www-lib-markdown/js/markdown.js

// Blocks
// - Paragraph
// - Header 1-6   # ## ### #### ##### ######  or   ===  ---
// - Blockquote (nestable)   >
// - Unordered list (nestable)   *_
// - Ordered list (nestable)    1._
// - Code block   ```\ncode\n```  or  4 spaces/tab indent
// - Horizontal rule   ---    - - -    * * *  etc
// - Table   -|-
// - Definition list     term\n: definition\n: alternate definition
// - Footnote (bottom)   citation[^1]
// - Abbreviation (definition)   *[ABC]: Abbrev Blah Cat
// Inline
// - Link   [text](https://url)
// - Emphasis   *emphasized*
// - Strong   **bold**
// - Inline code   `code`
// - Strikethrough   ~strike~
// - Image   ![alt text](https://image){.cssclass}
// - Footnote (inline)   [^1]: footnote text
// - Abbreviation (inline)

class _MDHAlign {
	static Left = new _MDHAlign('Left');
	static Center = new _MDHAlign('Center');
	static Right = new _MDHAlign('Right');

	/** @var {String} */
	name;

	constructor(name) {
		this.name = name;
	}

	toString() {
		return `_MDHAlign.${this.name}`;
	}

	static toHTMLAttribute(align) {
		switch (align) {
			case _MDHAlign.Left: return ' align="left"';
			case _MDHAlign.Center: return ' align="center"';
			case _MDHAlign.Right: return ' align="right"';
		}
		return '';
	}
}

class _MDTokenType {
	static Text = new _MDTokenType('Text');
	static Whitespace = new _MDTokenType('Whitespace');

	static Underscore = new _MDTokenType('Underscore');
	static Asterisk = new _MDTokenType('Asterisk');
	static Slash = new _MDTokenType('Slash');
	static Tilde = new _MDTokenType('Tilde');
	static Bang = new _MDTokenType('Bang');
	static Backtick = new _MDTokenType('Backtick');

	static Label = new _MDTokenType('Label'); // content=label
	static URL = new _MDTokenType('URL'); // content=URL, extra=title
	static Email = new _MDTokenType('Email'); // content=email address, extra=title
	static SimpleLink = new _MDTokenType('SimpleLink'); // content=URL
	static SimpleEmail = new _MDTokenType('SimpleEmail'); // content=email address
	static Footnote = new _MDTokenType('Footnote'); // content=symbol

	static HTMLTag = new _MDTokenType('HTMLTag'); // content=tag string, tag=_MDHTMLTag

	#name;

	get name() {
		return this.#name;
	}

	constructor(name) {
		this.#name = name;
	}

	toString() {
		return this.constructor.name + `.${this.#name}`;
	}
}
class _MDToken {

	/** @var {String} */
	original;
	/** @var {_MDTokenType} */
	type;
	/** @var {String|null} */
	content;
	/** @var {String|null} */
	extra;
	/** @var {_MDHTMLTag|null} */
	tag;

	constructor(original, type, content=null, extra=null, tag=null) {
		this.original = original;
		this.type = type;
		this.content = content;
		this.extra = extra;
		this.tag = tag;
	}
}

class _MDSpan {
	toHTML(config) {
		throw new Error(self.constructor.name + ".toHTML not implemented");
	}

	static toHTML(spans, config) {
		return spans.map((span) => span.toHTML(config)).join("");
	}
}
class _MDMultiSpan extends _MDSpan {
	/** @var {_MDSpan[]} */
	content;
	/**
	 * @param {_MDSpan[]} content
	 */
	constructor(content) {
		super();
		this.content = content;
	}
	toHTML() {
		return _MDSpan.toHTML(this.content);
	}
}
class _MDTextSpan extends _MDSpan {
	/** @param {String} text */
	text;
	/**
	 * @param {String} text
	 */
	constructor(text) {
		super();
		this.text = text;
	}
	toHTML(config) {
		return this.text.replace('<', '&lt;');
	}
}
class _MDHTMLSpan extends _MDSpan {
	/** @param {String} html */
	html;
	/**
	 * @param {String} html
	 */
	constructor(html) {
		super();
		this.html = html;
	}
	toHTML(config) {
		return this.html;
	}
}
class _MDLink extends _MDSpan {
	/** @var {String} */
	link;
	/** @var {String|null} */
	target = null;
	/** @var {_MDSpan} */
	content;

	/**
	 * @param {String} link
	 * @param {_MDSpan} content
	 */
	constructor(link, content) {
		super();
		this.link = link;
		this.content = content;
	}

