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Separate earley from parse() | add valuator to Rule
The earley function takes several parameters and spits out a set of states (one for each token). This should be its own function since it must be tested apart from the DFS tree constructor. The Rule constructor takes an optional third parameter, the valuator, which is the function used to evaluate the expression given values for each symbol.
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Original file line number | Diff line number | Diff line change |
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/*eslint no-console:0*/ | ||
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const parser = require('./lib/parser'); | ||
//const interp = require('./interp'); | ||
const readline = require('readline'); | ||
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const rl = readline.createInterface(process.stdin, process.stdout); | ||
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function printTree(tree, level) { | ||
if (tree === undefined) { return; } | ||
if (typeof tree === 'object') { | ||
console.log(`${Array(level).join(' ')}(${tree.item.lhs.name}`); | ||
tree.children.forEach(t => printTree(t, level + 2)); | ||
console.log(`${Array(level).join(' ')})`); | ||
return; | ||
} | ||
return console.log(`${Array(level).join(' ')}${tree}`); | ||
} | ||
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function interpret(parseTree) { | ||
if (typeof parseTree === 'string' || parseTree == null) { | ||
return parseTree; | ||
} | ||
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let values = parseTree.children | ||
.map((tree) => interpret(tree)) | ||
.filter((value) => value != null); | ||
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return parseTree.item.evaluate(values); | ||
} | ||
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rl.setPrompt('expr> '); | ||
rl.prompt(); | ||
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rl.on('line', (line) => { | ||
if (line.trim() === '') { | ||
return rl.prompt(); | ||
} | ||
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try { | ||
let tree = parser.parse(line.trim()); | ||
//console.log(JSON.stringify(tree, null, 2)); | ||
printTree(tree, 1); | ||
console.log('=>', interpret(tree)); | ||
} catch (e) { | ||
console.error(e.message); | ||
} | ||
rl.prompt(); | ||
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}).on('close', () => { | ||
console.log(); | ||
process.exit(0); | ||
}); |