings at the given position.\n\t *\n\t * Node before and after the position have to be an element. Otherwise `writer-merge-no-element-before` or\n\t * `writer-merge-no-element-after` error will be thrown.\n\t *\n\t * @param {module:engine/model/position~Position} position Position between merged elements.\n\t */\n\tmerge( position ) {\n\t\tthis._assertWriterUsedCorrectly();\n\n\t\tconst nodeBefore = position.nodeBefore;\n\t\tconst nodeAfter = position.nodeAfter;\n\n\t\tif ( !( nodeBefore instanceof Element ) ) {\n\t\t\t/**\n\t\t\t * Node before merge position must be an element.\n\t\t\t *\n\t\t\t * @error writer-merge-no-element-before\n\t\t\t */\n\t\t\tthrow new CKEditorError( 'writer-merge-no-element-before: Node before merge position must be an element.' );\n\t\t}\n\n\t\tif ( !( nodeAfter instanceof Element ) ) {\n\t\t\t/**\n\t\t\t * Node after merge position must be an element.\n\t\t\t *\n\t\t\t * @error writer-merge-no-element-after\n\t\t\t */\n\t\t\tthrow new CKEditorError( 'writer-merge-no-element-after: Node after merge position must be an element.' );\n\t\t}\n\n\t\tif ( !position.root.document ) {\n\t\t\tthis._mergeDetached( position );\n\t\t} else {\n\t\t\tthis._merge( position );\n\t\t}\n\t}\n\n\t/**\n\t * Performs merge action in a detached tree.\n\t *\n\t * @private\n\t * @param {module:engine/model/position~Position} position Position between merged elements.\n\t */\n\t_mergeDetached( position ) {\n\t\tconst nodeBefore = position.nodeBefore;\n\t\tconst nodeAfter = position.nodeAfter;\n\n\t\tthis.move( Range.createIn( nodeAfter ), Position.createAt( nodeBefore, 'end' ) );\n\t\tthis.remove( nodeAfter );\n\t}\n\n\t/**\n\t * Performs merge action in a non-detached tree.\n\t *\n\t * @private\n\t * @param {module:engine/model/position~Position} position Position between merged elements.\n\t */\n\t_merge( position ) {\n\t\tconst targetPosition = Position.createAt( position.nodeBefore, 'end' );\n\t\tconst sourcePosition = Position.createAt( position.nodeAfter, 0 );\n\n\t\tconst graveyard = position.root.document.graveyard;\n\t\tconst graveyardPosition = new Position( graveyard, [ 0 ] );\n\n\t\tconst version = position.root.document.version;\n\n\t\tconst merge = new MergeOperation( sourcePosition, position.nodeAfter.maxOffset, targetPosition, graveyardPosition, version );\n\n\t\tthis.batch.addOperation( merge );\n\t\tthis.model.applyOperation( merge );\n\t}\n\n\t/**\n\t * Renames the given element.\n\t *\n\t * @param {module:engine/model/element~Element} element The element to rename.\n\t * @param {String} newName New element name.\n\t */\n\trename( element, newName ) {\n\t\tthis._assertWriterUsedCorrectly();\n\n\t\tif ( !( element instanceof Element ) ) {\n\t\t\t/**\n\t\t\t * Trying to rename an object which is not an instance of Element.\n\t\t\t *\n\t\t\t * @error writer-rename-not-element-instance\n\t\t\t */\n\t\t\tthrow new CKEditorError(\n\t\t\t\t'writer-rename-not-element-instance: Trying to rename an object which is not an instance of Element.'\n\t\t\t);\n\t\t}\n\n\t\tconst version = element.root.document ? element.root.document.version : null;\n\t\tconst renameOperation = new RenameOperation( Position.createBefore( element ), element.name, newName, version );\n\n\t\tthis.batch.addOperation( renameOperation );\n\t\tthis.model.applyOperation( renameOperation );\n\t}\n\n\t/**\n\t * Splits elements starting from the given position and going to the top of the model tree as long as given\n\t * `limitElement` is reached. When `limitElement` is not defined then only the parent of the given position will be split.\n\t *\n\t * The element needs to have a parent. It cannot be a root element nor a document fragment.\n\t * The `writer-split-element-no-parent` error will be thrown if you try to split an element with no parent.\n\t *\n\t * @param {module:engine/model/position~Position} position Position of split.\n\t * @param {module:engine/model/node~Node} [limitElement] Stop splitting when this element will be reached.\n\t * @returns {Object} result Split result.\n\t * @returns {module:engine/model/position~Position} result.position between split elements.\n\t * @returns {module:engine/model/range~Range} result.range Range that stars from the end of the first split element and ands\n\t * at the beginning of the first copy element.\n\t */\n\tsplit( position, limitElement ) {\n\t\tthis._assertWriterUsedCorrectly();\n\n\t\tlet splitElement = position.parent;\n\n\t\tif ( !splitElement.parent ) {\n\t\t\t/**\n\t\t\t * Element with no parent can not be split.\n\t\t\t *\n\t\t\t * @error writer-split-element-no-parent\n\t\t\t */\n\t\t\tthrow new CKEditorError( 'writer-split-element-no-parent: Element with no parent can not be split.' );\n\t\t}\n\n\t\t// When limit element is not defined lets set splitElement parent as limit.