Java example source code file (CastExpression.java)

This example Java source code file (CastExpression.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

binaryexpression, castexpression, classdefinition, classnotfound, context, convertexpression, environment, expression, hashtable, util, vset

The CastExpression.java Java example source code

/*
 * 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.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 CastExpression extends BinaryExpression {
    /**
     * constructor
     */
    public CastExpression(long where, Expression left, Expression right) {
        super(CAST, where, left.type, left, right);
    }

    /**
     * Check the expression
     */
    public Vset checkValue(Environment env, Context ctx, Vset vset, Hashtable exp) {
        type = left.toType(env, ctx);
        vset = right.checkValue(env, ctx, vset, exp);

        if (type.isType(TC_ERROR) || right.type.isType(TC_ERROR)) {
            // An error was already reported
            return vset;
        }

        if (type.equals(right.type)) {
            // The types are already the same
            return vset;
        }

        try {
            if (env.explicitCast(right.type, type)) {
                right = new ConvertExpression(where, type, right);
                return vset;
            }
        } catch (ClassNotFound e) {
            env.error(where, "class.not.found", e.name, opNames[op]);
        }

        // The cast is not allowed
        env.error(where, "invalid.cast", right.type, type);
        return vset;
    }

    /**
     * Check if constant
     */
    public boolean isConstant() {
        if (type.inMask(TM_REFERENCE) && !type.equals(Type.tString)) {
            // must be a primitive type, or String
            return false;
        }
        return right.isConstant();
    }

    /**
     * Inline
     */
    public Expression inline(Environment env, Context ctx) {
        return right.inline(env, ctx);
    }
    public Expression inlineValue(Environment env, Context ctx) {
        return right.inlineValue(env, ctx);
    }


    public int costInline(int thresh, Environment env, Context ctx) {
        if (ctx == null) {
            return 1 + right.costInline(thresh, env, ctx);
        }
        // sourceClass is the current class trying to inline this method
        ClassDefinition sourceClass = ctx.field.getClassDefinition();
        try {
            // We only allow the inlining if the current class can access
            // the casting class
            if (left.type.isType(TC_ARRAY) ||
                 sourceClass.permitInlinedAccess(env,
                                  env.getClassDeclaration(left.type)))
                return 1 + right.costInline(thresh, env, ctx);
        } catch (ClassNotFound e) {
        }
        return thresh;
    }



    /**
     * Print
     */
    public void print(PrintStream out) {
        out.print("(" + opNames[op] + " ");
        if (type.isType(TC_ERROR)) {
            left.print(out);
        } else {
            out.print(type);
        }
        out.print(" ");
        right.print(out);
        out.print(")");
    }
}