X-Git-Url: https://git.yukkurigames.com/?p=string-lerp.git;a=blobdiff_plain;f=string-lerp.js;fp=string-lerp.js;h=40d9fd0c30655daaaac0e83a5fb648ae267cd8c1;hp=3a304886374373c3471aaf530a92f2615ea5544d;hb=245005bdfa792a76d55b0fafd2255c4c8325d28c;hpb=dd1c5bcbe8357a8bc2b83fc711ee16d0c7c8eaac

diff --git a/string-lerp.js b/string-lerp.js
index 3a30488..40d9fd0 100644
--- a/string-lerp.js
+++ b/string-lerp.js
@@ -61,24 +61,47 @@
 
     function patch(edits, s) {
         /** Apply the list of edits to s */
+        var edit;
         var i;
-        for (i = 0; i < edits.length; ++i) {
-            var edit = edits[i];
-            switch (edit[0]) {
-            case "sub":
-                s = s.slice(0, edit[1]) + edit[2] + s.slice(edit[1] + 1);
-                break;
-            case "ins":
-                s = s.slice(0, edit[1]) + edit[2] + s.slice(edit[1]);
-                break;
-            case "del":
-                s = s.slice(0, edit[1]) + s.slice(edit[1] + 1);
-                break;
+
+        if (Array.isArray(s)) {
+            for (i = 0; i < edits.length; ++i) {
+                edit = edits[i];
+                switch (edit[0]) {
+                case "sub":
+                    s[edit[1]] = edit[2];
+                    break;
+                case "ins":
+                    s.splice(edit[1], 0, edit[2]);
+                    break;
+                case "del":
+                    s.splice(edit[1], 1);
+                    break;
+                }
+            }
+        } else {
+            for (i = 0; i < edits.length; ++i) {
+                edit = edits[i];
+                switch (edit[0]) {
+                case "sub":
+                    s = s.slice(0, edit[1]) + edit[2] + s.slice(edit[1] + 1);
+                    break;
+                case "ins":
+                    s = s.slice(0, edit[1]) + edit[2] + s.slice(edit[1]);
+                    break;
+                case "del":
+                    s = s.slice(0, edit[1]) + s.slice(edit[1] + 1);
+                    break;
+                }
             }
         }
         return s;
     }
 
+    var MULTI = /[\uD800-\uDBFF][\uDC00-\uDFFF]|[\u0300-\u036F\u1DC0-\u1DFF\u20D0-\u20FF\uFE20-\uFE2F]/;
+
+    var GLYPH = /([\0-\u02FF\u0370-\u1DBF\u1E00-\u20CF\u2100-\uD7FF\uDC00-\uFE1F\uFE30-\uFFFF]|[\uD800-\uDBFF][\uDC00-\uDFFF]|[\uD800-\uDBFF])([\u0300-\u036F\u1DC0-\u1DFF\u20D0-\u20FF\uFE20-\uFE2F]*)/g;
+
     function diffLerp(a, b, p) {
         /** Interpolate between two strings based on edit distance
 
@@ -89,6 +112,19 @@
             longer than a few hundred characters.
          */
 
+        // If given strings with astral codepoints or combining
+        // characters, split them into arrays of "glyphs" first,
+        // do the edit on the list of "glyphs", and rejoin them.
+        //
+        // This split is not perfect for all languages, but at least
+        // it won't create invalid surrogate pairs or orphaned
+        // combining characters.
+        if (a.match && a.match(MULTI) || b.match && b.match(MULTI)) {
+            var ca = a.match(GLYPH) || [];
+            var cb = b.match(GLYPH) || [];
+            return diffLerp(ca, cb, p).join("");
+        }
+
         // The edit path works from the string end, forwards, because
         // that's how Levenshtein edits work. To match LTR reading
         // direction (and the behavior of fastLerp), swap the strings
@@ -149,9 +185,19 @@
             front of one string with another. This approach is fast
             but does not look good when the strings are similar.
         */
-        var alen = Math.round(a.length * p);
-        var blen = Math.round(b.length * p);
-        return b.substring(0, blen) + a.substring(alen, a.length);
+        if (a.match(MULTI) || b.match(MULTI)) {
+            var ca = a.match(GLYPH) || [];
+            var cb = b.match(GLYPH) || [];
+            var calen = Math.round(ca.length * p);
+            var cblen = Math.round(cb.length * p);
+            var r = cb.slice(0, cblen);
+            r.push.apply(r, ca.slice(calen, ca.length));
+            return r.join("");
+        } else {
+            var alen = Math.round(a.length * p);
+            var blen = Math.round(b.length * p);
+            return b.substring(0, blen) + a.substring(alen, a.length);
+        }
     }
 
     function lerp(a, b, p) {