\n\t\tif ( !limitElement ) {\n\t\t\tlimitElement = splitElement.parent;\n\t\t}\n\n\t\tif ( !position.parent.getAncestors( { includeSelf: true } ).includes( limitElement ) ) {\n\t\t\tthrow new CKEditorError( 'writer-split-invalid-limit-element: Limit element is not a position ancestor.' );\n\t\t}\n\n\t\t// We need to cache elements that will be created as a result of the first split because\n\t\t// we need to create a range from the end of the first split element to the beginning of the\n\t\t// first copy element. This should be handled by LiveRange but it doesn't work on detached nodes.\n\t\tlet firstSplitElement, firstCopyElement;\n\n\t\tdo {\n\t\t\tconst version = splitElement.root.document ? splitElement.root.document.version : null;\n\t\t\tconst howMany = splitElement.maxOffset - position.offset;\n\t\t\tconst split = new SplitOperation( position, howMany, null, version );\n\n\t\t\tthis.batch.addOperation( split );\n\t\t\tthis.model.applyOperation( split );\n\n\t\t\t// Cache result of the first split.\n\t\t\tif ( !firstSplitElement && !firstCopyElement ) {\n\t\t\t\tfirstSplitElement = splitElement;\n\t\t\t\tfirstCopyElement = position.parent.nextSibling;\n\t\t\t}\n\n\t\t\tposition = Position.createAfter( position.parent );\n\t\t\tsplitElement = position.parent;\n\t\t} while ( splitElement !== limitElement );\n\n\t\treturn {\n\t\t\tposition,\n\t\t\trange: new Range( Position.createAt( firstSplitElement, 'end' ), Position.createAt( firstCopyElement ) )\n\t\t};\n\t}\n\n\t/**\n\t * Wraps the given range with the given element or with a new element (if a string was passed).\n\t *\n\t * **Note:** range to wrap should be a \"flat range\" (see {@link module:engine/model/range~Range#isFlat `Range#isFlat`}).\n\t * If not, an error will be thrown.\n\t *\n\t * @param {module:engine/model/range~Range} range Range to wrap.\n\t * @param {module:engine/model/element~Element|String} elementOrString Element or name of element to wrap the range with.\n\t */\n\twrap( range, elementOrString ) {\n\t\tthis._assertWriterUsedCorrectly();\n\n\t\tif ( !range.isFlat ) {\n\t\t\t/**\n\t\t\t * Range to wrap is not flat.\n\t\t\t *\n\t\t\t * @error writer-wrap-range-not-flat\n\t\t\t */\n\t\t\tthrow new CKEditorError( 'writer-wrap-range-not-flat: Range to wrap is not flat.' );\n\t\t}\n\n\t\tconst element = elementOrString instanceof Element ? elementOrString : new Element( elementOrString );\n\n\t\tif ( element.childCount > 0 ) {\n\t\t\t/**\n\t\t\t * Element to wrap with is not empty.\n\t\t\t *\n\t\t\t * @error writer-wrap-element-not-empty\n\t\t\t */\n\t\t\tthrow new CKEditorError( 'writer-wrap-element-not-empty: Element to wrap with is not empty.' );\n\t\t}\n\n\t\tif ( element.parent !== null ) {\n\t\t\t/**\n\t\t\t * Element to wrap with is already attached to a tree model.\n\t\t\t *\n\t\t\t * @error writer-wrap-element-attached\n\t\t\t */\n\t\t\tthrow new CKEditorError( 'writer-wrap-element-attached: Element to wrap with is already attached to tree model.' );\n\t\t}\n\n\t\tconst version = range.root.document ? range.root.document.version : null;\n\n\t\t// Has to be `range.start` not `range.end` for better transformations.\n\t\tconst insert = new InsertOperation( range.start, element, version );\n\t\tthis.batch.addOperation( insert );\n\t\tthis.model.applyOperation( insert );\n\n\t\tconst move = new MoveOperation(\n\t\t\trange.start.getShiftedBy( 1 ),\n\t\t\trange.end.offset - range.start.offset,\n\t\t\tPosition.createAt( element, 0 ),\n\t\t\tversion === null ? null : version + 1\n\t\t);\n\n\t\tthis.batch.addOperation( move );\n\t\tthis.model.applyOperation( move );\n\t}\n\n\t/**\n\t * Unwraps children of the given element – all its children are moved before it and then the element is removed.\n\t * Throws error if you try to unwrap an element which does not have a parent.\n\t *\n\t * @param {module:engine/model/element~Element} element Element to unwrap.\n\t */\n\tunwrap( element ) {\n\t\tthis._assertWriterUsedCorrectly();\n\n\t\tif ( element.parent === null ) {\n\t\t\t/**\n\t\t\t * Trying to unwrap an element which has no parent.\n\t\t\t *\n\t\t\t * @error writer-unwrap-element-no-parent\n\t\t\t */\n\t\t\tthrow new CKEditorError( 'writer-unwrap-element-no-parent: Trying to unwrap an element which has no parent.' );\n\t\t}\n\n\t\tthis.move( Range.createIn( element ), Position.createAfter( element ) );\n\t\tthis.remove( element );\n\t}\n\n\t/**\n\t * Adds a {@link module:engine/model/markercollection~Marker marker}. Marker is a named range, which tracks\n\t * changes in the document and updates its range automatically, when model tree changes.\n\t *\n\t * As the first parameter you can set marker name.