110 lines
3.3 KiB
JavaScript
110 lines
3.3 KiB
JavaScript
const TAGS = {
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'': ['<em>','</em>'],
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_: ['<strong>','</strong>'],
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'*': ['<strong>','</strong>'],
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'~': ['<s>','</s>'],
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'\n': ['<br />'],
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' ': ['<br />'],
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'-': ['<hr />']
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};
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/** Outdent a string based on the first indented line's leading whitespace
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* @private
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*/
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function outdent(str) {
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return str.replace(RegExp('^'+(str.match(/^(\t| )+/) || '')[0], 'gm'), '');
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}
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/** Encode special attribute characters to HTML entities in a String.
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* @private
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*/
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function encodeAttr(str) {
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return (str+'').replace(/"/g, '"').replace(/</g, '<').replace(/>/g, '>');
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}
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/** Parse Markdown into an HTML String. */
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export default function parse(md, prevLinks) {
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let tokenizer = /((?:^|\n+)(?:\n---+|\* \*(?: \*)+)\n)|(?:^``` *(\w*)\n([\s\S]*?)\n```$)|((?:(?:^|\n+)(?:\t| {2,}).+)+\n*)|((?:(?:^|\n)([>*+-]|\d+\.)\s+.*)+)|(?:!\[([^\]]*?)\]\(([^)]+?)\))|(\[)|(\](?:\(([^)]+?)\))?)|(?:(?:^|\n+)([^\s].*)\n(-{3,}|={3,})(?:\n+|$))|(?:(?:^|\n+)(#{1,6})\s*(.+)(?:\n+|$))|(?:`([^`].*?)`)|( \n\n*|\n{2,}|__|\*\*|[_*]|~~)/gm,
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context = [],
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out = '',
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links = prevLinks || {},
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last = 0,
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chunk, prev, token, inner, t;
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function tag(token) {
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let desc = TAGS[token[1] || ''];
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let end = context[context.length-1] == token;
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if (!desc) return token;
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if (!desc[1]) return desc[0];
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if (end) context.pop();
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else context.push(token);
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return desc[end|0];
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}
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function flush() {
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let str = '';
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while (context.length) str += tag(context[context.length-1]);
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return str;
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}
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md = md.replace(/^\[(.+?)\]:\s*(.+)$/gm, (s, name, url) => {
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links[name.toLowerCase()] = url;
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return '';
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}).replace(/^\n+|\n+$/g, '');
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while ( (token=tokenizer.exec(md)) ) {
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prev = md.substring(last, token.index);
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last = tokenizer.lastIndex;
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chunk = token[0];
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if (prev.match(/[^\\](\\\\)*\\$/)) {
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// escaped
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}
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// Code/Indent blocks:
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else if (t = (token[3] || token[4])) {
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chunk = '<pre class="code '+(token[4]?'poetry':token[2].toLowerCase())+'"><code'+(token[2] ? ` class="language-${token[2].toLowerCase()}"` : '')+'>'+outdent(encodeAttr(t).replace(/^\n+|\n+$/g, ''))+'</code></pre>';
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}
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// > Quotes, -* lists:
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else if (t = token[6]) {
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if (t.match(/\./)) {
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token[5] = token[5].replace(/^\d+/gm, '');
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}
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inner = parse(outdent(token[5].replace(/^\s*[>*+.-]/gm, '')));
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if (t=='>') t = 'blockquote';
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else {
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t = t.match(/\./) ? 'ol' : 'ul';
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inner = inner.replace(/^(.*)(\n|$)/gm, '<li>$1</li>');
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}
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chunk = '<'+t+'>' + inner + '</'+t+'>';
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}
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// Images:
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else if (token[8]) {
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chunk = `<img src="${encodeAttr(token[8])}" alt="${encodeAttr(token[7])}">`;
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}
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// Links:
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else if (token[10]) {
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out = out.replace('<a>', `<a href="${encodeAttr(token[11] || links[prev.toLowerCase()])}">`);
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chunk = flush() + '</a>';
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}
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else if (token[9]) {
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chunk = '<a>';
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}
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// Headings:
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else if (token[12] || token[14]) {
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t = 'h' + (token[14] ? token[14].length : (token[13]>'=' ? 1 : 2));
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chunk = '<'+t+'>' + parse(token[12] || token[15], links) + '</'+t+'>';
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}
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// `code`:
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else if (token[16]) {
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chunk = '<code>'+encodeAttr(token[16])+'</code>';
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}
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// Inline formatting: *em*, **strong** & friends
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else if (token[17] || token[1]) {
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chunk = tag(token[17] || '--');
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}
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out += prev;
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out += chunk;
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}
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return (out + md.substring(last) + flush()).replace(/^\n+|\n+$/g, '');
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}
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