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// Copyright 2016 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.ANY_RULE;
import static com.google.devtools.build.lib.packages.Attribute.attr;
import static com.google.devtools.build.lib.packages.BuildType.LABEL;
import com.google.common.collect.ImmutableMap;
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.ConfiguredTarget;
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.VisibilityProvider;
import com.google.devtools.build.lib.analysis.VisibilityProviderImpl;
import com.google.devtools.build.lib.analysis.configuredtargets.RuleConfiguredTarget.Mode;
import com.google.devtools.build.lib.packages.RuleClass;
import com.google.devtools.build.lib.util.FileTypeSet;
/**
* Implementation of the <code>alias</code> rule.
*/
public class Alias implements RuleConfiguredTargetFactory {
@Override
public ConfiguredTarget create(RuleContext ruleContext)
throws InterruptedException, RuleErrorException, ActionConflictException {
ConfiguredTarget actual = (ConfiguredTarget) ruleContext.getPrerequisite("actual", Mode.TARGET);
return new AliasConfiguredTarget(
ruleContext,
actual,
ImmutableMap.of(
AliasProvider.class,
AliasProvider.fromAliasRule(ruleContext.getLabel(), actual),
VisibilityProvider.class,
new VisibilityProviderImpl(ruleContext.getVisibility())));
}
/**
* Rule definition.
*/
public static class AliasRule implements RuleDefinition {
@Override
public RuleClass build(RuleClass.Builder builder, RuleDefinitionEnvironment environment) {
return builder
/*<!-- #BLAZE_RULE(alias).ATTRIBUTE(actual) -->
The target this alias refers to. It does not need to be a rule, it can also be an input
file.
<!-- #END_BLAZE_RULE.ATTRIBUTE -->*/
.removeAttribute("licenses")
.removeAttribute("distribs")
.add(
attr("actual", LABEL)
.allowedFileTypes(FileTypeSet.ANY_FILE)
.allowedRuleClasses(ANY_RULE)
.mandatory())
.canHaveAnyProvider()
// Aliases themselves do not need toolchains or an execution platform, so this is fine.
// The actual target
// will resolve platforms and toolchains with no issues regardless of this setting.
.supportsPlatforms(false)
.build();
}
@Override
public Metadata getMetadata() {
return Metadata.builder()
.name("alias")
.factoryClass(Alias.class)
.ancestors(BaseRuleClasses.BaseRule.class)
.build();
}
}
}
/*<!-- #BLAZE_RULE (NAME = alias, TYPE = OTHER, FAMILY = General)[GENERIC_RULE] -->
<p>
The <code>alias</code> rule creates another name a rule can be referred to as.
</p>
<p>
Aliasing only works for "regular" targets. In particular, <code>package_group</code>,
<code>config_setting</code> and <code>test_suite</code> rules cannot be aliased.
</p>
<p>
The alias rule has its own visibility declaration. In all other respects, it behaves
like the rule it references with some minor exceptions:
<ul>
<li>
Tests are not run if their alias is mentioned on the command line
</li>
<li>
When defining environment groups, the aliases to <code>environment</code> rules are not
supported. They are not supported in the <code>--target_environment</code> command line
option, either.
</li>
</ul>
</p>
<h4 id="alias_example">Examples</h4>
<pre class="code">
filegroup(
name = "data",
srcs = ["data.txt"],
)
alias(
name = "other",
actual = ":data",
)
</pre>
<!-- #END_BLAZE_RULE -->*/
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