public override BlockState TryOpen(BlockProcessor processor)
{
// If we are in a CodeIndent, early exit
if (processor.IsCodeIndent)
{
return(BlockState.None);
}
// 4.2 ATX headings
// An ATX heading consists of a string of characters, parsed as inline content,
// between an opening sequence of 1–6(configurable) unescaped # characters and an optional
// closing sequence of any number of unescaped # characters. The opening sequence
// of # characters must be followed by a space or by the end of line. The optional
// closing sequence of #s must be preceded by a space and may be followed by spaces
// only. The opening # character may be indented 0-3 spaces. The raw contents of
// the heading are stripped of leading and trailing spaces before being parsed as
// inline content. The heading level is equal to the number of # characters in the
// opening sequence.
var column = processor.Column;
var line = processor.Line;
var sourcePosition = line.Start;
var c = line.CurrentChar;
var matchingChar = c;
Debug.Assert(MaxLeadingCount > 0);
int leadingCount = 0;
while (c != '\0' && leadingCount <= MaxLeadingCount)
{
if (c != matchingChar)
{
break;
}
c = processor.NextChar();
leadingCount++;
}
// A space is required after leading #
if (leadingCount > 0 && leadingCount <= MaxLeadingCount && (c.IsSpaceOrTab() || c == '\0'))
{
StringSlice trivia = StringSlice.Empty;
if (processor.TrackTrivia && c.IsSpaceOrTab())
{
trivia = new StringSlice(processor.Line.Text, processor.Start, processor.Start);
processor.NextChar();
}
// Move to the content
var headingBlock = new HeadingBlock(this)
{
HeaderChar = matchingChar,
TriviaAfterAtxHeaderChar = trivia,
Level = leadingCount,
Column = column,
Span = { Start = sourcePosition },
TriviaBefore = processor.UseTrivia(sourcePosition - 1),
LinesBefore = processor.UseLinesBefore(),
NewLine = processor.Line.NewLine,
};
processor.NewBlocks.Push(headingBlock);
if (!processor.TrackTrivia)
{
processor.GoToColumn(column + leadingCount + 1);
}
// Gives a chance to parse attributes
TryParseAttributes?.Invoke(processor, ref processor.Line, headingBlock);
// The optional closing sequence of #s must be preceded by a space and may be followed by spaces only.
int endState = 0;
int countClosingTags = 0;
int sourceEnd = processor.Line.End;
for (int i = processor.Line.End; i >= processor.Line.Start - 1; i--) // Go up to Start - 1 in order to match the space after the first ###
{
c = processor.Line.Text[i];
if (endState == 0)
{
if (c.IsSpaceOrTab())
{
continue;
}
endState = 1;
}
if (endState == 1)
{
if (c == matchingChar)
{
countClosingTags++;
continue;
}
if (countClosingTags > 0)
{
if (c.IsSpaceOrTab())
{
processor.Line.End = i - 1;
}
break;
}
else
{
break;
}
}
}
// Setup the source end position of this element
headingBlock.Span.End = processor.Line.End;
if (processor.TrackTrivia)
{
var wsa = new StringSlice(processor.Line.Text, processor.Line.End + 1, sourceEnd);
headingBlock.TriviaAfter = wsa;
if (wsa.Overlaps(headingBlock.TriviaAfterAtxHeaderChar))
{
// prevent double whitespace allocation in case of closing # i.e. "# #"
headingBlock.TriviaAfterAtxHeaderChar = StringSlice.Empty;
}
}
// We expect a single line, so don't continue
return(BlockState.Break);
}
// Else we don't have an header
processor.Line.Start = sourcePosition;
processor.Column = column;
return(BlockState.None);
}