chevrotain - npm Package Compare versions

Comparing version 10.3.0 to 10.4.0

lib/src/api.js

 "use strict";
 /* istanbul ignore file - tricky to import some things from this module during testing */
 Object.defineProperty(exports, "__esModule", { value: true });
-exports.Parser = exports.createSyntaxDiagramsCode = exports.clearCache = exports.generateCstDts = exports.GAstVisitor = exports.serializeProduction = exports.serializeGrammar = exports.Terminal = exports.Rule = exports.RepetitionWithSeparator = exports.RepetitionMandatoryWithSeparator = exports.RepetitionMandatory = exports.Repetition = exports.Option = exports.NonTerminal = exports.Alternative = exports.Alternation = exports.defaultLexerErrorProvider = exports.NoViableAltException = exports.NotAllInputParsedException = exports.MismatchedTokenException = exports.isRecognitionException = exports.EarlyExitException = exports.defaultParserErrorProvider = exports.tokenName = exports.tokenMatcher = exports.tokenLabel = exports.EOF = exports.createTokenInstance = exports.createToken = exports.LexerDefinitionErrorType = exports.Lexer = exports.EMPTY_ALT = exports.ParserDefinitionErrorType = exports.EmbeddedActionsParser = exports.CstParser = exports.VERSION = void 0;
+exports.Parser = exports.createSyntaxDiagramsCode = exports.clearCache = exports.generateCstDts = exports.GAstVisitor = exports.serializeProduction = exports.serializeGrammar = exports.Terminal = exports.Rule = exports.RepetitionWithSeparator = exports.RepetitionMandatoryWithSeparator = exports.RepetitionMandatory = exports.Repetition = exports.Option = exports.NonTerminal = exports.Alternative = exports.Alternation = exports.defaultLexerErrorProvider = exports.NoViableAltException = exports.NotAllInputParsedException = exports.MismatchedTokenException = exports.isRecognitionException = exports.EarlyExitException = exports.defaultParserErrorProvider = exports.LLkLookaheadStrategy = exports.getLookaheadPaths = exports.tokenName = exports.tokenMatcher = exports.tokenLabel = exports.EOF = exports.createTokenInstance = exports.createToken = exports.LexerDefinitionErrorType = exports.Lexer = exports.EMPTY_ALT = exports.ParserDefinitionErrorType = exports.EmbeddedActionsParser = exports.CstParser = exports.VERSION = void 0;
 // semantic version
@@ -24,2 +24,7 @@ var version_1 = require("./version");
 Object.defineProperty(exports, "tokenName", { enumerable: true, get: function () { return tokens_public_1.tokenName; } });
+// Lookahead
+var lookahead_1 = require("./parse/grammar/lookahead");
+Object.defineProperty(exports, "getLookaheadPaths", { enumerable: true, get: function () { return lookahead_1.getLookaheadPaths; } });
+var llk_lookahead_1 = require("./parse/grammar/llk_lookahead");
+Object.defineProperty(exports, "LLkLookaheadStrategy", { enumerable: true, get: function () { return llk_lookahead_1.LLkLookaheadStrategy; } });
 // Other Utilities
@@ -26,0 +31,0 @@ var errors_public_1 = require("./parse/errors_public");

