Improve the memory consumption and performance of our string buffer implementation.

sdk/lib/_internal/compiler/implementation/code_buffer.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of dart2js;
 
 class CodeBuffer implements StringBuffer {
-  StringBuffer buffer;
-  List<CodeBufferMarker> markers;
+
+  StringBuffer buffer = new StringBuffer();
+  List<CodeBufferMarker> markers = new List<CodeBufferMarker>();
+
   int lastBufferOffset = 0;
   int mappedRangeCounter = 0;
 
-  CodeBuffer()
-      : buffer = new StringBuffer(),
-        markers = new List<CodeBufferMarker>();
+  CodeBuffer();

[Lasse Reichstein Nielsen, 2013/09/20 11:40:17]

You can even remove the constructor entirely.
Probably too confusing.

 
   int get length => buffer.length;
-
-  bool get isEmpty {
-    return buffer.isEmpty;
-  }
-
-  bool get isNotEmpty => !isEmpty;
+  bool get isEmpty => buffer.isEmpty;
+  bool get isNotEmpty => buffer.isNotEmpty;
 
   CodeBuffer add(var object) {
     write(object);
     return this;
   }
   /**
    * Converts [object] to a string and adds it to the buffer. If [object] is a
    * [CodeBuffer], adds its markers to [markers].
    */
   CodeBuffer write(var object) {
@@ skipping 40 matching lines @@
     }
     buffer.write(other.getText());
     return this;
   }
 
   CodeBuffer addAll(Iterable<Object> iterable) => writeAll(iterable);
 
   CodeBuffer addCharCode(int charCode) => writeCharCode(charCode);
 
   CodeBuffer writeCharCode(int charCode) {
-    return write(new String.fromCharCodes([charCode]));

[Lasse Reichstein Nielsen, 2013/09/20 11:40:17]

Ouch. How much would you gain from just this change?

+    buffer.writeCharCode(charCode);
+    return this;
   }
 
   CodeBuffer clear() {
     buffer = new StringBuffer();

[Lasse Reichstein Nielsen, 2013/09/20 11:40:17]

Per my earlier comments, this is probably a good thing, but you could also do
buffer.clear();

     markers.clear();
     lastBufferOffset = 0;
     return this;
   }
 
   String toString() {
     throw "Don't use CodeBuffer.toString() since it drops sourcemap data.";
   }
 
   String getText() {
@@ skipping 23 matching lines @@
     });
   }
 }
 
 class CodeBufferMarker {
   final int offsetDelta;
   final sourcePosition;
 
   CodeBufferMarker(this.offsetDelta, this.sourcePosition);
 }