Allow intra-word strikethrough in GFM (#313)
Allow intra-word strikethrough in GFM
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 5c15d30..daffada 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,6 +3,8 @@
* **Breaking change:** Remove `ListSyntax.removeLeadingEmptyLine`,
`ListSyntax.removeTrailingEmptyLines`, `TableSyntax.parseAlignments`,
`TableSyntax.parseRow`.
+* Allow intra-word strikethrough in GFM
+ ([#300](https://github.com/dart-lang/markdown/issues/300)).
## 2.1.8
diff --git a/lib/src/inline_parser.dart b/lib/src/inline_parser.dart
index d1d0eaa..bd3c900 100644
--- a/lib/src/inline_parser.dart
+++ b/lib/src/inline_parser.dart
@@ -500,6 +500,7 @@
final bool isRightFlanking;
final bool isPrecededByPunctuation;
final bool isFollowedByPunctuation;
+ final bool allowIntraWord;
_DelimiterRun._({
@required this.char,
@@ -508,9 +509,11 @@
@required this.isRightFlanking,
@required this.isPrecededByPunctuation,
@required this.isFollowedByPunctuation,
+ @required this.allowIntraWord,
});
- static _DelimiterRun tryParse(InlineParser parser, int runStart, int runEnd) {
+ static _DelimiterRun tryParse(InlineParser parser, int runStart, int runEnd,
+ {bool allowIntraWord = false}) {
bool leftFlanking,
rightFlanking,
precededByPunctuation,
@@ -538,7 +541,8 @@
} else {
leftFlanking = !followedByPunctuation ||
whitespace.contains(preceding) ||
- precededByPunctuation;
+ precededByPunctuation ||
+ allowIntraWord;
}
// http://spec.commonmark.org/0.28/#right-flanking-delimiter-run
@@ -547,7 +551,8 @@
} else {
rightFlanking = !precededByPunctuation ||
whitespace.contains(following) ||
- followedByPunctuation;
+ followedByPunctuation ||
+ allowIntraWord;
}
if (!leftFlanking && !rightFlanking) {
@@ -562,6 +567,7 @@
isRightFlanking: rightFlanking,
isPrecededByPunctuation: precededByPunctuation,
isFollowedByPunctuation: followedByPunctuation,
+ allowIntraWord: allowIntraWord,
);
}
@@ -573,12 +579,18 @@
// Whether a delimiter in this run can open emphasis or strong emphasis.
bool get canOpen =>
isLeftFlanking &&
- (char == $asterisk || !isRightFlanking || isPrecededByPunctuation);
+ (char == $asterisk ||
+ !isRightFlanking ||
+ allowIntraWord ||
+ isPrecededByPunctuation);
// Whether a delimiter in this run can close emphasis or strong emphasis.
bool get canClose =>
isRightFlanking &&
- (char == $asterisk || !isLeftFlanking || isFollowedByPunctuation);
+ (char == $asterisk ||
+ !isLeftFlanking ||
+ allowIntraWord ||
+ isFollowedByPunctuation);
}
/// Matches syntax that has a pair of tags and becomes an element, like `*` for
@@ -592,6 +604,11 @@
/// [emphasis delimiters]: http://spec.commonmark.org/0.28/#can-open-emphasis
final bool requiresDelimiterRun;
+ /// Whether to allow intra-word delimiter runs. CommonMark emphasis and
+ /// strong emphasis does not allow this, but GitHub-Flavored Markdown allows
+ /// it on strikethrough.
+ final bool allowIntraWord;
+
/// Create a new [TagSyntax] which matches text on [pattern].
///
/// If [end] is passed, it is used as the pattern which denotes the end of
@@ -600,7 +617,10 @@
/// emphasis delimiters. If [startCharacter] is passed, it is used as a
/// pre-matching check which is faster than matching against [pattern].
