lib/src/block_syntaxes/list_syntax.dart - markdown - Git at Google

 // Copyright (c) 2022, 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.

 import '../ast.dart';
 import '../block_parser.dart';
 import '../patterns.dart';
 import 'block_syntax.dart';
 import 'ordered_list_with_checkbox_syntax.dart';
 import 'unordered_list_with_checkbox_syntax.dart';

 /// As of Markdown 6.0.1 invisible indicators for checked/unchecked checkboxes are
 /// no longer used.  These constants are now empty strings to reflect that.
 @Deprecated(
     'This string is no longer used internally.  It will be removed in a future version.')
 const indicatorForUncheckedCheckBox = '';

 /// As of Markdown 6.0.1 invisible indicators for checked/unchecked checkboxes are
 /// no longer used.  These constants are now empty strings to reflect that.
 @Deprecated(
     'This string is no longer used internally.  It be will be removed in a future version.')
 const indicatorForCheckedCheckBox = '';

 class ListItem {
   const ListItem(
     this.lines, {
     this.taskListItemState,
   });

   final List<String> lines;
   final TaskListItemState? taskListItemState;
 }

 enum TaskListItemState { checked, unchecked }

 /// Base class for both ordered and unordered lists.
 abstract class ListSyntax extends BlockSyntax {
   @override
   bool canEndBlock(BlockParser parser) {
     // An empty list cannot interrupt a paragraph. See
     // https://spec.commonmark.org/0.29/#example-255.
     // Ideally, [BlockSyntax.canEndBlock] should be changed to be a method
     // which accepts a [BlockParser], but this would be a breaking change,
     // so we're going with this temporarily.
     final match = pattern.firstMatch(parser.current)!;
     // The seventh group, in both [olPattern] and [ulPattern] is the text
     // after the delimiter.
     return match[7]?.isNotEmpty ?? false;
   }

   String get listTag;

   const ListSyntax();

   /// A list of patterns that can start a valid block within a list item.
   static final blocksInList = [
     blockquotePattern,
     headerPattern,
     hrPattern,
     indentPattern,
     ulPattern,
     olPattern
   ];

   static final _whitespaceRe = RegExp('[ \t]*');

   @override
   Node parse(BlockParser parser) {
     final taskListParserEnabled = this is UnorderedListWithCheckboxSyntax ||
         this is OrderedListWithCheckboxSyntax;
     final items = <ListItem>[];
     var childLines = <String>[];
     TaskListItemState? taskListItemState;

     void endItem() {
       if (childLines.isNotEmpty) {
         items.add(ListItem(childLines, taskListItemState: taskListItemState));
         childLines = <String>[];
       }
     }

     String parseTaskListItem(String text) {
       final pattern = RegExp(r'^ {0,3}\[([ xX])\][ \t]');

       if (taskListParserEnabled && pattern.hasMatch(text)) {
         return text.replaceFirstMapped(pattern, ((match) {
           taskListItemState = match[1] == ' '
               ? TaskListItemState.unchecked
               : TaskListItemState.checked;

           return '';
         }));
       } else {
         taskListItemState = null;
         return text;
       }
     }

     late Match? possibleMatch;
     bool tryMatch(RegExp pattern) {
       possibleMatch = pattern.firstMatch(parser.current);
       return possibleMatch != null;
     }

     String? listMarker;
     String? indent;
     // In case the first number in an ordered list is not 1, use it as the
     // "start".
     int? startNumber;

