88 lines
1.9 KiB
JavaScript
88 lines
1.9 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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* Flattens a nested disjunction node to a list.
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*
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* /a|b|c|d/
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*
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* {{{a, b}, c}, d} -> [a, b, c, d]
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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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function disjunctionToList(node) {
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if (node.type !== 'Disjunction') {
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throw new TypeError('Expected "Disjunction" node, got "' + node.type + '"');
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}
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var list = [];
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if (node.left && node.left.type === 'Disjunction') {
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list.push.apply(list, _toConsumableArray(disjunctionToList(node.left)).concat([node.right]));
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} else {
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list.push(node.left, node.right);
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}
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return list;
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}
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/**
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* Builds a nested disjunction node from a list.
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*
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* /a|b|c|d/
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*
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* [a, b, c, d] -> {{{a, b}, c}, d}
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*/
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function listToDisjunction(list) {
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return list.reduce(function (left, right) {
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return {
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type: 'Disjunction',
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left: left,
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right: right
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};
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});
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}
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/**
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* Increases a quantifier by one.
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* Does not change greediness.
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* * -> +
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* + -> {2,}
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* ? -> {1,2}
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* {2} -> {3}
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* {2,} -> {3,}
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* {2,3} -> {3,4}
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*/
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function increaseQuantifierByOne(quantifier) {
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if (quantifier.kind === '*') {
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quantifier.kind = '+';
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} else if (quantifier.kind === '+') {
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quantifier.kind = 'Range';
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quantifier.from = 2;
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delete quantifier.to;
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} else if (quantifier.kind === '?') {
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quantifier.kind = 'Range';
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quantifier.from = 1;
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quantifier.to = 2;
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} else if (quantifier.kind === 'Range') {
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quantifier.from += 1;
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if (quantifier.to) {
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quantifier.to += 1;
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}
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}
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}
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module.exports = {
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disjunctionToList: disjunctionToList,
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listToDisjunction: listToDisjunction,
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increaseQuantifierByOne: increaseQuantifierByOne
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};
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