chevrotain/lib/src/parse/parser/traits/error_handler.js

Chevrotain is a high performance fault tolerant javascript parsing DSL for building recursive decent parsers

import { EarlyExitException, isRecognitionException, NoViableAltException, } from "../../exceptions_public.js";
import { getLookaheadPathsForOptionalProd, getLookaheadPathsForOr, } from "../../grammar/lookahead.js";
import { DEFAULT_PARSER_CONFIG } from "../parser.js";
/**
 * Trait responsible for runtime parsing errors.
 */
export class ErrorHandler {
    initErrorHandler(config) {
        this._errors = [];
        this.errorMessageProvider = Object.hasOwn(config, "errorMessageProvider")
            ? config.errorMessageProvider // assumes end user provides the correct config value/type
            : DEFAULT_PARSER_CONFIG.errorMessageProvider;
    }
    SAVE_ERROR(error) {
        if (isRecognitionException(error)) {
            error.context = {
                ruleStack: this.getHumanReadableRuleStack(),
                ruleOccurrenceStack: this.RULE_OCCURRENCE_STACK.slice(0, this.RULE_OCCURRENCE_STACK_IDX + 1),
            };
            this._errors.push(error);
            return error;
        }
        else {
            throw Error("Trying to save an Error which is not a RecognitionException");
        }
    }
    get errors() {
        return [...this._errors];
    }
    set errors(newErrors) {
        this._errors = newErrors;
    }
    // TODO: consider caching the error message computed information
    raiseEarlyExitException(occurrence, prodType, userDefinedErrMsg) {
        const ruleName = this.getCurrRuleFullName();
        const ruleGrammar = this.getGAstProductions()[ruleName];
        const lookAheadPathsPerAlternative = getLookaheadPathsForOptionalProd(occurrence, ruleGrammar, prodType, this.maxLookahead);
        const insideProdPaths = lookAheadPathsPerAlternative[0];
        const actualTokens = [];
        for (let i = 1; i <= this.maxLookahead; i++) {
            actualTokens.push(this.LA(i));
        }
        const msg = this.errorMessageProvider.buildEarlyExitMessage({
            expectedIterationPaths: insideProdPaths,
            actual: actualTokens,
            previous: this.LA(0),
            customUserDescription: userDefinedErrMsg,
            ruleName: ruleName,
        });
        throw this.SAVE_ERROR(new EarlyExitException(msg, this.LA(1), this.LA(0)));
    }
    // TODO: consider caching the error message computed information
    raiseNoAltException(occurrence, errMsgTypes) {
        const ruleName = this.getCurrRuleFullName();
        const ruleGrammar = this.getGAstProductions()[ruleName];
        // TODO: getLookaheadPathsForOr can be slow for large enough maxLookahead and certain grammars, consider caching ?
        const lookAheadPathsPerAlternative = getLookaheadPathsForOr(occurrence, ruleGrammar, this.maxLookahead);
        const actualTokens = [];
        for (let i = 1; i <= this.maxLookahead; i++) {
            actualTokens.push(this.LA(i));
        }
        const previousToken = this.LA(0);
        const errMsg = this.errorMessageProvider.buildNoViableAltMessage({
            expectedPathsPerAlt: lookAheadPathsPerAlternative,
            actual: actualTokens,
            previous: previousToken,
            customUserDescription: errMsgTypes,
            ruleName: this.getCurrRuleFullName(),
        });
        throw this.SAVE_ERROR(new NoViableAltException(errMsg, this.LA(1), previousToken));
    }
}
//# sourceMappingURL=error_handler.js.map