     while (!parser.isDone) {
       final leadingSpace =
           _whitespaceRe.matchAsPrefix(parser.current)!.group(0)!;
       final leadingExpandedTabLength = _expandedTabLength(leadingSpace);
       if (emptyPattern.hasMatch(parser.current)) {
         if (emptyPattern.hasMatch(parser.next ?? '')) {
           // Two blank lines ends a list.
           break;
         }
         // Add a blank line to the current list item.
         childLines.add('');
       } else if (indent != null && indent.length <= leadingExpandedTabLength) {
         // Strip off indent and add to current item.
         final line = parser.current
             .replaceFirst(leadingSpace, ' ' * leadingExpandedTabLength)
             .replaceFirst(indent, '');
         childLines.add(parseTaskListItem(line));
       } else if (tryMatch(hrPattern)) {
         // Horizontal rule takes precedence to a new list item.
         break;
       } else if (tryMatch(ulPattern) || tryMatch(olPattern)) {
         final match = possibleMatch!;
         final precedingWhitespace = match[1]!;
         final digits = match[2] ?? '';
         if (startNumber == null && digits.isNotEmpty) {
           startNumber = int.parse(digits);
         }
         final marker = match[3]!;
         final firstWhitespace = match[5] ?? '';
         final restWhitespace = match[6] ?? '';
         final content = match[7] ?? '';
         final isBlank = content.isEmpty;
         if (listMarker != null && listMarker != marker) {
           // Changing the bullet or ordered list delimiter starts a new list.
           break;
         }
         listMarker = marker;
         final markerAsSpaces = ' ' * (digits.length + marker.length);
         if (isBlank) {
           // See http://spec.commonmark.org/0.28/#list-items under "3. Item
           // starting with a blank line."
           //
           // If the list item starts with a blank line, the final piece of the
           // indentation is just a single space.
           indent = '$precedingWhitespace$markerAsSpaces ';
         } else if (restWhitespace.length >= 4) {
           // See http://spec.commonmark.org/0.28/#list-items under "2. Item
           // starting with indented code."
           //
           // If the list item starts with indented code, we need to _not_ count
           // any indentation past the required whitespace character.
           indent = precedingWhitespace + markerAsSpaces + firstWhitespace;
         } else {
           indent = precedingWhitespace +
               markerAsSpaces +
               firstWhitespace +
               restWhitespace;
         }
         // End the current list item and start a new one.
         endItem();
         childLines.add(parseTaskListItem('$restWhitespace$content'));
       } else if (BlockSyntax.isAtBlockEnd(parser)) {
         // Done with the list.
         break;
       } else {
         // If the previous item is a blank line, this means we're done with the
         // list and are starting a new top-level paragraph.
         if ((childLines.isNotEmpty) && (childLines.last == '')) {
           parser.encounteredBlankLine = true;
           break;
         }

         // Anything else is paragraph continuation text.
         childLines.add(parser.current);
       }
       parser.advance();
     }

     endItem();
     final itemNodes = <Element>[];

     items.forEach(_removeLeadingEmptyLine);
     final anyEmptyLines = _removeTrailingEmptyLines(items);
     var anyEmptyLinesBetweenBlocks = false;
     var containsTaskList = false;

     for (final item in items) {
       Element? checkboxToInsert;
       if (item.taskListItemState != null) {
         containsTaskList = true;
         checkboxToInsert = Element.withTag('input')
           ..attributes['type'] = 'checkbox';
         if (item.taskListItemState == TaskListItemState.checked) {
           checkboxToInsert.attributes['checked'] = 'true';
         }
       }

       final itemParser = BlockParser(item.lines, parser.document);
       final children = itemParser.parseLines();
       final itemElement = checkboxToInsert == null
           ? Element('li', children)
           : (Element('li', [checkboxToInsert, ...children])
             ..attributes['class'] = 'task-list-item');

       itemNodes.add(itemElement);
       anyEmptyLinesBetweenBlocks =
           anyEmptyLinesBetweenBlocks || itemParser.encounteredBlankLine;
     }

     // Must strip paragraph tags if the list is "tight".
     // http://spec.commonmark.org/0.28/#lists
     final listIsTight = !anyEmptyLines && !anyEmptyLinesBetweenBlocks;

     if (listIsTight) {
       // We must post-process the list items, converting any top-level paragraph
       // elements to just text elements.
       for (final item in itemNodes) {
         final children = item.children;
         if (children != null) {
           for (var i = 0; i < children.length; i++) {
             final child = children[i];
             if (child is Element && child.tag == 'p') {
               children.removeAt(i);
               children.insertAll(i, child.children!);
             }
           }
         }
       }
     }

     final listElement = Element(listTag, itemNodes);
     if (listTag == 'ol' && startNumber != 1) {
       listElement.attributes['start'] = '$startNumber';
     }

     if (containsTaskList) {
       listElement.attributes['class'] = 'contains-task-list';
     }
     return listElement;
   }

   void _removeLeadingEmptyLine(ListItem item) {
     if (item.lines.isNotEmpty && emptyPattern.hasMatch(item.lines.first)) {
       item.lines.removeAt(0);
     }
   }

   /// Removes any trailing empty lines and notes whether any items are separated
   /// by such lines.
   bool _removeTrailingEmptyLines(List<ListItem> items) {
     var anyEmpty = false;
     for (var i = 0; i < items.length; i++) {
       if (items[i].lines.length == 1) continue;
       while (items[i].lines.isNotEmpty &&
           emptyPattern.hasMatch(items[i].lines.last)) {
         if (i < items.length - 1) {
           anyEmpty = true;
         }
         items[i].lines.removeLast();
       }
     }
     return anyEmpty;
   }

   static int _expandedTabLength(String input) {
     var length = 0;
     for (final char in input.codeUnits) {
       length += char == 0x9 ? 4 - (length % 4) : 1;
     }
     return length;
   }
 }
	// Copyright (c) 2022, 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.

