packages/flutter_markdown/lib/src/markdown_raw.dart - mirrors/flutter - Git at Google

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.

 import 'package:markdown/markdown.dart' as md;
 import 'package:flutter/widgets.dart';
 import 'package:flutter/gestures.dart';

 import 'markdown_style_raw.dart';

 typedef void MarkdownLinkCallback(String href);


 /// A [Widget] that renders markdown formatted text. It supports all standard
 /// markdowns from the original markdown specification found here:
 /// https://daringfireball.net/projects/markdown/ The rendered markdown is
 /// placed in a padded scrolling view port. If you do not want the scrolling
 /// behaviour, use the [MarkdownBodyRaw] class instead.
 class MarkdownRaw extends StatelessWidget {

   /// Creates a new Markdown [Widget] that renders the markdown formatted string
   /// passed in as [data]. By default the markdown will be rendered using the
   /// styles from the current theme, but you can optionally pass in a custom
   /// [markdownStyle] that specifies colors and fonts to use. Code blocks are
   /// by default not using syntax highlighting, but it's possible to pass in
   /// a custom [syntaxHighlighter].
   ///
   ///     new MarkdownRaw(data: "Hello _world_!", markdownStyle: myStyle);
   MarkdownRaw({
     this.data,
     this.markdownStyle,
     this.syntaxHighlighter,
     this.padding: const EdgeInsets.all(16.0),
     this.onTapLink
   });

   /// Markdown styled text
   final String data;

   /// Style used for rendering the markdown
   final MarkdownStyleRaw markdownStyle;

   /// The syntax highlighter used to color text in code blocks
   final SyntaxHighlighter syntaxHighlighter;

   /// Padding used
   final EdgeInsets padding;

   /// Callback when a link is tapped
   final MarkdownLinkCallback onTapLink;

   @override
   Widget build(BuildContext context) {
     // TODO(abarth): We should use a ListView here and lazily build the widgets
     // from the markdown.
     return new SingleChildScrollView(
       padding: padding,
       child: createMarkdownBody(
         data: data,
         markdownStyle: markdownStyle,
         syntaxHighlighter: syntaxHighlighter,
         onTapLink: onTapLink,
       ),
     );
   }

   MarkdownBodyRaw createMarkdownBody({
     String data,
     covariant MarkdownStyleRaw markdownStyle,
     SyntaxHighlighter syntaxHighlighter,
     MarkdownLinkCallback onTapLink
   }) {
     return new MarkdownBodyRaw(
       data: data,
       markdownStyle: markdownStyle,
       syntaxHighlighter: syntaxHighlighter,
       onTapLink: onTapLink
     );
   }
 }

 /// A [Widget] that renders markdown formatted text.
 ///
 /// It supports all standard markdowns from the original markdown specification
 /// found here: <https://daringfireball.net/projects/markdown/>.
 ///
 /// This class doesn't implement any scrolling behavior, if you want scrolling
 /// either wrap the widget in a [SingleChildScrollView] or use the [MarkdownRaw]
 /// widget.
 class MarkdownBodyRaw extends StatefulWidget {

   /// Creates a new Markdown [Widget] that renders the markdown formatted string
   /// passed in as [data]. You need to pass in a [markdownStyle] that defines
   /// how the code is rendered. Code blocks are by default not using syntax
   /// highlighting, but it's possible to pass in a custom [syntaxHighlighter].
   ///
   /// Typically, you may want to wrap the [MarkdownBodyRaw] widget in a
   /// a [SingleChildScrollView], or use the [Markdown class].
   ///
   /// ```dart
   /// new SingleChildScrollView(
   ///   padding: new EdgeInsets.all(16.0),
   ///   child: new MarkdownBodyRaw(
   ///     data: markdownSource,
   ///     markdownStyle: myStyle,
   ///   ),
   /// ),
   /// ```
   MarkdownBodyRaw({
     this.data,
     this.markdownStyle,
     this.syntaxHighlighter,
     this.onTapLink
   });

   /// Markdown styled text
   final String data;

   /// Style used for rendering the markdown
   final MarkdownStyleRaw markdownStyle;

   /// The syntax highlighter used to color text in code blocks
   final SyntaxHighlighter syntaxHighlighter;

