ReturnNode.java revision 953:221a84ef44c0 
1/*
2 * Copyright (c) 2010, 2013, 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
26package jdk.nashorn.internal.ir;
27
28import static jdk.nashorn.internal.parser.TokenType.RETURN;
29import static jdk.nashorn.internal.parser.TokenType.YIELD;
30
31import jdk.nashorn.internal.ir.annotations.Immutable;
32import jdk.nashorn.internal.ir.visitor.NodeVisitor;
33
34/**
35 * IR representation for RETURN or YIELD statements.
36 */
37@Immutable
38public class ReturnNode extends Statement {
39    /** Optional expression. */
40    private final Expression expression;
41
42    /**
43     * Constructor
44     *
45     * @param lineNumber line number
46     * @param token      token
47     * @param finish     finish
48     * @param expression expression to return
49     */
50    public ReturnNode(final int lineNumber, final long token, final int finish, final Expression expression) {
51        super(lineNumber, token, finish);
52        this.expression = expression;
53    }
54
55    private ReturnNode(final ReturnNode returnNode, final Expression expression) {
56        super(returnNode);
57        this.expression = expression;
58    }
59
60    @Override
61    public boolean isTerminal() {
62        return true;
63    }
64
65    /**
66     * Return true if is a RETURN node.
67     * @return true if is RETURN node.
68     */
69    public boolean isReturn() {
70        return isTokenType(RETURN);
71    }
72
73    /**
74     * Check if this return node has an expression
75     * @return true if not a void return
76     */
77    public boolean hasExpression() {
78        return expression != null;
79    }
80
81    /**
82     * Return true if is a YIELD node.
83     * @return TRUE if is YIELD node.
84     */
85    public boolean isYield() {
86        return isTokenType(YIELD);
87    }
88
89    @Override
90    public Node accept(final NodeVisitor<? extends LexicalContext> visitor) {
91        if (visitor.enterReturnNode(this)) {
92            if (expression != null) {
93                return visitor.leaveReturnNode(setExpression((Expression)expression.accept(visitor)));
94            }
95            return visitor.leaveReturnNode(this);
96        }
97
98        return this;
99    }
100
101
102    @Override
103    public void toString(final StringBuilder sb, final boolean printType) {
104        sb.append(isYield() ? "yield" : "return");
105        if (expression != null) {
106            sb.append(' ');
107            expression.toString(sb, printType);
108        }
109    }
110
111    /**
112     * Get the expression this node returns
113     * @return return expression, or null if void return
114     */
115    public Expression getExpression() {
116        return expression;
117    }
118
119    /**
120     * Reset the expression this node returns
121     * @param expression new expression, or null if void return
122     * @return new or same return node
123     */
124    public ReturnNode setExpression(final Expression expression) {
125        if (this.expression == expression) {
126            return this;
127        }
128        return new ReturnNode(this, expression);
129    }
130
131}
132