	import '../ast.dart';
	import '../block_parser.dart';
	import '../patterns.dart';
	import 'block_syntax.dart';
	import 'ordered_list_with_checkbox_syntax.dart';
	import 'unordered_list_with_checkbox_syntax.dart';

	/// As of Markdown 6.0.1 invisible indicators for checked/unchecked checkboxes are
	/// no longer used. These constants are now empty strings to reflect that.
	@Deprecated(
	'This string is no longer used internally. It will be removed in a future version.')
	const indicatorForUncheckedCheckBox = '';

	/// As of Markdown 6.0.1 invisible indicators for checked/unchecked checkboxes are
	/// no longer used. These constants are now empty strings to reflect that.
	@Deprecated(
	'This string is no longer used internally. It be will be removed in a future version.')
	const indicatorForCheckedCheckBox = '';

	class ListItem {
	const ListItem(
	this.lines, {
	this.taskListItemState,
	});

	final List<String> lines;
	final TaskListItemState? taskListItemState;
	}

	enum TaskListItemState { checked, unchecked }

	/// Base class for both ordered and unordered lists.
	abstract class ListSyntax extends BlockSyntax {
	@override
	bool canEndBlock(BlockParser parser) {
	// An empty list cannot interrupt a paragraph. See
	// https://spec.commonmark.org/0.29/#example-255.
	// Ideally, [BlockSyntax.canEndBlock] should be changed to be a method
	// which accepts a [BlockParser], but this would be a breaking change,
	// so we're going with this temporarily.
	final match = pattern.firstMatch(parser.current)!;
	// The seventh group, in both [olPattern] and [ulPattern] is the text
	// after the delimiter.
	return match[7]?.isNotEmpty ?? false;
	}

	String get listTag;

	const ListSyntax();

	/// A list of patterns that can start a valid block within a list item.
	static final blocksInList = [
	blockquotePattern,
	headerPattern,
	hrPattern,
	indentPattern,
	ulPattern,
	olPattern
	];

	static final _whitespaceRe = RegExp('[ \t]*');

	@override
	Node parse(BlockParser parser) {
	final taskListParserEnabled = this is UnorderedListWithCheckboxSyntax \|\|
	this is OrderedListWithCheckboxSyntax;
	final items = <ListItem>[];
	var childLines = <String>[];
	TaskListItemState? taskListItemState;

	void endItem() {
	if (childLines.isNotEmpty) {
	items.add(ListItem(childLines, taskListItemState: taskListItemState));
	childLines = <String>[];
	}
	}

	String parseTaskListItem(String text) {
	final pattern = RegExp(r'^ {0,3}\[([ xX])\][ \t]');

	if (taskListParserEnabled && pattern.hasMatch(text)) {
	return text.replaceFirstMapped(pattern, ((match) {
	taskListItemState = match[1] == ' '
	? TaskListItemState.unchecked
	: TaskListItemState.checked;

	return '';
	}));
	} else {
	taskListItemState = null;
	return text;
	}
	}

	late Match? possibleMatch;
	bool tryMatch(RegExp pattern) {
	possibleMatch = pattern.firstMatch(parser.current);
	return possibleMatch != null;
	}

	String? listMarker;
	String? indent;
	// In case the first number in an ordered list is not 1, use it as the
	// "start".
	int? startNumber;