	toHTML(config) {
		let escapedLink = this.link.replace('"', '&quot;');
		var html = `<a href="${escapedLink}"`;
		if (target) {
			let escapedTarget = this.target.replace('"', '&quot;');
			html += ` target="${escapedTarget}"`;
		}
		html += '>' + this.content.toHTML(config) + '</a>';
		return html;
	}
}
class _MDReferencedLink extends _MDLink {
	/** @var {String} id */
	id;
	constructor(id, content) {
		super(null, content);
		this.id = id;
	}
	toHTML(config) {
		if (this.link) {
			return super.toHTML(config);
		} else {
			let contentHTML = this.content.toHTML(config);
			return `[${contentHTML}][${this.id}]`;
		}
	}
}
class _MDEmphasis extends _MDSpan {
	/** @var {_MDSpan} content */
	#content;
	/**
	 * @param {_MDSpan} content
	 */
	constructor(content) {
		super();
		this.#content = content;
	}
	toHTML(config) {
		let contentHTML = this.#content.toHTML(config);
		return `<em>${contentHTML}</em>`;
	}
}
class _MDStrong extends _MDSpan {
	/** @var {_MDSpan} content */
	#content;
	/**
	 * @param {_MDSpan} content
	 */
	constructor(content) {
		super();
		this.#content = content;
	}
	toHTML(config) {
		let contentHTML = this.#content.toHTML(config);
		return `<strong>${contentHTML}</strong>`;
	}
}
class _MDStrikethrough extends _MDSpan {
	/** @var {_MDSpan} content */
	#content;
	/**
	 * @param {_MDSpan} content
	 */
	constructor(content) {
		super();
		this.#content = content;
	}
	toHTML(config) {
		let contentHTML = this.#content.toHTML(config);
		return `<strike>${contentHTML}</strike>`;
	}
}
class _MDInlineCode extends _MDSpan {
	/** @var {_MDSpan} content */
	#content;
	/**
	 * @param {_MDSpan} content
	 */
	constructor(content) {
		super();
		this.#content = content;
	}
	toHTML(config) {
		let contentHTML = this.#content.toHTML(config);
		return `<code>${contentHTML}</code>`;
	}
}
class _MDImage extends _MDSpan {
	/** @var {String} */
	source;
	/** @var {String|null} */
	alt;
	/**
	 * @param {String} source
	 */
	constructor(source, alt) {
		super();
		this.source = source;
		this.alt = alt;
	}
	toHTML(config) {
		let escapedSource = this.source.replace('"', '&quot;');
		let html = `<img src="${escapedSource}"`;
		if (this.alt) {
			let altEscaped = this.alt.replace('"', '&quot');
			html += ` alt="${altEscaped}"`;
		}
		html += '>';
		return html;
	}
}
class _MDReferencedImage extends _MDImage {
	/** @var {String} */
	id;
	/**
	 * @param {String} id
	 */
	constructor(id, alt) {
		super(null, alt);
		this.id = id;
	}
	toHTML(config) {
		if (this.source) {
			return super.toHTML(config);
		} else {
			let altEscaped = this.alt.replace('"', '&quot;');
			let idEscaped = this.id.replace('"', '&quot;');
			return `![${altEscaped}][${idEscaped}]`;
		}
	}
}
class _MDFootnoteReference extends _MDSpan {
	/** @var {String} */
	symbol;
	/** @var {Number} */
	differentiator = 0;
	/**
	 * @param {String} symbol
	 */
	constructor(symbol) {
		super();
		this.symbol = symbol;
	}
	toHTML(config) {
		return `<sup id="fnref-${this.symbol}-${this.differentiator}"><a href="#fndef-${this.symbol}">${this.symbol}</a></sup>`;
	}
}
class _MDAbbreviationReference extends _MDSpan {
	/** @var {_MDSpan} content */
	#content;
	/** @var {String} definition */
	#definition;
	/**
	 * @param {_MDSpan} content
	 */
	constructor(content, definition) {
		super();
		this.#content = content;
		this.#definition = definition;
	}
	toHTML(config) {
		let contentHTML = this.#content.toHTML(config);
		let definitionEscaped = this.#definition.replace('"', '&quot;');
		return `<abbr title="${definitionEscaped}">${contentHTML}</em>`;
	}
}

class _MDBlock {
	toHTML(config) {
		throw new Error(self.constructor.name + ".toHTML not implemented");
	}

	/**
	 * @param {_MDBlock[]} blocks
	 * @returns {String}
	 */
	static toHTML(blocks, config) {
		return blocks.map((block) => block.toHTML(config)).join("\n");
	}
}

class _MDMultiBlock extends _MDBlock {
	/** @var {_MDBlock[]} */
	#blocks;
	/**
	 * @param {_MDBlock[]} blocks
	 */
	constructor(blocks) {
		super();
		this.#blocks = blocks;
	}
	toHTML(config) {
		return _MDBlock.toHTML(this.#blocks, config);
	}
}

class _MDParagraph extends _MDBlock {
	/** @var {_MDBlock} */
	content;

	/**
	 * @param {_MDBlock} content
	 */
	constructor(content) {
		super();
		this.content = content;
	}

	toHTML(config) {
		let contentHTML = this.content.toHTML(config);
		return `<p>${contentHTML}</p>\n`;
	}
}

class _MDHeader extends _MDBlock {
	/** @var {number} */
	level;
	/** @var {_MDBlock} */
	content;

