PassRunner.java

/*
 * Copyright 2011 Google Inc.
 *
 * 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.common.css.compiler.passes;

import com.google.common.base.Predicates;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.ImmutableSet;
import com.google.common.css.JobDescription;
import com.google.common.css.PrefixingSubstitutionMap;
import com.google.common.css.RecordingSubstitutionMap;
import com.google.common.css.SubstitutionMap;
import com.google.common.css.compiler.ast.CssCompilerPass;
import com.google.common.css.compiler.ast.CssTree;
import com.google.common.css.compiler.ast.ErrorManager;
import com.google.common.css.compiler.ast.GssFunction;

import java.util.Map;

import javax.annotation.Nullable;

/**
 * {@link PassRunner} runs applies a sequence of {@link CssCompilerPass}es to a
 * {@link CssTree}.
 *
 * @author bolinfest@google.com (Michael Bolin)
 */
public class PassRunner {

  private static final ImmutableMap<String, GssFunction>
      EMPTY_GSS_FUNCTION_MAP = ImmutableMap.of();

  private final JobDescription job;
  private final ErrorManager errorManager;
  private final RecordingSubstitutionMap recordingSubstitutionMap;

  public PassRunner(JobDescription job, ErrorManager errorManager) {
    this(job, errorManager, createSubstitutionMap(job));
  }

  public PassRunner(JobDescription job, ErrorManager errorManager,
      RecordingSubstitutionMap recordingSubstitutionMap) {
    this.job = job;
    this.errorManager = errorManager;
    this.recordingSubstitutionMap = recordingSubstitutionMap;
  }

  /**
   * Runs the passes on the specified {@link CssTree}. This method may be
   * invoked multiple times, as one compilation job may have one {@link CssTree}
   * per input file.
   */
  public void runPasses(CssTree cssTree) {
    new CheckDependencyNodes(cssTree.getMutatingVisitController(),
        errorManager, job.suppressDependencyCheck).runPass();
    new CreateStandardAtRuleNodes(cssTree.getMutatingVisitController(),
        errorManager).runPass();
    new CreateMixins(cssTree.getMutatingVisitController(),
        errorManager).runPass();
    new CreateDefinitionNodes(cssTree.getMutatingVisitController(),
        errorManager).runPass();
    new CreateConstantReferences(cssTree.getMutatingVisitController())
        .runPass();
    new CreateConditionalNodes(cssTree.getMutatingVisitController(),
        errorManager).runPass();
    new CreateForLoopNodes(cssTree.getMutatingVisitController(),
        errorManager).runPass();
    new CreateComponentNodes(cssTree.getMutatingVisitController(),
        errorManager).runPass();
    new ValidatePropertyValues(cssTree.getVisitController(), errorManager).runPass();

    new HandleUnknownAtRuleNodes(cssTree.getMutatingVisitController(),
        errorManager, job.allowedAtRules,
        true /* report */, false /* remove */).runPass();
    new ProcessKeyframes(cssTree.getMutatingVisitController(),
        errorManager, job.allowKeyframes || job.allowWebkitKeyframes,
        job.simplifyCss).runPass();
    new CreateVendorPrefixedKeyframes(cssTree.getMutatingVisitController(),
        errorManager).runPass();
    new EvaluateCompileConstants(cssTree.getMutatingVisitController(),
        job.compileConstants).runPass();
    new UnrollLoops(cssTree.getMutatingVisitController(), errorManager).runPass();
    new ProcessRefiners(cssTree.getMutatingVisitController(), errorManager,
        job.simplifyCss).runPass();

    // Eliminate conditional nodes.
    new EliminateConditionalNodes(
        cssTree.getMutatingVisitController(),
        ImmutableSet.copyOf(job.trueConditionNames)).runPass();

    // Collect mixin definitions and replace mixins
    CollectMixinDefinitions collectMixinDefinitions =
        new CollectMixinDefinitions(cssTree.getMutatingVisitController(),
            errorManager);
    collectMixinDefinitions.runPass();
    new ReplaceMixins(cssTree.getMutatingVisitController(), errorManager,
        collectMixinDefinitions.getDefinitions()).runPass();

    new ProcessComponents<Object>(cssTree.getMutatingVisitController(),
        errorManager).runPass();
    // Collect constant definitions.
    CollectConstantDefinitions collectConstantDefinitionsPass =
        new CollectConstantDefinitions(cssTree);
    collectConstantDefinitionsPass.runPass();
    // Replace constant references.
    ReplaceConstantReferences replaceConstantReferences =
        new ReplaceConstantReferences(cssTree,
            collectConstantDefinitionsPass.getConstantDefinitions(),
            true /* removeDefs */, errorManager, job.allowUndefinedConstants);
    replaceConstantReferences.runPass();

