Add markdown to third_party/pkg

third_party/pkg/markdown/lib/src/markdown/block_parser.dart

 // Copyright (c) 2012, 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.
 
 part of markdown;
 
 /// The line contains only whitespace or is empty.
 final _RE_EMPTY = new RegExp(r'^([ \t]*)$');
 
 /// A series of `=` or `-` (on the next line) define setext-style headers.
 final _RE_SETEXT = new RegExp(r'^((=+)|(-+))$');
 
 /// Leading (and trailing) `#` define atx-style headers.
 final _RE_HEADER = new RegExp(r'^(#{1,6})(.*?)#*$');
 
 /// The line starts with `>` with one optional space after.
 final _RE_BLOCKQUOTE = new RegExp(r'^[ ]{0,3}>[ ]?(.*)$');
 
 /// A line indented four spaces. Used for code blocks and lists.
 final _RE_INDENT = new RegExp(r'^(?:    |\t)(.*)$');
 
+/// GitHub style triple quoted code block.
+final _RE_CODE = new RegExp(r'^```(.*)$');
+
 /// Three or more hyphens, asterisks or underscores by themselves. Note that
 /// a line like `----` is valid as both HR and SETEXT. In case of a tie,
 /// SETEXT should win.
 final _RE_HR = new RegExp(r'^[ ]{0,3}((-+[ ]{0,2}){3,}|'
                                  r'(_+[ ]{0,2}){3,}|'
                                  r'(\*+[ ]{0,2}){3,})$');
 
 /// Really hacky way to detect block-level embedded HTML. Just looks for
 /// "<somename".
 final _RE_HTML = new RegExp(r'^<[ ]*\w+[ >]');
@@ skipping 55 matching lines @@
   /// into blocks, each of these will be tried in turn. Order matters here.
   static List<BlockSyntax> get syntaxes {
     // Lazy initialize.
     if (_syntaxes == null) {
       _syntaxes = [
           new EmptyBlockSyntax(),
           new BlockHtmlSyntax(),
           new SetextHeaderSyntax(),
           new HeaderSyntax(),
           new CodeBlockSyntax(),
+          new GitHubCodeBlockSyntax(),
           new BlockquoteSyntax(),
           new HorizontalRuleSyntax(),
           new UnorderedListSyntax(),
           new OrderedListSyntax(),
           new ParagraphSyntax()
         ];
     }
 
     return _syntaxes;
   }
@@ skipping 126 matching lines @@
     // The Markdown tests expect a trailing newline.
     childLines.add('');
 
     // Escape the code.
     final escaped = escapeHtml(childLines.join('\n'));
 
     return new Element('pre', [new Element.text('code', escaped)]);
   }
 }
 
+/// Parses preformatted code blocks between two ``` sequences.
+class GitHubCodeBlockSyntax extends BlockSyntax {
+  RegExp get pattern => _RE_CODE;
+
+  List<String> parseChildLines(BlockParser parser) {
+    final childLines = <String>[];
+    parser.advance();
+    while (!parser.isDone) {
+      var match = pattern.firstMatch(parser.current);
+      if (match == null) {
+        childLines.add(parser.current);
+        parser.advance();
+      } else {
+        parser.advance();
+        break;
+      }
+    }
+    return childLines;
+  }
+
+  Node parse(BlockParser parser) {
+    // Get the syntax identifier, if there is one.
+    var syntax = pattern.firstMatch(parser.current).group(1);
+    
+    final childLines = parseChildLines(parser);
+
+    // The Markdown tests expect a trailing newline.
+    childLines.add('');
+
+    // Escape the code.
+    final escaped = escapeHtml(childLines.join('\n'));
+
+    return new Element('pre', [new Element.text('code', escaped)]);
+  }
+}
+
 /// Parses horizontal rules like `---`, `_ _ _`, `*  *  *`, etc.
 class HorizontalRuleSyntax extends BlockSyntax {
   RegExp get pattern => _RE_HR;
 
   Node parse(BlockParser parser) {
     final match = pattern.firstMatch(parser.current);
     parser.advance();
     return new Element.empty('hr');
   }
 }
@@ skipping 201 matching lines @@
     // Eat until we hit something that ends a paragraph.
     while (!BlockSyntax.isAtBlockEnd(parser)) {
       childLines.add(parser.current);
       parser.advance();
     }
 
     final contents = parser.document.parseInline(childLines.join('\n'));
     return new Element('p', contents);
   }
 }