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Closure Compiler is a JavaScript optimizing compiler. It parses your JavaScript, analyzes it, removes dead code and rewrites and minimizes what's left. It also checks syntax, variable references, and types, and warns about common JavaScript pitfalls. It is used in many of Google's JavaScript apps, including Gmail, Google Web Search, Google Maps, and Google Docs. This binary checks for style issues such as incorrect or missing JSDoc usage, and missing goog.require() statements. It does not do more advanced checks such as typechecking.
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/*
 * Copyright 2016 The Closure Compiler Authors.
 *
 * 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.javascript.jscomp;

import com.google.common.base.Preconditions;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableSet;
import com.google.javascript.jscomp.GlobalNamespace.Name;
import com.google.javascript.jscomp.GlobalNamespace.Ref;
import com.google.javascript.jscomp.PolymerPass.MemberDefinition;
import com.google.javascript.jscomp.parsing.parser.FeatureSet;
import com.google.javascript.rhino.JSDocInfo;
import com.google.javascript.rhino.Node;
import java.util.List;

/**
 * Helpers to extract behaviors from Polymer element declarations.
 */
final class PolymerBehaviorExtractor {

  private static final ImmutableSet BEHAVIOR_NAMES_NOT_TO_COPY = ImmutableSet.of(
        "created", "attached", "detached", "attributeChanged", "configure", "ready",
        "properties", "listeners", "observers", "hostAttributes");

  private final AbstractCompiler compiler;
  private final GlobalNamespace globalNames;

  PolymerBehaviorExtractor(AbstractCompiler compiler, GlobalNamespace globalNames) {
    this.compiler = compiler;
    this.globalNames = globalNames;
  }

  /**
   * Extracts all Behaviors from an array literal, recursively. Entries in the array can be
   * object literals or array literals (of other behaviors). Behavior names must be
   * global, fully qualified names.
   * @see https://github.com/Polymer/polymer/blob/0.8-preview/PRIMER.md#behaviors
   * @return A list of all {@code BehaviorDefinitions} in the array.
   */
  ImmutableList extractBehaviors(Node behaviorArray) {
    if (behaviorArray == null) {
      return ImmutableList.of();
    }

    if (!behaviorArray.isArrayLit()) {
      compiler.report(
          JSError.make(behaviorArray, PolymerPassErrors.POLYMER_INVALID_BEHAVIOR_ARRAY));
      return ImmutableList.of();
    }

    ImmutableList.Builder behaviors = ImmutableList.builder();
    for (Node behaviorName : behaviorArray.children()) {
      if (behaviorName.isObjectLit()) {
        PolymerPassStaticUtils.switchDollarSignPropsToBrackets(behaviorName, compiler);
        PolymerPassStaticUtils.quoteListenerAndHostAttributeKeys(behaviorName);
        behaviors.add(
            new BehaviorDefinition(
                PolymerPassStaticUtils.extractProperties(behaviorName, compiler),
                getBehaviorFunctionsToCopy(behaviorName),
                getNonPropertyMembersToCopy(behaviorName),
                !NodeUtil.isInFunction(behaviorName),
                (FeatureSet) NodeUtil.getEnclosingScript(behaviorName).getProp(Node.FEATURE_SET)));
        continue;
      }

      Name behaviorGlobalName = globalNames.getSlot(behaviorName.getQualifiedName());
      boolean isGlobalDeclaration = true;
      if (behaviorGlobalName == null) {
        compiler.report(JSError.make(behaviorName, PolymerPassErrors.POLYMER_UNQUALIFIED_BEHAVIOR));
        continue;
      }

      Ref behaviorDeclaration = behaviorGlobalName.getDeclaration();

      // Use any set as a backup declaration, even if it's local.
      if (behaviorDeclaration == null) {
        List behaviorRefs = behaviorGlobalName.getRefs();
        for (Ref ref : behaviorRefs) {
          if (ref.isSet()) {
            isGlobalDeclaration = false;
            behaviorDeclaration = ref;
            break;
          }
        }
      }

      if (behaviorDeclaration == null) {
        compiler.report(JSError.make(behaviorName, PolymerPassErrors.POLYMER_UNQUALIFIED_BEHAVIOR));
        continue;
      }

      Node behaviorDeclarationNode = behaviorDeclaration.getNode();
      JSDocInfo behaviorInfo = NodeUtil.getBestJSDocInfo(behaviorDeclarationNode);
      if (behaviorInfo == null || !behaviorInfo.isPolymerBehavior()) {
        compiler.report(
            JSError.make(behaviorDeclarationNode, PolymerPassErrors.POLYMER_UNANNOTATED_BEHAVIOR));
      }

