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// Copyright 2015 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.skyframe;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.Iterables;
import com.google.devtools.build.lib.cmdline.Label;
import com.google.devtools.build.lib.events.Event;
import com.google.devtools.build.lib.packages.SkylarkAspect;
import com.google.devtools.build.lib.skyframe.AspectFunction.AspectCreationException;
import com.google.devtools.build.lib.skyframe.AspectValue.SkylarkAspectLoadingKey;
import com.google.devtools.build.lib.skyframe.SkylarkImportLookupFunction.SkylarkImportFailedException;
import com.google.devtools.build.lib.syntax.SkylarkImport;
import com.google.devtools.build.skyframe.SkyFunction;
import com.google.devtools.build.skyframe.SkyFunctionException;
import com.google.devtools.build.skyframe.SkyKey;
import com.google.devtools.build.skyframe.SkyValue;
import javax.annotation.Nullable;
/**
* SkyFunction to load aspects from Skylark extensions and calculate their values.
*
* Used for loading top-level aspects. At top level, in
* {@link com.google.devtools.build.lib.analysis.BuildView}, we cannot invoke two SkyFunctions
* one after another, so BuildView calls this function to do the work.
*/
public class ToplevelSkylarkAspectFunction implements SkyFunction {
@Nullable private final SkylarkImportLookupFunction skylarkImportLookupFunctionForInlining;
ToplevelSkylarkAspectFunction(
@Nullable SkylarkImportLookupFunction skylarkImportLookupFunctionForInlining) {
this.skylarkImportLookupFunctionForInlining = skylarkImportLookupFunctionForInlining;
}
@Nullable
@Override
public SkyValue compute(SkyKey skyKey, Environment env)
throws LoadSkylarkAspectFunctionException, InterruptedException {
SkylarkAspectLoadingKey aspectLoadingKey = (SkylarkAspectLoadingKey) skyKey.argument();
String skylarkValueName = aspectLoadingKey.getSkylarkValueName();
SkylarkImport extensionFile = aspectLoadingKey.getSkylarkImport();
// Find label corresponding to skylark file, if one exists.
ImmutableMap<String, Label> labelLookupMap;
try {
labelLookupMap =
SkylarkImportLookupFunction.findLabelsForLoadStatements(
ImmutableList.of(extensionFile),
Label.parseAbsoluteUnchecked("//:empty"),
env
);
} catch (SkylarkImportFailedException e) {
env.getListener().handle(Event.error(e.getMessage()));
throw new LoadSkylarkAspectFunctionException(
new AspectCreationException(e.getMessage()));
}
if (labelLookupMap == null) {
return null;
}
SkylarkAspect skylarkAspect;
Label extensionFileLabel = Iterables.getOnlyElement(labelLookupMap.values());
try {
skylarkAspect =
AspectFunction.loadSkylarkAspect(
env, extensionFileLabel, skylarkValueName, skylarkImportLookupFunctionForInlining);
if (skylarkAspect == null) {
return null;
}
if (!skylarkAspect.getParamAttributes().isEmpty()) {
throw new AspectCreationException("Cannot instantiate parameterized aspect "
+ skylarkAspect.getName() + " at the top level.", extensionFileLabel);
}
} catch (AspectCreationException e) {
throw new LoadSkylarkAspectFunctionException(e);
}
SkyKey aspectKey = aspectLoadingKey.toAspectKey(skylarkAspect.getAspectClass());
return env.getValue(aspectKey);
}
@Nullable
@Override
public String extractTag(SkyKey skyKey) {
return null;
}
/**
* Exceptions thrown from ToplevelSkylarkAspectFunction.
*/
public class LoadSkylarkAspectFunctionException extends SkyFunctionException {
public LoadSkylarkAspectFunctionException(AspectCreationException cause) {
super(cause, Transience.PERSISTENT);
}
}
}
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