/*

 * 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.

 */

public

class 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_ixor);

    }

}