Chen Xiao
+586
@@ -0,0 +1,586 @@
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/******************************************************************************
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* Copyright 2022 TypeFox GmbH
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* This program and the accompanying materials are made available under the
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* terms of the MIT License, which is available in the project root.
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******************************************************************************/
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import { tokenMatcher, tokenLabel, NonTerminal, Alternation, Option, RepetitionMandatory, RepetitionMandatoryWithSeparator, RepetitionWithSeparator, Repetition, Terminal, LLkLookaheadStrategy, getLookaheadPaths, EOF } from "chevrotain";
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import { ATN_RULE_STOP, AtomTransition, buildATNKey, createATN, EpsilonTransition, RuleTransition } from "./atn.js";
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import { ATNConfigSet, DFA_ERROR, getATNConfigKey } from "./dfa.js";
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import min from "lodash-es/min.js";
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import flatMap from "lodash-es/flatMap.js";
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import uniqBy from "lodash-es/uniqBy.js";
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import map from "lodash-es/map.js";
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import flatten from "lodash-es/flatten.js";
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import forEach from "lodash-es/forEach.js";
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import isEmpty from "lodash-es/isEmpty.js";
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import reduce from "lodash-es/reduce.js";
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function createDFACache(startState, decision) {
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const map = {};
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return (predicateSet) => {
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const key = predicateSet.toString();
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let existing = map[key];
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if (existing !== undefined) {
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return existing;
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}
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else {
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existing = {
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atnStartState: startState,
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decision,
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states: {}
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};
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map[key] = existing;
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return existing;
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}
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};
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}
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class PredicateSet {
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constructor() {
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this.predicates = [];
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}
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is(index) {
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return index >= this.predicates.length || this.predicates[index];
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}
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set(index, value) {
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this.predicates[index] = value;
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}
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toString() {
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let value = "";
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const size = this.predicates.length;
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for (let i = 0; i < size; i++) {
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value += this.predicates[i] === true ? "1" : "0";
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}
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return value;
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}
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}
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const EMPTY_PREDICATES = new PredicateSet();
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export class LLStarLookaheadStrategy extends LLkLookaheadStrategy {
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constructor(options) {
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var _a, _b;
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super();
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this.logging = (_a = options === null || options === void 0 ? void 0 : options.logging) !== null && _a !== void 0 ? _a : ((message) => console.log(message));
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this.incomplete = (_b = options === null || options === void 0 ? void 0 : options.incomplete) !== null && _b !== void 0 ? _b : false;
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}
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initialize(options) {
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this.atn = createATN(options.rules);
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this.dfas = initATNSimulator(this.atn);
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}
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validateAmbiguousAlternationAlternatives() {
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return [];
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}
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validateEmptyOrAlternatives() {
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return [];
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}
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buildLookaheadForAlternation(options) {
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const { prodOccurrence, rule, hasPredicates, dynamicTokensEnabled } = options;
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const dfas = this.dfas;
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const logging = this.logging;
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const incomplete = this.incomplete;
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const key = buildATNKey(rule, 'Alternation', prodOccurrence);
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const decisionState = this.atn.decisionMap[key];
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const decisionIndex = decisionState.decision;
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const partialAlts = map(getLookaheadPaths({
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maxLookahead: 1,
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occurrence: prodOccurrence,
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prodType: "Alternation",
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rule: rule
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}), (currAlt) => map(currAlt, (path) => path[0]));