	/**
	 * @param {number} level
	 * @param {_MDBlock} content
	 */
	constructor(level, content) {
		super();
		this.level = level;
		this.content = content;
	}

	toHTML(config) {
		let contentHTML = this.content.toHTML(config);
		return `<h${this.level}>${contentHTML}</h${this.level}>\n`;
	}
}

class _MDBlockquote extends _MDBlock {
	/** @var {_MDBlock[]} */
	content;
	/**
	 * @param {_MDBlock[]} content
	 */
	constructor(content) {
		super();
		this.content = content;
	}
	toHTML(config) {
		let contentHTML = _MDBlock.toHTML(this.content, config);
		return `<blockquote>\n${contentHTML}\n</blockquote>`;
	}
}

class _MDUnorderedList extends _MDBlock {
	/** @var {_MDListItem[]} */
	items;
	/**
	 * @param {_MDListItem[]} items
	 */
	constructor(items) {
		super();
		this.items = items;
	}
	toHTML(config) {
		let contentHTML = _MDBlock.toHTML(this.items);
		return `<ul>\n${contentHTML}\n</ul>`;
	}
}

class _MDOrderedList extends _MDBlock {
	/** @var {_MDListItem[]} */
	items;
	/**
	 * @param {_MDListItem[]} items
	 */
	constructor(items) {
		super();
		this.items = items;
	}
	toHTML(config) {
		let contentHTML = _MDBlock.toHTML(this.items);
		return `<ol>\n${contentHTML}\n</ol>`;
	}
}

class _MDListItem extends _MDBlock {
	/** @var {_MDBlock} */
	content;

	/**
	 * @param {_MDBlock} content
	 */
	constructor(content) {
		super();
		this.content = content;
	}

	toHTML(config) {
		let contentHTML = this.content.toHTML(config);
		return `<li>${contentHTML}</li>`;
	}
}

class _MDCodeBlock extends _MDBlock {
	/** @var {String} */
	#code;
	/**
	 * @param {String} code
	 */
	constructor(code) {
		super();
		this.#code = code;
	}
	toHTML(config) {
		return `<pre><code>${this.#code}</code></pre>`;
	}
}

class _MDHorizontalRule extends _MDBlock {
	toHTML(config) {
		return "<hr>\n";
	}
}

class _MDTableCell extends _MDBlock {
	/** @var {_MDBlock} */
	#content;
	/** @var {_MDHAlign|null} */
	align = null;
	/**
	 * @param {_MDBlock} content
	 */
	constructor(content) {
		super();
		this.#content = content;
	}
	toHTML(config) {
		let contentHTML = this.#content.toHTML(config);
		let alignAttribute = _MDHAlign.toHTMLAttribute(this.align);
		return `<td${alignAttribute}>${contentHTML}</td>`;
	}
}

class _MDTableHeaderCell extends _MDTableCell {
	toHTML(config) {
		let html = super.toHTML(config);
		let groups = /^<td(.*)td>$/.exec(html);
		return `<th${groups[1]}th>`;
	}
}

class _MDTableRow extends _MDBlock {
	/** @var {_MDTableCell[]|_MDTableHeaderCell[]} */
	#cells;
	/**
	 * @param {_MDTableCell[]|_MDTableHeaderCell[]} cells
	 */
	constructor(cells) {
		super();
		this.#cells = cells;
	}
	/**
	 * @param {_MDHAlign[]} alignments
	 */
	applyAlignments(alignments) {
		for (var i = 0; i < this.#cells.length; i++) {
			let cell = this.#cells[i];
			let align = i < alignments.length ? alignments[i] : null;
			cell.align = align;
		}
	}
	toHTML(config) {
		let cellsHTML = _MDBlock.toHTML(this.#cells, config);
		return `<tr>\n${cellsHTML}\n</tr>`;
	}
}

class _MDTable extends _MDBlock {
	/** @var {_MDTableRow} */
	#headerRow;
	/** @var {_MDTableRow[]} */
	#bodyRows;
	/**
	 * @param {_MDTableRow} headerRow
	 * @param {_MDTableRow[]} bodyRows
	 */
	constructor(headerRow, bodyRows) {
		super();
		this.#headerRow = headerRow;
		this.#bodyRows = bodyRows;
	}
	toHTML(config) {
		let headerRowHTML = this.#headerRow.toHTML(config);
		let bodyRowsHTML = _MDBlock.toHTML(this.#bodyRows);
		return `<table>\n<thead>\n${headerRowHTML}\n</thead>\n<tbody>\n${bodyRowsHTML}\n</tbody>\n</table>`;
	}
}

class _MDDefinitionList extends _MDBlock {
	/** @var {_MDBlock[]} */
	#content;
	/**
	 * @param {_MDBlock[]} content
	 */
	constructor(content) {
		super();
		this.#content = content;
	}
	toHTML(config) {
		let contentHTML = _MDBlock.toHTML(this.#content);
		return `<dl>\n${contentHTML}\n</dl>`;
	}
}

class _MDDefinitionTerm extends _MDBlock {
	/** @var {_MDBlock} */
	#content;
	/**
	 * @param {_MDBlock} content
	 */
	constructor(content) {
		super();
		this.#content = content;
	}
	toHTML(config) {
		let contentHTML = this.#content.toHTML(config);
		return `<dt>${contentHTML}</dt>`;
	}
}

class _MDDefinitionDefinition extends _MDBlock {
	/** @var {_MDBlock} */
	#content;
	/**
	 * @param {_MDBlock} content
	 */
	constructor(content) {
		super();
		this.#content = content;
	}
	toHTML(config) {
		let contentHTML = this.#content.toHTML(config);
		return `<dd>${contentHTML}</dd>`;
	}
}

class _MDFootnoteContent extends _MDBlock {
	/** @var {String} */
	#id;
	/** @var {_MDBlock} */
	#content;
	/**
	 * @param {String} id
	 * @param {_MDBlock} content
	 */
	constructor(id, content) {
		super();
		this.#id = id;
		this.#content = content;
	}
	toHTML(config) {
		// TODO: Forward and back links
		// TODO: Deferring footnotes to end of document
		//<ol>
		//<li id="fn:1" role="doc-endnote">
		//<p>Footnote&nbsp;<a href="#fnref:1" class="footnote-backref" role="doc-backlink">↩︎</a></p>
		//</li>
		//</ol>
		return '';
	}
}

class _MDAbbreviationOccurrence extends _MDBlock {
	/** @var {String} */
	#label;
	/** @var {String} */
	#definition;