   /// Callback when a link is tapped
   final MarkdownLinkCallback onTapLink;

   @override
   _MarkdownBodyRawState createState() => new _MarkdownBodyRawState();

   MarkdownStyleRaw createDefaultStyle(BuildContext context) => null;
 }

 class _MarkdownBodyRawState extends State<MarkdownBodyRaw> {

   @override
   void dependenciesChanged() {
     _buildMarkdownCache();
     super.dependenciesChanged();
   }

   @override
   void dispose() {
     _linkHandler.dispose();
     super.dispose();
   }

   @override
   void didUpdateConfig(MarkdownBodyRaw oldConfig) {
     super.didUpdateConfig(oldConfig);

     if (oldConfig.data != config.data ||
         oldConfig.markdownStyle != config.markdownStyle ||
         oldConfig.syntaxHighlighter != config.syntaxHighlighter ||
         oldConfig.onTapLink != config.onTapLink)
       _buildMarkdownCache();
   }

   void _buildMarkdownCache() {
     MarkdownStyleRaw markdownStyle = config.markdownStyle ?? config.createDefaultStyle(context);
     SyntaxHighlighter syntaxHighlighter = config.syntaxHighlighter ?? new _DefaultSyntaxHighlighter(markdownStyle.code);

     _linkHandler?.dispose();
     _linkHandler = new _LinkHandler(config.onTapLink);

     // TODO: This can be optimized by doing the split and removing \r at the same time
     List<String> lines = config.data.replaceAll('\r\n', '\n').split('\n');
     md.Document document = new md.Document();

     _Renderer renderer = new _Renderer();
     _cachedBlocks = renderer.render(document.parseLines(lines), markdownStyle, syntaxHighlighter, _linkHandler);
   }

   List<_Block> _cachedBlocks;
   _LinkHandler _linkHandler;

   @override
   Widget build(BuildContext context) {
     List<Widget> blocks = <Widget>[];
     for (_Block block in _cachedBlocks) {
       blocks.add(block.build(context));
     }

     return new Column(
       crossAxisAlignment: CrossAxisAlignment.stretch,
       children: blocks
     );
   }

   @override
   void debugFillDescription(List<String> description) {
     super.debugFillDescription(description);
     description.add('cached blocks identity: ${_cachedBlocks.hashCode}');
   }
 }

 class _Renderer implements md.NodeVisitor {
   List<_Block> render(List<md.Node> nodes, MarkdownStyleRaw markdownStyle, SyntaxHighlighter syntaxHighlighter, _LinkHandler linkHandler) {
     assert(markdownStyle != null);

     _blocks = <_Block>[];
     _listIndents = <String>[];
     _markdownStyle = markdownStyle;
     _syntaxHighlighter = syntaxHighlighter;
     _linkHandler = linkHandler;

     for (final md.Node node in nodes) {
       node.accept(this);
     }

     return _blocks;
   }

   List<_Block> _blocks;
   List<String> _listIndents;
   MarkdownStyleRaw _markdownStyle;
   SyntaxHighlighter _syntaxHighlighter;
   _LinkHandler _linkHandler;

   @override
   void visitText(md.Text text) {
     if (_currentBlock != null) { // ignore if no corresponding block
       _MarkdownNodeList topList = _currentBlock.stack.last;
       List<_MarkdownNode> top = topList.list;

       if (_currentBlock.tag == 'pre')
         top.add(
             new _MarkdownNodeTextSpan(_syntaxHighlighter.format(text.text)));
       else
         top.add(new _MarkdownNodeString(text.text));
     }
   }

   @override
   bool visitElementBefore(md.Element element) {
     if (_isListTag(element.tag))
       _listIndents.add(element.tag);

     if (_isBlockTag(element.tag)) {
       List<_Block> blockList;
       if (_currentBlock == null)
         blockList = _blocks;
       else
         blockList = _currentBlock.subBlocks;

       _Block newBlock = new _Block(element.tag, element.attributes, _markdownStyle, new List<String>.from(_listIndents), blockList.length);
       blockList.add(newBlock);
     } else {
       _LinkInfo linkInfo;
       if (element.tag == 'a') {
         linkInfo = _linkHandler.createLinkInfo(element.attributes['href']);
       }

