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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.rules;
import static com.google.devtools.build.lib.packages.Attribute.attr;
import static com.google.devtools.build.lib.packages.BuildType.LABEL;
import static com.google.devtools.build.lib.packages.RuleClass.Builder.STARLARK_BUILD_SETTING_DEFAULT_ATTR_NAME;
import com.google.common.base.Preconditions;
import com.google.common.collect.ImmutableClassToInstanceMap;
import com.google.devtools.build.lib.actions.MutableActionGraph.ActionConflictException;
import com.google.devtools.build.lib.analysis.AliasProvider;
import com.google.devtools.build.lib.analysis.BaseRuleClasses;
import com.google.devtools.build.lib.analysis.BuildSettingProvider;
import com.google.devtools.build.lib.analysis.ConfiguredTarget;
import com.google.devtools.build.lib.analysis.RuleConfiguredTargetBuilder;
import com.google.devtools.build.lib.analysis.RuleConfiguredTargetFactory;
import com.google.devtools.build.lib.analysis.RuleContext;
import com.google.devtools.build.lib.analysis.RuleDefinition;
import com.google.devtools.build.lib.analysis.RuleDefinitionEnvironment;
import com.google.devtools.build.lib.analysis.Runfiles;
import com.google.devtools.build.lib.analysis.RunfilesProvider;
import com.google.devtools.build.lib.analysis.config.Fragment;
import com.google.devtools.build.lib.cmdline.Label;
import com.google.devtools.build.lib.packages.Attribute;
import com.google.devtools.build.lib.packages.Attribute.LabelLateBoundDefault;
import com.google.devtools.build.lib.packages.BuildSetting;
import com.google.devtools.build.lib.packages.RuleClass;
import java.util.function.Function;
/** Implements template for creating custom alias rules. */
public final class LateBoundAlias implements RuleConfiguredTargetFactory {
private static final String ATTRIBUTE_NAME = ":alias";
@Override
public ConfiguredTarget create(RuleContext ruleContext)
throws ActionConflictException, InterruptedException {
ConfiguredTarget actual = (ConfiguredTarget) ruleContext.getPrerequisite(ATTRIBUTE_NAME);
if (actual == null) {
return createEmptyConfiguredTarget(ruleContext);
}
if (!ruleContext.getRule().isBuildSetting()) {
return AliasConfiguredTarget.create(ruleContext, actual, ruleContext.getVisibility());
}
// This makes label_setting and label_flag work with select().
BuildSetting buildSetting = ruleContext.getRule().getRuleClassObject().getBuildSetting();
Object defaultValue =
ruleContext
.attributes()
.get(STARLARK_BUILD_SETTING_DEFAULT_ATTR_NAME, buildSetting.getType());
return AliasConfiguredTarget.createWithOverrides(
ruleContext,
actual,
ruleContext.getVisibility(),
ImmutableClassToInstanceMap.of(
BuildSettingProvider.class,
new BuildSettingProvider(buildSetting, defaultValue, ruleContext.getLabel())));
}
private static ConfiguredTarget createEmptyConfiguredTarget(RuleContext ruleContext)
throws ActionConflictException, InterruptedException {
return new RuleConfiguredTargetBuilder(ruleContext)
.addProvider(RunfilesProvider.class, RunfilesProvider.simple(Runfiles.EMPTY))
.build();
}
/** Rule definition for custom alias rules. */
public abstract static class CommonAliasRule<FragmentT extends Fragment>
extends AbstractAliasRule {
private static final String ATTRIBUTE_NAME = ":alias";
private final Function<RuleDefinitionEnvironment, LabelLateBoundDefault<FragmentT>>
labelResolver;
private final Class<FragmentT> fragmentClass;
protected CommonAliasRule(
String ruleName,
Function<RuleDefinitionEnvironment, LabelLateBoundDefault<FragmentT>> labelResolver,
Class<FragmentT> fragmentClass) {
super(ruleName);
this.labelResolver = Preconditions.checkNotNull(labelResolver);
this.fragmentClass = Preconditions.checkNotNull(fragmentClass);
}
protected Attribute.Builder<Label> makeAttribute(RuleDefinitionEnvironment environment) {
return attr(ATTRIBUTE_NAME, LABEL).value(labelResolver.apply(environment));
}
@Override
public RuleClass build(RuleClass.Builder builder, RuleDefinitionEnvironment environment) {
Attribute attribute = makeAttribute(environment).build();
Preconditions.checkArgument(attribute.getName().equals(ATTRIBUTE_NAME));
Preconditions.checkArgument(attribute.getType().equals(LABEL));
return builder
.requiresConfigurationFragments(fragmentClass)
.removeAttribute("licenses")
.removeAttribute("distribs")
.advertiseProvider(AliasProvider.class)
.addAttribute(attribute)
.build();
}
}
abstract static class AbstractAliasRule implements RuleDefinition {
private final String ruleName;
AbstractAliasRule(String ruleName) {
this.ruleName = Preconditions.checkNotNull(ruleName);
}
@Override
public final Metadata getMetadata() {
return Metadata.builder()
.name(ruleName)
.ancestors(BaseRuleClasses.NativeBuildRule.class)
.factoryClass(LateBoundAlias.class)
.build();
}
}
}