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// Copyright 2021 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.common.base.Preconditions;
/**
* {@link AttributeMap} implementation that triggers an {@link IllegalStateException} if called on
* any attribute that is configured (has a select statement).
*
* <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.
*
* <p>This is different from {@link NonconfigurableAttributeMapper} as it does not require the
* attribute be declared as nonconfigurable. Instead, the attributes must not currently be
* configured (that is, have select statements). This distinction is crucial when considering
* Starlark-defined rules as they cannot declare attributes as nonconfigurable.
*/
public class NonconfiguredAttributeMapper extends AbstractAttributeMapper {
private NonconfiguredAttributeMapper(Rule rule) {
super(rule);
}
/**
* Example usage:
*
* <pre>
* Label fooLabel = UnconfiguredAttributeMapper.of(rule).get("foo", Type.LABEL);
* </pre>
*/
public static NonconfiguredAttributeMapper of(Rule rule) {
return new NonconfiguredAttributeMapper(rule);
}
@Override
public <T> T get(String attributeName, com.google.devtools.build.lib.packages.Type<T> type) {
if (getAttributeDefinition(attributeName).isConfigurable()) {
Preconditions.checkState(
getSelectorList(attributeName, type) == null,
"Attribute '%s' is configured - not allowed here",
attributeName);
}
return super.get(attributeName, type);
}
}