Add the initial implementation I provided to ACE.

diff --git a/utf16.js b/utf16.js
index e42f42f34c757e64dad1ddf1b1e2874ba6cbe38f..3aea6915e596140fdde4616a2ff227223ce73847 100644 (file)
--- a/utf16.js
+++ b/utf16.js
@@ -39,9 +39,84 @@ var encode = function(points) {
     } return String.fromCharCode.apply(String, units);
 };
 
+var adjust = function(mode, string, after) {
+    var before = after.slice();
+    var offset = 0, index = 0;
+
+    var check = function() {
+        var from = mode ? index : offset;
+        var to = mode ? offset : index;
+
+        for (var o = 0, l = after.length; o != l; ++o)
+            if (before[o] == from) {
+                before[o] = null;
+                after[o] = to;
+            }
+    };
+
+    for (var e = string.length; index != e; ++index) {
+        check();
+
+        var unit = string.charCodeAt(index);
+        var part = unit & 0xfc00;
+
+        if (part == 0xdc00)
+            return null;
+        else if (part != 0xd800);
+        else if (++index == e)
+            return null;
+        else {
+            var next = string.charCodeAt(index);
+            if ((next & 0xfc00) != 0xdc00)
+                return null;
+        }
+
+        ++offset;
+    }
+
+    check();
+    return after;
+};
+
+var point2unit = function(string, offsets) {
+    return adjust(false, string, offsets);
+};
+
+var unit2point = function(string, offsets) {
+    return adjust(true, string, offsets);
+};
+
+var charAt = function(string, offset) {
+    return substring(string, offset, offset + 1);
+};
+
+var length = function(string) {
+    return unit2point(string, [string.length])[0];
+};
+
+var substr = function(string, start, length) {
+    var stop;
+    if (typeof length !== "undefined")
+        stop = start + length;
+    return substring(string, start, stop);
+};
+
+var substring = function(string, start, stop) {
+    var range = point2unit(string, [start, stop]);
+    return string.substring(range[0], range[1]);
+};
+
 return {
     decode: decode,
     encode: encode,
+
+    point2unit: point2unit,
+    unit2point: unit2point,
+
+    charAt: charAt,
+    length: length,
+    substr: substr,
+    substring: substring,
 };
 
 });