| // 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.common.collect.ImmutableMap; |
| 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 PROVIDER = |
| * 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 SkylarkInfo(this, kwargs, loc); |
| } |
| |
| public Info create(Map<String, Object> values, String message) { |
| return new SkylarkInfo(this, values, message); |
| } |
| |
| public Info create(Location loc) { |
| return new SkylarkInfo(this, ImmutableMap.of(), 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. |
| */ |
| @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; |
| } |
| } |
| } |