SkylarkAspectFactory.java example

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// Copyright 2014 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.devtools.build.lib.analysis.AnalysisEnvironment;
import com.google.devtools.build.lib.analysis.ConfiguredAspect;
import com.google.devtools.build.lib.analysis.ConfiguredAspectFactory;
import com.google.devtools.build.lib.analysis.ConfiguredTarget;
import com.google.devtools.build.lib.analysis.RuleContext;
import com.google.devtools.build.lib.analysis.SkylarkProviderValidationUtil;
import com.google.devtools.build.lib.events.Location;
import com.google.devtools.build.lib.packages.AspectDescriptor;
import com.google.devtools.build.lib.packages.AspectParameters;
import com.google.devtools.build.lib.packages.SkylarkAspect;
import com.google.devtools.build.lib.packages.SkylarkClassObject;
import com.google.devtools.build.lib.rules.SkylarkRuleConfiguredTargetBuilder;
import com.google.devtools.build.lib.rules.SkylarkRuleContext;
import com.google.devtools.build.lib.skylarkinterface.SkylarkValue;
import com.google.devtools.build.lib.syntax.Environment;
import com.google.devtools.build.lib.syntax.EvalException;
import com.google.devtools.build.lib.syntax.EvalExceptionWithStackTrace;
import com.google.devtools.build.lib.syntax.EvalUtils;
import com.google.devtools.build.lib.syntax.Mutability;
import com.google.devtools.build.lib.syntax.SkylarkType;
import java.util.Map;

/**
 * A factory for aspects that are defined in Skylark.
 */
public class SkylarkAspectFactory implements ConfiguredAspectFactory {

  private final SkylarkAspect skylarkAspect;

  public SkylarkAspectFactory(SkylarkAspect skylarkAspect) {
    this.skylarkAspect = skylarkAspect;
  }

  @Override
  public ConfiguredAspect create(
      ConfiguredTarget base, RuleContext ruleContext, AspectParameters parameters)
      throws InterruptedException {
    SkylarkRuleContext skylarkRuleContext = null;
    try (Mutability mutability = Mutability.create("aspect")) {
      AspectDescriptor aspectDescriptor = new AspectDescriptor(
          skylarkAspect.getAspectClass(), parameters);
      try {
        skylarkRuleContext = new SkylarkRuleContext(ruleContext, aspectDescriptor);
      } catch (EvalException e) {
        ruleContext.ruleError(e.getMessage());
        return null;
      }
      AnalysisEnvironment analysisEnv = ruleContext.getAnalysisEnvironment();
      Environment env =
          Environment.builder(mutability)
              .setGlobals(skylarkAspect.getFuncallEnv().getGlobals())
              .setSemantics(analysisEnv.getSkylarkSemantics())
              .setEventHandler(analysisEnv.getEventHandler())
              .build(); // NB: loading phase functions are not available: this is analysis already,
      // so we do *not* setLoadingPhase().
      Object aspectSkylarkObject;
      try {
        aspectSkylarkObject =
            skylarkAspect
                .getImplementation()
                .call(
                    ImmutableList.<Object>of(base, skylarkRuleContext),
                    ImmutableMap.<String, Object>of(),
                    /*ast=*/ null,
                    env);

        if (ruleContext.hasErrors()) {
          return null;
        } else if (!(aspectSkylarkObject instanceof SkylarkClassObject)
            && !(aspectSkylarkObject instanceof Iterable)) {
          ruleContext.ruleError(
              String.format(
                  "Aspect implementation should return a struct or a list, but got %s",
                  SkylarkType.typeOf(aspectSkylarkObject)));
          return null;
        }
        return createAspect(aspectSkylarkObject, aspectDescriptor, ruleContext);
      } catch (EvalException e) {
        addAspectToStackTrace(base, e);
        ruleContext.ruleError("\n" + e.print());
        return null;
      }
    } finally {
       if (skylarkRuleContext != null) {
         skylarkRuleContext.nullify();
       }
    }
  }

  private ConfiguredAspect createAspect(
      Object aspectSkylarkObject, AspectDescriptor aspectDescriptor, RuleContext ruleContext)
      throws EvalException {

    ConfiguredAspect.Builder builder = new ConfiguredAspect.Builder(aspectDescriptor, ruleContext);

    if (aspectSkylarkObject instanceof Iterable) {
      addDeclaredProviders(builder, (Iterable) aspectSkylarkObject);
    } else {
      SkylarkClassObject struct = (SkylarkClassObject) aspectSkylarkObject;
      Location loc = struct.getCreationLoc();
      for (String key : struct.getKeys()) {
        if (key.equals("output_groups")) {
          addOutputGroups(struct.getValue(key), loc, builder);
        } else if (key.equals("providers")) {
          Object value = struct.getValue(key);
          Iterable providers =
              SkylarkType.cast(
                  value,
                  Iterable.class,
                  loc,
                  "The value for \"providers\" should be a list of declared providers, "
                      + "got %s instead",
                  EvalUtils.getDataTypeName(value, false));
          addDeclaredProviders(builder, providers);
        } else {
          builder.addSkylarkTransitiveInfo(key, struct.getValue(key), loc);
        }
      }
    }

    ConfiguredAspect configuredAspect = builder.build();
    SkylarkProviderValidationUtil.checkOrphanArtifacts(ruleContext);
    return configuredAspect;
  }

  private void addDeclaredProviders(ConfiguredAspect.Builder builder, Iterable aspectSkylarkObject)
      throws EvalException {
    for (Object o : aspectSkylarkObject) {
      Location loc = skylarkAspect.getImplementation().getLocation();
      SkylarkClassObject declaredProvider =
          SkylarkType.cast(
              o,
              SkylarkClassObject.class,
              loc,
              "A return value of an aspect implementation function should be "
                  + "a sequence of declared providers");
      Location creationLoc = declaredProvider.getCreationLocOrNull();
      builder.addSkylarkDeclaredProvider(declaredProvider, creationLoc != null ? creationLoc : loc);
    }
  }

  private static void addOutputGroups(Object value, Location loc,
      ConfiguredAspect.Builder builder)
      throws EvalException {
    Map<String, SkylarkValue> outputGroups =
        SkylarkType.castMap(value, String.class, SkylarkValue.class, "output_groups");

    for (String outputGroup : outputGroups.keySet()) {
      SkylarkValue objects = outputGroups.get(outputGroup);

      builder.addOutputGroup(outputGroup,
          SkylarkRuleConfiguredTargetBuilder.convertToOutputGroupValue(loc, outputGroup, objects));
    }
  }

  private void addAspectToStackTrace(ConfiguredTarget base, EvalException e) {
    if (e instanceof EvalExceptionWithStackTrace) {
      ((EvalExceptionWithStackTrace) e)
          .registerPhantomFuncall(
              String.format("%s(...)", skylarkAspect.getName()),
              base.getTarget().getAssociatedRule().getLocation(),
              skylarkAspect.getImplementation());
    }
  }
}