       TextStyle style = _markdownStyle.styles[element.tag] ?? const TextStyle();
       List<_MarkdownNode> styleElement = <_MarkdownNode>[new _MarkdownNodeTextStyle(style, linkInfo)];
       _currentBlock.stack.add(new _MarkdownNodeList(styleElement));
     }
     return true;
   }

   @override
   void visitElementAfter(md.Element element) {
     if (_isListTag(element.tag))
       _listIndents.removeLast();

     if (_isBlockTag(element.tag)) {
       if (_currentBlock.stack.length > 0) {
         _MarkdownNodeList stackList = _currentBlock.stack.first;
         _currentBlock.stack = stackList.list;
         _currentBlock.open = false;
       } else {
         _currentBlock.stack = <_MarkdownNode>[new _MarkdownNodeString('')];
       }
     } else {
       if (_currentBlock.stack.length > 1) {
         _MarkdownNodeList poppedList = _currentBlock.stack.last;
         List<_MarkdownNode> popped = poppedList.list;
         _currentBlock.stack.removeLast();

         _MarkdownNodeList topList = _currentBlock.stack.last;
         List<_MarkdownNode> top = topList.list;
         top.add(new _MarkdownNodeList(popped));
       }
     }
   }

   static const List<String> _kBlockTags = const <String>['p', 'h1', 'h2', 'h3', 'h4', 'h5', 'h6', 'li', 'blockquote', 'img', 'pre', 'ol', 'ul'];
   static const List<String> _kListTags = const <String>['ul', 'ol'];

   bool _isBlockTag(String tag) {
     return _kBlockTags.contains(tag);
   }

   bool _isListTag(String tag) {
     return _kListTags.contains(tag);
   }

   _Block get _currentBlock => _currentBlockInList(_blocks);

   _Block _currentBlockInList(List<_Block> blocks) {
     if (blocks.isEmpty)
       return null;

     if (!blocks.last.open)
       return null;

     _Block childBlock = _currentBlockInList(blocks.last.subBlocks);
     if (childBlock != null)
       return childBlock;

     return blocks.last;
   }
 }

 abstract class _MarkdownNode {
 }

 class _MarkdownNodeList extends _MarkdownNode {
   _MarkdownNodeList(this.list);
   List<_MarkdownNode> list;
 }

 class _MarkdownNodeTextStyle extends _MarkdownNode {
   _MarkdownNodeTextStyle(this.style, [this.linkInfo = null]);
   TextStyle style;
   _LinkInfo linkInfo;
 }

 class _MarkdownNodeString extends _MarkdownNode {
   _MarkdownNodeString(this.string);
   String string;
 }

 class _MarkdownNodeTextSpan extends _MarkdownNode {
   _MarkdownNodeTextSpan(this.textSpan);
   TextSpan textSpan;
 }

 class _Block {
   _Block(this.tag, this.attributes, this.markdownStyle, this.listIndents, this.blockPosition) {
     TextStyle style = markdownStyle.styles[tag];
     if (style == null)
       style = const TextStyle(color: const Color(0xffff0000));

     stack = <_MarkdownNode>[new _MarkdownNodeList(<_MarkdownNode>[new _MarkdownNodeTextStyle(style)])];
     subBlocks = <_Block>[];
   }

   final String tag;
   final Map<String, String> attributes;
   final MarkdownStyleRaw markdownStyle;
   final List<String> listIndents;
   final int blockPosition;

   List<_MarkdownNode> stack;
   List<_Block> subBlocks;

   bool get open => _open;
   set open(bool open) {
     _open = open;
     if (!open && subBlocks.length > 0)
       subBlocks.last.isLast = true;
   }

   bool _open = true;
   bool isLast = false;

   Widget build(BuildContext context) {

     if (tag == 'img') {
       return _buildImage(context, attributes['src']);
     }

     double spacing = markdownStyle.blockSpacing;
     if (isLast) spacing = 0.0;

