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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 2009 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.javascript.jscomp.parsing.parser.util.format.SimpleFormat;
import com.google.javascript.rhino.IR;
import com.google.javascript.rhino.Node;

import java.util.regex.Pattern;

/**
 * Generates goog.exportSymbol for test functions, so they can be recognized
 * by the test runner, even if the code is compiled.
 *
 */
public class ExportTestFunctions implements CompilerPass {

  private static final Pattern TEST_FUNCTIONS_NAME_PATTERN =
      Pattern.compile(
          "^(?:((\\w+\\.)+prototype\\.||window\\.)*" +
          "(setUpPage|setUp|shouldRunTests|tearDown|tearDownPage|test[\\w\\$]+))$");

  private AbstractCompiler compiler;
  private final String exportSymbolFunction;
  private final String exportPropertyFunction;

  /**
   * Creates a new export test functions compiler pass.
   * @param compiler
   * @param exportSymbolFunction The function name used to export symbols in JS.
   * @param exportPropertyFunction The function name used to export properties
   *     in JS.
   */
  ExportTestFunctions(AbstractCompiler compiler,
      String exportSymbolFunction, String exportPropertyFunction) {

    Preconditions.checkNotNull(compiler);
    this.compiler = compiler;
    this.exportSymbolFunction = exportSymbolFunction;
    this.exportPropertyFunction = exportPropertyFunction;
  }

  private class ExportTestFunctionsNodes extends
      NodeTraversal.AbstractShallowCallback {

    @Override
    public void visit(NodeTraversal t, Node n, Node parent) {

      if (parent == null) {
        return;
      }

      if (parent.isScript()) {
        if (NodeUtil.isFunctionDeclaration(n)) {
          // Check for a test function statement.
          String functionName = NodeUtil.getName(n);
          if (isTestFunction(functionName)) {
            exportTestFunctionAsSymbol(functionName, n, parent);
          }
        } else if (isNameDeclaredFunction(n)) {
          // Check for a test function expression.
          Node functionNode = n.getFirstFirstChild();
          String functionName = NodeUtil.getName(functionNode);
          if (isTestFunction(functionName)) {
            exportTestFunctionAsSymbol(functionName, n, parent);
          }
        }
      } else if (NodeUtil.isExprAssign(parent) &&
            !n.getLastChild().isAssign()) {
        // Check for a test method assignment.
        Node grandparent = parent.getParent();
        if (grandparent != null && grandparent.isScript()) {
          String functionName = n.getFirstChild().getQualifiedName();
          if (isTestFunction(functionName)) {
            exportTestFunctionAsProperty(functionName, parent, n, grandparent);
          }
        }
      } else if (n.isObjectLit()
          && isCallTargetQName(n.getParent(), "goog.testing.testSuite")) {
        for (Node c : n.children()) {
          if (c.isStringKey() && !c.isQuotedString()) {
            c.setQuotedString();
            compiler.reportCodeChange();
          } else if (c.isMemberFunctionDef()) {
            rewriteMemberDefInObjLit(c, n);
          }
        }
      }
    }

    private void rewriteMemberDefInObjLit(Node memberDef, Node objLit) {
      String name = memberDef.getString();
      Node stringKey = IR.stringKey(name, memberDef.getFirstChild().detachFromParent());
      objLit.replaceChild(memberDef, stringKey);
      stringKey.setQuotedString();
      compiler.reportCodeChange();
    }

    // TODO(johnlenz): move test suite declaration into the
    // coding convention class.
    private boolean isCallTargetQName(Node n, String qname) {
      return (n.isCall() && n.getFirstChild().matchesQualifiedName(qname));
    }

    /**
     * Whether node corresponds to a function expression declared with var, let
     * or const which is of the form:
     *      * var/let/const functionName = function() {
     *   // Implementation
     * };
     * 
     * This has the AST structure VAR/LET/CONST -> NAME -> FUNCTION
     * @param node
     */
    private boolean isNameDeclaredFunction(Node node) {
      if (!NodeUtil.isNameDeclaration(node)) {
        return false;
      }
      Node grandchild = node.getFirstFirstChild();
      return grandchild != null && grandchild.isFunction();
    }
  }

  @Override
  public void process(Node externs, Node root) {
    NodeTraversal.traverseEs6(compiler, root, new ExportTestFunctionsNodes());
  }

  // Adds exportSymbol(testFunctionName, testFunction);
  private void exportTestFunctionAsSymbol(String testFunctionName, Node node,
      Node scriptNode) {

    Node exportCallTarget = NodeUtil.newQName(compiler,
        exportSymbolFunction, node, testFunctionName);
    Node call = IR.call(exportCallTarget);
    if (exportCallTarget.isName()) {
      call.putBooleanProp(Node.FREE_CALL, true);
    }
    call.addChildToBack(IR.string(testFunctionName));
    call.addChildToBack(NodeUtil.newQName(compiler,
        testFunctionName, node, testFunctionName));

    Node expression = IR.exprResult(call);

    scriptNode.addChildAfter(expression, node);
    compiler.reportCodeChange();
  }


  // Adds exportProperty() of the test function name on the prototype object
  private void exportTestFunctionAsProperty(String fullyQualifiedFunctionName,
      Node parent, Node node, Node scriptNode) {

    String testFunctionName =
        NodeUtil.getPrototypePropertyName(node.getFirstChild());
    if (node.getFirstChild().getQualifiedName().startsWith("window.")) {
      testFunctionName = node.getFirstChild().getQualifiedName().substring("window.".length());
    }
    String objectName = fullyQualifiedFunctionName.substring(0,
        fullyQualifiedFunctionName.lastIndexOf('.'));
    String exportCallStr = SimpleFormat.format("%s(%s, '%s', %s);",
        exportPropertyFunction, objectName, testFunctionName,
        fullyQualifiedFunctionName);

    Node exportCall = this.compiler.parseSyntheticCode(exportCallStr)
        .removeChildren();
    exportCall.useSourceInfoFromForTree(scriptNode);

    scriptNode.addChildAfter(exportCall, parent);
    compiler.reportCodeChange();
  }


  /**
   * Whether a function is recognized as a test function. We follow the JsUnit
   * convention for naming (functions should start with "test"), and we also
   * check if it has no parameters declared.
   *
   * @param functionName The name of the function
   * @return {@code true} if the function is recognized as a test function.
   */
  public static boolean isTestFunction(String functionName) {
    return functionName != null
        && TEST_FUNCTIONS_NAME_PATTERN.matcher(functionName).matches();
  }
}