lib/src/parse/grammar/checks.js

@@ -17,2 +17,13 @@ "use strict";
 })();
+var __assign = (this && this.__assign) || function () {
+    __assign = Object.assign || function(t) {
+        for (var s, i = 1, n = arguments.length; i < n; i++) {
+            s = arguments[i];
+            for (var p in s) if (Object.prototype.hasOwnProperty.call(s, p))
+                t[p] = s[p];
+        }
+        return t;
+    };
+    return __assign.apply(this, arguments);
+};
 var __importDefault = (this && this.__importDefault) || function (mod) {
@@ -22,3 +33,3 @@ return (mod && mod.__esModule) ? mod : { "default": mod };
 Object.defineProperty(exports, "__esModule", { value: true });
-exports.checkPrefixAlternativesAmbiguities = exports.validateSomeNonEmptyLookaheadPath = exports.validateTooManyAlts = exports.RepetitionCollector = exports.validateAmbiguousAlternationAlternatives = exports.validateEmptyOrAlternative = exports.getFirstNoneTerminal = exports.validateNoLeftRecursion = exports.validateRuleIsOverridden = exports.validateRuleDoesNotAlreadyExist = exports.OccurrenceValidationCollector = exports.identifyProductionForDuplicates = exports.validateGrammar = void 0;
+exports.checkPrefixAlternativesAmbiguities = exports.validateSomeNonEmptyLookaheadPath = exports.validateTooManyAlts = exports.RepetitionCollector = exports.validateAmbiguousAlternationAlternatives = exports.validateEmptyOrAlternative = exports.getFirstNoneTerminal = exports.validateNoLeftRecursion = exports.validateRuleIsOverridden = exports.validateRuleDoesNotAlreadyExist = exports.OccurrenceValidationCollector = exports.identifyProductionForDuplicates = exports.validateGrammar = exports.validateLookahead = void 0;
 var first_1 = __importDefault(require("lodash/first"));
@@ -49,23 +60,13 @@ var isEmpty_1 = __importDefault(require("lodash/isEmpty"));
 var tokens_1 = require("../../scan/tokens");
-function validateGrammar(topLevels, globalMaxLookahead, tokenTypes, errMsgProvider, grammarName) {
-    var duplicateErrors = (0, flatMap_1.default)(topLevels, function (currTopLevel) {
-        return validateDuplicateProductions(currTopLevel, errMsgProvider);
+function validateLookahead(options) {
+    var lookaheadValidationErrorMessages = options.lookaheadStrategy.validate({
+        rules: options.rules,
+        tokenTypes: options.tokenTypes,
+        grammarName: options.grammarName
     });
-    var leftRecursionErrors = (0, flatMap_1.default)(topLevels, function (currTopRule) {
-        return validateNoLeftRecursion(currTopRule, currTopRule, errMsgProvider);
-    });
-    var emptyAltErrors = [];
-    var ambiguousAltsErrors = [];
-    var emptyRepetitionErrors = [];
-    // left recursion could cause infinite loops in the following validations.
-    // It is safest to first have the user fix the left recursion errors first and only then examine Further issues.
-    if ((0, isEmpty_1.default)(leftRecursionErrors)) {
-        emptyAltErrors = (0, flatMap_1.default)(topLevels, function (currTopRule) {
-            return validateEmptyOrAlternative(currTopRule, errMsgProvider);
-        });
-        ambiguousAltsErrors = (0, flatMap_1.default)(topLevels, function (currTopRule) {
-            return validateAmbiguousAlternationAlternatives(currTopRule, globalMaxLookahead, errMsgProvider);
-        });
-        emptyRepetitionErrors = validateSomeNonEmptyLookaheadPath(topLevels, globalMaxLookahead, errMsgProvider);
-    }
+    return (0, map_1.default)(lookaheadValidationErrorMessages, function (errorMessage) { return (__assign({ type: parser_1.ParserDefinitionErrorType.CUSTOM_LOOKAHEAD_VALIDATION }, errorMessage)); });
+}
+exports.validateLookahead = validateLookahead;
+function validateGrammar(topLevels, tokenTypes, errMsgProvider, grammarName) {
+    var duplicateErrors = (0, flatMap_1.default)(topLevels, function (currTopLevel) { return validateDuplicateProductions(currTopLevel, errMsgProvider); });
     var termsNamespaceConflictErrors = checkTerminalAndNoneTerminalsNameSpace(topLevels, tokenTypes, errMsgProvider);
@@ -78,3 +79,3 @@ var tooManyAltsErrors = (0, flatMap_1.default)(topLevels, function (curRule) {
     });
-    return duplicateErrors.concat(emptyRepetitionErrors, leftRecursionErrors, emptyAltErrors, ambiguousAltsErrors, termsNamespaceConflictErrors, tooManyAltsErrors, duplicateRulesError);
+    return duplicateErrors.concat(termsNamespaceConflictErrors, tooManyAltsErrors, duplicateRulesError);
 }
@@ -81,0 +82,0 @@ exports.validateGrammar = validateGrammar;

lib/src/parse/grammar/gast/gast_resolver_public.js

@@ -27,5 +27,5 @@ "use strict";
     });
-    return (0, checks_1.validateGrammar)(options.rules, options.maxLookahead, options.tokenTypes, options.errMsgProvider, options.grammarName);
+    return (0, checks_1.validateGrammar)(options.rules, options.tokenTypes, options.errMsgProvider, options.grammarName);
 }
 exports.validateGrammar = validateGrammar;
 //# sourceMappingURL=gast_resolver_public.js.map

lib/src/parse/grammar/lookahead.js

@@ -21,3 +21,3 @@ "use strict";
 Object.defineProperty(exports, "__esModule", { value: true });
-exports.areTokenCategoriesNotUsed = exports.isStrictPrefixOfPath = exports.containsPath = exports.getLookaheadPathsForOptionalProd = exports.getLookaheadPathsForOr = exports.lookAheadSequenceFromAlternatives = exports.buildSingleAlternativeLookaheadFunction = exports.buildAlternativesLookAheadFunc = exports.buildLookaheadFuncForOptionalProd = exports.buildLookaheadFuncForOr = exports.getProdType = exports.PROD_TYPE = void 0;
+exports.areTokenCategoriesNotUsed = exports.isStrictPrefixOfPath = exports.containsPath = exports.getLookaheadPathsForOptionalProd = exports.getLookaheadPathsForOr = exports.lookAheadSequenceFromAlternatives = exports.buildSingleAlternativeLookaheadFunction = exports.buildAlternativesLookAheadFunc = exports.buildLookaheadFuncForOptionalProd = exports.buildLookaheadFuncForOr = exports.getLookaheadPaths = exports.getProdType = exports.PROD_TYPE = void 0;
 var isEmpty_1 = __importDefault(require("lodash/isEmpty"));
@@ -46,18 +46,21 @@ var flatten_1 = __importDefault(require("lodash/flatten"));
     /* istanbul ignore else */
-    if (prod instanceof gast_1.Option) {
+    if (prod instanceof gast_1.Option || prod === "Option") {
         return PROD_TYPE.OPTION;
     }
-    else if (prod instanceof gast_1.Repetition) {
+    else if (prod instanceof gast_1.Repetition || prod === "Repetition") {
         return PROD_TYPE.REPETITION;
     }
-    else if (prod instanceof gast_1.RepetitionMandatory) {
+    else if (prod instanceof gast_1.RepetitionMandatory ||
+        prod === "RepetitionMandatory") {
         return PROD_TYPE.REPETITION_MANDATORY;
     }
-    else if (prod instanceof gast_1.RepetitionMandatoryWithSeparator) {
+    else if (prod instanceof gast_1.RepetitionMandatoryWithSeparator ||
+        prod === "RepetitionMandatoryWithSeparator") {
         return PROD_TYPE.REPETITION_MANDATORY_WITH_SEPARATOR;
     }
-    else if (prod instanceof gast_1.RepetitionWithSeparator) {
+    else if (prod instanceof gast_1.RepetitionWithSeparator ||
+        prod === "RepetitionWithSeparator") {
         return PROD_TYPE.REPETITION_WITH_SEPARATOR;
     }
-    else if (prod instanceof gast_1.Alternation) {
+    else if (prod instanceof gast_1.Alternation || prod === "Alternation") {
         return PROD_TYPE.ALTERNATION;
@@ -70,2 +73,13 @@ }
 exports.getProdType = getProdType;
+function getLookaheadPaths(options) {
+    var occurrence = options.occurrence, rule = options.rule, prodType = options.prodType, maxLookahead = options.maxLookahead;
+    var type = getProdType(prodType);
+    if (type === PROD_TYPE.ALTERNATION) {
+        return getLookaheadPathsForOr(occurrence, rule, maxLookahead);
+    }
+    else {
+        return getLookaheadPathsForOptionalProd(occurrence, rule, type, maxLookahead);
+    }
+}
+exports.getLookaheadPaths = getLookaheadPaths;
 function buildLookaheadFuncForOr(occurrence, ruleGrammar, maxLookahead, hasPredicates, dynamicTokensEnabled, laFuncBuilder) {
@@ -72,0 +86,0 @@ var lookAheadPaths = getLookaheadPathsForOr(occurrence, ruleGrammar, maxLookahead);