      Node behaviorValue = NodeUtil.getRValueOfLValue(behaviorDeclarationNode);

      if (behaviorValue == null) {
        compiler.report(JSError.make(behaviorName, PolymerPassErrors.POLYMER_UNQUALIFIED_BEHAVIOR));
      } else if (behaviorValue.isArrayLit()) {
        // Individual behaviors can also be arrays of behaviors. Parse them recursively.
        behaviors.addAll(extractBehaviors(behaviorValue));
      } else if (behaviorValue.isObjectLit()) {
        PolymerPassStaticUtils.switchDollarSignPropsToBrackets(behaviorValue, compiler);
        PolymerPassStaticUtils.quoteListenerAndHostAttributeKeys(behaviorValue);
        behaviors.add(
            new BehaviorDefinition(
                PolymerPassStaticUtils.extractProperties(behaviorValue, compiler),
                getBehaviorFunctionsToCopy(behaviorValue),
                getNonPropertyMembersToCopy(behaviorValue),
                isGlobalDeclaration,
                (FeatureSet) NodeUtil.getEnclosingScript(behaviorValue).getProp(Node.FEATURE_SET)));
      } else {
        compiler.report(JSError.make(behaviorName, PolymerPassErrors.POLYMER_UNQUALIFIED_BEHAVIOR));
      }
    }

    return behaviors.build();
  }

  /**
   * @return A list of functions from a behavior which should be copied to the element prototype.
   */
  private static ImmutableList getBehaviorFunctionsToCopy(Node behaviorObjLit) {
    Preconditions.checkState(behaviorObjLit.isObjectLit());
    ImmutableList.Builder functionsToCopy = ImmutableList.builder();

    for (Node keyNode : behaviorObjLit.children()) {
      boolean isFunctionDefinition = (keyNode.isStringKey() && keyNode.getFirstChild().isFunction())
          || keyNode.isMemberFunctionDef();
      if (isFunctionDefinition && !BEHAVIOR_NAMES_NOT_TO_COPY.contains(keyNode.getString())) {
        functionsToCopy.add(new MemberDefinition(NodeUtil.getBestJSDocInfo(keyNode), keyNode,
          keyNode.getFirstChild()));
      }
    }

    return functionsToCopy.build();
  }

  /**
   * @return A list of MemberDefinitions in a behavior which are not in the properties block, but
   *     should still be copied to the element prototype.
   */
  private static ImmutableList getNonPropertyMembersToCopy(Node behaviorObjLit) {
    Preconditions.checkState(behaviorObjLit.isObjectLit());
    ImmutableList.Builder membersToCopy = ImmutableList.builder();

    for (Node keyNode : behaviorObjLit.children()) {
      boolean isNonFunctionMember = keyNode.isGetterDef()
          || (keyNode.isStringKey() && !keyNode.getFirstChild().isFunction());
      if (isNonFunctionMember && !BEHAVIOR_NAMES_NOT_TO_COPY.contains(keyNode.getString())) {
        membersToCopy.add(new MemberDefinition(NodeUtil.getBestJSDocInfo(keyNode), keyNode,
          keyNode.getFirstChild()));
      }
    }

    return membersToCopy.build();
  }

  /**
   * Parsed definition of a Polymer Behavior. Includes members which should be copied to elements
   * which use the behavior.
   */
  static final class BehaviorDefinition {
    /**
     * Properties declared in the behavior 'properties' block.
     */
    final List props;

    /**
     * Functions intended to be copied to elements which use this Behavior.
     */
    final List functionsToCopy;

    /**
     * Other members intended to be copied to elements which use this Behavior.
     */
    final List nonPropertyMembersToCopy;

    /**
     * Whether this Behvaior is declared in the global scope.
     */
    final boolean isGlobalDeclaration;

    /**
     * Language features to carry over to the extraction destination.
     */
    final FeatureSet features;

    BehaviorDefinition(
        List props, List functionsToCopy,
        List nonPropertyMembersToCopy, boolean isGlobalDeclaration,
        FeatureSet features) {
      this.props = props;
      this.functionsToCopy = functionsToCopy;
      this.nonPropertyMembersToCopy = nonPropertyMembersToCopy;
      this.isGlobalDeclaration = isGlobalDeclaration;
      this.features = features;
    }
  }
}