// Copyright 2014 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.packages; import com.google.devtools.build.lib.util.Preconditions; /** * {@link AttributeMap} implementation that triggers an {@link IllegalStateException} if called * on any attribute that supports configurable values, as determined by * {@link Attribute#isConfigurable()}. * *

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: * *

   *   Label fooLabel = NonconfigurableAttributeMapper.of(rule).get("foo", Type.LABEL);
   * 
*/ public static NonconfigurableAttributeMapper of (Rule rule) { return new NonconfigurableAttributeMapper(rule); } @Override public T get(String attributeName, com.google.devtools.build.lib.syntax.Type type) { T attr = super.get(attributeName, type); Preconditions.checkState(!getAttributeDefinition(attributeName).isConfigurable(), "Attribute '%s' is potentially configurable - not allowed here", attributeName); return attr; } }