     Widget contents;

     if (subBlocks.length > 0) {
       List<Widget> subWidgets = <Widget>[];
       for (_Block subBlock in subBlocks) {
         subWidgets.add(subBlock.build(context));
       }

       contents = new Column(
         crossAxisAlignment: CrossAxisAlignment.stretch,
         children: subWidgets
       );
     } else {
       TextSpan span = _stackToTextSpan(new _MarkdownNodeList(stack));
       contents = new RichText(text: span);

       if (listIndents.length > 0) {
         Widget bullet;
         if (listIndents.last == 'ul') {
           bullet = new Text(
             '•',
             textAlign: TextAlign.center
           );
         }
         else {
           bullet = new Padding(
             padding: const EdgeInsets.only(right: 5.0),
             child: new Text(
               "${blockPosition + 1}.",
               textAlign: TextAlign.right
             )
           );
         }

         contents = new Row(
           crossAxisAlignment: CrossAxisAlignment.start,
           children: <Widget>[
             new SizedBox(
               width: listIndents.length * markdownStyle.listIndent,
               child: bullet
             ),
             new Expanded(child: contents)
           ]
         );
       }
     }

     BoxDecoration decoration;
     EdgeInsets padding;

     if (tag == 'blockquote') {
       decoration = markdownStyle.blockquoteDecoration;
       padding = new EdgeInsets.all(markdownStyle.blockquotePadding);
     } else if (tag == 'pre') {
       decoration = markdownStyle.codeblockDecoration;
       padding = new EdgeInsets.all(markdownStyle.codeblockPadding);
     }

     return new Container(
       padding: padding,
       margin: new EdgeInsets.only(bottom: spacing),
       child: contents,
       decoration: decoration
     );
   }

   TextSpan _stackToTextSpan(_MarkdownNode stack) {
     if (stack is _MarkdownNodeTextSpan)
       return stack.textSpan;

     if (stack is _MarkdownNodeList) {
       List<_MarkdownNode> list = stack.list;
       _MarkdownNodeTextStyle styleNode = list[0];
       _LinkInfo linkInfo = styleNode.linkInfo;
       TextStyle style = styleNode.style;

       List<TextSpan> children = <TextSpan>[];
       for (int i = 1; i < list.length; i++) {
         children.add(_stackToTextSpan(list[i]));
       }

       String text;
       if (children.length == 1 && _isPlainText(children[0])) {
         text = children[0].text;
         children = null;
       }

       TapGestureRecognizer recognizer = linkInfo?.recognizer;

       return new TextSpan(style: style, children: children, recognizer: recognizer, text: text);
     }

     if (stack is _MarkdownNodeString) {
       return new TextSpan(text: stack.string);
     }

     return null;
   }

   bool _isPlainText(TextSpan span) {
     return (span.text != null && span.style == null && span.recognizer == null && span.children == null);
   }

   Widget _buildImage(BuildContext context, String src) {
     List<String> parts = src.split('#');
     if (parts.length == 0) return new Container();

     String path = parts.first;
     double width;
     double height;
     if (parts.length == 2) {
       List<String> dimensions = parts.last.split('x');
       if (dimensions.length == 2) {
         width = double.parse(dimensions[0]);
         height = double.parse(dimensions[1]);
       }
     }

     return new Image.network(path, width: width, height: height);
   }
 }

 class _LinkInfo {
   _LinkInfo(this.href, this.recognizer);

   final String href;
   final TapGestureRecognizer recognizer;
 }

 class _LinkHandler {
   _LinkHandler(this.onTapLink);

   List<_LinkInfo> links = <_LinkInfo>[];
   MarkdownLinkCallback onTapLink;

   _LinkInfo createLinkInfo(String href) {
     TapGestureRecognizer recognizer = new TapGestureRecognizer();
     recognizer.onTap = () {
       if (onTapLink != null)
         onTapLink(href);
     };

     _LinkInfo linkInfo = new _LinkInfo(href, recognizer);
     links.add(linkInfo);

     return linkInfo;
   }

   void dispose() {
     for (_LinkInfo linkInfo in links) {
       linkInfo.recognizer.dispose();
     }
   }
 }

 abstract class SyntaxHighlighter { // ignore: one_member_abstracts
   TextSpan format(String source);
 }

 class _DefaultSyntaxHighlighter extends SyntaxHighlighter{
   _DefaultSyntaxHighlighter(this.style);

   final TextStyle style;

   @override
   TextSpan format(String source) {
     return new TextSpan(style: style, children: <TextSpan>[new TextSpan(text: source)]);
   }
 }
	// Copyright 2016 The Chromium Authors. All rights reserved.
	// Use of this source code is governed by a BSD-style license that can be
	// found in the LICENSE file.