\n\t *\n\t * The required `options.usingOperation` parameter lets you decide if the marker should be managed by operations or not. See\n\t * {@link module:engine/model/markercollection~Marker marker class description} to learn about the difference between\n\t * markers managed by operations and not-managed by operations.\n\t *\n\t * The `options.affectsData` parameter, which defaults to `false`, allows you to define if a marker affects the data. It should be\n\t * `true` when the marker change changes the data returned by the\n\t * {@link module:core/editor/utils/dataapimixin~DataApi#getData `editor.getData()`} method.\n\t * When set to `true` it fires the {@link module:engine/model/document~Document#event:change:data `change:data`} event.\n\t * When set to `false` it fires the {@link module:engine/model/document~Document#event:change `change`} event.\n\t *\n\t * Create marker directly base on marker's name:\n\t *\n\t *\t\taddMarker( markerName, { range, usingOperation: false } );\n\t *\n\t * Create marker using operation:\n\t *\n\t *\t\taddMarker( markerName, { range, usingOperation: true } );\n\t *\n\t * Create marker that affects the editor data:\n\t *\n\t *\t\taddMarker( markerName, { range, usingOperation: false, affectsData: true } );\n\t *\n\t * Note: For efficiency reasons, it's best to create and keep as little markers as possible.\n\t *\n\t * @see module:engine/model/markercollection~Marker\n\t * @param {String} name Name of a marker to create - must be unique.\n\t * @param {Object} options\n\t * @param {Boolean} options.usingOperation Flag indicating that the marker should be added by MarkerOperation.\n\t * See {@link module:engine/model/markercollection~Marker#managedUsingOperations}.\n\t * @param {module:engine/model/range~Range} options.range Marker range.\n\t * @param {Boolean} [options.affectsData=false] Flag indicating that the marker changes the editor data.\n\t * @returns {module:engine/model/markercollection~Marker} Marker that was set.\n\t */\n\taddMarker( name, options ) {\n\t\tthis._assertWriterUsedCorrectly();\n\n\t\tif ( !options || typeof options.usingOperation != 'boolean' ) {\n\t\t\t/**\n\t\t\t * The `options.usingOperations` parameter is required when adding a new marker.\n\t\t\t *\n\t\t\t * @error writer-addMarker-no-usingOperations\n\t\t\t */\n\t\t\tthrow new CKEditorError(\n\t\t\t\t'writer-addMarker-no-usingOperations: The options.usingOperations parameter is required when adding a new marker.'\n\t\t\t);\n\t\t}\n\n\t\tconst usingOperation = options.usingOperation;\n\t\tconst range = options.range;\n\t\tconst affectsData = options.affectsData === undefined ? false : options.affectsData;\n\n\t\tif ( this.model.markers.has( name ) ) {\n\t\t\t/**\n\t\t\t * Marker with provided name already exists.\n\t\t\t *\n\t\t\t * @error writer-addMarker-marker-exists\n\t\t\t */\n\t\t\tthrow new CKEditorError( 'writer-addMarker-marker-exists: Marker with provided name already exists.' );\n\t\t}\n\n\t\tif ( !range ) {\n\t\t\t/**\n\t\t\t * Range parameter is required when adding a new marker.\n\t\t\t *\n\t\t\t * @error writer-addMarker-no-range\n\t\t\t */\n\t\t\tthrow new CKEditorError( 'writer-addMarker-no-range: Range parameter is required when adding a new marker.' );\n\t\t}\n\n\t\tif ( !usingOperation ) {\n\t\t\treturn this.model.markers._set( name, range, usingOperation, affectsData );\n\t\t}\n\n\t\tapplyMarkerOperation( this, name, null, range, affectsData );\n\n\t\treturn this.model.markers.get( name );\n\t}\n\n\t/**\n\t * Adds or updates a {@link module:engine/model/markercollection~Marker marker}. Marker is a named range, which tracks\n\t * changes in the document and updates its range automatically, when model tree changes. Still, it is possible to change the\n\t * marker's range directly using this method.\n\t *\n\t * As the first parameter you can set marker name or instance. If none of them is provided, new marker, with a unique\n\t * name is created and returned.\n\t *\n\t * The `options.usingOperation` parameter lets you change if the marker should be managed by operations or not. See\n\t * {@link module:engine/model/markercollection~Marker marker class description} to learn about the difference between\n\t * markers managed by operations and not-managed by operations. It is possible to change this option for an existing marker.\n\t *\n\t * The `options.affectsData` parameter, which defaults to `false`, allows you to define if a marker affects the data. It should be\n\t * `true` when the marker change changes the data returned by\n\t * the {@link module:core/editor/utils/dataapimixin~DataApi#getData `editor.getData()`} method.\n\t * When set to `true` it fires the {@link module:engine/model/document~Document#event:change:data `change:data`} event.\n\t * When set to `false` it fires the {@link module:engine/model/document~Document#event:change `change`} event.