	/**
	 * @param {String} label
	 * @param {String} definition
	 */
	constructor(label, definition) {
		super();
		this.#label = label;
		this.#definition = definition;
	}

	toHTML(config) {
		return `<abbr title="${this.#definition.replace('"', '&quot;')}">${this.#label}</abbr>`;
	}
}

class _MDInline extends _MDBlock {
	/** @var {String} */
	#raw;
	/**
	 * @param {String} raw
	 */
	constructor(raw) {
		super();
		this.#raw = raw;
	}

	toHTML(config) {
		return this.#raw;
	}
}

class _MDHTMLTag {
	/** @var {String} */
	fullTag;
	/** @var {String} */
	tagName;
	/** @var {Boolean} */
	isCloser;
	/** @var {Object} */
	attributes;

	/**
	 * @param {String} fullTag
	 * @param {String} tagName
	 * @param {Boolean} isCloser
	 * @param {Object} attributes
	 */
	constructor(fullTag, tagName, isCloser, attributes) {
		this.fullTag = fullTag;
		this.tagName = tagName;
		this.isCloser = isCloser;
		this.attributes = attributes;
	}
}

class _MDState {
	/** @var {String[]} */
	lines = [];

	/** @var {object} */
	abbreviations = {};

	/** @var {object} */
	footnotes = {};

	/** @var {number} */
	p = 0;

	copy() {
		let cp = new _MDState();
		cp.abbreviations = this.abbreviations;
		cp.footnotes = this.footnotes;
		cp.p = this.p;
		return cp;
	}

	/** @param {_MDState} other */
	apply(other) {
		this.abbreviations = other.abbreviations;
		this.footnotes = other.footnotes;
		this.p = other.p;
	}

	hasLines(minCount, p=-1) {
		let relativeTo = (p < 0) ? this.p : p;
		return relativeTo + minCount <= this.lines.length;
	}
}

class MDConfig {

}

class Markdown {
	/**
	 * @param {String} line
	 */
	static #stripIndent(line, count=1) {
		let regex = new RegExp(`^(: {1,4}|\\t){${count}}`);
		return line.replace(regex, '');
	}

	/**
	 * @param {String} line
	 * @param {Boolean} fullIndentsOnly
	 * @returns {Number} indent count
	 */
	static #countIndents(line, fullIndentsOnly=false) {
		var count = 0;
		var lastLine = line;
		while (line.length > 0) {
			line = (fullIndentsOnly)
				? line.replace(/^(?: {4}|\t)/, '')
				: line.replace(/^(?: {1,4}|\t)/, '');
			if (line != lastLine) {
				count++;
			} else {
				break;
			}
			lastLine = line;
		}
		return count;
	}

	/**
	 * @param {_MDState} state
	 * @returns {_MDBlock[]}
	 */
	static #readBlocks(state) {
		var blocks = [];
		while (state.hasLines(1)) {
			let block = this.#readNextBlock(state);
			if (block) {
				blocks.push(block);
			} else {
				break;
			}
		}
		return blocks;
	}

	/**
	 * @param {_MDState} state
	 * @returns {_MDBlock}
	 */
	static #readNextBlock(state) {
		while (state.hasLines(1) && state.lines[state.p].trim().length == 0) {
			console.info("Skipping blank line " + state.p);
			state.p++;
		}
		var block;
		block = this.#readUnderlineHeader(state); if (block) return block;
		block = this.#readHashHeader(state); if (block) return block;
		block = this.#readBlockQuote(state); if (block) return block;
		block = this.#readUnorderedList(state); if (block) return block;
		block = this.#readOrderedList(state); if (block) return block;
		block = this.#readFencedCodeBlock(state); if (block) return block;
		block = this.#readIndentedCodeBlock(state); if (block) return block;
		block = this.#readHorizontalRule(state); if (block) return block;
		block = this.#readTable(state); if (block) return block;
		block = this.#readDefinitionList(state); if (block) return block;
		block = this.#readFootnoteDef(state); if (block) return block;
		block = this.#readAbbreviationDef(state); if (block) return block;
		block = this.#readParagraph(state); if (block) return block;
		return null;
	}

	static #baseURLRegex = /(?:(?:(?:[a-z]{3,9}:(?:\/\/)?)(?:[\-;:&=\+\$,\w]+@)?[a-z0-9\.\-]+|(?:www\.|[\-;:&=\+\$,\w]+@)[a-z0-9\.\-]+)(?:(?:\/[\+~%\/\.\w\-_]*)?\??(?:[\-\+=&;%@\.\w_]*)#?(?:[\.\!\/\\\w]*))?)/i;
	static #baseEmailRegex = /(?:(?:[^<>()\[\]\\.,;:\s@"]+(?:\.[^<>()\[\]\\.,;:\s@"]+)*)|(?:".+"))@(?:(?:\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}])|(?:(?:[a-z\-0-9]+\.)+[a-z]{2,}))/i;

