1/*
2 * Copyright (c) 1994, 2003, 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 sun.tools.tree;
27
28import sun.tools.java.*;
29import sun.tools.asm.Assembler;
30import sun.tools.asm.Label;
31import java.util.Hashtable;
32
33/**
34 * WARNING: The contents of this source file are not part of any
35 * supported API.  Code that depends on them does so at its own risk:
36 * they are subject to change or removal without notice.
37 */
38public
39class OrExpression extends BinaryLogicalExpression {
40    /**
41     * constructor
42     */
43    public OrExpression(long where, Expression left, Expression right) {
44        super(OR, where, left, right);
45    }
46
47    /*
48     * Check an "or" expression.
49     *
50     * cvars is modified so that
51     *    cvar.vsTrue indicates variables with a known value if
52     *        either the left and right hand side isn true
53     *    cvars.vsFalse indicates variables with a known value if
54     *        both the left or right hand side are false
55     */
56    public void checkCondition(Environment env, Context ctx, Vset vset,
57                               Hashtable<Object, Object> exp, ConditionVars cvars) {
58        // Find out when the left side is true/false
59        left.checkCondition(env, ctx, vset, exp, cvars);
60        left = convert(env, ctx, Type.tBoolean, left);
61        Vset vsTrue = cvars.vsTrue.copy();
62        Vset vsFalse = cvars.vsFalse.copy();
63
64        // Only look at the right side if the left side is false
65        right.checkCondition(env, ctx, vsFalse, exp, cvars);
66        right = convert(env, ctx, Type.tBoolean, right);
67
68        // cvars.vsFalse actually reports that both returned false
69        // cvars.vsTrue must be set back to either left side or the right
70        //     side returning false;
71        cvars.vsTrue = cvars.vsTrue.join(vsTrue);
72    }
73
74    /**
75     * Evaluate
76     */
77    Expression eval(boolean a, boolean b) {
78        return new BooleanExpression(where, a || b);
79    }
80
81    /**
82     * Simplify
83     */
84    Expression simplify() {
85        if (right.equals(false)) {
86            return left;
87        }
88        if (left.equals(true)) {
89            return left;
90        }
91        if (left.equals(false)) {
92            return right;
93        }
94        if (right.equals(true)) {
95            // Preserve effects of left argument.
96            return new CommaExpression(where, left, right).simplify();
97        }
98        return this;
99    }
100
101    /**
102     * Code
103     */
104    void codeBranch(Environment env, Context ctx, Assembler asm, Label lbl, boolean whenTrue) {
105        if (whenTrue) {
106            left.codeBranch(env, ctx, asm, lbl, true);
107            right.codeBranch(env, ctx, asm, lbl, true);
108        } else {
109            Label lbl2 = new Label();
110            left.codeBranch(env, ctx, asm, lbl2, true);
111            right.codeBranch(env, ctx, asm, lbl, false);
112            asm.add(lbl2);
113        }
114    }
115}
116