\n\t *\n\t * Update marker directly base on marker's name:\n\t *\n\t *\t\tupdateMarker( markerName, { range } );\n\t *\n\t * Update marker using operation:\n\t *\n\t *\t\tupdateMarker( marker, { range, usingOperation: true } );\n\t *\t\tupdateMarker( markerName, { range, usingOperation: true } );\n\t *\n\t * Change marker's option (start using operations to manage it):\n\t *\n\t *\t\tupdateMarker( marker, { usingOperation: true } );\n\t *\n\t * Change marker's option (inform the engine, that the marker does not affect the data anymore):\n\t *\n\t *\t\tupdateMarker( markerName, { affectsData: false } );\n\t *\n\t * @see module:engine/model/markercollection~Marker\n\t * @param {String} markerOrName Name of a marker to update, or a marker instance.\n\t * @param {Object} options\n\t * @param {module:engine/model/range~Range} [options.range] Marker range to update.\n\t * @param {Boolean} [options.usingOperation] Flag indicated whether the marker should be added by MarkerOperation.\n\t * See {@link module:engine/model/markercollection~Marker#managedUsingOperations}.\n\t * @param {Boolean} [options.affectsData] Flag indicating that the marker changes the editor data.\n\t */\n\tupdateMarker( markerOrName, options = {} ) {\n\t\tthis._assertWriterUsedCorrectly();\n\n\t\tconst markerName = typeof markerOrName == 'string' ? markerOrName : markerOrName.name;\n\t\tconst currentMarker = this.model.markers.get( markerName );\n\n\t\tif ( !currentMarker ) {\n\t\t\t/**\n\t\t\t * Marker with provided name does not exists.\n\t\t\t *\n\t\t\t * @error writer-updateMarker-marker-not-exists\n\t\t\t */\n\t\t\tthrow new CKEditorError( 'writer-updateMarker-marker-not-exists: Marker with provided name does not exists.' );\n\t\t}\n\n\t\tconst hasUsingOperationDefined = typeof options.usingOperation == 'boolean';\n\t\tconst affectsDataDefined = typeof options.affectsData == 'boolean';\n\n\t\t// Use previously defined marker's affectsData if the property is not provided.\n\t\tconst affectsData = affectsDataDefined ? options.affectsData : currentMarker.affectsData;\n\n\t\tif ( !hasUsingOperationDefined && !options.range && !affectsDataDefined ) {\n\t\t\t/**\n\t\t\t * One of the options is required - provide range, usingOperations or affectsData.\n\t\t\t *\n\t\t\t * @error writer-updateMarker-wrong-options\n\t\t\t */\n\t\t\tthrow new CKEditorError(\n\t\t\t\t'writer-updateMarker-wrong-options: One of the options is required - provide range, usingOperations or affectsData.'\n\t\t\t);\n\t\t}\n\n\t\tconst currentRange = currentMarker.getRange();\n\t\tconst updatedRange = options.range ? options.range : currentRange;\n\n\t\tif ( hasUsingOperationDefined && options.usingOperation !== currentMarker.managedUsingOperations ) {\n\t\t\t// The marker type is changed so it's necessary to create proper operations.\n\t\t\tif ( options.usingOperation ) {\n\t\t\t\t// If marker changes to a managed one treat this as synchronizing existing marker.\n\t\t\t\t// Create `MarkerOperation` with `oldRange` set to `null`, so reverse operation will remove the marker.\n\t\t\t\tapplyMarkerOperation( this, markerName, null, updatedRange, affectsData );\n\t\t\t} else {\n\t\t\t\t// If marker changes to a marker that do not use operations then we need to create additional operation\n\t\t\t\t// that removes that marker first.\n\t\t\t\tapplyMarkerOperation( this, markerName, currentRange, null, affectsData );\n\n\t\t\t\t// Although not managed the marker itself should stay in model and its range should be preserver or changed to passed range.\n\t\t\t\tthis.model.markers._set( markerName, updatedRange, undefined, affectsData );\n\t\t\t}\n\n\t\t\treturn;\n\t\t}\n\n\t\t// Marker's type doesn't change so update it accordingly.\n\t\tif ( currentMarker.managedUsingOperations ) {\n\t\t\tapplyMarkerOperation( this, markerName, currentRange, updatedRange, affectsData );\n\t\t} else {\n\t\t\tthis.model.markers._set( markerName, updatedRange, undefined, affectsData );\n\t\t}\n\t}\n\n\t/**\n\t * Removes given {@link module:engine/model/markercollection~Marker marker} or marker with given name.\n\t * The marker is removed accordingly to how it has been created, so if the marker was created using operation,\n\t * it will be destroyed using operation.\n\t *\n\t * @param {module:engine/model/markercollection~Marker|String} markerOrName Marker or marker name to remove.\n\t */\n\tremoveMarker( markerOrName ) {\n\t\tthis._assertWriterUsedCorrectly();\n\n\t\tconst name = typeof markerOrName == 'string' ? markerOrName : markerOrName.name;\n\n\t\tif ( !this.model.markers.has( name ) ) {\n\t\t\t/**\n\t\t\t * Trying to remove marker which does not exist.