	static #footnoteWithTitleRegex = /^\[\^\s*([^\]"]+?)\s+"(.*?)"\s*\]/;
	static #footnoteRegex = /^\[\^\s*([^\]]+?)\s*\]/;
	static #labelRegex = /^\[(.*?)\]/;
	static #urlWithTitleRegex = /^\((\S+?)\s+"(.*?)"\)/i;
	static #urlRegex = /^\((\S+?)\)/i;
	static #emailWithTitleRegex = new RegExp("^\\(\\s*(" + this.#baseEmailRegex.source + ")\\s+\"(.*?)\"\\s*\\)", "i");
	static #emailRegex = new RegExp("^\\(\\s*(" + this.#baseEmailRegex.source + ")\\s*\\)", "i");
	static #simpleURLRegex = new RegExp("^<" + this.#baseURLRegex.source + ">", "i");
	static #simpleEmailRegex = new RegExp("^<" + this.#baseEmailRegex.source + ">", "i");

	/**
	 * @param {String} line
	 * @returns {_MDHTMLTag|null} HTML tag if possible
	 */
	static #htmlTag(line) {
		let expectOpenBracket = 0;
		let expectCloserOrName = 1;
		let expectName = 2;
		let expectAttributeNameOrEnd = 3;
		let expectEqualsOrAttributeOrEnd = 4;
		let expectAttributeValue = 5;
		let expectCloseBracket = 6;

		var isCloser = false;
		var tagName = '';
		var attributeName = '';
		var attributeValue = '';
		var attributeQuote = null;
		var attributes = {};
		var fullTag = null;
		let endAttribute = function() {
			if (attributeName.length > 0) {
				if (attributeValue.length > 0 || attributeQuote) {
					attributes[attributeName] = attributeValue;
				} else {
					attributes[attributeName] = true;
				}
			}
			attributeName = '';
			attributeValue = '';
			attributeQuote = null;
		};

		var expect = expectOpenBracket;
		for (var p = 0; p < line.length && fullTag === null; p++) {
			let ch = line.substring(p, p + 1);
			switch (expect) {
				case expectOpenBracket:
					if (ch != '<') return null;
					expect = expectCloserOrName;
					break;
				case expectCloserOrName:
					if (ch == '/') {
						isCloser = true;
					} else {
						p--;
					}
					expect = expectName;
					break;
				case expectName:
					if (tagName.length == 0) {
						if (/[a-z]/i.exec(ch) === null) return null;
						tagName += ch;
					} else {
						if (/[a-z0-9]/i.exec(ch)) {
							tagName += ch;
						} else {
							p--;
							expect = (isCloser) ? expectCloseBracket : expectAttributeNameOrEnd;
						}
					}
					break;
				case expectAttributeNameOrEnd:
					if (attributeName.length == 0) {
						if (/\s/.exec(ch)) {
							// skip whitespace
						} else if (ch == '/') {
							expect = expectCloseBracket;
						} else if (ch == '>') {
							fullTag = line.substring(0, p + 1);
							break;
						} else if (/[a-z0-9-]/i.exec(ch)) {
							attributeName += ch;
						} else {
							return null;
						}
					} else if (/\s/.exec(ch)) {
						expect = expectEqualsOrAttributeOrEnd;
					} else if (ch == '/') {
						endAttribute();
						expect = expectCloseBracket;
					} else if (ch == '>') {
						endAttribute();
						fullTag = line.substring(0, p + 1);
						break;
					} else if (ch == '=') {
						expect = expectAttributeValue;
					} else if (/[a-z0-9-]/i.exec(ch)) {
						attributeName += ch;
					} else {
						return null;
					}
					break;
				case expectEqualsOrAttributeOrEnd:
					if (ch == '=') {
						expect = expectAttributeValue;
					} else if (/\s/.exec(ch)) {
						// skip whitespace
					} else if (ch == '/') {
						expect = expectCloseBracket;
					} else if (ch == '>') {
						fullTag = line.substring(0, p + 1);
						break;
					} else if (/[a-z]/i.exec(ch)) {
						endAttribute();
						expect = expectAttributeNameOrEnd;
						p--;
					}
					break;
				case expectAttributeValue:
					if (attributeValue.length == 0) {
						if (attributeQuote === null) {
							if (/\s/.exec(ch)) {
								// skip whitespace
							} else if (ch == '"' || ch == "'") {
								attributeQuote = ch;
							} else {
								attributeQuote = '';
								p--;
							}
						} else {
							if (ch === attributeQuote) {
								// Empty string
								endAttribute();
								expect = expectAttributeNameOrEnd;
							} else if (attributeQuote === '' && (ch == '/' || ch == '>')) {
								return null;
							} else {
								attributeValue += ch;
							}
						}
					} else {
						if (ch === attributeQuote) {
							endAttribute();
							expect = expectAttributeNameOrEnd;
						} else if (attributeQuote === '' && /\s/.exec(ch)) {
							endAttribute();
							expect = expectAttributeNameOrEnd;
						} else {
							attributeValue += ch;
						}
					}
					break;
				case expectCloseBracket:
					if (/\s/.exec(ch)) {
						// ignore whitespace
					} else if (ch == '>') {
						fullTag = line.substring(0, p + 1);
						break;
					}
					break;
			}
		}
		if (fullTag === null) return null;
		endAttribute();
		return new _MDHTMLTag(fullTag, tagName, isCloser, attributes);
	}

