Introduce CodeBuffer as StringBuffer replacement in compiler.

lib/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.
+
+class CodeBuffer implements StringBuffer {

[floitsch, 2012/07/16 09:55:43]

Please implement the 'addAll' method, too.

+  StringBuffer buffer;
+  List<SourceLocation> sourceLocations;
+  int lastBufferOffset = 0;
+
+  CodeBuffer()
+      : buffer = new StringBuffer(),
+        sourceLocations = new List<SourceLocation>();
+
+  int get length() {

[sra1, 2012/07/16 20:00:49]

nit: int get length() => buffer.length;

+    return buffer.length;
+  }
+
+  bool isEmpty() {
+    return buffer.isEmpty();
+  }
+
+  /**
+   * Converts [object] to a string and adds it to the buffer. If [object] is a
+   * [CodeBuffer], adds its source locations to [sourceLocations].
+   */
+  CodeBuffer add(var object) {
+    if (object is CodeBuffer) {
+      return addBuffer(object);
+    }
+    buffer.add(object.toString());
+    return this;
+  }
+
+  CodeBuffer addBuffer(CodeBuffer other) {
+    if (other.sourceLocations.length > 0) {
+      SourceLocation firstMapping = other.sourceLocations[0];
+      int offsetDelta =
+          buffer.length + firstMapping.offsetDelta - lastBufferOffset;
+      sourceLocations.add(new SourceLocation(firstMapping.element,
+                                             firstMapping.token,
+                                             offsetDelta));
+      for (int i = 1; i < other.sourceLocations.length; ++i) {
+        sourceLocations.add(other.sourceLocations[i]);
+      }
+      lastBufferOffset = buffer.length + other.lastBufferOffset;
+    }
+    buffer.add(other.toString());
+  }
+
+  CodeBuffer addCharCode(int charCode) {
+    return add(new String.fromCharCodes([charCode]));
+  }
+
+  CodeBuffer clear() {
+    buffer.clear();
+    sourceLocations.clear();
+    lastBufferOffset = 0;
+    return this;
+  }
+
+  String toString() {
+    return buffer.toString();
+  }
+
+  void setSourceLocation(Element element, Token token) {

[ahe, 2012/08/02 19:31:55]

I mentioned in a comment in another CL that it looks like bad offsets are
sneaking through. Here is an assertion that will catch that:

assert(() {
  for (Token current = element.position; current !== null; current =
current.next) {
    if (token === current) return true;
  }
  return false;
});

+    int offsetDelta = buffer.length - lastBufferOffset;
+    sourceLocations.add(new SourceLocation(element, token, offsetDelta));
+    lastBufferOffset = buffer.length;
+  }
+
+  void forEachSourceLocation(void f(Element element, Token token, int offset)) {
+    int offset = 0;
+    sourceLocations.forEach((sourceLocation) {
+      offset += sourceLocation.offsetDelta;
+      f(sourceLocation.element, sourceLocation.token, offset);
+    });
+  }
+}
+
+class SourceLocation {
+  Element element;

[sra1, 2012/07/16 20:00:49]

final?

+  Token token;
+  int offsetDelta;
+  SourceLocation(this.element, this.token, this.offsetDelta);
+}