👌 IMPROVE: emphasis parsing performance

Implements: markdown-it/markdown-it@83b0575,
and strikethrough fix: markdown-it/markdown-it@c9dd942

Author: chrisjsewell

markdown_it/rules_inline/balance_pairs.py

@@ -28,20 +28,23 @@ def processDelimiters(state: StateInline, delimiters, *args):
             openersBottom[closer.marker] = [-1, -1, -1]
 
         minOpenerIdx = openersBottom[closer.marker][closer.length % 3]
-        newMinOpenerIdx = -1
 
         openerIdx = closerIdx - closer.jump - 1
 
+        # avoid crash if `closer.jump` is pointing outside of the array,
+        # e.g. for strikethrough
+        if openerIdx < -1:
+            openerIdx = -1
+
+        newMinOpenerIdx = openerIdx
+
         while openerIdx > minOpenerIdx:
             opener = delimiters[openerIdx]
 
             if opener.marker != closer.marker:
                 openerIdx -= opener.jump + 1
                 continue
 
-            if newMinOpenerIdx == -1:
-                newMinOpenerIdx = openerIdx
-
             if opener.open and opener.end < 0:
 
                 isOddMatch = False

markdown_it/rules_inline/strikethrough.py

@@ -35,7 +35,7 @@ def tokenize(state: StateInline, silent: bool):
                 **{
                     "marker": marker,
                     "length": 0,  # disable "rule of 3" length checks meant for emphasis
-                    "jump": i,
+                    "jump": i // 2,  # for `~~` 1 marker = 2 characters,
                     "token": len(state.tokens) - 1,
                     "end": -1,
                     "open": scanned.can_open,

tests/test_port/fixtures/strikethrough.md

@@ -127,3 +127,10 @@ Coverage: single tilde
 .
 <p>~a~</p>
 .
+
+Regression test for #742:
+.
+-~~~~;~~~~~~
+.
+<p>-<s><s>;</s></s>~~</p>
+.