\n\t\t\t *\n\t\t\t * @error writer-removeMarker-no-marker\n\t\t\t */\n\t\t\tthrow new CKEditorError( 'writer-removeMarker-no-marker: Trying to remove marker which does not exist.' );\n\t\t}\n\n\t\tconst marker = this.model.markers.get( name );\n\n\t\tif ( !marker.managedUsingOperations ) {\n\t\t\tthis.model.markers._remove( name );\n\n\t\t\treturn;\n\t\t}\n\n\t\tconst oldRange = marker.getRange();\n\n\t\tapplyMarkerOperation( this, name, oldRange, null, marker.affectsData );\n\t}\n\n\t/**\n\t * Sets this selection's ranges and direction to the specified location based on the given\n\t * {@link module:engine/model/selection~Selection selection}, {@link module:engine/model/position~Position position},\n\t * {@link module:engine/model/node~Node node}, {@link module:engine/model/position~Position position},\n\t * {@link module:engine/model/range~Range range}, an iterable of {@link module:engine/model/range~Range ranges} or null.\n\t *\n\t *\t\t// Sets selection to the given range.\n\t *\t\tconst range = new Range( start, end );\n\t *\t\twriter.setSelection( range );\n\t *\n\t *\t\t// Sets selection to given ranges.\n\t *\t\tconst ranges = [ new Range( start1, end2 ), new Range( star2, end2 ) ];\n\t *\t\twriter.setSelection( range );\n\t *\n\t *\t\t// Sets selection to other selection.\n\t *\t\tconst otherSelection = new Selection();\n\t *\t\twriter.setSelection( otherSelection );\n\t *\n\t *\t\t// Sets selection to the given document selection.\n\t *\t\tconst documentSelection = new DocumentSelection( doc );\n\t *\t\twriter.setSelection( documentSelection );\n\t *\n\t *\t\t// Sets collapsed selection at the given position.\n\t *\t\tconst position = new Position( root, path );\n\t *\t\twriter.setSelection( position );\n\t *\n\t *\t\t// Sets collapsed selection at the position of the given node and an offset.\n\t *\t\twriter.setSelection( paragraph, offset );\n\t *\n\t * Creates a range inside an {@link module:engine/model/element~Element element} which starts before the first child of\n \t * that element and ends after the last child of that element.\n\t *\n\t *\t\twriter.setSelection( paragraph, 'in' );\n\t *\n\t * Creates a range on an {@link module:engine/model/item~Item item} which starts before the item and ends just after the item.\n\t *\n\t *\t\twriter.setSelection( paragraph, 'on' );\n\t *\n\t *\t\t// Removes all selection's ranges.\n\t *\t\twriter.setSelection( null );\n\t *\n\t * `Writer#setSelection()` allow passing additional options (`backward`) as the last argument.\n\t *\n\t *\t\t// Sets selection as backward.\n\t *\t\twriter.setSelection( range, { backward: true } );\n\t *\n\t * Throws `writer-incorrect-use` error when the writer is used outside the `change()` block.\n\t *\n\t * @param {module:engine/model/selection~Selection|module:engine/model/documentselection~DocumentSelection|\n\t * module:engine/model/position~Position|module:engine/model/node~Node|\n\t * Iterable.|module:engine/model/range~Range|null} selectable\n\t * @param {Number|'before'|'end'|'after'|'on'|'in'} [placeOrOffset] Sets place or offset of the selection.\n\t * @param {Object} [options]\n\t * @param {Boolean} [options.backward] Sets this selection instance to be backward.\n\t */\n\tsetSelection( selectable, placeOrOffset, options ) {\n\t\tthis._assertWriterUsedCorrectly();\n\n\t\tthis.model.document.selection._setTo( selectable, placeOrOffset, options );\n\t}\n\n\t/**\n\t * Moves {@link module:engine/model/documentselection~DocumentSelection#focus} to the specified location.\n\t *\n\t * The location can be specified in the same form as\n\t * {@link module:engine/model/position~Position.createAt `Position.createAt()`} parameters.\n\t *\n\t * @param {module:engine/model/item~Item|module:engine/model/position~Position} itemOrPosition\n\t * @param {Number|'end'|'before'|'after'} [offset=0] Offset or one of the flags. Used only when\n\t * first parameter is a {@link module:engine/model/item~Item model item}.\n\t */\n\tsetSelectionFocus( itemOrPosition, offset ) {\n\t\tthis._assertWriterUsedCorrectly();\n\n\t\tthis.model.document.selection._setFocus( itemOrPosition, offset );\n\t}\n\n\t/**\n\t * Sets attribute(s) on the selection. If attribute with the same key already is set, it's value is overwritten.\n\t *\n\t * Using key and value pair:\n\t *\n\t * \twriter.setSelectionAttribute( 'italic', true );\n\t *\n\t * Using key-value object:\n\t *\n\t * \twriter.setSelectionAttribute( { italic: true, bold: false } );\n\t *\n\t * Using iterable object:\n\t *\n\t * \twriter.setSelectionAttribute( new Map( [ [ 'italic', true ] ] ) );\n\t *\n\t * @param {String|Object|Iterable.<*>} keyOrObjectOrIterable Key of the attribute to set\n\t * or object / iterable of key => value attribute pairs.\n\t * @param {*} [value] Attribute value.