Revert "Removes dartc reliance on its own libraries, now can be targeted at any implementation's li…

compiler/lib/implementation/string_buffer.dart

Index: compiler/lib/implementation/string_buffer.dart
diff --git a/compiler/lib/implementation/string_buffer.dart b/compiler/lib/implementation/string_buffer.dart
new file mode 100644
index 0000000000000000000000000000000000000000..373c78d37a1f851e0f7c80816bc7792285d9fad8
--- /dev/null
+++ b/compiler/lib/implementation/string_buffer.dart
@@ -0,0 +1,87 @@
+// Copyright (c) 2011, 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.
+
+/**
+ * The StringBuffer class is useful for concatenating strings
+ * efficiently. Only on a call to [toString] are the strings
+ * concatenated to a single String.
+ */
+class StringBufferImpl implements StringBuffer {
+  /**
+   * Creates the string buffer with an initial content.
+   */
+  StringBufferImpl([Object content = ""]) {
+    clear();
+    add(content);
+  }
+
+  /**
+   * Returns the length of the buffer.
+   */
+  int get length() {
+    return _length;
+  }
+
+  bool isEmpty() {
+    return _length == 0;
+  }
+
+  /**
+   * Adds [obj] to the buffer. Returns [this].
+   */
+  StringBuffer add(Object obj) {
+    String str = obj.toString();
+    if (str === null || str.isEmpty()) return this;
+    _buffer.add(str);
+    _length += str.length;
+    return this;
+  }
+
+  /**
+   * Adds all items in [objects] to the buffer. Returns [this].
+   */
+  StringBuffer addAll(Collection<Object> objects) {
+    if (objects == null) {
+      throw const NullPointerException();
+    }
+    for (Object obj in objects) {
+      add(obj);
+    }
+    return this;
+  }
+
+  /**
+   * Adds the string representation of [charCode] to the buffer.
+   * Returns [this].
+   */
+  StringBuffer addCharCode(int charCode) {
+    return add(new String.fromCharCodes([charCode]));
+  }
+
+  /**
+   * Clears the string buffer. Returns [this].
+   */
+  StringBuffer clear() {
+    _buffer = new List<String>();
+    _length = 0;
+    return this;
+  }
+
+  /**
+   * Returns the contents of buffer as a concatenated string.
+   */
+  String toString() {
+    if (_buffer.length == 0) return "";
+    if (_buffer.length == 1) return _buffer[0];
+    String result = StringBase.concatAll(_buffer);
+    _buffer.clear();
+    _buffer.add(result);
+    // Since we track the length at each add operation, there is no
+    // need to update it in this function.
+    return result;
+  }
+
+  List<String> _buffer;
+  int _length;
+}