	while (!parser.isDone) {
	final leadingSpace =
	_whitespaceRe.matchAsPrefix(parser.current)!.group(0)!;
	final leadingExpandedTabLength = _expandedTabLength(leadingSpace);
	if (emptyPattern.hasMatch(parser.current)) {
	if (emptyPattern.hasMatch(parser.next ?? '')) {
	// Two blank lines ends a list.
	break;
	}
	// Add a blank line to the current list item.
	childLines.add('');
	} else if (indent != null && indent.length <= leadingExpandedTabLength) {
	// Strip off indent and add to current item.
	final line = parser.current
	.replaceFirst(leadingSpace, ' ' * leadingExpandedTabLength)
	.replaceFirst(indent, '');
	childLines.add(parseTaskListItem(line));
	} else if (tryMatch(hrPattern)) {
	// Horizontal rule takes precedence to a new list item.
	break;
	} else if (tryMatch(ulPattern) \|\| tryMatch(olPattern)) {
	final match = possibleMatch!;
	final precedingWhitespace = match[1]!;
	final digits = match[2] ?? '';
	if (startNumber == null && digits.isNotEmpty) {
	startNumber = int.parse(digits);
	}
	final marker = match[3]!;
	final firstWhitespace = match[5] ?? '';
	final restWhitespace = match[6] ?? '';
	final content = match[7] ?? '';
	final isBlank = content.isEmpty;
	if (listMarker != null && listMarker != marker) {
	// Changing the bullet or ordered list delimiter starts a new list.
	break;
	}
	listMarker = marker;
	final markerAsSpaces = ' ' * (digits.length + marker.length);
	if (isBlank) {
	// See http://spec.commonmark.org/0.28/#list-items under "3. Item
	// starting with a blank line."
	//
	// If the list item starts with a blank line, the final piece of the
	// indentation is just a single space.
	indent = '$precedingWhitespace$markerAsSpaces ';
	} else if (restWhitespace.length >= 4) {
	// See http://spec.commonmark.org/0.28/#list-items under "2. Item
	// starting with indented code."
	//
	// If the list item starts with indented code, we need to _not_ count
	// any indentation past the required whitespace character.
	indent = precedingWhitespace + markerAsSpaces + firstWhitespace;
	} else {
	indent = precedingWhitespace +
	markerAsSpaces +
	firstWhitespace +
	restWhitespace;
	}
	// End the current list item and start a new one.
	endItem();
	childLines.add(parseTaskListItem('$restWhitespace$content'));
	} else if (BlockSyntax.isAtBlockEnd(parser)) {
	// Done with the list.
	break;
	} else {
	// If the previous item is a blank line, this means we're done with the
	// list and are starting a new top-level paragraph.
	if ((childLines.isNotEmpty) && (childLines.last == '')) {
	parser.encounteredBlankLine = true;
	break;
	}

	// Anything else is paragraph continuation text.
	childLines.add(parser.current);
	}
	parser.advance();
	}

	endItem();
	final itemNodes = <Element>[];

	items.forEach(_removeLeadingEmptyLine);
	final anyEmptyLines = _removeTrailingEmptyLines(items);
	var anyEmptyLinesBetweenBlocks = false;
	var containsTaskList = false;

	for (final item in items) {
	Element? checkboxToInsert;
	if (item.taskListItemState != null) {
	containsTaskList = true;
	checkboxToInsert = Element.withTag('input')
	..attributes['type'] = 'checkbox';
	if (item.taskListItemState == TaskListItemState.checked) {
	checkboxToInsert.attributes['checked'] = 'true';
	}
	}

	final itemParser = BlockParser(item.lines, parser.document);
	final children = itemParser.parseLines();
	final itemElement = checkboxToInsert == null
	? Element('li', children)
	: (Element('li', [checkboxToInsert, ...children])
	..attributes['class'] = 'task-list-item');

	itemNodes.add(itemElement);
	anyEmptyLinesBetweenBlocks =
	anyEmptyLinesBetweenBlocks \|\| itemParser.encounteredBlankLine;
	}

	// Must strip paragraph tags if the list is "tight".
	// http://spec.commonmark.org/0.28/#lists
	final listIsTight = !anyEmptyLines && !anyEmptyLinesBetweenBlocks;

	if (listIsTight) {
	// We must post-process the list items, converting any top-level paragraph
	// elements to just text elements.
	for (final item in itemNodes) {
	final children = item.children;
	if (children != null) {
	for (var i = 0; i < children.length; i++) {
	final child = children[i];
	if (child is Element && child.tag == 'p') {
	children.removeAt(i);
	children.insertAll(i, child.children!);
	}
	}
	}
	}
	}

	final listElement = Element(listTag, itemNodes);
	if (listTag == 'ol' && startNumber != 1) {
	listElement.attributes['start'] = '$startNumber';
	}

	if (containsTaskList) {
	listElement.attributes['class'] = 'contains-task-list';
	}
	return listElement;
	}

	void _removeLeadingEmptyLine(ListItem item) {
	if (item.lines.isNotEmpty && emptyPattern.hasMatch(item.lines.first)) {
	item.lines.removeAt(0);
	}
	}

	/// Removes any trailing empty lines and notes whether any items are separated
	/// by such lines.
	bool _removeTrailingEmptyLines(List<ListItem> items) {
	var anyEmpty = false;
	for (var i = 0; i < items.length; i++) {
	if (items[i].lines.length == 1) continue;
	while (items[i].lines.isNotEmpty &&
	emptyPattern.hasMatch(items[i].lines.last)) {
	if (i < items.length - 1) {
	anyEmpty = true;
	}
	items[i].lines.removeLast();
	}
	}
	return anyEmpty;
	}

	static int _expandedTabLength(String input) {
	var length = 0;
	for (final char in input.codeUnits) {
	length += char == 0x9 ? 4 - (length % 4) : 1;
	}
	return length;
	}
	}