parjs/src/internal/parsers/newline.ts

A parser-combinator library for JavaScript.

/**
 * @module parjs
 */
/** */

import {ResultKind} from "../result";
import {ParsingState} from "../state";
import {Parjser} from "../parjser";
import {ParjserBase} from "../parser";
import {
    uniIsNewline,
    AsciiCodes

} from "char-info";


function innerNewline(unicodeRecognizer?: (x: number) => boolean): Parjser<string> {
    return new class Newline extends ParjserBase {
        expecting = "expecting newline";
        type = "newline";
        _apply(ps: ParsingState) {
            let {position, input} = ps;
            if (position >= input.length) {
                ps.kind = ResultKind.SoftFail;
                return;
            }

            let pair = input.slice(position, position + 2);

            if (pair === "\r\n") {
                ps.position += 2;
                ps.value = pair;
                ps.kind = ResultKind.Ok;
                return;
            }
            let firstChar = pair.charCodeAt(0);
            if (firstChar === AsciiCodes.newline || firstChar === AsciiCodes.carriageReturn || (unicodeRecognizer && unicodeRecognizer(firstChar))) {
                ps.position++;
                ps.value = pair[0];
                ps.kind = ResultKind.Ok;
                return;
            }
            ps.kind = ResultKind.SoftFail;
        }
    }();
}

/**
 * Parses an ASCII newline, which can be a single character or the sequence
 * `\r\n`. Yields the text that was parsed.
 */
export function newline() {
    return innerNewline();
}

/**
 * Parses a Unicode newline, which includes ASCII newline strings as well as
 * other vertical separators such as PARAGRAPH SEPARATOR.
 */
export function uniNewline() {
    return innerNewline(uniIsNewline.code);
}