implement a running diff

customize.dist/delta-words.js

@@ -0,0 +1,61 @@
+define([
+    '/bower_components/chainpad/chainpad.dist.js',
+], function (ChainPad) {
+    var Diff = ChainPad.Diff;
+
+    var isSpace = function (S, i) {
+        return /^\s$/.test(S.charAt(i));
+    };
+
+    var leadingBoundary = function (S, offset) {
+        if (/\s/.test(S.charAt(offset))) { return offset; }
+        while (offset > 0) {
+            offset--;
+            if (isSpace(S, offset)) { offset++; break; }
+        }
+        return offset;
+    };
+
+    var trailingBoundary = function (S, offset) {
+        if (isSpace(S, offset)) { return offset; }
+        while (offset < S.length && !/\s/.test(S.charAt(offset))) {
+            offset++;
+        }
+        return offset;
+    };
+
+    var opsToWords = function (last, current) {
+        var output = [];
+        Diff.diff(A, B).forEach(function (op) {
+            // ignore deleted sections...
+            var offset = op.offset;
+            var toInsert = op.toInsert;
+
+            // given an operation,  check whether it is a word fragment,
+            // if it is, expand it to its word boundaries
+            var first = B.slice(leadingBoundary(B, offset), offset);
+            var last = B.slice(offset + toInsert.length, trailingBoundary(B, offset + toInsert.length));
+
+            var result = first + toInsert + last;
+            // concat-in-place
+            Array.prototype.push.apply(output, result.split(/\s+/));
+        });
+        return output;
+    };
+
+    var runningDiff = function (getter, f, time) {
+        var last = getter();
+        // first time through, send all the words :D
+        f(opsToWords("", last));
+        return setInterval(function () {
+            var current = getter();
+
+            // find inserted words...
+            var words = opsToWords(last, current);
+            last = current;
+            f(words);
+        }, time);
+    };
+
+    return runningDiff;
+});