380 lines
11 KiB
JavaScript
380 lines
11 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 _createClass = function () { function defineProperties(target, props) { for (var i = 0; i < props.length; i++) { var descriptor = props[i]; descriptor.enumerable = descriptor.enumerable || false; descriptor.configurable = true; if ("value" in descriptor) descriptor.writable = true; Object.defineProperty(target, descriptor.key, descriptor); } } return function (Constructor, protoProps, staticProps) { if (protoProps) defineProperties(Constructor.prototype, protoProps); if (staticProps) defineProperties(Constructor, staticProps); return Constructor; }; }();
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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 _classCallCheck(instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } }
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var DFAMinimizer = require('./dfa-minimizer');
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var _require = require('../special-symbols'),
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EPSILON_CLOSURE = _require.EPSILON_CLOSURE;
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/**
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* DFA is build by converting from NFA (subset construction).
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*/
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var DFA = function () {
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function DFA(nfa) {
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_classCallCheck(this, DFA);
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this._nfa = nfa;
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}
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/**
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* Minimizes DFA.
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*/
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_createClass(DFA, [{
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key: 'minimize',
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value: function minimize() {
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this.getTransitionTable();
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this._originalAcceptingStateNumbers = this._acceptingStateNumbers;
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this._originalTransitionTable = this._transitionTable;
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DFAMinimizer.minimize(this);
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}
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/**
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* Returns alphabet for this DFA.
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*/
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}, {
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key: 'getAlphabet',
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value: function getAlphabet() {
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return this._nfa.getAlphabet();
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}
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/**
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* Returns accepting states.
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*/
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}, {
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key: 'getAcceptingStateNumbers',
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value: function getAcceptingStateNumbers() {
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if (!this._acceptingStateNumbers) {
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// Accepting states are determined during table construction.
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this.getTransitionTable();
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}
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return this._acceptingStateNumbers;
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}
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/**
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* Returns original accepting states.
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*/
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}, {
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key: 'getOriginaAcceptingStateNumbers',
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value: function getOriginaAcceptingStateNumbers() {
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if (!this._originalAcceptingStateNumbers) {
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// Accepting states are determined during table construction.
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this.getTransitionTable();
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}
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return this._originalAcceptingStateNumbers;
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}
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/**
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* Sets transition table.
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*/
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}, {
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key: 'setTransitionTable',
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value: function setTransitionTable(table) {
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this._transitionTable = table;
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}
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/**
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* Sets accepting states.
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*/
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}, {
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key: 'setAcceptingStateNumbers',
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value: function setAcceptingStateNumbers(stateNumbers) {
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this._acceptingStateNumbers = stateNumbers;
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}
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/**
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* DFA transition table is built from NFA table.
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*/
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}, {
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key: 'getTransitionTable',
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value: function getTransitionTable() {
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var _this = this;
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if (this._transitionTable) {
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return this._transitionTable;
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}
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// Calculate from NFA transition table.
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var nfaTable = this._nfa.getTransitionTable();
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var nfaStates = Object.keys(nfaTable);
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this._acceptingStateNumbers = new Set();
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// Start state of DFA is E(S[nfa])
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var startState = nfaTable[nfaStates[0]][EPSILON_CLOSURE];
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// Init the worklist (states which should be in the DFA).
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var worklist = [startState];
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var alphabet = this.getAlphabet();
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var nfaAcceptingStates = this._nfa.getAcceptingStateNumbers();
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var dfaTable = {};
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// Determine whether the combined DFA state is accepting.
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var updateAcceptingStates = function updateAcceptingStates(states) {
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var _iteratorNormalCompletion = true;
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var _didIteratorError = false;
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var _iteratorError = undefined;
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try {
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for (var _iterator = nfaAcceptingStates[Symbol.iterator](), _step; !(_iteratorNormalCompletion = (_step = _iterator.next()).done); _iteratorNormalCompletion = true) {
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var nfaAcceptingState = _step.value;
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// If any of the states from NFA is accepting, DFA's
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// state is accepting as well.
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if (states.indexOf(nfaAcceptingState) !== -1) {
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_this._acceptingStateNumbers.add(states.join(','));
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break;
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}
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}
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} catch (err) {
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_didIteratorError = true;
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_iteratorError = err;
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} finally {
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try {
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if (!_iteratorNormalCompletion && _iterator.return) {
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_iterator.return();
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}
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} finally {
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if (_didIteratorError) {
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throw _iteratorError;
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}
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}
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}
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};
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while (worklist.length > 0) {
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var states = worklist.shift();
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var dfaStateLabel = states.join(',');
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dfaTable[dfaStateLabel] = {};
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var _iteratorNormalCompletion2 = true;
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var _didIteratorError2 = false;
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var _iteratorError2 = undefined;
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try {
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for (var _iterator2 = alphabet[Symbol.iterator](), _step2; !(_iteratorNormalCompletion2 = (_step2 = _iterator2.next()).done); _iteratorNormalCompletion2 = true) {
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var symbol = _step2.value;
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var onSymbol = [];
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// Determine whether the combined state is accepting.
