Use new emphasis logic in strikethrough

lib/rules_inline/emphasis.js

@@ -1,7 +1,8 @@
 // Process *this* and _that_
-
+//
 'use strict';
 
+
 var isWhiteSpace   = require('../common/utils').isWhiteSpace;
 var isPunctChar    = require('../common/utils').isPunctChar;
 var isMdAsciiPunct = require('../common/utils').isMdAsciiPunct;

lib/rules_inline/strikethrough.js

@@ -1,10 +1,19 @@
+// ~~strike through~~
+//
 'use strict';
 
 
+var isWhiteSpace   = require('../common/utils').isWhiteSpace;
+var isPunctChar    = require('../common/utils').isPunctChar;
+var isMdAsciiPunct = require('../common/utils').isMdAsciiPunct;
+
+
 // parse sequence of markers,
 // "start" should point at a valid marker
 function scanDelims(state, start) {
   var pos = start, lastChar, nextChar, count,
+      isLastWhiteSpace, isLastPunctChar,
+      isNextWhiteSpace, isNextPunctChar,
       can_open = true,
       can_close = true,
       max = state.posMax,
@@ -18,9 +27,28 @@ function scanDelims(state, start) {
 
   nextChar = pos < max ? state.src.charCodeAt(pos) : -1;
 
-  // check whitespace conditions
-  if (nextChar === 0x20 || nextChar === 0x0A) { can_open = false; }
-  if (lastChar === 0x20 || lastChar === 0x0A) { can_close = false; }
+  isLastPunctChar = lastChar >= 0 &&
+    (isMdAsciiPunct(lastChar) || isPunctChar(String.fromCharCode(lastChar)));
+  isNextPunctChar = nextChar >= 0 &&
+    (isMdAsciiPunct(nextChar) || isPunctChar(String.fromCharCode(nextChar)));
+  isLastWhiteSpace = lastChar >= 0 && isWhiteSpace(lastChar);
+  isNextWhiteSpace = nextChar >= 0 && isWhiteSpace(nextChar);
+
+  if (isNextWhiteSpace) {
+    can_open = false;
+  } else if (isNextPunctChar) {
+    if (!(isLastWhiteSpace || isLastPunctChar || lastChar === -1)) {
+      can_open = false;
+    }
+  }
+
+  if (isLastWhiteSpace) {
+    can_close = false;
+  } else if (isLastPunctChar) {
+    if (!(isNextWhiteSpace || isNextPunctChar || nextChar === -1)) {
+      can_close = false;
+    }
+  }
 
   return {
     can_open: can_open,