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if (isLL1Sequence(partialAlts, false) && !dynamicTokensEnabled) {
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const choiceToAlt = reduce(partialAlts, (result, currAlt, idx) => {
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forEach(currAlt, (currTokType) => {
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if (currTokType) {
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result[currTokType.tokenTypeIdx] = idx;
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forEach(currTokType.categoryMatches, (currExtendingType) => {
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result[currExtendingType] = idx;
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});
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}
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});
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return result;
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}, {});
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if (hasPredicates) {
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return function (orAlts) {
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var _a;
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const nextToken = this.LA_FAST(1);
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const prediction = choiceToAlt[nextToken.tokenTypeIdx];
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if (orAlts !== undefined && prediction !== undefined) {
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const gate = (_a = orAlts[prediction]) === null || _a === void 0 ? void 0 : _a.GATE;
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if (gate !== undefined && gate.call(this) === false) {
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return undefined;
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}
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}
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return prediction;
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};
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}
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else {
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return function () {
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const nextToken = this.LA_FAST(1);
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return choiceToAlt[nextToken.tokenTypeIdx];
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};
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}
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}
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else if (hasPredicates) {
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return function (orAlts) {
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const predicates = new PredicateSet();
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const length = orAlts === undefined ? 0 : orAlts.length;
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for (let i = 0; i < length; i++) {
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const gate = orAlts === null || orAlts === void 0 ? void 0 : orAlts[i].GATE;
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predicates.set(i, gate === undefined || gate.call(this));
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}
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const result = adaptivePredict.call(this, dfas, decisionIndex, predicates, logging, incomplete);
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return typeof result === 'number' ? result : undefined;
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};
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}
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else {
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return function () {
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const result = adaptivePredict.call(this, dfas, decisionIndex, EMPTY_PREDICATES, logging, incomplete);
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return typeof result === 'number' ? result : undefined;
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};
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}
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}
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buildLookaheadForOptional(options) {
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const { prodOccurrence, rule, prodType, dynamicTokensEnabled } = options;
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const dfas = this.dfas;
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const logging = this.logging;
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const incomplete = this.incomplete;
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const key = buildATNKey(rule, prodType, prodOccurrence);
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const decisionState = this.atn.decisionMap[key];
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const decisionIndex = decisionState.decision;
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const alts = map(getLookaheadPaths({
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maxLookahead: 1,
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occurrence: prodOccurrence,
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prodType,
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rule
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}), (e) => {
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return map(e, (g) => g[0]);
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});
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if (isLL1Sequence(alts) && alts[0][0] && !dynamicTokensEnabled) {
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const alt = alts[0];
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const singleTokensTypes = flatten(alt);
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if (singleTokensTypes.length === 1 &&
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isEmpty(singleTokensTypes[0].categoryMatches)) {
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const expectedTokenType = singleTokensTypes[0];
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const expectedTokenUniqueKey = expectedTokenType.tokenTypeIdx;
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return function () {
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return this.LA_FAST(1).tokenTypeIdx === expectedTokenUniqueKey;
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};
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}
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else {
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const choiceToAlt = reduce(singleTokensTypes, (result, currTokType) => {
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if (currTokType !== undefined) {
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result[currTokType.tokenTypeIdx] = true;
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forEach(currTokType.categoryMatches, (currExtendingType) => {
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result[currExtendingType] = true;
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});
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}
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return result;
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}, {});
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return function () {
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const nextToken = this.LA_FAST(1);
