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/* * Copyright (c) 1994, 2003, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation.  Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package sun.tools.tree; import sun.tools.java.*;import sun.tools.asm.Assembler;import sun.tools.asm.Label;import java.util.Hashtable; /** * WARNING: The contents of this source file are not part of any * supported API.  Code that depends on them does so at its own risk: * they are subject to change or removal without notice. */publicclass NotExpression extends UnaryExpression {    /**     * Constructor     */    public NotExpression(long where, Expression right) {        super(NOT, where, Type.tBoolean, right);    }     /**     * Select the type of the expression     */    void selectType(Environment env, Context ctx, int tm) {        right = convert(env, ctx, Type.tBoolean, right);    }     /*     * Check a "not" expression.     *     * cvars is modified so that     *    cvar.vsTrue indicates variables with a known value if     *         the expression is true.     *    cvars.vsFalse indicates variables with a known value if     *         the expression is false     *     * For "not" expressions, we look at the inside expression, and then     * swap true and false.     */     public void checkCondition(Environment env, Context ctx, Vset vset,                               Hashtable exp, ConditionVars cvars) {        right.checkCondition(env, ctx, vset, exp, cvars);        right = convert(env, ctx, Type.tBoolean, right);        // swap true and false        Vset temp = cvars.vsFalse;        cvars.vsFalse = cvars.vsTrue;        cvars.vsTrue = temp;    }     /**     * Evaluate     */    Expression eval(boolean a) {        return new BooleanExpression(where, !a);    }     /**     * Simplify     */    Expression simplify() {        // Check if the expression can be optimized        switch (right.op) {          case NOT:            return ((NotExpression)right).right;           case EQ:          case NE:          case LT:          case LE:          case GT:          case GE:            break;           default:            return this;        }         // Can't negate real comparisons        BinaryExpression bin = (BinaryExpression)right;        if (bin.left.type.inMask(TM_REAL)) {            return this;        }         // Negate comparison        switch (right.op) {          case EQ:            return new NotEqualExpression(where, bin.left, bin.right);          case NE:            return new EqualExpression(where, bin.left, bin.right);          case LT:            return new GreaterOrEqualExpression(where, bin.left, bin.right);          case LE:            return new GreaterExpression(where, bin.left, bin.right);          case GT:            return new LessOrEqualExpression(where, bin.left, bin.right);          case GE:            return new LessExpression(where, bin.left, bin.right);        }        return this;    }     /**     * Code     */    void codeBranch(Environment env, Context ctx, Assembler asm, Label lbl, boolean whenTrue) {        right.codeBranch(env, ctx, asm, lbl, !whenTrue);    }     /**     * Instead of relying on the default code generation which uses     * conditional branching, generate a simpler stream using XOR.     */    public void codeValue(Environment env, Context ctx, Assembler asm) {        right.codeValue(env, ctx, asm);        asm.add(where, opc_ldc, new Integer(1));        asm.add(where, opc_ixor);    } }