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updateAcceptingStates(states);
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var _iteratorNormalCompletion3 = true;
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var _didIteratorError3 = false;
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var _iteratorError3 = undefined;
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try {
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for (var _iterator3 = states[Symbol.iterator](), _step3; !(_iteratorNormalCompletion3 = (_step3 = _iterator3.next()).done); _iteratorNormalCompletion3 = true) {
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var state = _step3.value;
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var nfaStatesOnSymbol = nfaTable[state][symbol];
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if (!nfaStatesOnSymbol) {
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continue;
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}
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var _iteratorNormalCompletion4 = true;
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var _didIteratorError4 = false;
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var _iteratorError4 = undefined;
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try {
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for (var _iterator4 = nfaStatesOnSymbol[Symbol.iterator](), _step4; !(_iteratorNormalCompletion4 = (_step4 = _iterator4.next()).done); _iteratorNormalCompletion4 = true) {
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var nfaStateOnSymbol = _step4.value;
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if (!nfaTable[nfaStateOnSymbol]) {
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continue;
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}
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onSymbol.push.apply(onSymbol, _toConsumableArray(nfaTable[nfaStateOnSymbol][EPSILON_CLOSURE]));
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}
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} catch (err) {
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_didIteratorError4 = true;
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_iteratorError4 = err;
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} finally {
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try {
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if (!_iteratorNormalCompletion4 && _iterator4.return) {
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_iterator4.return();
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}
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} finally {
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if (_didIteratorError4) {
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throw _iteratorError4;
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}
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}
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}
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}
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} catch (err) {
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_didIteratorError3 = true;
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_iteratorError3 = err;
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} finally {
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try {
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if (!_iteratorNormalCompletion3 && _iterator3.return) {
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_iterator3.return();
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}
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} finally {
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if (_didIteratorError3) {
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throw _iteratorError3;
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}
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}
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}
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var dfaStatesOnSymbolSet = new Set(onSymbol);
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var dfaStatesOnSymbol = [].concat(_toConsumableArray(dfaStatesOnSymbolSet));
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if (dfaStatesOnSymbol.length > 0) {
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var dfaOnSymbolStr = dfaStatesOnSymbol.join(',');
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dfaTable[dfaStateLabel][symbol] = dfaOnSymbolStr;
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if (!dfaTable.hasOwnProperty(dfaOnSymbolStr)) {
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worklist.unshift(dfaStatesOnSymbol);
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}
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}
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}
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} catch (err) {
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_didIteratorError2 = true;
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_iteratorError2 = err;
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} finally {
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try {
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if (!_iteratorNormalCompletion2 && _iterator2.return) {
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_iterator2.return();
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}
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} finally {
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if (_didIteratorError2) {
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throw _iteratorError2;
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}
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}
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}
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}
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return this._transitionTable = this._remapStateNumbers(dfaTable);
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}
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/**
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* Remaps state numbers in the resulting table:
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* combined states '1,2,3' -> 1, '3,4' -> 2, etc.
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*/
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}, {
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key: '_remapStateNumbers',
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value: function _remapStateNumbers(calculatedDFATable) {
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var newStatesMap = {};
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this._originalTransitionTable = calculatedDFATable;
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var transitionTable = {};
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Object.keys(calculatedDFATable).forEach(function (originalNumber, newNumber) {
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newStatesMap[originalNumber] = newNumber + 1;
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});
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for (var originalNumber in calculatedDFATable) {
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var originalRow = calculatedDFATable[originalNumber];
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var row = {};
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for (var symbol in originalRow) {
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row[symbol] = newStatesMap[originalRow[symbol]];
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}
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transitionTable[newStatesMap[originalNumber]] = row;
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}
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// Remap accepting states.
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this._originalAcceptingStateNumbers = this._acceptingStateNumbers;
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this._acceptingStateNumbers = new Set();
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var _iteratorNormalCompletion5 = true;
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var _didIteratorError5 = false;
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var _iteratorError5 = undefined;
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try {
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for (var _iterator5 = this._originalAcceptingStateNumbers[Symbol.iterator](), _step5; !(_iteratorNormalCompletion5 = (_step5 = _iterator5.next()).done); _iteratorNormalCompletion5 = true) {
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var _originalNumber = _step5.value;
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this._acceptingStateNumbers.add(newStatesMap[_originalNumber]);
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}
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} catch (err) {
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_didIteratorError5 = true;
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_iteratorError5 = err;
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} finally {
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try {
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if (!_iteratorNormalCompletion5 && _iterator5.return) {
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_iterator5.return();
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}
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} finally {
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if (_didIteratorError5) {
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throw _iteratorError5;
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}
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}
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}
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return transitionTable;
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}
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/**
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* Returns original DFA table, where state numbers
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* are combined numbers from NFA.
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*/
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}, {
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key: 'getOriginalTransitionTable',
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value: function getOriginalTransitionTable() {
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if (!this._originalTransitionTable) {
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// Original table is determined during table construction.
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this.getTransitionTable();
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}
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return this._originalTransitionTable;
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}
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/**
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* Checks whether this DFA accepts a string.
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*/
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}, {
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key: 'matches',
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value: function matches(string) {
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var state = 1;
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var i = 0;
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var table = this.getTransitionTable();
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while (string[i]) {
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state = table[state][string[i++]];
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if (!state) {
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return false;
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}
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}
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if (!this.getAcceptingStateNumbers().has(state)) {
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return false;
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}
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return true;
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}
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}]);
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return DFA;
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}();
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module.exports = DFA;
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