// 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()}.
*
* <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, com.google.devtools.build.lib.syntax.Type<T> type) {
T attr = super.get(attributeName, type);
Preconditions.checkState(!getAttributeDefinition(attributeName).isConfigurable(),
"Attribute '%s' is potentially configurable - not allowed here", attributeName);
return attr;
}
}