01: /* Copyright (C) 2004 - 2007 db4objects Inc. http://www.db4o.com
02:
03: This file is part of the db4o open source object database.
04:
05: db4o is free software; you can redistribute it and/or modify it under
06: the terms of version 2 of the GNU General Public License as published
07: by the Free Software Foundation and as clarified by db4objects' GPL
08: interpretation policy, available at
09: http://www.db4o.com/about/company/legalpolicies/gplinterpretation/
10: Alternatively you can write to db4objects, Inc., 1900 S Norfolk Street,
11: Suite 350, San Mateo, CA 94403, USA.
12:
13: db4o is distributed in the hope that it will be useful, but WITHOUT ANY
14: WARRANTY; without even the implied warranty of MERCHANTABILITY or
15: FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
16: for more details.
17:
18: You should have received a copy of the GNU General Public License along
19: with this program; if not, write to the Free Software Foundation, Inc.,
20: 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
21: package EDU.purdue.cs.bloat.tree;
22:
23: import EDU.purdue.cs.bloat.editor.*;
24:
25: /**
26: * CheckExpr is a superclass for classes representing a check on an expression.
27: * For instance, a CheckExpr is inserted into the tree before the divisor of a
28: * divide operation. The CheckExpr checks to make sure that the divisor is not
29: * zero.
30: *
31: * @see RCExpr
32: * @see UCExpr
33: * @see ZeroCheckExpr
34: */
35: public abstract class CheckExpr extends Expr {
36: Expr expr;
37:
38: /**
39: * Constructor.
40: *
41: * @param expr
42: * An expression that is to be checked.
43: * @param type
44: * The type of this expression.
45: */
46: public CheckExpr(final Expr expr, final Type type) {
47: super (type);
48: this .expr = expr;
49: expr.setParent(this );
50: }
51:
52: public void visitForceChildren(final TreeVisitor visitor) {
53: if (visitor.reverse()) {
54: expr.visit(visitor);
55: } else {
56: expr.visit(visitor);
57: }
58: }
59:
60: /**
61: * Returns the expression being checked.
62: */
63: public Expr expr() {
64: return expr;
65: }
66:
67: public int exprHashCode() {
68: return 9 + expr.exprHashCode() ^ type.simple().hashCode();
69: }
70:
71: public boolean equalsExpr(final Expr other) {
72: return (other != null) && (other instanceof CheckExpr)
73: && ((CheckExpr) other).expr.equalsExpr(expr);
74: }
75: }
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