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return choiceToAlt[nextToken.tokenTypeIdx] === true;
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};
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}
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}
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return function () {
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const result = adaptivePredict.call(this, dfas, decisionIndex, EMPTY_PREDICATES, logging, incomplete);
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return typeof result === "object" ? false : result === 0;
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};
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}
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}
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function isLL1Sequence(sequences, allowEmpty = true) {
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const fullSet = new Set();
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for (const alt of sequences) {
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const altSet = new Set();
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for (const tokType of alt) {
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if (tokType === undefined) {
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if (allowEmpty) {
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// Epsilon production encountered
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break;
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}
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else {
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return false;
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}
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}
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const indices = [tokType.tokenTypeIdx].concat(tokType.categoryMatches);
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for (const index of indices) {
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if (fullSet.has(index)) {
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if (!altSet.has(index)) {
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return false;
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}
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}
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else {
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fullSet.add(index);
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altSet.add(index);
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}
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}
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}
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}
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return true;
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}
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function initATNSimulator(atn) {
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const decisionLength = atn.decisionStates.length;
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const decisionToDFA = Array(decisionLength);
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for (let i = 0; i < decisionLength; i++) {
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decisionToDFA[i] = createDFACache(atn.decisionStates[i], i);
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}
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return decisionToDFA;
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}
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function adaptivePredict(dfaCaches, decision, predicateSet, logging, incomplete) {
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const dfa = dfaCaches[decision](predicateSet);
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let start = dfa.start;
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if (start === undefined) {
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const closure = computeStartState(dfa.atnStartState);
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start = addDFAState(dfa, newDFAState(closure));
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dfa.start = start;
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}
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const alt = performLookahead.apply(this, [dfa, start, predicateSet, logging, incomplete]);
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return alt;
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}
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function performLookahead(dfa, s0, predicateSet, logging, incomplete) {
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let previousD = s0;
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let i = 1;
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const path = [];
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// Using LA_FAST is fine here
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let t = this.LA_FAST(i++);
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while (true) {
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let d = getExistingTargetState(previousD, t);
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if (d === undefined) {
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d = computeLookaheadTarget.apply(this, [dfa, previousD, t, i, predicateSet, logging]);
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}
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if (d === DFA_ERROR) {
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return buildAdaptivePredictError(path, previousD, t);
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}
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if (d.isAcceptState === true) {
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if (incomplete === true && tokenMatcher(t, EOF)) {
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// We run into this case, when we reached the end of the input, but we are in the middle of evaluating a lookahead sequence
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// The sequence is incomplete, but we can still make an educated guess on which alternative is more likely to be correct
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const bestGuess = getBestGuess(previousD, predicateSet);
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if (bestGuess !== undefined) {
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return bestGuess;
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}
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}
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return d.prediction;
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}
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previousD = d;
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path.push(t);
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// We might be reading out of bounds
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// Therefore, no LA_FAST here
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t = this.LA(i++);
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}
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}
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function computeLookaheadTarget(dfa, previousD, token, lookahead, predicateSet, logging) {
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const reach = computeReachSet(previousD.configs, token, predicateSet);