lib/src/parse/parser/parser.js

@@ -44,2 +44,3 @@ "use strict";
 var apply_mixins_1 = require("./utils/apply_mixins");
+var checks_1 = require("../grammar/checks");
 exports.END_OF_FILE = (0, tokens_public_1.createTokenInstance)(tokens_public_1.EOF, "", NaN, NaN, NaN, NaN, NaN, NaN);
@@ -76,2 +77,3 @@ Object.freeze(exports.END_OF_FILE);
     ParserDefinitionErrorType[ParserDefinitionErrorType["TOO_MANY_ALTS"] = 12] = "TOO_MANY_ALTS";
+    ParserDefinitionErrorType[ParserDefinitionErrorType["CUSTOM_LOOKAHEAD_VALIDATION"] = 13] = "CUSTOM_LOOKAHEAD_VALIDATION";
 })(ParserDefinitionErrorType = exports.ParserDefinitionErrorType || (exports.ParserDefinitionErrorType = {}));
@@ -159,3 +161,2 @@ function EMPTY_ALT(value) {
                         rules: (0, values_1.default)(_this.gastProductionsCache),
-                        maxLookahead: _this.maxLookahead,
                         tokenTypes: (0, values_1.default)(_this.tokensMap),
@@ -165,3 +166,9 @@ errMsgProvider: errors_public_1.defaultGrammarValidatorErrorProvider,
                     });
-                    _this.definitionErrors = _this.definitionErrors.concat(validationErrors);
+                    var lookaheadValidationErrors = (0, checks_1.validateLookahead)({
+                        lookaheadStrategy: _this.lookaheadStrategy,
+                        rules: (0, values_1.default)(_this.gastProductionsCache),
+                        tokenTypes: (0, values_1.default)(_this.tokensMap),
+                        grammarName: className
+                    });
+                    _this.definitionErrors = _this.definitionErrors.concat(validationErrors, lookaheadValidationErrors);
                 }
@@ -168,0 +175,0 @@ });

