cmark

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Commit: c50197bab81d7105c9c790548821b61bcb97a62a
Parent: c71830e3db5047322f5e8601f9ec7154dbe1dd30
Author: John MacFarlane <jgm@berkeley.edu>
Date: Wed, 13 Apr 2016 16:50:38 -0700

Changed `process_emphasis` to get better results in corner cases.

This will need corresponding spec changes.

The change is this: when considering matches between an interior delimiter run (one that can open and can close) and another delimiter run, we require that the sum of the lengths of the two delimiter runs mod 3 is not 0.

Thus, for example, in

*a**b* 1 23 4

delimiter 1 cannot match 2, since the sum of the lengths of the first delimiter run (1) and the second (1,2) == 3. Thus we get `a**b` instead of `ab`.

This gives better behavior on things like

*a**b**c*

which previously got parsed as

abc

and now would be parsed as

abc

With this change we get four spec test failures, but in each case the output seems more "intuitive":

``` Example 386 (lines 6490-6494) Emphasis and strong emphasis *foo**bar**baz*

--- expected HTML +++ actual HTML @@ -1 +1 @@ -foobarbaz +foobarbaz

Example 389 (lines 6518-6522) Emphasis and strong emphasis *foo**bar***

--- expected HTML +++ actual HTML @@ -1 +1 @@ -foobar** +foobar

Example 401 (lines 6620-6624) Emphasis and strong emphasis **foo*bar*baz**

--- expected HTML +++ actual HTML @@ -1 +1 @@ -foobarbaz** +foobarbaz

Example 442 (lines 6944-6948) Emphasis and strong emphasis **foo*bar**

--- expected HTML +++ actual HTML @@ -1 +1 @@ -foobar* +foo*bar ```

Diffstat

1 file changed, 17 insertions, 3 deletions

Status	File Name	N° Changes	Insertions	Deletions
Modified	src/inlines.c	20	17	3

diff --git a/src/inlines.c b/src/inlines.c
@@ -483,6 +483,7 @@ static void process_emphasis(subject *subj, delimiter *stack_bottom) {
   delimiter *opener;
   delimiter *old_closer;
   bool opener_found;
+  bool odd_match;
   delimiter *openers_bottom[128];
 
   // initialize openers_bottom:
@@ -502,9 +503,18 @@ static void process_emphasis(subject *subj, delimiter *stack_bottom) {
       // Now look backwards for first matching opener:
       opener = closer->previous;
       opener_found = false;
+      odd_match = false;
       while (opener != NULL && opener != stack_bottom &&
              opener != openers_bottom[closer->delim_char]) {
-        if (opener->delim_char == closer->delim_char && opener->can_open) {
+	// interior closer of size 2 can't match opener of size 1
+	// or of size 1 can't match 2
+	odd_match = (closer->can_open || opener->can_close) &&
+		opener->inl_text->as.literal.len !=
+		  closer->inl_text->as.literal.len &&
+		((opener->inl_text->as.literal.len +
+		    closer->inl_text->as.literal.len) % 3 == 0);
+        if (opener->delim_char == closer->delim_char && opener->can_open &&
+			!odd_match) {
           opener_found = true;
           break;
         }
@@ -534,8 +544,12 @@ static void process_emphasis(subject *subj, delimiter *stack_bottom) {
         }
         closer = closer->next;
       }
-      if (!opener_found) {
-        // set lower bound for future searches for openers:
+      if (!opener_found && !odd_match) {
+        // set lower bound for future searches for openers
+	// (we don't do this with 'odd_match' set because
+	// a ** that didn't match an earlier * might turn into
+	// an opener, and the * might be matched by something
+	// else.
         openers_bottom[old_closer->delim_char] = old_closer->previous;
         if (!old_closer->can_open) {
           // we can remove a closer that can't be an