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// Copyright 2018 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.concurrent.ThreadSafety.Immutable;
import com.google.devtools.build.lib.events.Location;
import com.google.devtools.build.lib.syntax.BaseFunction;
import com.google.devtools.build.lib.syntax.Environment;
import com.google.devtools.build.lib.syntax.EvalException;
import com.google.devtools.build.lib.syntax.FuncallExpression;
import com.google.devtools.build.lib.syntax.FunctionSignature;
import com.google.devtools.build.lib.syntax.SkylarkType;
import javax.annotation.Nullable;
/**
* Implementation of {@link Provider} that is represented by a {@link BaseFunction}, and thus
* callable from Skylark.
*/
@Immutable
abstract class ProviderFromFunction extends BaseFunction implements Provider {
/**
* Constructs a provider.
*
* @param name provider name; should be null iff the subclass overrides {@link #getName}
* @param signature the signature for calling this provider as a Skylark function (to construct an
* instance of the provider)
* @param location the location of this provider's Skylark definition. Use {@link
* Location#BUILTIN} if it is a native provider.
*/
protected ProviderFromFunction(
@Nullable String name,
FunctionSignature.WithValues<Object, SkylarkType> signature,
Location location) {
super(name, signature, location);
}
public SkylarkProviderIdentifier id() {
return SkylarkProviderIdentifier.forKey(getKey());
}
@Override
protected Object call(Object[] args, @Nullable FuncallExpression ast, Environment env)
throws EvalException, InterruptedException {
Location loc = ast != null ? ast.getLocation() : Location.BUILTIN;
return createInstanceFromSkylark(args, env, loc);
}
/**
* Override this method to provide logic that is used to instantiate a declared provider from
* Skylark.
*
* <p>This is a method that is called when a constructor {@code c} is invoked as<br>
* {@code c(arg1 = val1, arg2 = val2, ...)}.
*
* @param args an array of argument values sorted as per the signature ({@see BaseFunction#call})
*/
protected abstract Info createInstanceFromSkylark(Object[] args, Environment env, Location loc)
throws EvalException;
}
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