optimize composing rest of delta

ranglang · Aug 1, 2018 · 5c40363 · 5c40363
1 parent 4836397
commit 5c40363
Show file tree

Hide file tree

Showing 4 changed files with 70 additions and 2 deletions.
diff --git a/lib/delta.js b/lib/delta.js
@@ -188,6 +188,13 @@ Delta.prototype.compose = function (other) {
         var attributes = op.attributes.compose(thisOp.attributes, otherOp.attributes, typeof thisOp.retain === 'number');
         if (attributes) newOp.attributes = attributes;
         delta.push(newOp);
+
+        // Optimization if rest of other is just retain
+        if (!otherIter.hasNext() && equal(delta.ops[delta.ops.length - 1], newOp)) {
+          var rest = new Delta(thisIter.rest());
+          return delta.concat(rest).chop();
+        }
+
       // Other op should be delete, we could be an insert or retain
       // Insert + delete cancels out
       } else if (typeof otherOp['delete'] === 'number' && typeof thisOp.retain === 'number') {

diff --git a/lib/op.js b/lib/op.js
@@ -135,5 +135,21 @@ Iterator.prototype.peekType = function () {
   return 'retain';
 };
 
+Iterator.prototype.rest = function () {
+  if (!this.hasNext()) {
+    return [];
+  } else if (this.offset === 0) {
+    return this.ops.slice(this.index);
+  } else {
+    var offset = this.offset;
+    var index = this.index;
+    var next = this.next();
+    var rest = this.ops.slice(this.index);
+    this.offset = offset;
+    this.index = index;
+    return [next].concat(rest);
+  }
+};
+
 
 module.exports = lib;
diff --git a/test/delta/compose.js b/test/delta/compose.js
@@ -138,7 +138,7 @@ describe('compose()', function () {
     expect(attr1).toEqual(attr2);
   });
 
-  it('retain optimization', function () {
+  it('retain start optimization', function () {
     var a = new Delta().insert('A', { bold: true })
                        .insert('B')
                        .insert('C', { bold: true })
@@ -152,7 +152,7 @@ describe('compose()', function () {
     expect(a.compose(b)).toEqual(expected);
   });
 
-  it('retain optimization split', function () {
+  it('retain start optimization split', function () {
     var a = new Delta().insert('A', { bold: true })
                        .insert('B')
                        .insert('C', { bold: true })
@@ -168,4 +168,28 @@ describe('compose()', function () {
                               .delete(1);
     expect(a.compose(b)).toEqual(expected);
   });
+
+  it('retain end optimization', function () {
+    var a = new Delta().insert('A', { bold: true })
+                       .insert('B')
+                       .insert('C', { bold: true });
+    var b = new Delta().delete(1);
+    var expected = new Delta().insert('B').insert('C', { bold: true })
+    expect(a.compose(b)).toEqual(expected);
+  });
+
+  it('retain end optimization join', function () {
+    var a = new Delta().insert('A', { bold: true })
+                       .insert('B')
+                       .insert('C', { bold: true })
+                       .insert('D')
+                       .insert('E', { bold: true })
+                       .insert('F')
+    var b = new Delta().retain(1).delete(1);
+    var expected = new Delta().insert('AC', { bold: true })
+                              .insert('D')
+                              .insert('E', { bold: true })
+                              .insert('F')
+    expect(a.compose(b)).toEqual(expected);
+  });
 });
diff --git a/test/op.js b/test/op.js
@@ -88,5 +88,26 @@ describe('op', function () {
       expect(iter.next(1)).toEqual({ retain: 1 });
       expect(iter.next(2)).toEqual({ retain: 2 });
     });
+
+    it('rest()', function () {
+      var iter = op.iterator(this.delta.ops);
+      iter.next(2);
+      expect(iter.rest()).toEqual([
+        { insert: 'llo', attributes: { bold: true }},
+        { retain: 3 },
+        { insert: 2, attributes: { src: 'http://quilljs.com/' } },
+        { delete: 4 }
+      ]);
+      iter.next(3);
+      expect(iter.rest()).toEqual([
+        { retain: 3 },
+        { insert: 2, attributes: { src: 'http://quilljs.com/' } },
+        { delete: 4 }
+      ]);
+      iter.next(3);
+      iter.next(2);
+      iter.next(4);
+      expect(iter.rest()).toEqual([]);
+    })
   });
 });