91 lines
2.8 KiB
JavaScript
91 lines
2.8 KiB
JavaScript
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/**
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* The MIT License (MIT)
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* Copyright (c) 2017-present Dmitry Soshnikov <dmitry.soshnikov@gmail.com>
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*/
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'use strict';
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var clone = require('../utils/clone');
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var parser = require('../parser');
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var transform = require('../transform');
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var optimizationTransforms = require('./transforms');
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module.exports = {
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/**
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* Optimizer transforms a regular expression into an optimized version,
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* replacing some sub-expressions with their idiomatic patterns.
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*
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* @param string | RegExp | AST - a regexp to optimize.
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*
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* @return TransformResult - an optimized regexp.
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*
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* Example:
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*
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* /[a-zA-Z_0-9][a-zA-Z_0-9]*\e{1,}/
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*
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* Optimized to:
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*
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* /\w+e+/
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*/
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optimize: function optimize(regexp) {
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var _ref = arguments.length > 1 && arguments[1] !== undefined ? arguments[1] : {},
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_ref$whitelist = _ref.whitelist,
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whitelist = _ref$whitelist === undefined ? [] : _ref$whitelist,
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_ref$blacklist = _ref.blacklist,
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blacklist = _ref$blacklist === undefined ? [] : _ref$blacklist;
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var transformsRaw = whitelist.length > 0 ? whitelist : Array.from(optimizationTransforms.keys());
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var transformToApply = transformsRaw.filter(function (transform) {
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return !blacklist.includes(transform);
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});
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var ast = regexp;
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if (regexp instanceof RegExp) {
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regexp = '' + regexp;
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}
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if (typeof regexp === 'string') {
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ast = parser.parse(regexp);
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}
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var result = new transform.TransformResult(ast);
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var prevResultString = void 0;
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do {
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// Get a copy of the current state here so
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// we can compare it with the state at the
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// end of the loop.
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prevResultString = result.toString();
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ast = clone(result.getAST());
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transformToApply.forEach(function (transformName) {
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if (!optimizationTransforms.has(transformName)) {
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throw new Error('Unknown optimization-transform: ' + transformName + '. ' + 'Available transforms are: ' + Array.from(optimizationTransforms.keys()).join(', '));
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}
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var transformer = optimizationTransforms.get(transformName);
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// Don't override result just yet since we
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// might want to rollback the transform
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var newResult = transform.transform(ast, transformer);
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if (newResult.toString() !== result.toString()) {
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if (newResult.toString().length <= result.toString().length) {
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result = newResult;
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} else {
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// Result has changed but is not shorter:
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// restore ast to its previous state.
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ast = clone(result.getAST());
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}
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}
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});
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// Keep running the optimizer until it stops
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// making any change to the regexp.
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} while (result.toString() !== prevResultString);
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return result;
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}
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};
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