[pkg/ottl] Add Double converter (open-telemetry#27457)

**Description:** Adding a Double converter to pkg/ottl

**Link to tracking Issue:** closes open-telemetry#22056

.chloggen/double-converter.yaml

@@ -0,0 +1,27 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: 'enhancement'
+
+# The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver)
+component: doubleconverter
+
+# A brief description of the change. Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: "Adding a double converter into pkg/ottl"
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [22056]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext:
+
+# If your change doesn't affect end users or the exported elements of any package,
+# you should instead start your pull request title with [chore] or use the "Skip Changelog" label.
+# Optional: The change log or logs in which this entry should be included.
+# e.g. '[user]' or '[user, api]'
+# Include 'user' if the change is relevant to end users.
+# Include 'api' if there is a change to a library API.
+# Default: '[user]'
+change_logs: [user]

pkg/ottl/ottlfuncs/README.md

@@ -294,6 +294,7 @@ Available Converters:
 - [ExtractPatterns](#extractpatterns)
 - [FNV](#fnv)
 - [Hours](#hours)
+- [Double](#double)
 - [Duration](#duration)
 - [Int](#int)
 - [IsMap](#ismap)
@@ -365,6 +366,29 @@ Examples:
 
 - `ConvertCase(metric.name, "snake")`
 
+### Double
+
+The `Double` Converter converts an inputted `value` into a double.
+
+The returned type is float64.
+
+The input `value` types:
+* float64. returns the `value` without changes.
+* string. Tries to parse a double from string. If it fails then nil will be returned.
+* bool. If `value` is true, then the function will return 1 otherwise 0.
+* int64. The function converts the integer to a double.
+
+If `value` is another type or parsing failed nil is always returned.
+
+The `value` is either a path expression to a telemetry field to retrieve or a literal.
+
+Examples:
+
+- `Double(attributes["http.status_code"])`
+
+
+- `Double("2.0")`
+
 ### Duration
 
 `Duration(duration)`

pkg/ottl/ottlfuncs/func_double.go

@@ -0,0 +1,42 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package ottlfuncs // import "github.com/open-telemetry/opentelemetry-collector-contrib/pkg/ottl/ottlfuncs"
+
+import (
+ "context"
+ "fmt"
+
+ "github.com/open-telemetry/opentelemetry-collector-contrib/pkg/ottl"
+)
+
+type DoubleArguments[K any] struct {
+ Target ottl.FloatLikeGetter[K]
+}
+
+func NewDoubleFactory[K any]() ottl.Factory[K] {
+ return ottl.NewFactory("Double", &DoubleArguments[K]{}, createDoubleFunction[K])
+}
+
+func createDoubleFunction[K any](_ ottl.FunctionContext, oArgs ottl.Arguments) (ottl.ExprFunc[K], error) {
+ args, ok := oArgs.(*DoubleArguments[K])
+
+ if !ok {
+ return nil, fmt.Errorf("DoubleFactory args must be of type *DoubleArguments[K]")
+ }
+
+ return doubleFunc(args.Target), nil
+}
+
+func doubleFunc[K any](target ottl.FloatLikeGetter[K]) ottl.ExprFunc[K] {
+ return func(ctx context.Context, tCtx K) (interface{}, error) {
+ value, err := target.Get(ctx, tCtx)
+ if err != nil {
+ return nil, err
+ }
+ if value == nil {
+ return nil, nil
+ }
+ return *value, nil
+ }
+}

pkg/ottl/ottlfuncs/func_double_test.go

@@ -0,0 +1,93 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package ottlfuncs
+
+import (
+ "context"
+ "testing"
+
+ "github.com/stretchr/testify/assert"
+
+ "github.com/open-telemetry/opentelemetry-collector-contrib/pkg/ottl"
+)
+
+func Test_Double(t *testing.T) {
+ tests := []struct {
+ name string
+ value interface{}
+ expected interface{}
+ err bool
+ }{
+ {
+ name: "string",
+ value: "50",
+ expected: float64(50),
+ },
+ {
+ name: "empty string",
+ value: "",
+ expected: nil,
+ err: true,
+ },
+ {
+ name: "not a number string",
+ value: "test",
+ expected: nil,
+ err: true,
+ },
+ {
+ name: "int64",
+ value: int64(333),
+ expected: float64(333),
+ },
+ {
+ name: "float64",
+ value: float64(2.7),
+ expected: float64(2.7),
+ },
+ {
+ name: "float64 without decimal",
+ value: float64(55),
+ expected: float64(55),
+ },
+ {
+ name: "true",
+ value: true,
+ expected: float64(1),
+ },
+ {
+ name: "false",
+ value: false,
+ expected: float64(0),
+ },
+ {
+ name: "nil",
+ value: nil,
+ expected: nil,
+ },
+ {
+ name: "some struct",
+ value: struct{}{},
+ expected: nil,
+ err: true,
+ },
+ }
+ for _, test := range tests {
+ t.Run(test.name, func(t *testing.T) {
+ exprFunc := doubleFunc[interface{}](&ottl.StandardFloatLikeGetter[interface{}]{
+
+ Getter: func(context.Context, interface{}) (interface{}, error) {
+ return test.value, nil
+ },
+ })
+ result, err := exprFunc(nil, nil)
+ if test.err {
+ assert.Error(t, err)
+ } else {
+ assert.NoError(t, err)
+ }
+ assert.Equal(t, test.expected, result)
+ })
+ }
+}

pkg/ottl/ottlfuncs/functions.go

@@ -36,6 +36,7 @@ func converters[K any]() []ottl.Factory[K] {
  // Converters
  NewConcatFactory[K](),
  NewConvertCaseFactory[K](),
+ NewDoubleFactory[K](),
  NewDurationFactory[K](),
  NewExtractPatternsFactory[K](),
  NewFnvFactory[K](),