parjs/dist/internal/combinators/backtrack.js

Library for building parsers using combinators.

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.backtrack = void 0;
const combinated_1 = require("../combinated");
const combinator_1 = require("./combinator");
class Backtrack extends combinated_1.Combinated {
    constructor() {
        super(...arguments);
        this.type = "backtrack";
        this.expecting = this.source.expecting;
    }
    _apply(ps) {
        const { position } = ps;
        this.source.apply(ps);
        if (ps.isOk) {
            // if inner succeeded, we backtrack.
            ps.position = position;
        }
        // whatever code ps had, we return it.
    }
}
/**
 * Applies the source parser. If it succeeds, backtracks to the current position in the input and
 * yields the result.
 */
function backtrack() {
    return (0, combinator_1.defineCombinator)(source => {
        return new Backtrack(source);
    });
}
exports.backtrack = backtrack;
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