1 /*
   2  * Copyright (c) 2016, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 package jdk.nashorn.api.tree;
  27 
  28 /**
  29  *  A tree node for <a href="http://www.ecma-international.org/ecma-262/6.0/#sec-generator-function-definitions">yield expressions</a> used in generator functions.
  30  *
  31  * For example:
  32  * <pre>
  33  * <em>function*</em> id(){
  34  *     var index = 0;
  35  *     while(index &lt; 10)
  36  *         <em>yield index++;</em>
  37  * }
  38  * </pre>
  39  *
  40  * @since 9
  41  */
  42 public interface YieldTree extends ExpressionTree {
  43     /**
  44      * Returns the expression that is yielded.
  45      *
  46      * @return The expression that is yielded.
  47      */
  48     ExpressionTree getExpression();
  49 
  50     /**
  51      * Is this a yield * expression in a generator function?
  52      *
  53      * For example:
  54      * <pre>
  55      * function* id(){
  56      *     yield 1;
  57      *     <em>yield * anotherGeneratorFunc();</em>
  58      *     yield 10;
  59      * }
  60      * </pre>
  61      *
  62      *
  63      * @return true if this is a yield * expression
  64      */
  65     boolean isStar();
  66 }