1 files changed, 79 insertions, 0 deletions
diff --git a/src/main/java/com/google/devtools/build/lib/actions/Actions.java b/src/main/java/com/google/devtools/build/lib/actions/Actions.java
new file mode 100644
index 0000000000..fb2b834785
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/actions/Actions.java
@@ -0,0 +1,79 @@
+// Copyright 2014 Google Inc. 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.actions;
+
+import com.google.common.collect.Iterables;
+import com.google.common.escape.Escaper;
+import com.google.common.escape.Escapers;
+import com.google.devtools.build.lib.concurrent.ThreadSafety.ThreadSafe;
+import com.google.devtools.build.lib.syntax.Label;
+
+/**
+ * Helper class for actions.
+ */
+@ThreadSafe
+public final class Actions {
+  private static final Escaper PATH_ESCAPER = Escapers.builder()
+      .addEscape('_', "_U")
+      .addEscape('/', "_S")
+      .addEscape('\\', "_B")
+      .addEscape(':', "_C")
+      .build();
+
+  /**
+   * Checks if the two actions are equivalent. This method exists to support sharing actions between
+   * configured targets for cases where there is no canonical target that could own the action. In
+   * the action graph construction this case shows up as two actions generating the same output
+   * file.
+   *
+   * <p>This method implements an equivalence relationship across actions, based on the action
+   * class, the key, and the list of inputs and outputs.
+   */
+  public static boolean canBeShared(Action a, Action b) {
+    if (!a.getMnemonic().equals(b.getMnemonic())) {
+      return false;
+    }
+    if (!a.getKey().equals(b.getKey())) {
+      return false;
+    }
+    // Don't bother to check input and output counts first; the expected result for these tests is
+    // to always be true (i.e., that this method returns true).
+    if (!Iterables.elementsEqual(a.getMandatoryInputs(), b.getMandatoryInputs())) {
+      return false;
+    }
+    if (!Iterables.elementsEqual(a.getOutputs(), b.getOutputs())) {
+      return false;
+    }
+    return true;
+  }
+
+  /**
+   * Returns the escaped name for a given relative path as a string. This takes
+   * a short relative path and turns it into a string suitable for use as a
+   * filename. Invalid filename characters are escaped with an '_' + a single
+   * character token.
+   */
+  public static String escapedPath(String path) {
+    return PATH_ESCAPER.escape(path);
+  }
+
+  /**
+   * Returns a string that is usable as a unique path component for a label. It is guaranteed
+   * that no other label maps to this string.
+   */
+  public static String escapeLabel(Label label) {
+    return PATH_ESCAPER.escape(label.getPackageName() + ":" + label.getName());
+  }
+}