| package org.apache.bcel.classfile; |
| |
| /* ==================================================================== |
| * The Apache Software License, Version 1.1 |
| * |
| * Copyright (c) 2001 The Apache Software Foundation. All rights |
| * reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * |
| * 1. Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * |
| * 2. Redistributions in binary form must reproduce the above copyright |
| * notice, this list of conditions and the following disclaimer in |
| * the documentation and/or other materials provided with the |
| * distribution. |
| * |
| * 3. The end-user documentation included with the redistribution, |
| * if any, must include the following acknowledgment: |
| * "This product includes software developed by the |
| * Apache Software Foundation (http://www.apache.org/)." |
| * Alternately, this acknowledgment may appear in the software itself, |
| * if and wherever such third-party acknowledgments normally appear. |
| * |
| * 4. The names "Apache" and "Apache Software Foundation" and |
| * "Apache BCEL" must not be used to endorse or promote products |
| * derived from this software without prior written permission. For |
| * written permission, please contact apache@apache.org. |
| * |
| * 5. Products derived from this software may not be called "Apache", |
| * "Apache BCEL", nor may "Apache" appear in their name, without |
| * prior written permission of the Apache Software Foundation. |
| * |
| * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED |
| * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
| * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE |
| * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR |
| * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
| * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF |
| * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND |
| * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, |
| * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT |
| * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
| * SUCH DAMAGE. |
| * ==================================================================== |
| * |
| * This software consists of voluntary contributions made by many |
| * individuals on behalf of the Apache Software Foundation. For more |
| * information on the Apache Software Foundation, please see |
| * <http://www.apache.org/>. |
| */ |
| |
| import org.apache.bcel.Constants; |
| import java.io.*; |
| |
| /** |
| * Abstract superclass for classes to represent the different constant types |
| * in the constant pool of a class file. The classes keep closely to |
| * the JVM specification. |
| * |
| * @version $Id$ |
| * @author <A HREF="mailto:markus.dahm@berlin.de">M. Dahm</A> |
| */ |
| public abstract class Constant implements Cloneable, Node { |
| /* In fact this tag is redundant since we can distinguish different |
| * `Constant' objects by their type, i.e., via `instanceof'. In some |
| * places we will use the tag for switch()es anyway. |
| * |
| * First, we want match the specification as closely as possible. Second we |
| * need the tag as an index to select the corresponding class name from the |
| * `CONSTANT_NAMES' array. |
| */ |
| protected byte tag; |
| |
| Constant(byte tag) { this.tag = tag; } |
| |
| /** |
| * Called by objects that are traversing the nodes of the tree implicitely |
| * defined by the contents of a Java class. I.e., the hierarchy of methods, |
| * fields, attributes, etc. spawns a tree of objects. |
| * |
| * @param v Visitor object |
| */ |
| public abstract void accept(Visitor v); |
| |
| public abstract void dump(DataOutputStream file) throws IOException; |
| |
| /** |
| * @return Tag of constant, i.e., its type. No setTag() method to avoid |
| * confusion. |
| */ |
| public final byte getTag() { return tag; } |
| |
| /** |
| * @return String representation. |
| */ |
| public String toString() { |
| return Constants.CONSTANT_NAMES[tag] + "[" + tag + "]"; |
| } |
| |
| /** |
| * @return deep copy of this constant |
| */ |
| public Constant copy() { |
| try { |
| return (Constant)super.clone(); |
| } catch(CloneNotSupportedException e) {} |
| |
| return null; |
| } |
| |
| public Object clone() throws CloneNotSupportedException { |
| return super.clone(); |
| } |
| |
| /** |
| * Read one constant from the given file, the type depends on a tag byte. |
| * |
| * @param file Input stream |
| * @return Constant object |
| */ |
| static final Constant readConstant(DataInputStream file) |
| throws IOException, ClassFormatError |
| { |
| byte b = file.readByte(); // Read tag byte |
| |
| switch(b) { |
| case Constants.CONSTANT_Class: return new ConstantClass(file); |
| case Constants.CONSTANT_Fieldref: return new ConstantFieldref(file); |
| case Constants.CONSTANT_Methodref: return new ConstantMethodref(file); |
| case Constants.CONSTANT_InterfaceMethodref: return new |
| ConstantInterfaceMethodref(file); |
| case Constants.CONSTANT_String: return new ConstantString(file); |
| case Constants.CONSTANT_Integer: return new ConstantInteger(file); |
| case Constants.CONSTANT_Float: return new ConstantFloat(file); |
| case Constants.CONSTANT_Long: return new ConstantLong(file); |
| case Constants.CONSTANT_Double: return new ConstantDouble(file); |
| case Constants.CONSTANT_NameAndType: return new ConstantNameAndType(file); |
| case Constants.CONSTANT_Utf8: return new ConstantUtf8(file); |
| default: |
| throw new ClassFormatError("Invalid byte tag in constant pool: " + b); |
| } |
| } |
| } |