src/MDReplacer.js

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
/**
 * the Markdown Replacer class parse a markdown string to a HTML string
 */
class MDReplacer {
    /**
     * ctor
     */
    constructor() {
        /**
         * dictionary with md token and html replacement tags
         */
        this.dictionary = {
            "## ": {
                start: '<h2>',
                end: '</h2>'
            },
            "# ": {
                start: '<h1>',
                end: '</h1>'
            },
            "**": {
                start: '<b>',
                end: '</b>'
            },
            "* ": {
                start: '<ul><li>',
                end: '</li></ul>'
            },
            "*": {
                start: '<i>',
                end: '</i>'
            },
            ">": {
                start: '<blockquote><p>',
                end: '</p></blockquote>'
            },
            " ": {
                start: '<p>',
                end: '</p>'
            }
        };
    }
    /**
     * the replace method splits the string in blocks and parse each line
     * @param input : the whole document as string input
     * @return the parsed input string with all replaced tags
     */
    replace(input) {
        // return if input is empty
        if (input == "")
            return "";
        let blocks = input.split('\n');
        let result = "";
        for (let line in blocks) {
            for (let key in this.dictionary) {
                while (blocks[line].indexOf(key) !== -1) {
                    if ((key === '>' || key === ' ') && !this.startsWith(blocks[line], key)) {
                        break;
                    }
                    blocks[line] = this.replaceKey(blocks[line], key);
                }
            }
            if (line !== '0') {
                result = result.concat('<br/>');
            }
            result = result.concat(blocks[line]);
        }
        result = this.combineMultiLineTags(result);
        return result;
    }
    /**
     * replace md tokens to html tags
     * @param input: string to parse
     * @param key: token to search
     * @return this method returns the string with the replaced html tags
     */
    replaceKey(input, key) {
        let result = input;
        switch (key) {
            case '**':
                result = this.replaceDouble(result, key);
                break;
            case '*':
                result = this.replaceDouble(result, key);
                break;
            default:
                result = result.replace(key, this.dictionary[key]['start']).concat(this.dictionary[key]['end']);
                break;
        }
        return result;
    }
    /**
     * If the markdown token has a start and end token,
     * we replaces both
     * @param input: string to parse
     * @param key: token to replace
     * @return parsed string with html tag at beginning and ending
     */
    replaceDouble(input, key) {
        let result = input;
        let tmp = result.split(key);
        if (tmp.length % 3 === 0) {
            for (let i = 0; i < 2; i++) {
                if (i === 0) {
                    result = result.replace(key, this.dictionary[key]['start']);
                }
                else {
                    result = result.replace(key, this.dictionary[key]['end']);
                }
            }
        }
        else if (key === '**' && tmp.length === 2) {
            result = this.replaceDouble(result, '*');
        }
        return result;
    }
    /**
     * small helper method to check if the current token is a starting token
     * @param input: string to check
     * @param key: token to check
     * @return the result as boolean, true if it is first else false
     */
    startsWith(input, key) {
        let inputNormalized = input;
        if (key !== ' ') {
            inputNormalized = input.replace(/ /g, '');
        }
        if (inputNormalized.charAt(0) === key) {
            return true;
        }
        return false;
    }
    /**
     * combine multiline list elements to one list
     * @param {string} input: string to parse
     * @return {string} parsed string
     */
    combineMultiLineTags(input) {
        let result = input;
        result = result.replace(new RegExp('</li></ul><br/><ul><li>', 'g'), '</li><br/><li>');
        result = result.replace(new RegExp('</p></blockquote><br/><blockquote><p>', 'g'), '</p><br/><p>');
        return result;
    }
}
exports.MDReplacer = MDReplacer;
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