parser-combinator/src/lib/standard/markdown/title-parser.js

Parser combinators

/**
 * Created by Simon on 14/12/2016.
 */
/*
 * This module try parse a title. The folowing will be recognised as titles:
 * "#foo\n"  "##foo\n"  "foo\n==="  "foo\n---"  "##########     foo     \n"
 *
 * Limits and axiomes
 * A \n in the markdown source ends the parsing of a title.  #foo\nbar  -> {title:foo},{text:bar}
 */
import {F, C} from '../../parsec/index';
import stream from '../../stream/index';
import T from './token';

function sharps() {
    return C.char('#').rep().map(string => string.array().length);
}

// a white is a sequence of at least one space, tab or non-breakable space
function white() {
    return C.charIn(' \t\u00A0').rep();
}

function equals() {
    return C.string('===')
        .then(T.rawTextUntil(T.eol()))
        .then(T.eol())
        .thenReturns(1); // this mean a level 1 title
}

function minuses() {
    return C.string('---')
        .then(T.rawTextUntil(T.eol()))
        .then(T.eol())
        .thenReturns(2); // this mean a level 2 title
}

function titleSharp() {
    return sharps()
        .thenLeft(white())
        .then(T.rawTextUntil(T.eol()))
        .thenLeft(T.eol().or(F.eos))
        .map(array => ({
            title: {
                level: array[0],
                text: array[1],
            },
        }));
}

function titleLine() {
    return T.blank().thenRight(
        T.rawTextUntilChar('\r\n')
            .thenLeft(T.eol())
            .then(equals().or(minuses()))
            .map(array => ({
                title: {
                    level: array[1],
                    text: array[0],
                },
            }))
    );
}

function title() {
    return titleSharp().or(titleLine());
}

function parseTitle(line, offset = 0) {
    return title().parse(stream.ofString(line), offset);
}

export default {
    titleLine,
    titleSharp,
    title,
    parse(line) {
        return parseTitle(line, 0);
    },
};

/*  SHORTCOMINGS :
* Can not have formatted text in a title.  "##2*3*4 = 24\n" will display "2*3*4 = 24"
 */