Move markdown library.

utils/markdown/lib.dart

-// Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
-// for details. All rights reserved. Use of this source code is governed by a
-// BSD-style license that can be found in the LICENSE file.
-
-/// Parses text in markdown format. Use this entrypoint if you want to parse
-/// markdown from your own Dart code. To parse markdown by running the script
-/// directly from the command line, see markdown.dart.
-#library('markdown');
-
-#source('ast.dart');
-#source('block_parser.dart');
-#source('html_renderer.dart');
-#source('inline_parser.dart');
-
-/// Converts the given string of markdown to HTML.
-String markdownToHtml(String markdown) {
-  final document = new Document();
-
-  final lines = markdown.split('\n');
-  document.parseRefLinks(lines);
-  final blocks = document.parseLines(lines);
-  return renderToHtml(blocks);
-}
-
-/// Replaces `<`, `&`, and `>`, with their HTML entity equivalents.
-String escapeHtml(String html) {
-  return html.replaceAll('&', '&amp;')
-             .replaceAll('<', '&lt;')
-             .replaceAll('>', '&gt;');
-}
-
-var _implicitLinkResolver;
-
-Node setImplicitLinkResolver(Node resolver(String text)) {
-  _implicitLinkResolver = resolver;
-}
-
-/// Maintains the context needed to parse a markdown document.
-class Document {
-  final Map<String, Link> refLinks;
-
-  Document()
-    : refLinks = <Link>{};
-
-  parseRefLinks(List<String> lines) {
-    // This is a hideous regex. It matches:
-    // [id]: http:foo.com "some title"
-    // Where there may whitespace in there, and where the title may be in
-    // single quotes, double quotes, or parentheses.
-    final indent = @'^[ ]{0,3}'; // Leading indentation.
-    final id = @'\[([^\]]+)\]';  // Reference id in [brackets].
-    final quote = @'"[^"]+"';    // Title in "double quotes".
-    final apos = @"'[^']+'";     // Title in 'single quotes'.
-    final paren = @"\([^)]+\)";  // Title in (parentheses).
-    final pattern = new RegExp(
-        '$indent$id:\\s+(\\S+)\\s*($quote|$apos|$paren|)\\s*\$');
-
-    for (int i = 0; i < lines.length; i++) {
-      final match = pattern.firstMatch(lines[i]);
-      if (match != null) {
-        // Parse the link.
-        final id = match[1];
-        final url = match[2];
-        var title = match[3];
-
-        if (title == '') {
-          // No title.
-          title = null;
-        } else {
-          // Remove "", '', or ().
-          title = title.substring(1, title.length - 1);
-        }
-
-        refLinks[id] = new Link(id, url, title);
-
-        // Remove it from the output. We replace it with a blank line which will
-        // get consumed by later processing.
-        lines[i] = '';
-      }
-    }
-  }
-
-  /// Parse the given [lines] of markdown to a series of AST nodes.
-  List<Node> parseLines(List<String> lines) {
-    final parser = new BlockParser(lines, this);
-
-    final blocks = [];
-    while (!parser.isDone) {
-      for (final syntax in BlockSyntax.syntaxes) {
-        if (syntax.canParse(parser)) {
-          final block = syntax.parse(parser);
-          if (block != null) blocks.add(block);
-          break;
-        }
-      }
-    }
-
-    return blocks;
-  }
-
-  /// Takes a string of raw text and processes all inline markdown tags,
-  /// returning a list of AST nodes. For example, given ``"*this **is** a*
-  /// `markdown`"``, returns:
-  /// `<em>this <strong>is</strong> a</em> <code>markdown</code>`.
-  List<Node> parseInline(String text) => new InlineParser(text, this).parse();
-}
-
-class Link {
-  final String id;
-  final String url;
-  final String title;
-  Link(this.id, this.url, this.title);
-}