	import 'package:markdown/markdown.dart' as md;
	import 'package:flutter/widgets.dart';
	import 'package:flutter/gestures.dart';

	import 'markdown_style_raw.dart';

	typedef void MarkdownLinkCallback(String href);


	/// A [Widget] that renders markdown formatted text. It supports all standard
	/// markdowns from the original markdown specification found here:
	/// https://daringfireball.net/projects/markdown/ The rendered markdown is
	/// placed in a padded scrolling view port. If you do not want the scrolling
	/// behaviour, use the [MarkdownBodyRaw] class instead.
	class MarkdownRaw extends StatelessWidget {

	/// Creates a new Markdown [Widget] that renders the markdown formatted string
	/// passed in as [data]. By default the markdown will be rendered using the
	/// styles from the current theme, but you can optionally pass in a custom
	/// [markdownStyle] that specifies colors and fonts to use. Code blocks are
	/// by default not using syntax highlighting, but it's possible to pass in
	/// a custom [syntaxHighlighter].
	///
	/// new MarkdownRaw(data: "Hello _world_!", markdownStyle: myStyle);
	MarkdownRaw({
	this.data,
	this.markdownStyle,
	this.syntaxHighlighter,
	this.padding: const EdgeInsets.all(16.0),
	this.onTapLink
	});

	/// Markdown styled text
	final String data;

	/// Style used for rendering the markdown
	final MarkdownStyleRaw markdownStyle;

	/// The syntax highlighter used to color text in code blocks
	final SyntaxHighlighter syntaxHighlighter;

	/// Padding used
	final EdgeInsets padding;

	/// Callback when a link is tapped
	final MarkdownLinkCallback onTapLink;

	@override
	Widget build(BuildContext context) {
	// TODO(abarth): We should use a ListView here and lazily build the widgets
	// from the markdown.
	return new SingleChildScrollView(
	padding: padding,
	child: createMarkdownBody(
	data: data,
	markdownStyle: markdownStyle,
	syntaxHighlighter: syntaxHighlighter,
	onTapLink: onTapLink,
	),
	);
	}

	MarkdownBodyRaw createMarkdownBody({
	String data,
	covariant MarkdownStyleRaw markdownStyle,
	SyntaxHighlighter syntaxHighlighter,
	MarkdownLinkCallback onTapLink
	}) {
	return new MarkdownBodyRaw(
	data: data,
	markdownStyle: markdownStyle,
	syntaxHighlighter: syntaxHighlighter,
	onTapLink: onTapLink
	);
	}
	}

	/// A [Widget] that renders markdown formatted text.
	///
	/// It supports all standard markdowns from the original markdown specification
	/// found here: <https://daringfireball.net/projects/markdown/>.
	///
	/// This class doesn't implement any scrolling behavior, if you want scrolling
	/// either wrap the widget in a [SingleChildScrollView] or use the [MarkdownRaw]
	/// widget.
	class MarkdownBodyRaw extends StatefulWidget {

	/// Creates a new Markdown [Widget] that renders the markdown formatted string
	/// passed in as [data]. You need to pass in a [markdownStyle] that defines
	/// how the code is rendered. Code blocks are by default not using syntax
	/// highlighting, but it's possible to pass in a custom [syntaxHighlighter].
	///
	/// Typically, you may want to wrap the [MarkdownBodyRaw] widget in a
	/// a [SingleChildScrollView], or use the [Markdown class].
	///
	/// ```dart
	/// new SingleChildScrollView(
	/// padding: new EdgeInsets.all(16.0),
	/// child: new MarkdownBodyRaw(
	/// data: markdownSource,
	/// markdownStyle: myStyle,
	/// ),
	/// ),
	/// ```
	MarkdownBodyRaw({
	this.data,
	this.markdownStyle,
	this.syntaxHighlighter,
	this.onTapLink
	});

	/// Markdown styled text
	final String data;

	/// Style used for rendering the markdown
	final MarkdownStyleRaw markdownStyle;

	/// The syntax highlighter used to color text in code blocks
	final SyntaxHighlighter syntaxHighlighter;

