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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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/*
 *
 * ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (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.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is Rhino code, released
 * May 6, 1999.
 *
 * The Initial Developer of the Original Code is
 * Netscape Communications Corporation.
 * Portions created by the Initial Developer are Copyright (C) 1997-1999
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *   Bob Jervis
 *   Google Inc.
 *
 * Alternatively, the contents of this file may be used under the terms of
 * the GNU General Public License Version 2 or later (the "GPL"), in which
 * case the provisions of the GPL are applicable instead of those above. If
 * you wish to allow use of your version of this file only under the terms of
 * the GPL and not to allow others to use your version of this file under the
 * MPL, indicate your decision by deleting the provisions above and replacing
 * them with the notice and other provisions required by the GPL. If you do
 * not delete the provisions above, a recipient may use your version of this
 * file under either the MPL or the GPL.
 *
 * ***** END LICENSE BLOCK ***** */

package com.google.javascript.rhino;

import com.google.javascript.rhino.jstype.JSType;
import com.google.javascript.rhino.jstype.JSTypeRegistry;
import com.google.javascript.rhino.jstype.StaticTypedScope;
import java.io.Serializable;

/**
 * When parsing a jsdoc, a type-annotation string is parsed to a type AST.
 * Somewhat confusingly, we use the Node class both for type ASTs and for the source-code AST.
 * JSTypeExpression wraps a type AST.
 * During type checking, type ASTs are evaluated to JavaScript types.
 *
 * @author [email protected] (Nick Santos)
 */
public final class JSTypeExpression implements Serializable {
  private static final long serialVersionUID = 1L;

  /** The root of the AST. */
  private final Node root;

  /** The source name where the type expression appears. */
  private final String sourceName;

  public JSTypeExpression(Node root, String sourceName) {
    this.root = root;
    this.sourceName = sourceName;
  }

  /**
   * Make the given type expression into an optional type expression,
   * if possible.
   */
  public static JSTypeExpression makeOptionalArg(JSTypeExpression expr) {
    if (expr.isOptionalArg() || expr.isVarArgs()) {
      return expr;
    } else {
      return new JSTypeExpression(
          new Node(Token.EQUALS, expr.root), expr.sourceName);
    }
  }

  /**
   * @return Whether this expression denotes an optional {@code @param}.
   */
  public boolean isOptionalArg() {
    return root.getToken() == Token.EQUALS;
  }

  /**
   * @return Whether this expression denotes a rest args {@code @param}.
   */
  public boolean isVarArgs() {
    return root.getToken() == Token.ELLIPSIS;
  }

  /**
   * Evaluates the type expression into a {@code JSType} object.
   */
  public JSType evaluate(StaticTypedScope scope, TypeIRegistry registry) {
    if (registry instanceof JSTypeRegistry) {
      JSType type = ((JSTypeRegistry) registry).createTypeFromCommentNode(root, sourceName, scope);
      root.setJSType(type);
      return type;
    }
    return null;
  }

  @Override
  public boolean equals(Object other) {
    return other instanceof JSTypeExpression &&
        ((JSTypeExpression) other).root.isEquivalentTo(root);
  }

  @Override
  public int hashCode() {
    return root.hashCode();
  }

  /**
   * @return The source for this type expression.  Note that it will not
   * contain an expression if there's an @override tag.
   */
  public Node getRoot() {
    return root;
  }

  public String getSourceName() {
    return this.sourceName;
  }

  @Override
  public String toString() {
    return "type: " + root.toStringTree();
  }

  public JSTypeExpression copy() {
    return new JSTypeExpression(root.cloneTree(), sourceName);
  }
}