langtools/src/share/classes/com/sun/tools/javac/jvm/ClassFile.java
author jjg
Tue, 16 Sep 2008 18:35:18 -0700
changeset 1260 a772ba9ba43d
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child 1264 076a3cde30d5
permissions -rw-r--r--
6574134: Allow for alternative implementation of Name Table with garbage collection of name bytes Reviewed-by: darcy, mcimadamore
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/*
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 * Copyright 1999-2005 Sun Microsystems, Inc.  All Rights Reserved.
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 *
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 * This code is free software; you can redistribute it and/or modify it
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 * under the terms of the GNU General Public License version 2 only, as
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 * published by the Free Software Foundation.  Sun designates this
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 * particular file as subject to the "Classpath" exception as provided
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 * by Sun in the LICENSE file that accompanied this code.
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 *
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 * This code is distributed in the hope that it will be useful, but WITHOUT
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 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
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 * version 2 for more details (a copy is included in the LICENSE file that
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 * accompanied this code).
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 *
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 * You should have received a copy of the GNU General Public License version
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 * 2 along with this work; if not, write to the Free Software Foundation,
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 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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 *
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 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
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 * CA 95054 USA or visit www.sun.com if you need additional information or
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 * have any questions.
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 */
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package com.sun.tools.javac.jvm;
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import com.sun.tools.javac.code.*;
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import com.sun.tools.javac.util.*;
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/** A JVM class file.
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 *
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 *  <p>Generic Java classfiles have one additional attribute for classes,
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 *  methods and fields:
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 *  <pre>
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 *   "Signature" (u4 attr-length, u2 signature-index)
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 *  </pre>
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 *
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 *  <p>A signature gives the full Java type of a method or field. When
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 *  used as a class attribute, it indicates type parameters, followed
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 *  by supertype, followed by all interfaces.
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 *  <pre>
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 *     methodOrFieldSignature ::= type
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 *     classSignature         ::= [ typeparams ] supertype { interfacetype }
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 *  </pre>
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 *  <p>The type syntax in signatures is extended as follows:
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 *  <pre>
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 *     type       ::= ... | classtype | methodtype | typevar
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 *     classtype  ::= classsig { '.' classsig }
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 *     classig    ::= 'L' name [typeargs] ';'
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 *     methodtype ::= [ typeparams ] '(' { type } ')' type
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 *     typevar    ::= 'T' name ';'
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 *     typeargs   ::= '<' type { type } '>'
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 *     typeparams ::= '<' typeparam { typeparam } '>'
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 *     typeparam  ::= name ':' type
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 *  </pre>
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 *  <p>This class defines constants used in class files as well
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 *  as routines to convert between internal ``.'' and external ``/''
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 *  separators in class names.
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 *
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 *  <p><b>This is NOT part of any API supported by Sun Microsystems.  If
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 *  you write code that depends on this, you do so at your own risk.
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 *  This code and its internal interfaces are subject to change or
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 *  deletion without notice.</b> */
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public class ClassFile {
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    public final static int JAVA_MAGIC = 0xCAFEBABE;
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    // see Target
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    public final static int CONSTANT_Utf8 = 1;
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    public final static int CONSTANT_Unicode = 2;
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    public final static int CONSTANT_Integer = 3;
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    public final static int CONSTANT_Float = 4;
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    public final static int CONSTANT_Long = 5;
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    public final static int CONSTANT_Double = 6;
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    public final static int CONSTANT_Class = 7;
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    public final static int CONSTANT_String = 8;
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    public final static int CONSTANT_Fieldref = 9;
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    public final static int CONSTANT_Methodref = 10;
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    public final static int CONSTANT_InterfaceMethodref = 11;
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    public final static int CONSTANT_NameandType = 12;
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    public final static int MAX_PARAMETERS = 0xff;
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    public final static int MAX_DIMENSIONS = 0xff;
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    public final static int MAX_CODE = 0xffff;
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    public final static int MAX_LOCALS = 0xffff;
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    public final static int MAX_STACK = 0xffff;
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/************************************************************************
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 * String Translation Routines
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 ***********************************************************************/
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    /** Return internal representation of buf[offset..offset+len-1],
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     *  converting '/' to '.'.
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     */
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    public static byte[] internalize(byte[] buf, int offset, int len) {
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        byte[] translated = new byte[len];
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        for (int j = 0; j < len; j++) {
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            byte b = buf[offset + j];
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            if (b == '/') translated[j] = (byte) '.';
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            else translated[j] = b;
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        }
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        return translated;
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    }
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    /** Return internal representation of given name,
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     *  converting '/' to '.'.
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     */
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    public static byte[] internalize(Name name) {
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        return internalize(name.getByteArray(), name.getByteOffset(), name.getByteLength());
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    }
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    /** Return external representation of buf[offset..offset+len-1],
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     *  converting '.' to '/'.
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     */
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    public static byte[] externalize(byte[] buf, int offset, int len) {
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        byte[] translated = new byte[len];
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        for (int j = 0; j < len; j++) {
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            byte b = buf[offset + j];
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            if (b == '.') translated[j] = (byte) '/';
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            else translated[j] = b;
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        }
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        return translated;
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    }
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    /** Return external representation of given name,
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     *  converting '/' to '.'.
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     */
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    public static byte[] externalize(Name name) {
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        return externalize(name.getByteArray(), name.getByteOffset(), name.getByteLength());
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    }
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/************************************************************************
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 * Name-and-type
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 ***********************************************************************/
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    /** A class for the name-and-type signature of a method or field.
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     */
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    public static class NameAndType {
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        Name name;
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        Type type;
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        NameAndType(Name name, Type type) {
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            this.name = name;
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            this.type = type;
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        }
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        public boolean equals(Object other) {
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            return
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                other instanceof NameAndType &&
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                name == ((NameAndType) other).name &&
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                type.equals(((NameAndType) other).type);
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        }
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        public int hashCode() {
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            return name.hashCode() * type.hashCode();
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        }
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    }
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}