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if (reach.size === 0) {
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addDFAEdge(dfa, previousD, token, DFA_ERROR);
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return DFA_ERROR;
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}
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let newState = newDFAState(reach);
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const predictedAlt = getUniqueAlt(reach, predicateSet);
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if (predictedAlt !== undefined) {
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newState.isAcceptState = true;
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newState.prediction = predictedAlt;
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newState.configs.uniqueAlt = predictedAlt;
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}
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else if (hasConflictTerminatingPrediction(reach)) {
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const prediction = min(reach.alts);
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newState.isAcceptState = true;
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newState.prediction = prediction;
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newState.configs.uniqueAlt = prediction;
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reportLookaheadAmbiguity.apply(this, [dfa, lookahead, reach.alts, logging]);
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}
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newState = addDFAEdge(dfa, previousD, token, newState);
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return newState;
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}
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function reportLookaheadAmbiguity(dfa, lookahead, ambiguityIndices, logging) {
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const prefixPath = [];
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for (let i = 1; i <= lookahead; i++) {
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prefixPath.push(this.LA(i).tokenType);
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}
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const atnState = dfa.atnStartState;
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const topLevelRule = atnState.rule;
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const production = atnState.production;
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const message = buildAmbiguityError({
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topLevelRule,
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ambiguityIndices,
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production,
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prefixPath
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});
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logging(message);
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}
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function buildAmbiguityError(options) {
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const pathMsg = map(options.prefixPath, (currtok) => tokenLabel(currtok)).join(", ");
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const occurrence = options.production.idx === 0 ? "" : options.production.idx;
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let currMessage = `Ambiguous Alternatives Detected: <${options.ambiguityIndices.join(", ")}> in <${getProductionDslName(options.production)}${occurrence}>` +
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` inside <${options.topLevelRule.name}> Rule,\n` +
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`<${pathMsg}> may appears as a prefix path in all these alternatives.\n`;
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currMessage =
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currMessage +
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`See: https://chevrotain.io/docs/guide/resolving_grammar_errors.html#AMBIGUOUS_ALTERNATIVES\n` +
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`For Further details.`;
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return currMessage;
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}
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function getProductionDslName(prod) {
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if (prod instanceof NonTerminal) {
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return "SUBRULE";
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}
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else if (prod instanceof Option) {
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return "OPTION";
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}
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else if (prod instanceof Alternation) {
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return "OR";
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}
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else if (prod instanceof RepetitionMandatory) {
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return "AT_LEAST_ONE";
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}
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else if (prod instanceof RepetitionMandatoryWithSeparator) {
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return "AT_LEAST_ONE_SEP";
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}
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else if (prod instanceof RepetitionWithSeparator) {
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return "MANY_SEP";
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}
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else if (prod instanceof Repetition) {
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return "MANY";
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}
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else if (prod instanceof Terminal) {
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return "CONSUME";
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}
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else {
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throw Error("non exhaustive match");
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}
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}
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function buildAdaptivePredictError(path, previous, current) {
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const nextTransitions = flatMap(previous.configs.elements, (e) => e.state.transitions);
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const nextTokenTypes = uniqBy(nextTransitions
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.filter((e) => e instanceof AtomTransition)
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.map((e) => e.tokenType), (e) => e.tokenTypeIdx);
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return {
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actualToken: current,
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possibleTokenTypes: nextTokenTypes,
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tokenPath: path
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};
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}
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function getExistingTargetState(state, token) {
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return state.edges[token.tokenTypeIdx];