	/**
	 * @param {String} line
	 * @returns {_MDToken[]} tokens
	 */
	static #tokenize(line) {
		var tokens = [];
		var text = '';
		var expectLiteral = false;
		var groups = null;
		var tag = null;
		const endText = function() {
			if (text.length == 0) return;
			let textGroups = /^(\s*)(?:(\S|\S.*\S)(\s*?))?$/.exec(text);
			if (textGroups !== null) {
				if (textGroups[1].length > 0) {
					tokens.push(new _MDToken(textGroups[1], _MDTokenType.Whitespace, textGroups[1]));
				}
				if (textGroups[2] !== undefined && textGroups[2].length > 0) {
					tokens.push(new _MDToken(textGroups[2], _MDTokenType.Text, textGroups[2]));
				}
				if (textGroups[3] !== undefined && textGroups[3].length > 0) {
					tokens.push(new _MDToken(textGroups[3], _MDTokenType.Whitespace, textGroups[3]));
				}
			} else {
				tokens.push(new _MDToken(text, _MDTokenType.Text, text));
			}
			text = '';
		}
		for (var p = 0; p < line.length; p++) {
			let ch = line.substring(p, p + 1);
			let remainder = line.substring(p);
			if (expectLiteral) {
				// TODO: Check for only allowable escapable characters
				text += ch;
				continue;
			}
			if (ch == '\\') {
				expectLiteral = true;
			} else if (ch == '*') {
				endText();
				tokens.push(new _MDToken(ch, _MDTokenType.Asterisk));
			} else if (ch == '_') {
				endText();
				tokens.push(new _MDToken(ch, _MDTokenType.Underscore));
			} else if (ch == '`') {
				endText();
				tokens.push(new _MDToken(ch, _MDTokenType.Backtick));
			} else if (ch == '~') {
				endText();
				tokens.push(new _MDToken(ch, _MDTokenType.Tilde));
			} else if (ch == '!') {
				endText();
				tokens.push(new _MDToken(ch, _MDTokenType.Bang));

			} else if (groups = this.#footnoteWithTitleRegex.exec(remainder)) {
				// Footnote with title   [^1 "Foo"]
				endText();
				tokens.push(new _MDToken(groups[0], _MDTokenType.Footnote, groups[1], groups[2]));
				p += groups[0].length - 1;
			} else if (groups = this.#footnoteRegex.exec(remainder)) {
				// Footnote without title   [^1]
				endText();
				tokens.push(new _MDToken(groups[0], _MDTokenType.Footnote, groups[1]));
				p += groups[0].length - 1;
			} else if (groups = this.#labelRegex.exec(remainder)) {
				// Label/ref for link/image   [Foo]
				endText();
				tokens.push(new _MDToken(groups[0], _MDTokenType.Label, groups[1]));
				p += groups[0].length - 1;
			} else if (groups = this.#urlWithTitleRegex.exec(remainder)) {
				// URL with title   (https://foo "Bar")
				endText();
				tokens.push(new _MDToken(groups[0], _MDTokenType.URL, groups[1], groups[2]));
				p += groups[0].length - 1;
			} else if (groups = this.#emailWithTitleRegex.exec(remainder)) {
				// Email address with title   (user@example.com  "Foo")
				endText();
				tokens.push(new _MDToken(groups[0], _MDTokenType.Email, groups[1]));
				p += groups[0].length - 1;
			} else if (groups = this.#urlRegex.exec(remainder)) {
				// URL   (https://example.com)
				endText();
				tokens.push(new _MDToken(groups[0], _MDTokenType.URL, groups[1]));
				p += groups[0].length - 1;
			} else if (groups = this.#emailRegex.exec(remainder)) {
				// Email   (user@example.com)
				endText();
				tokens.push(new _MDToken(groups[0], _MDTokenType.Email, groups[1]));
				p += groups[0].length - 1;
			} else if (groups = this.#simpleURLRegex.exec(remainder)) {
				// Simple URL   <https://example.com>
				endText();
				tokens.push(new _MDToken(groups[0], _MDTokenType.SimpleLink, groups[1]));
				p += groups[0].length - 1;
			} else if (groups = this.#simpleEmailRegex.exec(remainder)) {
				// Simple email   <user@example.com>
				endText();
				tokens.push(new _MDToken(groups[0], _MDTokenType.SimpleEmail, groups[1]));
				p += groups[0].length - 1;
			} else if (tag = this.#htmlTag(remainder)) {
				endText();
				tokens.push(new _MDToken(tag.fullTag, _MDTokenType.HTMLTag, tag.fullTag, null, tag));
				p += tag.fullTag.length - 1;
			} else {
				text += ch;
			}
		}
		endText();
		return tokens;
	}