\n\t */\n\tsetSelectionAttribute( keyOrObjectOrIterable, value ) {\n\t\tthis._assertWriterUsedCorrectly();\n\n\t\tif ( typeof keyOrObjectOrIterable === 'string' ) {\n\t\t\tthis._setSelectionAttribute( keyOrObjectOrIterable, value );\n\t\t} else {\n\t\t\tfor ( const [ key, value ] of toMap( keyOrObjectOrIterable ) ) {\n\t\t\t\tthis._setSelectionAttribute( key, value );\n\t\t\t}\n\t\t}\n\t}\n\n\t/**\n\t * Removes attribute(s) with given key(s) from the selection.\n\t *\n\t * Remove one attribute:\n\t *\n\t *\t\twriter.removeSelectionAttribute( 'italic' );\n\t *\n\t * Remove multiple attributes:\n\t *\n\t *\t\twriter.removeSelectionAttribute( [ 'italic', 'bold' ] );\n\t *\n\t * @param {String|Iterable.} keyOrIterableOfKeys Key of the attribute to remove or an iterable of attribute keys to remove.\n\t */\n\tremoveSelectionAttribute( keyOrIterableOfKeys ) {\n\t\tthis._assertWriterUsedCorrectly();\n\n\t\tif ( typeof keyOrIterableOfKeys === 'string' ) {\n\t\t\tthis._removeSelectionAttribute( keyOrIterableOfKeys );\n\t\t} else {\n\t\t\tfor ( const key of keyOrIterableOfKeys ) {\n\t\t\t\tthis._removeSelectionAttribute( key );\n\t\t\t}\n\t\t}\n\t}\n\n\t/**\n\t * Temporarily changes the {@link module:engine/model/documentselection~DocumentSelection#isGravityOverridden gravity}\n\t * of the selection from left to right.\n\t *\n\t * The gravity defines from which direction the selection inherits its attributes. If it's the default left gravity,\n\t * then the selection (after being moved by the user) inherits attributes from its left-hand side.\n\t * This method allows to temporarily override this behavior by forcing the gravity to the right.\n\t *\n\t * For the following model fragment:\n\t *\n\t *\t\t<$text bold=\"true\" linkHref=\"url\">bar[]$text><$text bold=\"true\">biz$text>\n\t *\n\t * * Default gravity: selection will have the `bold` and `linkHref` attributes.\n\t * * Overridden gravity: selection will have `bold` attribute.\n\t *\n\t * **Note**: It returns an unique identifier which is required to restore the gravity. It guarantees the symmetry\n\t * of the process.\n\t *\n\t * @returns {String} The unique id which allows restoring the gravity.\n\t */\n\toverrideSelectionGravity() {\n\t\treturn this.model.document.selection._overrideGravity();\n\t}\n\n\t/**\n\t * Restores {@link ~Writer#overrideSelectionGravity} gravity to default.\n\t *\n\t * Restoring the gravity is only possible using the unique identifier returned by\n\t * {@link ~Writer#overrideSelectionGravity}. Note that the gravity remains overridden as long as won't be restored\n\t * the same number of times it was overridden.\n\t *\n\t * @param {String} uid The unique id returned by {@link ~Writer#overrideSelectionGravity}.\n\t */\n\trestoreSelectionGravity( uid ) {\n\t\tthis.model.document.selection._restoreGravity( uid );\n\t}\n\n\t/**\n\t * @private\n\t * @param {String} key Key of the attribute to remove.\n\t * @param {*} value Attribute value.\n\t */\n\t_setSelectionAttribute( key, value ) {\n\t\tconst selection = this.model.document.selection;\n\n\t\t// Store attribute in parent element if the selection is collapsed in an empty node.\n\t\tif ( selection.isCollapsed && selection.anchor.parent.isEmpty ) {\n\t\t\tconst storeKey = DocumentSelection._getStoreAttributeKey( key );\n\n\t\t\tthis.setAttribute( storeKey, value, selection.anchor.parent );\n\t\t}\n\n\t\tselection._setAttribute( key, value );\n\t}\n\n\t/**\n\t * @private\n\t * @param {String} key Key of the attribute to remove.\n\t */\n\t_removeSelectionAttribute( key ) {\n\t\tconst selection = this.model.document.selection;\n\n\t\t// Remove stored attribute from parent element if the selection is collapsed in an empty node.\n\t\tif ( selection.isCollapsed && selection.anchor.parent.isEmpty ) {\n\t\t\tconst storeKey = DocumentSelection._getStoreAttributeKey( key );\n\n\t\t\tthis.removeAttribute( storeKey, selection.anchor.parent );\n\t\t}\n\n\t\tselection._removeAttribute( key );\n\t}\n\n\t/**\n\t * Throws `writer-detached-writer-tries-to-modify-model` error when the writer is used outside of the `change()` block.\n\t *\n\t * @private\n\t */\n\t_assertWriterUsedCorrectly() {\n\t\t/**\n\t\t * Trying to use a writer outside a {@link module:engine/model/model~Model#change `change()` or\n\t\t * {@link module:engine/model/model~Model#enqueueChange `enqueueChange()`} blocks.\n\t\t *\n\t\t * The writer can only be used inside these blocks which ensures that the model\n\t\t * can only be changed during such \"sessions\".\n\t\t *\n\t\t * @error writer-incorrect-use\n\t\t */\n\t\tif ( this.model._currentWriter !== this ) {\n\t\t\tthrow new CKEditorError( 'writer-incorrect-use: Trying to use a writer outside the change() block.' );\n\t\t}\n\t}\n}\n\n// Sets given attribute to each node in given range. When attribute value is null then attribute will be removed.