lib/src/parse/parser/traits/looksahead.js

@@ -22,3 +22,2 @@ "use strict";
 exports.collectMethods = exports.LooksAhead = void 0;
-var lookahead_1 = require("../../grammar/lookahead");
 var forEach_1 = __importDefault(require("lodash/forEach"));
@@ -30,2 +29,3 @@ var has_1 = __importDefault(require("lodash/has"));
 var gast_2 = require("@chevrotain/gast");
+var llk_lookahead_1 = require("../../grammar/llk_lookahead");
 /**
@@ -44,2 +44,5 @@ * Trait responsible for the lookahead related utilities and optimizations.
             : parser_1.DEFAULT_PARSER_CONFIG.maxLookahead;
+        this.lookaheadStrategy = (0, has_1.default)(config, "lookaheadStrategy")
+            ? config.lookaheadStrategy // assumes end user provides the correct config value/type
+            : new llk_lookahead_1.LLkLookaheadStrategy({ maxLookahead: this.maxLookahead });
         this.lookAheadFuncsCache = new Map();
@@ -55,3 +58,9 @@ };
                     _this.TRACE_INIT("".concat((0, gast_2.getProductionDslName)(currProd)).concat(prodIdx), function () {
-                        var laFunc = (0, lookahead_1.buildLookaheadFuncForOr)(currProd.idx, currRule, currProd.maxLookahead || _this.maxLookahead, currProd.hasPredicates, _this.dynamicTokensEnabled, _this.lookAheadBuilderForAlternatives);
+                        var laFunc = _this.lookaheadStrategy.buildLookaheadForAlternation({
+                            prodOccurrence: currProd.idx,
+                            rule: currRule,
+                            maxLookahead: currProd.maxLookahead || _this.maxLookahead,
+                            hasPredicates: currProd.hasPredicates,
+                            dynamicTokensEnabled: _this.dynamicTokensEnabled
+                        });
                         var key = (0, keys_1.getKeyForAutomaticLookahead)(_this.fullRuleNameToShort[currRule.name], keys_1.OR_IDX, currProd.idx);
@@ -62,15 +71,15 @@ _this.setLaFuncCache(key, laFunc);
                 (0, forEach_1.default)(repetition, function (currProd) {
-                    _this.computeLookaheadFunc(currRule, currProd.idx, keys_1.MANY_IDX, lookahead_1.PROD_TYPE.REPETITION, currProd.maxLookahead, (0, gast_2.getProductionDslName)(currProd));
+                    _this.computeLookaheadFunc(currRule, currProd.idx, keys_1.MANY_IDX, "Repetition", currProd.maxLookahead, (0, gast_2.getProductionDslName)(currProd));
                 });
                 (0, forEach_1.default)(option, function (currProd) {
-                    _this.computeLookaheadFunc(currRule, currProd.idx, keys_1.OPTION_IDX, lookahead_1.PROD_TYPE.OPTION, currProd.maxLookahead, (0, gast_2.getProductionDslName)(currProd));
+                    _this.computeLookaheadFunc(currRule, currProd.idx, keys_1.OPTION_IDX, "Option", currProd.maxLookahead, (0, gast_2.getProductionDslName)(currProd));
                 });
                 (0, forEach_1.default)(repetitionMandatory, function (currProd) {
-                    _this.computeLookaheadFunc(currRule, currProd.idx, keys_1.AT_LEAST_ONE_IDX, lookahead_1.PROD_TYPE.REPETITION_MANDATORY, currProd.maxLookahead, (0, gast_2.getProductionDslName)(currProd));
+                    _this.computeLookaheadFunc(currRule, currProd.idx, keys_1.AT_LEAST_ONE_IDX, "RepetitionMandatory", currProd.maxLookahead, (0, gast_2.getProductionDslName)(currProd));
                 });
                 (0, forEach_1.default)(repetitionMandatoryWithSeparator, function (currProd) {
-                    _this.computeLookaheadFunc(currRule, currProd.idx, keys_1.AT_LEAST_ONE_SEP_IDX, lookahead_1.PROD_TYPE.REPETITION_MANDATORY_WITH_SEPARATOR, currProd.maxLookahead, (0, gast_2.getProductionDslName)(currProd));
+                    _this.computeLookaheadFunc(currRule, currProd.idx, keys_1.AT_LEAST_ONE_SEP_IDX, "RepetitionMandatoryWithSeparator", currProd.maxLookahead, (0, gast_2.getProductionDslName)(currProd));
                 });
                 (0, forEach_1.default)(repetitionWithSeparator, function (currProd) {
-                    _this.computeLookaheadFunc(currRule, currProd.idx, keys_1.MANY_SEP_IDX, lookahead_1.PROD_TYPE.REPETITION_WITH_SEPARATOR, currProd.maxLookahead, (0, gast_2.getProductionDslName)(currProd));
+                    _this.computeLookaheadFunc(currRule, currProd.idx, keys_1.MANY_SEP_IDX, "RepetitionWithSeparator", currProd.maxLookahead, (0, gast_2.getProductionDslName)(currProd));
                 });
@@ -83,3 +92,9 @@ });
         this.TRACE_INIT("".concat(dslMethodName).concat(prodOccurrence === 0 ? "" : prodOccurrence), function () {
-            var laFunc = (0, lookahead_1.buildLookaheadFuncForOptionalProd)(prodOccurrence, rule, prodMaxLookahead || _this.maxLookahead, _this.dynamicTokensEnabled, prodType, _this.lookAheadBuilderForOptional);
+            var laFunc = _this.lookaheadStrategy.buildLookaheadForOptional({
+                prodOccurrence: prodOccurrence,
+                rule: rule,
+                maxLookahead: prodMaxLookahead || _this.maxLookahead,
+                dynamicTokensEnabled: _this.dynamicTokensEnabled,
+                prodType: prodType
+            });
             var key = (0, keys_1.getKeyForAutomaticLookahead)(_this.fullRuleNameToShort[rule.name], prodKey, prodOccurrence);
@@ -89,8 +104,2 @@ _this.setLaFuncCache(key, laFunc);
     };
-    LooksAhead.prototype.lookAheadBuilderForOptional = function (alt, tokenMatcher, dynamicTokensEnabled) {
-        return (0, lookahead_1.buildSingleAlternativeLookaheadFunction)(alt, tokenMatcher, dynamicTokensEnabled);
-    };
-    LooksAhead.prototype.lookAheadBuilderForAlternatives = function (alts, hasPredicates, tokenMatcher, dynamicTokensEnabled) {
-        return (0, lookahead_1.buildAlternativesLookAheadFunc)(alts, hasPredicates, tokenMatcher, dynamicTokensEnabled);
-    };
     // this actually returns a number, but it is always used as a string (object prop key)
@@ -97,0 +106,0 @@ LooksAhead.prototype.getKeyForAutomaticLookahead = function (dslMethodIdx, occurrence) {

lib/src/version.js

@@ -7,3 +7,3 @@ "use strict";
 // A separate file avoids cyclic dependencies and webpack errors.
-exports.VERSION = "10.3.0";
+exports.VERSION = "10.4.0";
 //# sourceMappingURL=version.js.map

