Initial implementation of 'Create Method' quick fix

editor/tools/plugins/com.google.dart.tools.ui/src/com/google/dart/tools/ui/internal/text/correction/proposals/SourceBuilder.java

Index: editor/tools/plugins/com.google.dart.tools.ui/src/com/google/dart/tools/ui/internal/text/correction/proposals/SourceBuilder.java
diff --git a/editor/tools/plugins/com.google.dart.tools.ui/src/com/google/dart/tools/ui/internal/text/correction/proposals/SourceBuilder.java b/editor/tools/plugins/com.google.dart.tools.ui/src/com/google/dart/tools/ui/internal/text/correction/proposals/SourceBuilder.java
new file mode 100644
index 0000000000000000000000000000000000000000..f613ebe917a3c05c2907ca7bf336b7dc94c544a8
--- /dev/null
+++ b/editor/tools/plugins/com.google.dart.tools.ui/src/com/google/dart/tools/ui/internal/text/correction/proposals/SourceBuilder.java
@@ -0,0 +1,83 @@
+/*
+ * Copyright (c) 2012, the Dart project authors.
+ * 
+ * Licensed under the Eclipse Public License v1.0 (the "License"); you may not use this file except
+ * in compliance with the License. You may obtain a copy of the License at
+ * 
+ * http://www.eclipse.org/legal/epl-v10.html
+ * 
+ * Unless required by applicable law or agreed to in writing, software distributed under the License
+ * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
+ * or implied. See the License for the specific language governing permissions and limitations under
+ * the License.
+ */
+package com.google.dart.tools.ui.internal.text.correction.proposals;
+
+import com.google.common.collect.Lists;
+import com.google.common.collect.Maps;
+import com.google.dart.tools.core.dom.rewrite.TrackedNodePosition;
+import com.google.dart.tools.core.model.SourceRange;
+
+import org.eclipse.core.runtime.Assert;
+
+import java.util.List;
+import java.util.Map;
+
+/**
+ * Helper for building Dart source with tracked positions.
+ */
+public class SourceBuilder {
+  private final int base;
+  private final StringBuilder buffer = new StringBuilder();
+  private final Map<String, List<TrackedNodePosition>> trackedPositions = Maps.newHashMap();
+  private String currentPositionGroupId;
+  private int currentPositionStart;
+
+  public SourceBuilder(int base) {
+    this.base = base;
+  }
+
+  public SourceBuilder(SourceRange base) {
+    this(base.getOffset());
+  }
+
+  public SourceBuilder append(CharSequence s) {
+    buffer.append(s);
+    return this;
+  }
+
+  public void endPosition() {
+    Assert.isNotNull(currentPositionGroupId);
+    addPosition();
+    currentPositionGroupId = null;
+  }
+
+  public Map<String, List<TrackedNodePosition>> getTrackedPositions() {
+    return trackedPositions;
+  }
+
+  public void startPosition(String groupId) {
+    Assert.isTrue(currentPositionGroupId == null);
+    currentPositionGroupId = groupId;
+    currentPositionStart = buffer.length();
+  }
+
+  @Override
+  public String toString() {
+    return buffer.toString();
+  }
+
+  /**
+   * Adds {@link TrackedNodePosition} using current fields.
+   */
+  private void addPosition() {
+    List<TrackedNodePosition> positions = trackedPositions.get(currentPositionGroupId);
+    if (positions == null) {
+      positions = Lists.newArrayList();
+      trackedPositions.put(currentPositionGroupId, positions);
+    }
+    int start = base + currentPositionStart;
+    int end = base + buffer.length();
+    positions.add(TrackedPositions.forStartEnd(start, end));
+  }
+}