    Map<String, GssFunction> gssFunctionMap = getGssFunctionMap();
    new ResolveCustomFunctionNodes(
        cssTree.getMutatingVisitController(), errorManager,
        gssFunctionMap, job.allowUnrecognizedFunctions,
        job.allowedNonStandardFunctions)
        .runPass();

    if (job.simplifyCss) {
      // Eliminate empty rules.
      new EliminateEmptyRulesetNodes(cssTree.getMutatingVisitController())
          .runPass();
      // Eliminating units for zero values.
      new EliminateUnitsFromZeroNumericValues(
          cssTree.getMutatingVisitController()).runPass();
      // Optimize color values.
      new ColorValueOptimizer(
          cssTree.getMutatingVisitController()).runPass();
      // Compress redundant top-right-bottom-left value lists.
      new AbbreviatePositionalValues(
          cssTree.getMutatingVisitController()).runPass();
    }
    if (job.eliminateDeadStyles) {
      // Report errors for duplicate declarations
      new DisallowDuplicateDeclarations(
          cssTree.getVisitController(), errorManager).runPass();
      // Split rules by selector and declaration.
      new SplitRulesetNodes(cssTree.getMutatingVisitController()).runPass();
      // Dead code elimination.
      new MarkRemovableRulesetNodes(cssTree).runPass();
      new EliminateUselessRulesetNodes(cssTree).runPass();
      // Merge of rules with same selector.
      new MergeAdjacentRulesetNodesWithSameSelector(cssTree).runPass();
      new EliminateUselessRulesetNodes(cssTree).runPass();
      // Merge of rules with same styles.
      new MergeAdjacentRulesetNodesWithSameDeclarations(cssTree).runPass();
      new EliminateUselessRulesetNodes(cssTree).runPass();
    }
    // Perform BiDi flipping if required.
    if (job.needsBiDiFlipping()) {
      new MarkNonFlippableNodes(cssTree.getVisitController(),
          errorManager).runPass();
      new BiDiFlipper(cssTree.getMutatingVisitController(),
                        job.swapLtrRtlInUrl, job.swapLeftRightInUrl).runPass();
    }
    // If specified, remove all vendor-specific properties except for the
    // whitelisted vendor.
    if (job.vendor != null) {
      new RemoveVendorSpecificProperties(job.vendor,
          cssTree.getMutatingVisitController()).runPass();
    }
    // Unless all unrecognized properties are allowed, check for unrecognized
    // properties.
    if (!job.allowUnrecognizedProperties) {
      new VerifyRecognizedProperties(job.allowedUnrecognizedProperties,
          cssTree.getVisitController(), errorManager).runPass();
    }
    // Rename class names
    if (recordingSubstitutionMap != null) {
      new CssClassRenaming(
          cssTree.getMutatingVisitController(),
          recordingSubstitutionMap, null).runPass();
    }
  }

  @Nullable public RecordingSubstitutionMap getRecordingSubstitutionMap() {
    return recordingSubstitutionMap;
  }

  /**
   * Creates the CSS class substitution map from the provider, if any.
   * Wraps it in a substitution map that optionally prefixes all of the renamed
   * classes. Additionaly wraps in a recording substituion map which excludes a
   * blacklist of classnames and allows the map to produced as an output.
   */
  private static RecordingSubstitutionMap createSubstitutionMap(
      JobDescription job) {
    if (job.cssSubstitutionMapProvider != null) {
      SubstitutionMap baseMap = job.cssSubstitutionMapProvider.get();
      if (baseMap != null) {
        SubstitutionMap map = baseMap;
        if (!job.cssRenamingPrefix.isEmpty()) {
          map = new PrefixingSubstitutionMap(baseMap, job.cssRenamingPrefix);
        }
        return new RecordingSubstitutionMap(map,
            Predicates.not(Predicates.in(job.excludedClassesFromRenaming)));
      }
    }
    return null;
  }

  /**
   * Gets the GSS function map from the provider, if any.
   *
   * @return the provided map or an empty map if none is provided
   */
  private Map<String, GssFunction> getGssFunctionMap() {
    if (job.gssFunctionMapProvider == null) {
      return EMPTY_GSS_FUNCTION_MAP;
    }

    Map<String, GssFunction> map =
        job.gssFunctionMapProvider.get(GssFunction.class);
    if (map == null) {
      return EMPTY_GSS_FUNCTION_MAP;
    }

    return map;
  }
}