package.json

 {
   "name": "chevrotain",
-  "version": "10.3.0",
+  "version": "10.4.0",
   "description": "Chevrotain is a high performance fault tolerant javascript parsing DSL for building recursive decent parsers",
@@ -75,6 +75,6 @@ "keywords": [
   "dependencies": {
-    "@chevrotain/cst-dts-gen": "10.3.0",
-    "@chevrotain/gast": "10.3.0",
-    "@chevrotain/types": "10.3.0",
-    "@chevrotain/utils": "10.3.0",
+    "@chevrotain/cst-dts-gen": "10.4.0",
+    "@chevrotain/gast": "10.4.0",
+    "@chevrotain/types": "10.4.0",
+    "@chevrotain/utils": "10.4.0",
     "lodash": "4.17.21",
@@ -97,3 +97,3 @@ "regexp-to-ast": "0.5.0"
   },
-  "gitHead": "5ca7d276f475839c815a2686f38e2814371935c9"
+  "gitHead": "55b21562f046b11ccd9fdb06f7ccb4ed3e315116"
 }

src/api.ts

@@ -25,2 +25,8 @@ /* istanbul ignore file - tricky to import some things from this module during testing */
 
+// Lookahead
+
+export { getLookaheadPaths } from "./parse/grammar/lookahead"
+
+export { LLkLookaheadStrategy } from "./parse/grammar/llk_lookahead"
+
 // Other Utilities
@@ -27,0 +33,0 @@

src/parse/grammar/checks.ts

@@ -42,3 +42,2 @@ import first from "lodash/first"
   RepetitionWithSeparator,
-  Rule,
   Terminal
@@ -48,5 +47,7 @@ } from "@chevrotain/gast"
 import {
+  ILookaheadStrategy,
   IProduction,
   IProductionWithOccurrence,
-  TokenType
+  TokenType,
+  Rule
 } from "@chevrotain/types"
@@ -61,5 +62,21 @@ import {
 
+export function validateLookahead(options: {
+  lookaheadStrategy: ILookaheadStrategy
+  rules: Rule[]
+  tokenTypes: TokenType[]
+  grammarName: string
+}): IParserDefinitionError[] {
+  const lookaheadValidationErrorMessages = options.lookaheadStrategy.validate({
+    rules: options.rules,
+    tokenTypes: options.tokenTypes,
+    grammarName: options.grammarName
+  })
+  return map(lookaheadValidationErrorMessages, (errorMessage) => ({
+    type: ParserDefinitionErrorType.CUSTOM_LOOKAHEAD_VALIDATION,
+    ...errorMessage
+  }))
+}
+
 export function validateGrammar(
   topLevels: Rule[],
-  globalMaxLookahead: number,
   tokenTypes: TokenType[],
@@ -69,34 +86,7 @@ errMsgProvider: IGrammarValidatorErrorMessageProvider,
 ): IParserDefinitionError[] {
-  const duplicateErrors = flatMap(topLevels, (currTopLevel) =>
-    validateDuplicateProductions(currTopLevel, errMsgProvider)
+  const duplicateErrors: IParserDefinitionError[] = flatMap(
+    topLevels,
+    (currTopLevel) => validateDuplicateProductions(currTopLevel, errMsgProvider)
   )
-  const leftRecursionErrors = flatMap(topLevels, (currTopRule) =>
-    validateNoLeftRecursion(currTopRule, currTopRule, errMsgProvider)
-  )
 
-  let emptyAltErrors: IParserEmptyAlternativeDefinitionError[] = []
-  let ambiguousAltsErrors: IParserAmbiguousAlternativesDefinitionError[] = []
-  let emptyRepetitionErrors: IParserDefinitionError[] = []
-
-  // left recursion could cause infinite loops in the following validations.
-  // It is safest to first have the user fix the left recursion errors first and only then examine Further issues.
-  if (isEmpty(leftRecursionErrors)) {
-    emptyAltErrors = flatMap(topLevels, (currTopRule) =>
-      validateEmptyOrAlternative(currTopRule, errMsgProvider)
-    )
-    ambiguousAltsErrors = flatMap(topLevels, (currTopRule) =>
-      validateAmbiguousAlternationAlternatives(
-        currTopRule,
-        globalMaxLookahead,
-        errMsgProvider
-      )
-    )
-
-    emptyRepetitionErrors = validateSomeNonEmptyLookaheadPath(
-      topLevels,
-      globalMaxLookahead,
-      errMsgProvider
-    )
-  }
-
   const termsNamespaceConflictErrors = checkTerminalAndNoneTerminalsNameSpace(
@@ -121,7 +111,3 @@ topLevels,
 
-  return (duplicateErrors as IParserDefinitionError[]).concat(
-    emptyRepetitionErrors,
-    leftRecursionErrors,
-    emptyAltErrors,
-    ambiguousAltsErrors,
+  return duplicateErrors.concat(
     termsNamespaceConflictErrors,
@@ -300,3 +286,3 @@ tooManyAltsErrors,
     const ruleName = topRule.name
-    const foundLeftRecursion = includes(<any>nextNonTerminals, topRule)
+    const foundLeftRecursion = includes(nextNonTerminals, topRule)
     if (foundLeftRecursion) {
@@ -303,0 +289,0 @@ errors.push({

src/parse/grammar/gast/gast_resolver_public.ts

@@ -37,3 +37,2 @@ import { Rule } from "@chevrotain/gast"
   rules: Rule[]
-  maxLookahead: number
   tokenTypes: TokenType[]
@@ -49,3 +48,2 @@ grammarName: string
     options.rules,
-    options.maxLookahead,
     options.tokenTypes,
@@ -52,0 +50,0 @@ options.errMsgProvider,

