chrono-node/src/locales/en/parsers/ENSlashMonthFormatParser.ts

A natural language date parser in Javascript

import { ParsingContext } from "../../../chrono";
import { ParsingComponents } from "../../../results";
import { AbstractParserWithWordBoundaryChecking } from "../../../common/parsers/AbstractParserWithWordBoundary";

const PATTERN = new RegExp("([0-9]|0[1-9]|1[012])/([0-9]{4})" + "", "i");

const MONTH_GROUP = 1;
const YEAR_GROUP = 2;

/**
 * Month/Year date format with slash "/" (also "-" and ".") between numbers
 * - 11/05
 * - 06/2005
 */
export default class ENSlashMonthFormatParser extends AbstractParserWithWordBoundaryChecking {
    innerPattern(): RegExp {
        return PATTERN;
    }

    innerExtract(context: ParsingContext, match: RegExpMatchArray): ParsingComponents | null {
        // Do not extract a month/year suffix from an invalid numeric date (e.g. "50/6/2018").
        // Parsing can also resume within a rejected match, so check the original text.
        if (/\d\/?$/.test(context.text.substring(0, match.index))) {
            return null;
        }

        const year = parseInt(match[YEAR_GROUP]);
        const month = parseInt(match[MONTH_GROUP]);

        return context.createParsingComponents().imply("day", 1).assign("month", month).assign("year", year);
    }
}