Emphasis surrounded by `*` characters

Question

Emphasis surrounded by `*` characters

xcoulon opened this issue a year ago · 2 comments

In example 379 of the spec v0.30, a**"foo"** has no strong emphasis, because the opening ** is preceded by an alphanumeric and followed by punctuation, and hence not part of a left-flanking delimiter run, but I wonder which rules prevent this contents from having an emphasis and render as a*"foo"*?

My understanding is that the second * character before "foo" looks like a valid left-flanking delimiter run since it is preceded by a punctuation character (*) and followed by a punctuation character (") and similarly, the first * character after "foo" looks like a valid right-flanking delimiter run since it is preceded by a punctuation character (*) and followed by a punctuation character (").

Also, I'm a bit confused with the definition of a delimiter run:

is either a sequence of one or more * characters that is not preceded or followed by a non-backslash-escaped * character, or a sequence of one or more _ characters that is not preceded or followed by a non-backslash-escaped _ character.

because it seems to go against example 441 where **foo* is expected to render as *foo and example 442 where *foo** is expected to render as foo*

Answer 1 · 2023-03-26T16:21:42.000Z

For the first: entire runs are parsed as a whole. So it’s about what’s surrounding the entire run. Afterwards things are “taken” from the runs to form starts or ends of strong or emphasis. See rule 11 (“A literal * character cannot occur at the beginning...”) and 12.

For the second: the algorithm is super complex. Hard to capture in text. The algorithm in prose in the appendix might help: https://spec.commonmark.org/0.30/#phase-2-inline-structure

Answer 2 · 2023-03-27T06:42:40.000Z

@wooorm thanks for your quick response!

For the first: entire runs are parsed as a whole. So it’s about what’s surrounding the entire run. Afterwards things are “taken” from the runs to form starts or ends of strong or emphasis. See rule 11 (“A literal * character cannot occur at the beginning...”) and 12.

Yes, I saw the rules 11 and 12 but I thought it applied to the contents (interior) of the emphasis and strong emphasis, since in example 441 **foo* is expected to render as *foo and in example 442 *foo** is expected to render as foo*

For the second: the algorithm is super complex. Hard to capture in text. The algorithm in prose in the appendix might help: https://spec.commonmark.org/0.30/#phase-2-inline-structure

Ok, I'll give a closer look at the algorithm, then :)