TagSyntax(String pattern,
- {String end, this.requiresDelimiterRun = false, int startCharacter})
+ {String end,
+ this.requiresDelimiterRun = false,
+ int startCharacter,
+ this.allowIntraWord = false})
: endPattern = RegExp((end != null) ? end : pattern, multiLine: true),
super(pattern, startCharacter: startCharacter);
@@ -614,7 +634,8 @@
return true;
}
- var delimiterRun = _DelimiterRun.tryParse(parser, matchStart, matchEnd);
+ var delimiterRun = _DelimiterRun.tryParse(parser, matchStart, matchEnd,
+ allowIntraWord: allowIntraWord);
if (delimiterRun != null && delimiterRun.canOpen) {
parser.openTag(TagState(parser.pos, matchEnd + 1, this, delimiterRun));
return true;
@@ -629,7 +650,8 @@
var matchStart = parser.pos;
var matchEnd = parser.pos + runLength - 1;
var openingRunLength = state.endPos - state.startPos;
- var delimiterRun = _DelimiterRun.tryParse(parser, matchStart, matchEnd);
+ var delimiterRun = _DelimiterRun.tryParse(parser, matchStart, matchEnd,
+ allowIntraWord: allowIntraWord);
if (openingRunLength == 1 && runLength == 1) {
parser.addNode(Element('em', state.children));
@@ -665,14 +687,16 @@
/// Matches strikethrough syntax according to the GFM spec.
class StrikethroughSyntax extends TagSyntax {
- StrikethroughSyntax() : super('~+', requiresDelimiterRun: true);
+ StrikethroughSyntax()
+ : super('~+', requiresDelimiterRun: true, allowIntraWord: true);
@override
bool onMatchEnd(InlineParser parser, Match match, TagState state) {
var runLength = match.group(0).length;
var matchStart = parser.pos;
var matchEnd = parser.pos + runLength - 1;
- var delimiterRun = _DelimiterRun.tryParse(parser, matchStart, matchEnd);
+ var delimiterRun = _DelimiterRun.tryParse(parser, matchStart, matchEnd,
+ allowIntraWord: allowIntraWord);
if (!delimiterRun.isRightFlanking) {
return false;
}
@@ -1256,8 +1280,9 @@
var openingRunLength = endPos - startPos;
var closingMatchStart = parser.pos;
var closingMatchEnd = parser.pos + runLength - 1;
- var closingDelimiterRun =
- _DelimiterRun.tryParse(parser, closingMatchStart, closingMatchEnd);
+ var closingDelimiterRun = _DelimiterRun.tryParse(
+ parser, closingMatchStart, closingMatchEnd,
+ allowIntraWord: openingDelimiterRun.allowIntraWord);
if (closingDelimiterRun != null && closingDelimiterRun.canClose) {
// Emphasis rules #9 and #10:
var oneRunOpensAndCloses =
diff --git a/test/extensions/strikethrough.unit b/test/extensions/strikethrough.unit
new file mode 100644
index 0000000..3599718
--- /dev/null
+++ b/test/extensions/strikethrough.unit
@@ -0,0 +1,20 @@
+>>> Missing leading whitespace
+word pas~~t~~ word
+<<<
+<p>word pas<del>t</del> word</p>
+>>> Missing trailing whitespace
+word ~~p~~ast word
+<<<
+<p>word <del>p</del>ast word</p>
+>>> Middle of word
+word p~~as~~t word
+<<<
+<p>word p<del>as</del>t word</p>
+>>> Whitespace after opening
+word~~ past~~ word
+<<<
+<p>word~~ past~~ word</p>
+>>> Whitespace before closing
+word ~~past ~~word
+<<<
+<p>word ~~past ~~word</p>
diff --git a/test/markdown_test.dart b/test/markdown_test.dart
index f4769c9..524c9b9 100644
--- a/test/markdown_test.dart
+++ b/test/markdown_test.dart
@@ -22,6 +22,8 @@
// Inline syntax extensions
testFile('extensions/emojis.unit', inlineSyntaxes: [EmojiSyntax()]);
testFile('extensions/inline_html.unit', inlineSyntaxes: [InlineHtmlSyntax()]);
+ testFile('extensions/strikethrough.unit',
+ inlineSyntaxes: [StrikethroughSyntax()]);
testDirectory('common_mark');
testDirectory('gfm', extensionSet: ExtensionSet.gitHubFlavored);