	/**
	 * @param {_MDState} state
	 * @param {String} line
	 * @returns {_MDBlock|null}
	 */
	static #readInline(state, line) {
		let tokens = this.#tokenize(line);
		var spans = [];
// - Link   [text](https://url)
// - Emphasis   *emphasized* or _emphasized_ or /emphasized/
// - Strong   **bold** or __bold__
// - Inline code   `code` or ``code``
// - Strikethrough   ~strike~ or ~~strike~~
// - Image   ![alt text](https://image){.cssclass}
// - Footnote (inline)   [^1]: footnote text
// - Abbreviation (inline)
//
// Tokens:
// _
// *
// /
// ~
// [label] or []
// (url)
// !
// <>
// `

		return new _MDInline(line);
	}

	/**
	 * Reads the contents of something like a list item
	 * @param {_MDState} state
	 * @param {number} firstLineStartPos
	 * @param {RegExp} stopRegex
	 * @returns {_MDBlock}
	 */
	static #readInteriorContent(state, firstLineStartPos, stopRegex) {
		// FIXME: When reading <li> content need to detect nested list without
		// a blank line
		var p = state.p;
		var seenBlankLine = false;
		var needsBlocks = false;
		var lines = [];
		while (p < state.lines.length) {
			let line = state.lines[p++];
			if (p == state.p + 1) {
				line = line.substring(firstLineStartPos);
			}
			let isBlank = line.trim().length == 0;
			let isIndented = /^\s+/.exec(line) !== null;
			if (isBlank) {
				seenBlankLine = true;
				lines.push(line.trim());
			} else if (stopRegex && stopRegex.exec(line)) {
				p--;
				break;
			} else if (isIndented) {
				if (seenBlankLine) {
					needsBlocks = true;
				}
				lines.push(this.#stripIndent(line));
			} else {
				if (seenBlankLine) {
					p--;
					break;
				}
				lines.push(this.#stripIndent(line));
			}
		}
		while (lines.length > 0 && lines[lines.length - 1].trim().length == 0) {
			lines.pop();
		}
		if (needsBlocks) {
			let substate = new _MDState();
			substate.lines = lines;
			substate.abbreviations = state.abbreviations;
			substate.footnotes = state.footnotes;
			let blocks = this.#readBlocks(substate);
			state.p = p;
			return new _MDMultiBlock(blocks);
		} else {
			state.p = p;
			return this.#readInline(state, lines.join("\n"));
		}
	}

	/**
	 * @param {_MDState} state
	 * @returns {_MDBlock|null}
	 */
	static #readUnderlineHeader(state) {
		var p = state.p;
		if (!state.hasLines(2)) return null;
		let contentLine = state.lines[p++].trim();
		let underLine = state.lines[p++].trim();
		if (contentLine == '') return null;
		if (/^=+$/.exec(underLine)) {
			state.p = p;
			return new _MDHeader(1, this.#readInline(state, contentLine));
		}
		if (/^\-+$/.exec(underLine)) {
			state.p = p;
			return new _MDHeader(2, this.#readInline(state, contentLine));
		}
		return null;
	}

	/**
	 * @param {_MDState} state
	 * @returns {_MDBlock|null}
	 */
	static #readHashHeader(state) {
		var p = state.p;
		var groups = /^(#{1,6})\s*([^#].*)\s*$/.exec(state.lines[p++]);
		if (groups === null) return null;
		state.p = p;
		return new _MDHeader(groups[1].length, this.#readInline(state, groups[2]));
	}

	/**
	 * @param {_MDState} state
	 * @returns {_MDBlock|null}
	 */
	static #readBlockQuote(state) {
		var blockquoteLines = [];
		var p = state.p;
		while (p < state.lines.length) {
			let line = state.lines[p++];
			if (line.startsWith(">")) {
				blockquoteLines.push(line);
			} else {
				break;
			}
		}
		if (blockquoteLines.length > 0) {
			let contentLines = blockquoteLines.map(function(line) {
				return line.substring(1).replace(/^ {0,3}\t?/, '');
			});
			let substate = new _MDState();
			substate.lines = contentLines;
			substate.abbreviations = state.abbreviations;
			substate.footnotes = state.footnotes;
			let quotedBlocks = this.#readBlocks(substate);
			state.p = p;
			return new _MDBlockquote(quotedBlocks);
		}
		return null;
	}

	/**
	 * @param {_MDState} state
	 * @returns {_MDListItem|null}
	 */
	static #readUnorderedListItem(state) {
		var p = state.p;
		let line = state.lines[p];
		let groups = /^([\*\+\-]\s+)(.*)$/.exec(line);
		if (groups === null) return null;
		return new _MDListItem(this.#readInteriorContent(state, groups[1].length, /^[\*\+\-]\s+/));
	}

	/**
	 * @param {_MDState} state
	 * @returns {_MDBlock|null}
	 */
	static #readUnorderedList(state) {
		var items = [];
		var item = null;
		do {
			item = this.#readUnorderedListItem(state);
			if (item) items.push(item);
		} while (item);
		if (items.length == 0) return null;
		return new _MDUnorderedList(items);
	}

	/**
	 * @param {_MDState} state
	 * @returns {_MDListItem|null}
	 */
	static #readOrderedListItem(state) {
		var p = state.p;
		let line = state.lines[p];
		let groups = /^(\d+\.\s+)(.*)$/.exec(line);
		if (groups === null) return null;
		return new _MDListItem(this.#readInteriorContent(state, groups[1].length, /^\d+\.\s+/));
	}

	/**
	 * @param {_MDState} state
	 * @returns {_MDBlock|null}
	 */
	static #readOrderedList(state) {
		var items = [];
		var item = null;
		do {
			item = this.#readOrderedListItem(state);
			if (item) items.push(item);
		} while (item);
		if (items.length == 0) return null;
		return new _MDOrderedList(items);
	}