src/parse/grammar/lookahead.ts

@@ -10,3 +10,3 @@ import isEmpty from "lodash/isEmpty"
 import { RestWalker } from "./rest"
-import { Predicate, TokenMatcher, LookAheadSequence } from "../parser/parser"
+import { Predicate, TokenMatcher } from "../parser/parser"
 import {
@@ -23,4 +23,3 @@ tokenStructuredMatcher,
   RepetitionMandatoryWithSeparator,
-  RepetitionWithSeparator,
-  Rule
+  RepetitionWithSeparator
 } from "@chevrotain/gast"
@@ -32,3 +31,7 @@ import { GAstVisitor } from "@chevrotain/gast"
   IProductionWithOccurrence,
-  TokenType
+  LookaheadSequence,
+  LookaheadProductionType,
+  Rule,
+  TokenType,
+  BaseParser
 } from "@chevrotain/types"
@@ -45,15 +48,26 @@
 
-export function getProdType(prod: IProduction): PROD_TYPE {
+export function getProdType(
+  prod: IProduction | LookaheadProductionType
+): PROD_TYPE {
   /* istanbul ignore else */
-  if (prod instanceof Option) {
+  if (prod instanceof Option || prod === "Option") {
     return PROD_TYPE.OPTION
-  } else if (prod instanceof Repetition) {
+  } else if (prod instanceof Repetition || prod === "Repetition") {
     return PROD_TYPE.REPETITION
-  } else if (prod instanceof RepetitionMandatory) {
+  } else if (
+    prod instanceof RepetitionMandatory ||
+    prod === "RepetitionMandatory"
+  ) {
     return PROD_TYPE.REPETITION_MANDATORY
-  } else if (prod instanceof RepetitionMandatoryWithSeparator) {
+  } else if (
+    prod instanceof RepetitionMandatoryWithSeparator ||
+    prod === "RepetitionMandatoryWithSeparator"
+  ) {
     return PROD_TYPE.REPETITION_MANDATORY_WITH_SEPARATOR
-  } else if (prod instanceof RepetitionWithSeparator) {
+  } else if (
+    prod instanceof RepetitionWithSeparator ||
+    prod === "RepetitionWithSeparator"
+  ) {
     return PROD_TYPE.REPETITION_WITH_SEPARATOR
-  } else if (prod instanceof Alternation) {
+  } else if (prod instanceof Alternation || prod === "Alternation") {
     return PROD_TYPE.ALTERNATION
@@ -65,2 +79,22 @@ } else {
 
+export function getLookaheadPaths(options: {
+  occurrence: number
+  rule: Rule
+  prodType: LookaheadProductionType
+  maxLookahead: number
+}): LookaheadSequence[] {
+  const { occurrence, rule, prodType, maxLookahead } = options
+  const type = getProdType(prodType)
+  if (type === PROD_TYPE.ALTERNATION) {
+    return getLookaheadPathsForOr(occurrence, rule, maxLookahead)
+  } else {
+    return getLookaheadPathsForOptionalProd(
+      occurrence,
+      rule,
+      type,
+      maxLookahead
+    )
+  }
+}
+
 export function buildLookaheadFuncForOr(
@@ -73,3 +107,3 @@ occurrence: number,
   laFuncBuilder: Function
-): (orAlts?: IOrAlt<any>[]) => number {
+): (orAlts?: IOrAlt<any>[]) => number | undefined {
   const lookAheadPaths = getLookaheadPathsForOr(
@@ -112,3 +146,3 @@ occurrence,
   lookaheadBuilder: (
-    lookAheadSequence: LookAheadSequence,
+    lookAheadSequence: LookaheadSequence,
     tokenMatcher: TokenMatcher,
@@ -135,3 +169,3 @@ dynamicTokensEnabled: boolean
 export function buildAlternativesLookAheadFunc(
-  alts: LookAheadSequence[],
+  alts: LookaheadSequence[],
   hasPredicates: boolean,
@@ -153,3 +187,6 @@ tokenMatcher: TokenMatcher,
      */
-    return function (orAlts: IOrAlt<any>[]): number | undefined {
+    return function (
+      this: BaseParser,
+      orAlts: IOrAlt<any>[]
+    ): number | undefined {
       // unfortunately the predicates must be extracted every single time
@@ -221,3 +258,3 @@ // as they cannot be cached due to references to parameters(vars) which are no longer valid.
      */
-    return function (): number {
+    return function (this: BaseParser): number {
       const nextToken = this.LA(1)
@@ -232,3 +269,3 @@ return choiceToAlt[nextToken.tokenTypeIdx]
      */
-    return function (): number | undefined {
+    return function (this: BaseParser): number | undefined {
       for (let t = 0; t < numOfAlts; t++) {
@@ -262,3 +299,3 @@ const currAlt = alts[t]
 export function buildSingleAlternativeLookaheadFunction(
-  alt: LookAheadSequence,
+  alt: LookaheadSequence,
   tokenMatcher: TokenMatcher,
@@ -285,3 +322,3 @@ dynamicTokensEnabled: boolean
 
-      return function (): boolean {
+      return function (this: BaseParser): boolean {
         return this.LA(1).tokenTypeIdx === expectedTokenUniqueKey
@@ -302,3 +339,3 @@ }
 