	/// Callback when a link is tapped
	final MarkdownLinkCallback onTapLink;

	@override
	_MarkdownBodyRawState createState() => new _MarkdownBodyRawState();

	MarkdownStyleRaw createDefaultStyle(BuildContext context) => null;
	}

	class _MarkdownBodyRawState extends State<MarkdownBodyRaw> {

	@override
	void dependenciesChanged() {
	_buildMarkdownCache();
	super.dependenciesChanged();
	}

	@override
	void dispose() {
	_linkHandler.dispose();
	super.dispose();
	}

	@override
	void didUpdateConfig(MarkdownBodyRaw oldConfig) {
	super.didUpdateConfig(oldConfig);

	if (oldConfig.data != config.data \|\|
	oldConfig.markdownStyle != config.markdownStyle \|\|
	oldConfig.syntaxHighlighter != config.syntaxHighlighter \|\|
	oldConfig.onTapLink != config.onTapLink)
	_buildMarkdownCache();
	}

	void _buildMarkdownCache() {
	MarkdownStyleRaw markdownStyle = config.markdownStyle ?? config.createDefaultStyle(context);
	SyntaxHighlighter syntaxHighlighter = config.syntaxHighlighter ?? new _DefaultSyntaxHighlighter(markdownStyle.code);

	_linkHandler?.dispose();
	_linkHandler = new _LinkHandler(config.onTapLink);

	// TODO: This can be optimized by doing the split and removing \r at the same time
	List<String> lines = config.data.replaceAll('\r\n', '\n').split('\n');
	md.Document document = new md.Document();

	_Renderer renderer = new _Renderer();
	_cachedBlocks = renderer.render(document.parseLines(lines), markdownStyle, syntaxHighlighter, _linkHandler);
	}

	List<_Block> _cachedBlocks;
	_LinkHandler _linkHandler;

	@override
	Widget build(BuildContext context) {
	List<Widget> blocks = <Widget>[];
	for (_Block block in _cachedBlocks) {
	blocks.add(block.build(context));
	}

	return new Column(
	crossAxisAlignment: CrossAxisAlignment.stretch,
	children: blocks
	);
	}

	@override
	void debugFillDescription(List<String> description) {
	super.debugFillDescription(description);
	description.add('cached blocks identity: ${_cachedBlocks.hashCode}');
	}
	}

	class _Renderer implements md.NodeVisitor {
	List<_Block> render(List<md.Node> nodes, MarkdownStyleRaw markdownStyle, SyntaxHighlighter syntaxHighlighter, _LinkHandler linkHandler) {
	assert(markdownStyle != null);

	_blocks = <_Block>[];
	_listIndents = <String>[];
	_markdownStyle = markdownStyle;
	_syntaxHighlighter = syntaxHighlighter;
	_linkHandler = linkHandler;

	for (final md.Node node in nodes) {
	node.accept(this);
	}

	return _blocks;
	}

	List<_Block> _blocks;
	List<String> _listIndents;
	MarkdownStyleRaw _markdownStyle;
	SyntaxHighlighter _syntaxHighlighter;
	_LinkHandler _linkHandler;

	@override
	void visitText(md.Text text) {
	if (_currentBlock != null) { // ignore if no corresponding block
	_MarkdownNodeList topList = _currentBlock.stack.last;
	List<_MarkdownNode> top = topList.list;

	if (_currentBlock.tag == 'pre')
	top.add(
	new _MarkdownNodeTextSpan(_syntaxHighlighter.format(text.text)));
	else
	top.add(new _MarkdownNodeString(text.text));
	}
	}

	@override
	bool visitElementBefore(md.Element element) {
	if (_isListTag(element.tag))
	_listIndents.add(element.tag);

	if (_isBlockTag(element.tag)) {
	List<_Block> blockList;
	if (_currentBlock == null)
	blockList = _blocks;
	else
	blockList = _currentBlock.subBlocks;

	_Block newBlock = new _Block(element.tag, element.attributes, _markdownStyle, new List<String>.from(_listIndents), blockList.length);
	blockList.add(newBlock);
	} else {
	_LinkInfo linkInfo;
	if (element.tag == 'a') {
	linkInfo = _linkHandler.createLinkInfo(element.attributes['href']);
	}

