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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

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package sun.tools.tree;

import sun.tools.java.*;

import sun.tools.asm.Assembler;

import java.io.PrintStream;

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 AssignExpression extends BinaryAssignExpression {

    private FieldUpdater updater = null;

    /**

     * Constructor

     */

    public AssignExpression(long where, Expression left, Expression right) {

        super(ASSIGN, where, left, right);

    }

    /**

     * Check an assignment expression

     */

    public Vset checkValue(Environment env, Context ctx, Vset vset, Hashtable exp) {

        if (left instanceof IdentifierExpression) {

            // we don't want to mark an identifier as having a value

            // until having evaluated the right-hand side

            vset = right.checkValue(env, ctx, vset, exp);

            vset = left.checkLHS(env, ctx, vset, exp);

        } else {

            // normally left to right evaluation.

            vset = left.checkLHS(env, ctx, vset, exp);

            vset = right.checkValue(env, ctx, vset, exp);

        }

        type = left.type;

        right = convert(env, ctx, type, right);

        // Get field updater (access method) if needed, else null.

        updater = left.getAssigner(env, ctx);

        return vset;

    }

    /**

     * Inline

     */

    public Expression inlineValue(Environment env, Context ctx) {

        if (implementation != null)

            return implementation.inlineValue(env, ctx);

        // Must be 'inlineLHS' here.  But compare with similar case in

        // 'AssignOpExpression' and 'IncDecExpression', which needs 'inlineValue'.

        left = left.inlineLHS(env, ctx);

        right = right.inlineValue(env, ctx);

        if (updater != null) {

            updater = updater.inline(env, ctx);

        }

        return this;

    }

    /**

     * Create a copy of the expression for method inlining

     */

    public Expression copyInline(Context ctx) {

        if (implementation != null)

            return implementation.copyInline(ctx);

        AssignExpression e = (AssignExpression)clone();

        e.left = left.copyInline(ctx);

        e.right = right.copyInline(ctx);

        if (updater != null) {

            e.updater = updater.copyInline(ctx);

        }

        return e;

    }

    /**

     * The cost of inlining this expression

     */

    public int costInline(int thresh, Environment env, Context ctx) {

        /*----------*

        return 2 + super.costInline(thresh, env, ctx);

        *----------*/

        return (updater != null)

            // Cost of rhs expression + cost of access method call.

            // Access method call cost includes lhs cost.

            ? right.costInline(thresh, env, ctx) +

                  updater.costInline(thresh, env, ctx, false)

            // Cost of rhs expression + cost of lhs expression +

            // cost of store instruction.

            : right.costInline(thresh, env, ctx) +

                  left.costInline(thresh, env, ctx) + 2;

    }

    /**

     * Code

     */

    public void codeValue(Environment env, Context ctx, Assembler asm) {

        if (updater == null) {

            // Field is directly accessible.

            int depth = left.codeLValue(env, ctx, asm);

            right.codeValue(env, ctx, asm);

            codeDup(env, ctx, asm, right.type.stackSize(), depth);

            left.codeStore(env, ctx, asm);

        } else {

            // Must use access method.

            // Left operand is always a 'FieldExpression', or

            // is rewritten as one via 'implementation'.

            updater.startAssign(env, ctx, asm);

            right.codeValue(env, ctx, asm);

            updater.finishAssign(env, ctx, asm, true);

        }

    }

    public void code(Environment env, Context ctx, Assembler asm) {

        if (updater == null) {

            // Field is directly accessible.

            left.codeLValue(env, ctx, asm);

            right.codeValue(env, ctx, asm);

            left.codeStore(env, ctx, asm);

        } else {

            // Must use access method.

            // Left operand is always a 'FieldExpression', or

            // is rewritten as one via 'implementation'.

            updater.startAssign(env, ctx, asm);

            right.codeValue(env, ctx, asm);

            updater.finishAssign(env, ctx, asm, false);

        }

    }

}