1 files changed, 55 insertions, 0 deletions
diff --git a/src/main/java/com/google/devtools/build/lib/syntax/compiler/LoopLabels.java b/src/main/java/com/google/devtools/build/lib/syntax/compiler/LoopLabels.java
new file mode 100644
index 0000000000..e1bb9d36b1
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/syntax/compiler/LoopLabels.java
@@ -0,0 +1,55 @@
+// Copyright 2015 The Bazel Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (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.apache.org/licenses/LICENSE-2.0
+//
+// 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.devtools.build.lib.syntax.compiler;
+
+import com.google.common.base.Optional;
+import com.google.devtools.build.lib.syntax.FlowStatement.Kind;
+
+import org.objectweb.asm.Label;
+
+/**
+ * Container for passing around current loop labels during compilation.
+ */
+public class LoopLabels {
+  public final Label continueLabel;
+  public final Label breakLabel;
+
+  private LoopLabels(Label continueLabel, Label breakLabel) {
+    this.continueLabel = continueLabel;
+    this.breakLabel = breakLabel;
+  }
+
+  /**
+   * Only use Optional-wrapped instances of this class.
+   */
+  public static Optional<LoopLabels> of(Label continueLabel, Label breakLabel) {
+    return Optional.of(new LoopLabels(continueLabel, breakLabel));
+  }
+
+  public static final Optional<LoopLabels> ABSENT = Optional.absent();
+
+  /**
+   * Get the label for a certain kind of flow statement.
+   */
+  public Label labelFor(Kind kind) {
+    switch (kind) {
+      case BREAK:
+        return breakLabel;
+      case CONTINUE:
+        return continueLabel;
+      default:
+        throw new Error("missing flow kind: " + kind);
+    }
+  }
+}