\n//\n// Because attribute operation needs to have the same attribute value on the whole range, this function splits\n// the range into smaller parts.\n//\n// Given `range` must be flat.\n//\n// @private\n// @param {module:engine/model/writer~Writer} writer\n// @param {String} key Attribute key.\n// @param {*} value Attribute new value.\n// @param {module:engine/model/range~Range} range Model range on which the attribute will be set.\nfunction setAttributeOnRange( writer, key, value, range ) {\n\tconst model = writer.model;\n\tconst doc = model.document;\n\n\t// Position of the last split, the beginning of the new range.\n\tlet lastSplitPosition = range.start;\n\n\t// Currently position in the scanning range. Because we need value after the position, it is not a current\n\t// position of the iterator but the previous one (we need to iterate one more time to get the value after).\n\tlet position;\n\n\t// Value before the currently position.\n\tlet valueBefore;\n\n\t// Value after the currently position.\n\tlet valueAfter;\n\n\tfor ( const val of range.getWalker( { shallow: true } ) ) {\n\t\tvalueAfter = val.item.getAttribute( key );\n\n\t\t// At the first run of the iterator the position in undefined. We also do not have a valueBefore, but\n\t\t// because valueAfter may be null, valueBefore may be equal valueAfter ( undefined == null ).\n\t\tif ( position && valueBefore != valueAfter ) {\n\t\t\t// if valueBefore == value there is nothing to change, so we add operation only if these values are different.\n\t\t\tif ( valueBefore != value ) {\n\t\t\t\taddOperation();\n\t\t\t}\n\n\t\t\tlastSplitPosition = position;\n\t\t}\n\n\t\tposition = val.nextPosition;\n\t\tvalueBefore = valueAfter;\n\t}\n\n\t// Because position in the loop is not the iterator position (see let position comment), the last position in\n\t// the while loop will be last but one position in the range. We need to check the last position manually.\n\tif ( position instanceof Position && position != lastSplitPosition && valueBefore != value ) {\n\t\taddOperation();\n\t}\n\n\tfunction addOperation() {\n\t\tconst range = new Range( lastSplitPosition, position );\n\t\tconst version = range.root.document ? doc.version : null;\n\t\tconst operation = new AttributeOperation( range, key, valueBefore, value, version );\n\n\t\twriter.batch.addOperation( operation );\n\t\tmodel.applyOperation( operation );\n\t}\n}\n\n// Sets given attribute to the given node. When attribute value is null then attribute will be removed.\n//\n// @private\n// @param {module:engine/model/writer~Writer} writer\n// @param {String} key Attribute key.\n// @param {*} value Attribute new value.\n// @param {module:engine/model/item~Item} item Model item on which the attribute will be set.\nfunction setAttributeOnItem( writer, key, value, item ) {\n\tconst model = writer.model;\n\tconst doc = model.document;\n\tconst previousValue = item.getAttribute( key );\n\tlet range, operation;\n\n\tif ( previousValue != value ) {\n\t\tconst isRootChanged = item.root === item;\n\n\t\tif ( isRootChanged ) {\n\t\t\t// If we change attributes of root element, we have to use `RootAttributeOperation`.\n\t\t\tconst version = item.document ? doc.version : null;\n\n\t\t\toperation = new RootAttributeOperation( item, key, previousValue, value, version );\n\t\t} else {\n\t\t\trange = new Range( Position.createBefore( item ), Position.createAfter( item ) );\n\n\t\t\tconst version = range.root.document ? doc.version : null;\n\n\t\t\toperation = new AttributeOperation( range, key, previousValue, value, version );\n\t\t}\n\n\t\twriter.batch.addOperation( operation );\n\t\tmodel.applyOperation( operation );\n\t}\n}\n\n// Creates and applies marker operation to {@link module:engine/model/operation/operation~Operation operation}.\n//\n// @private\n// @param {module:engine/model/writer~Writer} writer\n// @param {String} name Marker name.\n// @param {module:engine/model/range~Range} oldRange Marker range before the change.\n// @param {module:engine/model/range~Range} newRange Marker range after the change.\n// @param {Boolean} affectsData\nfunction applyMarkerOperation( writer, name, oldRange, newRange, affectsData ) {\n\tconst model = writer.model;\n\tconst doc = model.document;\n\n\tconst operation = new MarkerOperation( name, oldRange, newRange, model.markers, affectsData, doc.version );\n\n\twriter.batch.addOperation( operation );\n\tmodel.applyOperation( operation );\n}\n\n// Creates `MoveOperation` or `DetachOperation` that removes `howMany` nodes starting from `position`.\n// The operation will be applied on given model instance and added to given operation instance.\n//\n// @private\n// @param {module:engine/model/position~Position} position Position from which nodes are removed.