-      return function (): boolean {
+      return function (this: BaseParser): boolean {
         const nextToken = this.LA(1)
@@ -309,3 +346,3 @@ return choiceToAlt[nextToken.tokenTypeIdx] === true
   } else {
-    return function (): boolean {
+    return function (this: BaseParser): boolean {
       nextPath: for (let j = 0; j < numOfPaths; j++) {
@@ -556,3 +593,3 @@ const currPath = alt[j]
   k: number
-): LookAheadSequence[] {
+): LookaheadSequence[] {
   const partialAlts = map(altsDefs, (currAlt) =>
@@ -634,3 +671,3 @@ possiblePathsFrom([currAlt], 1)
   orProd?: Alternation
-): LookAheadSequence[] {
+): LookaheadSequence[] {
   const visitor = new InsideDefinitionFinderVisitor(
@@ -650,3 +687,3 @@ occurrence,
   k: number
-): LookAheadSequence[] {
+): LookaheadSequence[] {
   const insideDefVisitor = new InsideDefinitionFinderVisitor(
@@ -715,3 +752,3 @@ occurrence,
 export function areTokenCategoriesNotUsed(
-  lookAheadPaths: LookAheadSequence[]
+  lookAheadPaths: LookaheadSequence[]
 ): boolean {
@@ -718,0 +755,0 @@ return every(lookAheadPaths, (singleAltPaths) =>

src/parse/grammar/types.ts

@@ -28,3 +28,4 @@ import {
   AMBIGUOUS_PREFIX_ALTS = 11,
-  TOO_MANY_ALTS = 12
+  TOO_MANY_ALTS = 12,
+  CUSTOM_LOOKAHEAD_VALIDATION = 13
 }
@@ -31,0 +32,0 @@

src/parse/parser/parser.ts

@@ -43,2 +43,3 @@ import isEmpty from "lodash/isEmpty"
 import { IParserConfigInternal, ParserMethodInternal } from "./types"
+import { validateLookahead } from "../grammar/checks"
 
@@ -59,16 +60,15 @@ export const END_OF_FILE = createTokenInstance(
 
-export type LookAheadSequence = TokenType[][]
+export const DEFAULT_PARSER_CONFIG: Required<
+  Omit<IParserConfigInternal, "lookaheadStrategy">
+> = Object.freeze({
+  recoveryEnabled: false,
+  maxLookahead: 3,
+  dynamicTokensEnabled: false,
+  outputCst: true,
+  errorMessageProvider: defaultParserErrorProvider,
+  nodeLocationTracking: "none",
+  traceInitPerf: false,
+  skipValidations: false
+})
 
-export const DEFAULT_PARSER_CONFIG: Required<IParserConfigInternal> =
-  Object.freeze({
-    recoveryEnabled: false,
-    maxLookahead: 3,
-    dynamicTokensEnabled: false,
-    outputCst: true,
-    errorMessageProvider: defaultParserErrorProvider,
-    nodeLocationTracking: "none",
-    traceInitPerf: false,
-    skipValidations: false
-  })
-
 export const DEFAULT_RULE_CONFIG: Required<IRuleConfig<any>> = Object.freeze({
@@ -92,3 +92,4 @@ recoveryValueFunc: () => undefined,
   AMBIGUOUS_PREFIX_ALTS = 11,
-  TOO_MANY_ALTS = 12
+  TOO_MANY_ALTS = 12,
+  CUSTOM_LOOKAHEAD_VALIDATION = 13
 }
@@ -207,3 +208,2 @@
             rules: values(this.gastProductionsCache),
-            maxLookahead: this.maxLookahead,
             tokenTypes: values(this.tokensMap),
@@ -213,3 +213,12 @@ errMsgProvider: defaultGrammarValidatorErrorProvider,
           })
-          this.definitionErrors = this.definitionErrors.concat(validationErrors)
+          const lookaheadValidationErrors = validateLookahead({
+            lookaheadStrategy: this.lookaheadStrategy,
+            rules: values(this.gastProductionsCache),
+            tokenTypes: values(this.tokensMap),
+            grammarName: className
+          })
+          this.definitionErrors = this.definitionErrors.concat(
+            validationErrors,
+            lookaheadValidationErrors
+          )
         }
@@ -216,0 +225,0 @@ })

src/parse/parser/traits/looksahead.ts

@@ -1,16 +0,9 @@
-import {
-  buildAlternativesLookAheadFunc,
-  buildLookaheadFuncForOptionalProd,
-  buildLookaheadFuncForOr,
-  buildSingleAlternativeLookaheadFunction,
-  PROD_TYPE
-} from "../../grammar/lookahead"
 import forEach from "lodash/forEach"
 import has from "lodash/has"
+import { DEFAULT_PARSER_CONFIG } from "../parser"
 import {
-  DEFAULT_PARSER_CONFIG,
-  LookAheadSequence,
-  TokenMatcher
-} from "../parser"
-import { IOrAlt, IParserConfig } from "@chevrotain/types"
+  ILookaheadStrategy,
+  IParserConfig,
+  OptionalProductionType
+} from "@chevrotain/types"
 import {
@@ -37,2 +30,3 @@ AT_LEAST_ONE_IDX,
 import { getProductionDslName } from "@chevrotain/gast"
+import { LLkLookaheadStrategy } from "../../grammar/llk_lookahead"
 
@@ -46,2 +40,3 @@ /**
   dynamicTokensEnabled: boolean
+  lookaheadStrategy: ILookaheadStrategy
 