	/**
	 * @param {_MDState} state
	 * @returns {_MDBlock|null}
	 */
	static #readFencedCodeBlock(state) {
		var p = state.p;
		if (state.lines[p++].trim() != '```') return null;
		var codeLines = [];
		while (state.hasLines(1, p)) {
			let line = state.lines[p++];
			if (line.trim() == '```') {
				state.p = p;
				return new _MDCodeBlock(codeLines.join("\n"));
			}
			codeLines.push(line);
		}
		return null;
	}

	/**
	 * @param {_MDState} state
	 * @returns {_MDBlock|null}
	 */
	static #readIndentedCodeBlock(state) {
		var p = state.p;
		var codeLines = [];
		while (state.hasLines(1, p)) {
			let line = state.lines[p++];
			if (this.#countIndents(line, true) < 1) {
				p--;
				break;
			}
			codeLines.push(this.#stripIndent(line));
		}
		if (codeLines.length == 0) return null;
		state.p = p;
		return new _MDCodeBlock(codeLines.join("\n"));
	}

	/**
	 * @param {_MDState} state
	 * @returns {_MDBlock|null}
	 */
	static #readHorizontalRule(state) {
		var p = state.p;
		let line = state.lines[p++];
		if (/^\s*(?:\-(?:\s*\-){2,}|\*(?:\s*\*){2,})\s*$/.exec(line)) {
			state.p = p;
			return new _MDHorizontalRule();
		}
		return null;
	}

	/**
	 * @param {_MDState} state
	 * @param {Boolean} isHeader
	 * @return {_MDTableRow|null}
	 */
	static #readTableRow(state, isHeader) {
		if (!state.hasLines(1)) return null;
		var p = state.p;
		let line = state.lines[p++].trim();
		if (/.*\|.*/.exec(line) === null) return null;
		if (line.startsWith('|')) line = line.substring(1);
		if (line.endsWith('|')) line = line.substring(0, line.length - 1);
		let cellTokens = line.split('|');
		let cells = cellTokens.map(function(token) {
			let content = Markdown.#readInline(state, token);
			return isHeader ? new _MDTableHeaderCell(content) : new _MDTableCell(content);
		});
		state.p = p;
		return new _MDTableRow(cells);
	}

	/**
	 * @param {String} line
	 * @returns {_MDHAlign[]}
	 */
	static #parseColumnAlignments(line) {
		line = line.trim();
		if (line.startsWith('|')) line = line.substring(1);
		if (line.endsWith('|')) line = line.substring(0, line.length - 1);
		return line.split('|').map(function(token) {
			token = token.trim();
			if (token.startsWith(':')) {
				if (token.endsWith(':')) {
					return _MDHAlign.Center;
				}
				return _MDHAlign.Left;
			} else if (token.endsWith(':')) {
				return _MDHAlign.Right;
			}
			return null;
		});
	}

	/**
	 * @param {_MDState} state
	 * @returns {_MDBlock|null}
	 */
	static #readTable(state) {
		if (!state.hasLines(2)) return null;
		let startP = state.p;
		let headerRow = this.#readTableRow(state, true);
		if (headerRow === null) {
			state.p = startP;
			return null;
		}
		let dividerLine = state.lines[state.p++];
		let dividerGroups = /^\s*[|]?(?:\s*[:]?-+[:]?\s*\|)(?:\s*[:]?-+[:]?\s*)[|]?\s*$/.exec(dividerLine);
		if (dividerGroups === null) {
			state.p = startP;
			return null;
		}
		let columnAlignments = this.#parseColumnAlignments(dividerLine);
		headerRow.applyAlignments(columnAlignments);
		var bodyRows = [];
		while (state.hasLines(1)) {
			let row = this.#readTableRow(state, false);
			if (row === null) break;
			row.applyAlignments(columnAlignments);
			bodyRows.push(row);
		}
		return new _MDTable(headerRow, bodyRows);
	}

	/**
	 * @param {_MDState} state
	 * @returns {_MDBlock|null}
	 */
	static #readDefinitionList(state) {
		// TODO
		return null;
	}

	/**
	 * @param {_MDState} state
	 * @returns {_MDBlock|null}
	 */
	static #readFootnoteDef(state) {
		// TODO
		return null;
	}

	/**
	 * @param {_MDState} state
	 * @returns {_MDBlock|null}
	 */
	static #readAbbreviationDef(state) {
		// TODO
		return null;
	}

	/**
	 * @param {_MDState} state
	 * @returns {_MDBlock|null}
	 */
	static #readParagraph(state) {
		if (!state.hasLines(1)) return null;
		var paragraphLines = [];
		var p = state.p;
		while (p < state.lines.length) {
			let line = state.lines[p++];
			if (line.trim().length == 0) {
				break;
			}
			paragraphLines.push(line);
		}
		if (paragraphLines.length > 0) {
			state.p = p;
			let content = paragraphLines.join("\n");
			return new _MDParagraph(this.#readInline(state, content));
		}
		return null;
	}

	/**
	 * @param  {String} markdown
	 * @returns {String} HTML
	 */
	static toHTML(markdown, config=new MDConfig()) {
		var state = new _MDState();
		let lines = markdown.replace("\r", "").split("\n");
		state.lines = lines;
		let blocks = this.#readBlocks(state);
		let html = _MDBlock.toHTML(blocks);
		return html;
	}
}