1 files changed, 85 insertions, 0 deletions
diff --git a/src/main/java/com/google/devtools/build/lib/rules/extra/ActionListener.java b/src/main/java/com/google/devtools/build/lib/rules/extra/ActionListener.java
new file mode 100644
index 0000000000..f3b302f13e
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/rules/extra/ActionListener.java
@@ -0,0 +1,85 @@
+// 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.rules.extra;
+
+import com.google.common.collect.Multimap;
+import com.google.common.collect.Sets;
+import com.google.devtools.build.lib.analysis.ConfiguredTarget;
+import com.google.devtools.build.lib.analysis.RuleConfiguredTarget.Mode;
+import com.google.devtools.build.lib.analysis.RuleConfiguredTargetBuilder;
+import com.google.devtools.build.lib.analysis.RuleContext;
+import com.google.devtools.build.lib.analysis.Runfiles;
+import com.google.devtools.build.lib.analysis.RunfilesProvider;
+import com.google.devtools.build.lib.analysis.TransitiveInfoCollection;
+import com.google.devtools.build.lib.collect.ImmutableSortedKeyListMultimap;
+import com.google.devtools.build.lib.packages.Type;
+import com.google.devtools.build.lib.rules.RuleConfiguredTargetFactory;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Set;
+
+/**
+ * Implementation for the 'action_listener' rule.
+ */
+public final class ActionListener implements RuleConfiguredTargetFactory {
+  @Override
+  public ConfiguredTarget create(RuleContext ruleContext) {
+    // This rule doesn't produce any output when listed as a build target.
+    // Only when used via the --experimental_action_listener flag,
+    // this rule instructs the build system to add additional outputs.
+
+    List<ExtraActionSpec> extraActions;
+
+    Multimap<String, ExtraActionSpec> extraActionMap;
+
+    Set<String> mnemonics = Sets.newHashSet(
+        ruleContext.attributes().get("mnemonics", Type.STRING_LIST));
+    extraActions = retrieveAndValidateExtraActions(ruleContext);
+    ImmutableSortedKeyListMultimap.Builder<String, ExtraActionSpec>
+        extraActionMapBuilder = ImmutableSortedKeyListMultimap.builder();
+    for (String mnemonic : mnemonics) {
+      extraActionMapBuilder.putAll(mnemonic, extraActions);
+    }
+    extraActionMap = extraActionMapBuilder.build();
+    return new RuleConfiguredTargetBuilder(ruleContext)
+        .add(RunfilesProvider.class, RunfilesProvider.simple(Runfiles.EMPTY))
+        .add(ExtraActionMapProvider.class, new ExtraActionMapProvider(extraActionMap))
+        .build();
+  }
+
+  /**
+   * Loads the targets listed in the 'extra_actions' attribute of this rule.
+   * Validates these targets to be extra_actions indeed. And checks if the
+   * blaze version number is in the range of the blaze_version restrictions on the rule.
+   */
+  private List<ExtraActionSpec> retrieveAndValidateExtraActions(RuleContext ruleContext) {
+    List<ExtraActionSpec> extraActions = new ArrayList<>();
+    for (TransitiveInfoCollection prerequisite :
+        ruleContext.getPrerequisites("extra_actions", Mode.TARGET)) {
+      ExtraActionSpec spec = prerequisite.getProvider(ExtraActionSpec.class);
+      if (spec == null) {
+        ruleContext.attributeError("extra_actions", String.format("target %s is not an "
+            + "extra_action rule", prerequisite.getLabel().toString()));
+      } else {
+        extraActions.add(spec);
+      }
+    }
+    if (extraActions.size() == 0) {
+      ruleContext.attributeWarning("extra_actions",
+          "No extra_action is specified for this version of blaze.");
+    }
+    return extraActions;
+  }
+}