@@ -57,2 +52,6 @@ initLooksAhead(config: IParserConfig) {
 
+    this.lookaheadStrategy = has(config, "lookaheadStrategy")
+      ? (config.lookaheadStrategy as ILookaheadStrategy) // assumes end user provides the correct config value/type
+      : new LLkLookaheadStrategy({ maxLookahead: this.maxLookahead })
+
     this.lookAheadFuncsCache = new Map()
@@ -76,10 +75,9 @@ }
           this.TRACE_INIT(`${getProductionDslName(currProd)}${prodIdx}`, () => {
-            const laFunc = buildLookaheadFuncForOr(
-              currProd.idx,
-              currRule,
-              currProd.maxLookahead || this.maxLookahead,
-              currProd.hasPredicates,
-              this.dynamicTokensEnabled,
-              this.lookAheadBuilderForAlternatives
-            )
+            const laFunc = this.lookaheadStrategy.buildLookaheadForAlternation({
+              prodOccurrence: currProd.idx,
+              rule: currRule,
+              maxLookahead: currProd.maxLookahead || this.maxLookahead,
+              hasPredicates: currProd.hasPredicates,
+              dynamicTokensEnabled: this.dynamicTokensEnabled
+            })
 
@@ -100,3 +98,3 @@ const key = getKeyForAutomaticLookahead(
             MANY_IDX,
-            PROD_TYPE.REPETITION,
+            "Repetition",
             currProd.maxLookahead,
@@ -112,3 +110,3 @@ getProductionDslName(currProd)
             OPTION_IDX,
-            PROD_TYPE.OPTION,
+            "Option",
             currProd.maxLookahead,
@@ -124,3 +122,3 @@ getProductionDslName(currProd)
             AT_LEAST_ONE_IDX,
-            PROD_TYPE.REPETITION_MANDATORY,
+            "RepetitionMandatory",
             currProd.maxLookahead,
@@ -136,3 +134,3 @@ getProductionDslName(currProd)
             AT_LEAST_ONE_SEP_IDX,
-            PROD_TYPE.REPETITION_MANDATORY_WITH_SEPARATOR,
+            "RepetitionMandatoryWithSeparator",
             currProd.maxLookahead,
@@ -148,3 +146,3 @@ getProductionDslName(currProd)
             MANY_SEP_IDX,
-            PROD_TYPE.REPETITION_WITH_SEPARATOR,
+            "RepetitionWithSeparator",
             currProd.maxLookahead,
@@ -163,3 +161,3 @@ getProductionDslName(currProd)
     prodKey: number,
-    prodType: PROD_TYPE,
+    prodType: OptionalProductionType,
     prodMaxLookahead: number | undefined,
@@ -171,10 +169,9 @@ dslMethodName: string
       () => {
-        const laFunc = buildLookaheadFuncForOptionalProd(
+        const laFunc = this.lookaheadStrategy.buildLookaheadForOptional({
           prodOccurrence,
           rule,
-          prodMaxLookahead || this.maxLookahead,
-          this.dynamicTokensEnabled,
-          prodType,
-          this.lookAheadBuilderForOptional
-        )
+          maxLookahead: prodMaxLookahead || this.maxLookahead,
+          dynamicTokensEnabled: this.dynamicTokensEnabled,
+          prodType
+        })
         const key = getKeyForAutomaticLookahead(
@@ -190,30 +187,2 @@ this.fullRuleNameToShort[rule.name],
 
-  lookAheadBuilderForOptional(
-    this: MixedInParser,
-    alt: LookAheadSequence,
-    tokenMatcher: TokenMatcher,
-    dynamicTokensEnabled: boolean
-  ): () => boolean {
-    return buildSingleAlternativeLookaheadFunction(
-      alt,
-      tokenMatcher,
-      dynamicTokensEnabled
-    )
-  }
-
-  lookAheadBuilderForAlternatives(
-    this: MixedInParser,
-    alts: LookAheadSequence[],
-    hasPredicates: boolean,
-    tokenMatcher: TokenMatcher,
-    dynamicTokensEnabled: boolean
-  ): (orAlts: IOrAlt<any>[]) => number | undefined {
-    return buildAlternativesLookAheadFunc(
-      alts,
-      hasPredicates,
-      tokenMatcher,
-      dynamicTokensEnabled
-    )
-  }
-
   // this actually returns a number, but it is always used as a string (object prop key)
@@ -220,0 +189,0 @@ getKeyForAutomaticLookahead(

src/version.ts

 // needs a separate module as this is required inside chevrotain productive code
 // and also in the entry point for webpack(api.ts).
 // A separate file avoids cyclic dependencies and webpack errors.
-export const VERSION = "10.3.0"
+export const VERSION = "10.4.0"

No alert changes

Improved metrics

Total package byte prevSize

3537280

increased by0.97%

Number of package files

148

increased by2.07%

Lines of code

46974

increased by1%

Dependency changes

• + Added@chevrotain/cst-dts-gen@10.4.0(transitive)

• + Added@chevrotain/gast@10.4.0(transitive)

• + Added@chevrotain/types@10.4.0(transitive)

• + Added@chevrotain/utils@10.4.0(transitive)

• - Removed@chevrotain/cst-dts-gen@10.3.0(transitive)

• - Removed@chevrotain/gast@10.3.0(transitive)

• - Removed@chevrotain/types@10.3.0(transitive)

• - Removed@chevrotain/utils@10.3.0(transitive)

• Updated@chevrotain/cst-dts-gen@10.4.0

• Updated@chevrotain/gast@10.4.0

• Updated@chevrotain/types@10.4.0

• Updated@chevrotain/utils@10.4.0