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// Copyright 2017 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.EvalException;
import com.google.devtools.build.lib.syntax.FunctionSignature;
import com.google.devtools.build.lib.syntax.SkylarkType;
import com.google.devtools.build.lib.util.Pair;
import java.util.Map;
import javax.annotation.Nullable;
/**
* Base class for declared providers {@see Provider} defined in native code.
*
* <p>Every non-abstract derived class of {@link NativeProvider} corresponds to a single declared
* provider. This is enforced by final {@link #equals(Object)} and {@link #hashCode()}.
*
* <p>Typical implementation of a non-constructable from Skylark declared provider is as follows:
*
* <pre>
* public static final Provider CC_LINK_PARAMS =
* new NativeProvider("link_params") { };
* </pre>
*
* To allow construction from Skylark and custom construction logic, override {@link
* #createInstanceFromSkylark(Object[], Location)} (see {@link #STRUCT} for an example.
*/
@Immutable
public abstract class NativeProvider<VALUE extends Info> extends Provider {
private final NativeKey key;
private final String errorMessageForInstances;
/** "struct" function. */
public static final StructConstructor STRUCT = new StructConstructor();
private final Class<VALUE> valueClass;
public Class<VALUE> getValueClass() {
return valueClass;
}
/**
* Implement this to mark that a native provider should be exported with certain name to Skylark.
* Broken: only works for rules, not for aspects. DO NOT USE FOR NEW CODE!
*
* <p>Use native declared providers mechanism exclusively to expose providers to both native and
* Skylark code.
*/
@Deprecated
public static interface WithLegacySkylarkName {
String getSkylarkName();
}
/**
* A constructor for default {@code struct}s.
*
* <p>Singleton, instance is {@link #STRUCT}.
*/
public static final class StructConstructor extends NativeProvider<Info> {
private StructConstructor() {
super(Info.class, "struct");
}
@Override
protected Info createInstanceFromSkylark(Object[] args, Location loc) {
@SuppressWarnings("unchecked")
Map<String, Object> kwargs = (Map<String, Object>) args[0];
return new Info(this, kwargs, loc);
}
public Info create(Map<String, Object> values, String message) {
return new Info(this, values, message);
}
public Info create(Location loc) {
return new Info(this, loc);
}
}
private static final FunctionSignature.WithValues<Object, SkylarkType> SIGNATURE =
FunctionSignature.WithValues.create(FunctionSignature.KWARGS);
protected NativeProvider(Class<VALUE> clazz, String name) {
this(clazz, name, SIGNATURE);
}
protected NativeProvider(
Class<VALUE> valueClass,
String name,
FunctionSignature.WithValues<Object, SkylarkType> signature) {
super(name, signature, Location.BUILTIN);
key = new NativeKey(name, getClass());
this.valueClass = valueClass;
errorMessageForInstances = String.format("'%s' object has no attribute '%%s'", name);
}
/**
* equals() implements singleton class semantics.
*
* <p>Every non-abstract derived class of {@link NativeProvider} corresponds to a single declared
* provider.
*/
@Override
public final boolean equals(@Nullable Object other) {
return other != null && this.getClass().equals(other.getClass());
}
/**
* hashCode() implements singleton class semantics.
*
* <p>Every non-abstract derived class of {@link NativeProvider} corresponds to a single declared
* provider.
*/
@Override
public final int hashCode() {
return getClass().hashCode();
}
@Override
public String getPrintableName() {
return getName();
}
@Override
public String getErrorMessageFormatForInstances() {
return errorMessageForInstances;
}
@Override
public boolean isExported() {
return true;
}
@Override
public NativeKey getKey() {
return key;
}
@Override
protected Info createInstanceFromSkylark(Object[] args, Location loc) throws EvalException {
throw new EvalException(
loc, String.format("'%s' cannot be constructed from Skylark", getPrintableName()));
}
public static Pair<String, String> getSerializedRepresentationForNativeKey(NativeKey key) {
return Pair.of(key.name, key.aClass.getName());
}
public static NativeKey getNativeKeyFromSerializedRepresentation(Pair<String, String> serialized)
throws ClassNotFoundException {
Class<? extends NativeProvider> aClass =
Class.forName(serialized.second).asSubclass(NativeProvider.class);
return new NativeKey(serialized.first, aClass);
}
/**
* A serializable representation of {@link NativeProvider}.
*
* <p>Just a wrapper around its class.
*/
// todo(vladmos,dslomov): when we allow declared providers in `requiredProviders`,
// we will need to serialize this somehow.
@Immutable
public static final class NativeKey extends Key {
private final String name;
private final Class<? extends NativeProvider> aClass;
private NativeKey(String name, Class<? extends NativeProvider> aClass) {
this.name = name;
this.aClass = aClass;
}
@Override
public int hashCode() {
return aClass.hashCode();
}
@Override
public boolean equals(Object obj) {
return obj instanceof NativeKey && aClass.equals(((NativeKey) obj).aClass);
}
@Override
public String toString() {
return name;
}
}
}
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