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// Copyright 2023 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.cmdline.Label;
import com.google.devtools.build.lib.concurrent.ThreadSafety.Immutable;
import com.google.devtools.build.lib.packages.RuleClass.ConfiguredTargetFactory.RuleErrorException;
/**
* A helper for wrapping an instance of a Starlark-defined provider with a native class {@code T}.
*
* <p>This is useful for allowing native rules to interoperate with Starlark-defined providers
* (including providers defined in {@code @_builtins}} while retaining the friendlier API of a Java
* class.
*
* <p>To use, create a subclass that overrides {@link #wrap}, and pass a singleton instance of that
* subclass to {@link
* com.google.devtools.build.lib.analysis.ProviderCollection#get(StarlarkProviderWrapper)}.
*
* <p>{@code T} is not typically itself a provider. There is no mechanism for converting {@code T}
* back into a Starlark provider instance; instead, the caller should construct that instance
* manually.
*/
@Immutable
public abstract class StarlarkProviderWrapper<T> {
private final StarlarkProvider.Key key;
protected StarlarkProviderWrapper(Label label, String name) {
this.key = new StarlarkProvider.Key(label, name);
}
/*
* Converts an instance of the Starlark-defined provider to an instance of the wrapping class
* {@code T}.
*
* <p>{@code value} may be assumed to be an instance of the provider identified by {@link
* #getKey}.
*
* <p>Any schema errors (missing or mistyped fields) should be reported by throwing {@link
* RuleErrorException}
*/
public abstract T wrap(Info value) throws RuleErrorException;
public StarlarkProvider.Key getKey() {
return key;
}
/** Returns the identifier of this provider. */
public StarlarkProviderIdentifier id() {
return StarlarkProviderIdentifier.forKey(key);
}
}