	TextStyle style = _markdownStyle.styles[element.tag] ?? const TextStyle();
	List<_MarkdownNode> styleElement = <_MarkdownNode>[new _MarkdownNodeTextStyle(style, linkInfo)];
	_currentBlock.stack.add(new _MarkdownNodeList(styleElement));
	}
	return true;
	}

	@override
	void visitElementAfter(md.Element element) {
	if (_isListTag(element.tag))
	_listIndents.removeLast();

	if (_isBlockTag(element.tag)) {
	if (_currentBlock.stack.length > 0) {
	_MarkdownNodeList stackList = _currentBlock.stack.first;
	_currentBlock.stack = stackList.list;
	_currentBlock.open = false;
	} else {
	_currentBlock.stack = <_MarkdownNode>[new _MarkdownNodeString('')];
	}
	} else {
	if (_currentBlock.stack.length > 1) {
	_MarkdownNodeList poppedList = _currentBlock.stack.last;
	List<_MarkdownNode> popped = poppedList.list;
	_currentBlock.stack.removeLast();

	_MarkdownNodeList topList = _currentBlock.stack.last;
	List<_MarkdownNode> top = topList.list;
	top.add(new _MarkdownNodeList(popped));
	}
	}
	}

	static const List<String> _kBlockTags = const <String>['p', 'h1', 'h2', 'h3', 'h4', 'h5', 'h6', 'li', 'blockquote', 'img', 'pre', 'ol', 'ul'];
	static const List<String> _kListTags = const <String>['ul', 'ol'];

	bool _isBlockTag(String tag) {
	return _kBlockTags.contains(tag);
	}

	bool _isListTag(String tag) {
	return _kListTags.contains(tag);
	}

	_Block get _currentBlock => _currentBlockInList(_blocks);

	_Block _currentBlockInList(List<_Block> blocks) {
	if (blocks.isEmpty)
	return null;

	if (!blocks.last.open)
	return null;

	_Block childBlock = _currentBlockInList(blocks.last.subBlocks);
	if (childBlock != null)
	return childBlock;

	return blocks.last;
	}
	}

	abstract class _MarkdownNode {
	}

	class _MarkdownNodeList extends _MarkdownNode {
	_MarkdownNodeList(this.list);
	List<_MarkdownNode> list;
	}

	class _MarkdownNodeTextStyle extends _MarkdownNode {
	_MarkdownNodeTextStyle(this.style, [this.linkInfo = null]);
	TextStyle style;
	_LinkInfo linkInfo;
	}

	class _MarkdownNodeString extends _MarkdownNode {
	_MarkdownNodeString(this.string);
	String string;
	}

	class _MarkdownNodeTextSpan extends _MarkdownNode {
	_MarkdownNodeTextSpan(this.textSpan);
	TextSpan textSpan;
	}

	class _Block {
	_Block(this.tag, this.attributes, this.markdownStyle, this.listIndents, this.blockPosition) {
	TextStyle style = markdownStyle.styles[tag];
	if (style == null)
	style = const TextStyle(color: const Color(0xffff0000));

	stack = <_MarkdownNode>[new _MarkdownNodeList(<_MarkdownNode>[new _MarkdownNodeTextStyle(style)])];
	subBlocks = <_Block>[];
	}

	final String tag;
	final Map<String, String> attributes;
	final MarkdownStyleRaw markdownStyle;
	final List<String> listIndents;
	final int blockPosition;

	List<_MarkdownNode> stack;
	List<_Block> subBlocks;

	bool get open => _open;
	set open(bool open) {
	_open = open;
	if (!open && subBlocks.length > 0)
	subBlocks.last.isLast = true;
	}

	bool _open = true;
	bool isLast = false;

	Widget build(BuildContext context) {

	if (tag == 'img') {
	return _buildImage(context, attributes['src']);
	}

	double spacing = markdownStyle.blockSpacing;
	if (isLast) spacing = 0.0;