\n// @param {Number} howMany Number of nodes to remove.\n// @param {Batch} batch Batch to which the operation will be added.\n// @param {module:engine/model/model~Model} model Model instance on which operation will be applied.\nfunction applyRemoveOperation( position, howMany, batch, model ) {\n\tlet operation;\n\n\tif ( position.root.document ) {\n\t\tconst doc = model.document;\n\t\tconst graveyardPosition = new Position( doc.graveyard, [ 0 ] );\n\n\t\toperation = new MoveOperation( position, howMany, graveyardPosition, doc.version );\n\t} else {\n\t\toperation = new DetachOperation( position, howMany );\n\t}\n\n\tbatch.addOperation( operation );\n\tmodel.applyOperation( operation );\n}\n\n// Returns `true` if both root elements are the same element or both are documents root elements.\n//\n// Elements in the same tree can be moved (for instance you can move element form one documents root to another, or\n// within the same document fragment), but when element supposed to be moved from document fragment to the document, or\n// to another document it should be removed and inserted to avoid problems with OT. This is because features like undo or\n// collaboration may track changes on the document but ignore changes on detached fragments and should not get\n// unexpected `move` operation.\nfunction isSameTree( rootA, rootB ) {\n\t// If it is the same root this is the same tree.\n\tif ( rootA === rootB ) {\n\t\treturn true;\n\t}\n\n\t// If both roots are documents root it is operation within the document what we still treat as the same tree.\n\tif ( rootA instanceof RootElement && rootB instanceof RootElement ) {\n\t\treturn true;\n\t}\n\n\treturn false;\n}\n","/**\n * @license Copyright (c) 2003-2018, CKSource - Frederico Knabben. All rights reserved.\n * For licensing, see LICENSE.md.\n */\n\n/**\n * @module engine/model/differ\n */\n\nimport Position from './position';\nimport Range from './range';\n\n/**\n * Calculates the difference between two model states.\n *\n * Receives operations that are to be applied on the model document. Marks parts of the model document tree which\n * are changed and saves the state of these elements before the change. Then, it compares saved elements with the\n * changed elements, after all changes are applied on the model document. Calculates the diff between saved\n * elements and new ones and returns a change set.\n */\nexport default class Differ {\n\t/**\n\t * Creates a `Differ` instance.\n\t *\n\t * @param {module:engine/model/markercollection~MarkerCollection} markerCollection Model's marker collection.\n\t */\n\tconstructor( markerCollection ) {\n\t\t/**\n\t\t * Reference to the model's marker collection.\n\t\t *\n\t\t * @private\n\t\t * @type {module:engine/model/markercollection~MarkerCollection}\n\t\t */\n\t\tthis._markerCollection = markerCollection;\n\n\t\t/**\n\t\t * A map that stores changes that happened in a given element.\n\t\t *\n\t\t * The keys of the map are references to the model elements.\n\t\t * The values of the map are arrays with changes that were done on this element.\n\t\t *\n\t\t * @private\n\t\t * @type {Map}\n\t\t */\n\t\tthis._changesInElement = new Map();\n\n\t\t/**\n\t\t * A map that stores \"element's children snapshots\". A snapshot is representing children of a given element before\n\t\t * the first change was applied on that element. Snapshot items are objects with two properties: `name`,\n\t\t * containing the element name (or `'$text'` for a text node) and `attributes` which is a map of the node's attributes.\n\t\t *\n\t\t * @private\n\t\t * @type {Map}\n\t\t */\n\t\tthis._elementSnapshots = new Map();\n\n\t\t/**\n\t\t * A map that stores all changed markers.\n\t\t *\n\t\t * The keys of the map are marker names.\n\t\t * The values of the map are objects with the `oldRange` and `newRange` properties. They store the marker range\n\t\t * state before and after the change.\n\t\t *\n\t\t * @private\n\t\t * @type {Map}\n\t\t */\n\t\tthis._changedMarkers = new Map();\n\n\t\t/**\n\t\t * Stores the number of changes that were processed. Used to order the changes chronologically. It is important\n\t\t * when changes are sorted.\n\t\t *\n\t\t * @private\n\t\t * @type {Number}\n\t\t */\n\t\tthis._changeCount = 0;\n\n\t\t/**\n\t\t * For efficiency purposes, `Differ` stores the change set returned by the differ after {@link #getChanges} call.\n\t\t * Cache is reset each time a new operation is buffered. If the cache has not been reset, {@link #getChanges} will\n\t\t * return the cached value instead of calculating it again.\n\t\t *\n\t\t * This property stores those changes that did not take place in graveyard root.\n\t\t *\n\t\t * @private\n\t\t * @type {Array.