fix : fix surrogate pairs splitting for toText()/fromText()

Author: michal-kurz

javascript/diff_match_patch_uncompressed.js

@@ -1423,17 +1423,17 @@ diff_match_patch.prototype.digit16 = function(c) {
 
 /**
  * Decode URI-encoded string but allow for encoded surrogate halves
- * 
+ *
  * diff_match_patch needs this relaxation of the requirements because
  * not all libraries and versions produce valid URI strings in toDelta
  * and we don't want to crash this code when the input is valid input
  * but at the same time invalid utf-8
- * 
+ *
  * @example: decodeURI( 'abcd%3A %F0%9F%85%B0' ) = 'abcd: \ud83c\udd70'
  * @example: decodeURI( 'abcd%3A %ED%A0%BC' ) = 'abcd: \ud83c'
- * 
+ *
  * @cite: @mathiasbynens utf8.js at https://github.com/mathiasbynens/utf8.js
- * 
+ *
  * @param {String} text input string encoded by encodeURI() or equivalent
  * @return {String}
  */
@@ -2215,6 +2215,46 @@ diff_match_patch.prototype.patch_splitMax = function(patches) {
   }
 };
 
+diff_match_patch.prototype.diffs_joinSurrogatePairs = function(diffs) {
+	var newDiffs = [];
+	
+	var lastEnd;
+	
+	for (var x = 0 ; x < diffs.length ; x++) {
+		var thisDiff = diffs[x];
+		var thisTop = thisDiff[1][0];
+		var thisEnd = thisDiff[1][thisDiff[1].length - 1];
+		
+		if (0 === thisDiff[1].length) {
+			continue;
+		}
+		
+		// trap a trailing high-surrogate so we can
+		// distribute it to the successive edits
+		if (thisEnd && this.isHighSurrogate(thisEnd)) {
+			lastEnd = thisEnd;
+			thisDiff[1] = thisDiff[1].slice(0, -1);
+		}
+		
+		if (lastEnd && thisTop && this.isHighSurrogate(lastEnd) && this.isLowSurrogate(thisTop)) {
+			thisDiff[1] = lastEnd + thisDiff[1];
+		}
+		
+		if (0 === thisDiff[1].length) {
+			continue;
+		}
+		
+		newDiffs.push(thisDiff)
+	}
+	
+	return newDiffs
+}
+
+diff_match_patch.prototype.patch_joinSurrogatePairs = function(patch) {
+	patch.diffs = this.diffs_joinSurrogatePairs(patch.diffs)
+	return patch
+}
+
 
 /**
  * Take a list of patches and return a textual representation.
@@ -2224,7 +2264,7 @@ diff_match_patch.prototype.patch_splitMax = function(patches) {
 diff_match_patch.prototype.patch_toText = function(patches) {
   var text = [];
   for (var x = 0; x < patches.length; x++) {
-    text[x] = patches[x];
+    text[x] = this.patch_joinSurrogatePairs(patches[x]);
   }
   return text.join('');
 };
@@ -2277,7 +2317,7 @@ diff_match_patch.prototype.patch_fromText = function(textline) {
     while (textPointer < text.length) {
       var sign = text[textPointer].charAt(0);
       try {
-        var line = decodeURI(text[textPointer].substring(1));
+        var line = this.decodeURI(text[textPointer].substring(1));
       } catch (ex) {
         // Malformed URI sequence.
         throw new Error('Illegal escape in patch_fromText: ' + line);

javascript/tests/diff_match_patch_test.js

@@ -502,14 +502,14 @@ function testDiffDelta() {
 
   (function(){
     const originalText = `U+1F17x	🅰️	🅱️		🅾️	🅿️ safhawifhkw
-    U+1F18x															🆎	
+    U+1F18x															🆎
     0	1	2	3	4	5	6	7	8	9	A	B	C	D	E	F
-    U+1F19x		🆑	🆒	🆓	🆔	🆕	🆖	🆗	🆘	🆙	🆚					
-    U+1F20x		🈁	🈂️							sfss.,_||saavvvbbds						
-    U+1F21x	🈚					
+    U+1F19x		🆑	🆒	🆓	🆔	🆕	🆖	🆗	🆘	🆙	🆚
+    U+1F20x		🈁	🈂️							sfss.,_||saavvvbbds
+    U+1F21x	🈚
     U+1F22x			🈯
-    U+1F23x			🈲	🈳	🈴	🈵	🈶	🈷️	🈸	🈹	🈺					
-    U+1F25x	🉐	🉑		
+    U+1F23x			🈲	🈳	🈴	🈵	🈶	🈷️	🈸	🈹	🈺
+    U+1F25x	🉐	🉑
     U+1F30x	🌀	🌁	🌂	🌃	🌄	🌅	🌆	🌇	🌈	🌉	🌊	🌋	🌌	🌍	🌎	🌏
     U+1F31x	🌐	🌑	🌒	🌓	🌔	🌕	🌖	🌗	🌘	🌙	🌚	🌛	🌜	🌝	🌞	`;
 
@@ -892,7 +892,7 @@ function testPatchFromText() {
 function testPatchToText() {
   var strp = '@@ -21,18 +22,17 @@\n jump\n-s\n+ed\n  over \n-the\n+a\n  laz\n';
   var p = dmp.patch_fromText(strp);
-  assertEquals(strp, dmp.patch_toText(p));
+	assertEquals(strp, dmp.patch_toText(p));
 
   strp = '@@ -1,9 +1,9 @@\n-f\n+F\n oo+fooba\n@@ -7,9 +7,9 @@\n obar\n-,\n+.\n  tes\n';
   p = dmp.patch_fromText(strp);