	Widget contents;

	if (subBlocks.length > 0) {
	List<Widget> subWidgets = <Widget>[];
	for (_Block subBlock in subBlocks) {
	subWidgets.add(subBlock.build(context));
	}

	contents = new Column(
	crossAxisAlignment: CrossAxisAlignment.stretch,
	children: subWidgets
	);
	} else {
	TextSpan span = _stackToTextSpan(new _MarkdownNodeList(stack));
	contents = new RichText(text: span);

	if (listIndents.length > 0) {
	Widget bullet;
	if (listIndents.last == 'ul') {
	bullet = new Text(
	'•',
	textAlign: TextAlign.center
	);
	}
	else {
	bullet = new Padding(
	padding: const EdgeInsets.only(right: 5.0),
	child: new Text(
	"${blockPosition + 1}.",
	textAlign: TextAlign.right
	)
	);
	}

	contents = new Row(
	crossAxisAlignment: CrossAxisAlignment.start,
	children: <Widget>[
	new SizedBox(
	width: listIndents.length * markdownStyle.listIndent,
	child: bullet
	),
	new Expanded(child: contents)
	]
	);
	}
	}

	BoxDecoration decoration;
	EdgeInsets padding;

	if (tag == 'blockquote') {
	decoration = markdownStyle.blockquoteDecoration;
	padding = new EdgeInsets.all(markdownStyle.blockquotePadding);
	} else if (tag == 'pre') {
	decoration = markdownStyle.codeblockDecoration;
	padding = new EdgeInsets.all(markdownStyle.codeblockPadding);
	}

	return new Container(
	padding: padding,
	margin: new EdgeInsets.only(bottom: spacing),
	child: contents,
	decoration: decoration
	);
	}

	TextSpan _stackToTextSpan(_MarkdownNode stack) {
	if (stack is _MarkdownNodeTextSpan)
	return stack.textSpan;

	if (stack is _MarkdownNodeList) {
	List<_MarkdownNode> list = stack.list;
	_MarkdownNodeTextStyle styleNode = list[0];
	_LinkInfo linkInfo = styleNode.linkInfo;
	TextStyle style = styleNode.style;

	List<TextSpan> children = <TextSpan>[];
	for (int i = 1; i < list.length; i++) {
	children.add(_stackToTextSpan(list[i]));
	}

	String text;
	if (children.length == 1 && _isPlainText(children[0])) {
	text = children[0].text;
	children = null;
	}

	TapGestureRecognizer recognizer = linkInfo?.recognizer;

	return new TextSpan(style: style, children: children, recognizer: recognizer, text: text);
	}

	if (stack is _MarkdownNodeString) {
	return new TextSpan(text: stack.string);
	}

	return null;
	}

	bool _isPlainText(TextSpan span) {
	return (span.text != null && span.style == null && span.recognizer == null && span.children == null);
	}

	Widget _buildImage(BuildContext context, String src) {
	List<String> parts = src.split('#');
	if (parts.length == 0) return new Container();

	String path = parts.first;
	double width;
	double height;
	if (parts.length == 2) {
	List<String> dimensions = parts.last.split('x');
	if (dimensions.length == 2) {
	width = double.parse(dimensions[0]);
	height = double.parse(dimensions[1]);
	}
	}

	return new Image.network(path, width: width, height: height);
	}
	}

	class _LinkInfo {
	_LinkInfo(this.href, this.recognizer);

	final String href;
	final TapGestureRecognizer recognizer;
	}

	class _LinkHandler {
	_LinkHandler(this.onTapLink);

	List<_LinkInfo> links = <_LinkInfo>[];
	MarkdownLinkCallback onTapLink;

	_LinkInfo createLinkInfo(String href) {
	TapGestureRecognizer recognizer = new TapGestureRecognizer();
	recognizer.onTap = () {
	if (onTapLink != null)
	onTapLink(href);
	};

	_LinkInfo linkInfo = new _LinkInfo(href, recognizer);
	links.add(linkInfo);

	return linkInfo;
	}

	void dispose() {
	for (_LinkInfo linkInfo in links) {
	linkInfo.recognizer.dispose();
	}
	}
	}

	abstract class SyntaxHighlighter { // ignore: one_member_abstracts
	TextSpan format(String source);
	}

	class _DefaultSyntaxHighlighter extends SyntaxHighlighter{
	_DefaultSyntaxHighlighter(this.style);

	final TextStyle style;

	@override
	TextSpan format(String source) {
	return new TextSpan(style: style, children: <TextSpan>[new TextSpan(text: source)]);
	}
	}