86 lines
2.2 KiB
JavaScript
86 lines
2.2 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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/**
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* A regexp-tree plugin to remove unnecessary groups.
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*
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* /(?:a)/ -> /a/
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*/
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function _toConsumableArray(arr) { if (Array.isArray(arr)) { for (var i = 0, arr2 = Array(arr.length); i < arr.length; i++) { arr2[i] = arr[i]; } return arr2; } else { return Array.from(arr); } }
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module.exports = {
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Group: function Group(path) {
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var node = path.node,
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parent = path.parent;
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var childPath = path.getChild();
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if (node.capturing || !childPath) {
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return;
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}
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// Don't optimize \1(?:0) to \10
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if (!hasAppropriateSiblings(path)) {
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return;
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}
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// Don't optimize /a(?:b|c)/ to /ab|c/
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// but /(?:b|c)/ to /b|c/ is ok
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if (childPath.node.type === 'Disjunction' && parent.type !== 'RegExp') {
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return;
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}
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// Don't optimize /(?:ab)+/ to /ab+/
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// but /(?:a)+/ to /a+/ is ok
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// and /(?:[a-d])+/ to /[a-d]+/ is ok too
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if (parent.type === 'Repetition' && childPath.node.type !== 'Char' && childPath.node.type !== 'CharacterClass') {
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return;
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}
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if (childPath.node.type === 'Alternative') {
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var parentPath = path.getParent();
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if (parentPath.node.type === 'Alternative') {
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// /abc(?:def)ghi/ When (?:def) is ungrouped its content must be merged with parent alternative
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parentPath.replace({
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type: 'Alternative',
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expressions: [].concat(_toConsumableArray(parent.expressions.slice(0, path.index)), _toConsumableArray(childPath.node.expressions), _toConsumableArray(parent.expressions.slice(path.index + 1)))
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});
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}
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} else {
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path.replace(childPath.node);
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}
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}
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};
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function hasAppropriateSiblings(path) {
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var parent = path.parent,
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index = path.index;
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if (parent.type !== 'Alternative') {
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return true;
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}
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var previousNode = parent.expressions[index - 1];
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if (previousNode == null) {
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return true;
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}
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// Don't optimized \1(?:0) to \10
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if (previousNode.type === 'Backreference' && previousNode.kind === 'number') {
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return false;
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}
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// Don't optimized \2(?:0) to \20
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if (previousNode.type === 'Char' && previousNode.kind === 'decimal') {
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return false;
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}
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return true;
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}
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