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}
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function computeReachSet(configs, token, predicateSet) {
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const intermediate = new ATNConfigSet();
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const skippedStopStates = [];
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for (const c of configs.elements) {
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if (predicateSet.is(c.alt) === false) {
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continue;
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}
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if (c.state.type === ATN_RULE_STOP) {
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skippedStopStates.push(c);
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continue;
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}
|
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const transitionLength = c.state.transitions.length;
|
||||
for (let i = 0; i < transitionLength; i++) {
|
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const transition = c.state.transitions[i];
|
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const target = getReachableTarget(transition, token);
|
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if (target !== undefined) {
|
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intermediate.add({
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||||
state: target,
|
||||
alt: c.alt,
|
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stack: c.stack
|
||||
});
|
||||
}
|
||||
}
|
||||
}
|
||||
let reach;
|
||||
if (skippedStopStates.length === 0 && intermediate.size === 1) {
|
||||
reach = intermediate;
|
||||
}
|
||||
if (reach === undefined) {
|
||||
reach = new ATNConfigSet();
|
||||
for (const c of intermediate.elements) {
|
||||
closure(c, reach);
|
||||
}
|
||||
}
|
||||
if (skippedStopStates.length > 0 && !hasConfigInRuleStopState(reach)) {
|
||||
for (const c of skippedStopStates) {
|
||||
reach.add(c);
|
||||
}
|
||||
}
|
||||
return reach;
|
||||
}
|
||||
function getReachableTarget(transition, token) {
|
||||
if (transition instanceof AtomTransition &&
|
||||
tokenMatcher(token, transition.tokenType)) {
|
||||
return transition.target;
|
||||
}
|
||||
return undefined;
|
||||
}
|
||||
function getUniqueAlt(configs, predicateSet) {
|
||||
let alt;
|
||||
for (const c of configs.elements) {
|
||||
if (predicateSet.is(c.alt) === true) {
|
||||
if (alt === undefined) {
|
||||
alt = c.alt;
|
||||
}
|
||||
else if (alt !== c.alt) {
|
||||
return undefined;
|
||||
}
|
||||
}
|
||||
}
|
||||
return alt;
|
||||
}
|
||||
function newDFAState(closure) {
|
||||
return {
|
||||
configs: closure,
|
||||
edges: {},
|
||||
isAcceptState: false,
|
||||
prediction: -1
|
||||
};
|
||||
}
|
||||
function addDFAEdge(dfa, from, token, to) {
|
||||
to = addDFAState(dfa, to);
|
||||
from.edges[token.tokenTypeIdx] = to;
|
||||
return to;
|
||||
}
|
||||
function addDFAState(dfa, state) {
|
||||
if (state === DFA_ERROR) {
|
||||
return state;
|
||||
}
|
||||
// Repetitions have the same config set
|
||||
// Therefore, storing the key of the config in a map allows us to create a loop in our DFA
|
||||
const mapKey = state.configs.key;
|
||||
const existing = dfa.states[mapKey];
|
||||
if (existing !== undefined) {
|
||||
return existing;
|
||||
}
|
||||
state.configs.finalize();
|
||||
dfa.states[mapKey] = state;
|
||||
return state;
|
||||
}
|
||||
function computeStartState(atnState) {
|
||||
const configs = new ATNConfigSet();
|
||||
const numberOfTransitions = atnState.transitions.length;
|
||||
for (let i = 0; i < numberOfTransitions; i++) {
|
||||
const target = atnState.transitions[i].target;
|
||||
const config = {
|
||||
state: target,
|
||||
alt: i,
|
||||
stack: []
|
||||
};
|
||||
closure(config, configs);
|
||||
}
|
||||
return configs;
|
||||
}
|
||||
function closure(config, configs) {
|
||||
const p = config.state;
|
||||
if (p.type === ATN_RULE_STOP) {
|
||||
if (config.stack.length > 0) {
|
||||
const atnStack = [...config.stack];
|
||||
const followState = atnStack.pop();
|
||||
const followConfig = {
|
||||
state: followState,
|
||||
alt: config.alt,
|
||||
stack: atnStack
|
||||
};
|
||||
closure(followConfig, configs);
|
||||
}
|
||||
else {
|
||||
// Dipping into outer context, simply add the config
|
||||
// This will stop computation once every config is at the rule stop state
|
||||
configs.add(config);
|
||||
}
|
||||
return;
|
||||
}
|
||||
if (!p.epsilonOnlyTransitions) {
|
||||
configs.add(config);
|
||||
}
|
||||
const transitionLength = p.transitions.length;
|
||||
for (let i = 0; i < transitionLength; i++) {
|
||||
const transition = p.transitions[i];
|
||||
const c = getEpsilonTarget(config, transition);
|
||||
if (c !== undefined) {
|
||||
closure(c, configs);
|
||||
}
|
||||
}
|
||||
}
|
||||
function getEpsilonTarget(config, transition) {
|
||||
if (transition instanceof EpsilonTransition) {
|
||||
return {
|
||||
state: transition.target,
|
||||
alt: config.alt,
|
||||
stack: config.stack
|
||||
};
|
||||
}
|
||||
else if (transition instanceof RuleTransition) {
|
||||
const stack = [...config.stack, transition.followState];
|
||||
return {
|
||||
state: transition.target,
|
||||
alt: config.alt,
|
||||
stack
|
||||
};
|
||||
}
|
||||
return undefined;
|
||||
}
|
||||
function hasConfigInRuleStopState(configs) {
|
||||
for (const c of configs.elements) {
|
||||
if (c.state.type === ATN_RULE_STOP) {
|
||||
return true;
|
||||
}
|
||||
}
|
||||
return false;
|
||||
}
|
||||
function allConfigsInRuleStopStates(configs) {
|
||||
for (const c of configs.elements) {
|
||||
if (c.state.type !== ATN_RULE_STOP) {
|
||||
return false;
|
||||
}
|
||||
}
|
||||
return true;
|
||||
}
|
||||
function hasConflictTerminatingPrediction(configs) {
|
||||
if (allConfigsInRuleStopStates(configs)) {
|
||||
return true;
|
||||
}
|
||||
const altSets = getConflictingAltSets(configs.elements);
|
||||
const heuristic = hasConflictingAltSet(altSets) && !hasStateAssociatedWithOneAlt(altSets);
|
||||
return heuristic;
|
||||
}
|
||||
function getConflictingAltSets(configs) {
|
||||
const configToAlts = new Map();
|
||||
for (const c of configs) {
|
||||
const key = getATNConfigKey(c, false);
|
||||
let alts = configToAlts.get(key);
|
||||
if (alts === undefined) {
|
||||
alts = {};
|
||||
configToAlts.set(key, alts);
|
||||
}
|
||||
alts[c.alt] = true;
|
||||
}
|
||||
return configToAlts;
|
||||
}
|
||||
function hasConflictingAltSet(altSets) {
|
||||
for (const value of Array.from(altSets.values())) {
|
||||
if (Object.keys(value).length > 1) {
|
||||
return true;
|
||||
}
|
||||
}
|
||||
return false;
|
||||
}
|
||||
function hasStateAssociatedWithOneAlt(altSets) {
|
||||
for (const value of Array.from(altSets.values())) {
|
||||
if (Object.keys(value).length === 1) {
|
||||
return true;
|
||||
}
|
||||
}
|
||||
return false;
|
||||
}
|
||||
function getBestGuess(state, predicateSet) {
|
||||
let bestAlt = undefined;
|
||||
for (const c of state.configs.elements) {
|
||||
// Ignore invalid and stop states
|
||||
if (predicateSet.is(c.alt) === false || c.state.type === ATN_RULE_STOP) {
|
||||
continue;
|
||||
}
|
||||
if (bestAlt === undefined) {
|
||||
bestAlt = c.alt;
|
||||
}
|
||||
else if (bestAlt !== c.alt) {
|
||||
return undefined;
|
||||
}
|
||||
}
|
||||
return bestAlt;
|
||||
}
|
||||
//# sourceMappingURL=all-star-lookahead.js.map
|
||||
Reference in New Issue
Block a user