From d08b27fa9701fecfdb69e1b0d1ac2459efc2129b Mon Sep 17 00:00:00 2001
From: Han-Wen Nienhuys <hanwen@google.com>
Date: Wed, 25 Feb 2015 16:45:20 +0100
Subject: Update from Google.

--
MOE_MIGRATED_REVID=85702957
---
 .../packages/NonconfigurableAttributeMapper.java   | 56 ++++++++++++++++++++++
 1 file changed, 56 insertions(+)
 create mode 100644 src/main/java/com/google/devtools/build/lib/packages/NonconfigurableAttributeMapper.java

(limited to 'src/main/java/com/google/devtools/build/lib/packages/NonconfigurableAttributeMapper.java')

diff --git a/src/main/java/com/google/devtools/build/lib/packages/NonconfigurableAttributeMapper.java b/src/main/java/com/google/devtools/build/lib/packages/NonconfigurableAttributeMapper.java
new file mode 100644
index 0000000000..d54c847318
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/packages/NonconfigurableAttributeMapper.java
@@ -0,0 +1,56 @@
+// 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.packages;
+
+import com.google.common.base.Preconditions;
+import com.google.common.collect.ImmutableList;
+
+/**
+ * {@link AttributeMap} implementation that triggers an {@link IllegalStateException} if called
+ * on any attribute that supports configurable values, as determined by
+ * {@link Attribute#isConfigurable()}.
+ *
+ * <p>This is particularly useful for logic that doesn't have access to configurations - it
+ * protects against undefined behavior in response to unexpected configuration-dependent inputs.
+ */
+public class NonconfigurableAttributeMapper extends AbstractAttributeMapper {
+  private NonconfigurableAttributeMapper(Rule rule) {
+    super(rule.getPackage(), rule.getRuleClassObject(), rule.getLabel(),
+        rule.getAttributeContainer());
+  }
+
+  /**
+   * Example usage:
+   *
+   * <pre>
+   *   Label fooLabel = NonconfigurableAttributeMapper.of(rule).get("foo", Type.LABEL);
+   * </pre>
+   */
+  public static NonconfigurableAttributeMapper of (Rule rule) {
+    return new NonconfigurableAttributeMapper(rule);
+  }
+
+  @Override
+  public <T> T get(String attributeName, Type<T> type) {
+    Preconditions.checkState(!getAttributeDefinition(attributeName).isConfigurable(),
+        "Attribute '" + attributeName + "' is potentially configurable - not allowed here");
+    return super.get(attributeName, type);
+  }
+
+  @Override
+  protected <T> Iterable<T> visitAttribute(String attributeName, Type<T> type) {
+    T value = get(attributeName, type);
+    return value == null ? ImmutableList.<T>of() : ImmutableList.of(value);
+  }
+}
-- 
cgit v1.2.3