classwriter.java

asm的源码包 并且包含英文的文档

/***
 * ASM: a very small and fast Java bytecode manipulation framework
 * Copyright (c) 2000-2005 INRIA, France Telecom
 * 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. Neither the name of the copyright holders nor the names of its
 *    contributors may be used to endorse or promote products derived from
 *    this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS 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 COPYRIGHT OWNER OR 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.
 */
package org.objectweb.asm;

/**
 * A {@link ClassVisitor} that generates classes in bytecode form. More
 * precisely this visitor generates a byte array conforming to the Java class
 * file format. It can be used alone, to generate a Java class "from scratch",
 * or with one or more {@link ClassReader ClassReader} and adapter class visitor
 * to generate a modified class from one or more existing Java classes.
 * 
 * @author Eric Bruneton
 */
public class ClassWriter implements ClassVisitor {

    /**
     * Flag to automatically compute the maximum stack size and the maximum
     * number of local variables of methods. If this flag is set, then the
     * arguments of the {@link MethodVisitor#visitMaxs visitMaxs} method of the
     * {@link MethodVisitor} returned by the {@link #visitMethod visitMethod}
     * method will be ignored, and computed automatically from the signature and
     * the bytecode of each method.
     * 
     * @see #ClassWriter(int)
     */
    public final static int COMPUTE_MAXS = 1;

    /**
     * Flag to automatically compute the stack map frames of methods from
     * scratch. If this flag is set, then the calls to the
     * {@link MethodVisitor#visitFrame} method are ignored, and the stack map
     * frames are recomputed from the methods bytecode. The arguments of the
     * {@link MethodVisitor#visitMaxs visitMaxs} method are also ignored and
     * recomputed from the bytecode. In other words, computeFrames implies
     * computeMaxs.
     * 
     * @see #ClassWriter(int)
     */
    public final static int COMPUTE_FRAMES = 2;

    /**
     * The type of instructions without any argument.
     */
    final static int NOARG_INSN = 0;

    /**
     * The type of instructions with an signed byte argument.
     */
    final static int SBYTE_INSN = 1;

    /**
     * The type of instructions with an signed short argument.
     */
    final static int SHORT_INSN = 2;

    /**
     * The type of instructions with a local variable index argument.
     */
    final static int VAR_INSN = 3;

    /**
     * The type of instructions with an implicit local variable index argument.
     */
    final static int IMPLVAR_INSN = 4;

    /**
     * The type of instructions with a type descriptor argument.
     */
    final static int TYPE_INSN = 5;

    /**
     * The type of field and method invocations instructions.
     */
    final static int FIELDORMETH_INSN = 6;

    /**
     * The type of the INVOKEINTERFACE instruction.
     */
    final static int ITFMETH_INSN = 7;

    /**
     * The type of instructions with a 2 bytes bytecode offset label.
     */
    final static int LABEL_INSN = 8;

    /**
     * The type of instructions with a 4 bytes bytecode offset label.
     */
    final static int LABELW_INSN = 9;

    /**
     * The type of the LDC instruction.
     */
    final static int LDC_INSN = 10;

    /**
     * The type of the LDC_W and LDC2_W instructions.
     */
    final static int LDCW_INSN = 11;

    /**
     * The type of the IINC instruction.
     */
    final static int IINC_INSN = 12;

    /**
     * The type of the TABLESWITCH instruction.
     */
    final static int TABL_INSN = 13;

    /**
     * The type of the LOOKUPSWITCH instruction.
     */
    final static int LOOK_INSN = 14;

    /**
     * The type of the MULTIANEWARRAY instruction.
     */
    final static int MANA_INSN = 15;

    /**
     * The type of the WIDE instruction.
     */
    final static int WIDE_INSN = 16;

    /**
     * The instruction types of all JVM opcodes.
     */
    static byte[] TYPE;

    /**
     * The type of CONSTANT_Class constant pool items.
     */
    final static int CLASS = 7;

    /**
     * The type of CONSTANT_Fieldref constant pool items.
     */
    final static int FIELD = 9;

    /**
     * The type of CONSTANT_Methodref constant pool items.
     */
    final static int METH = 10;

    /**
     * The type of CONSTANT_InterfaceMethodref constant pool items.
     */
    final static int IMETH = 11;

    /**
     * The type of CONSTANT_String constant pool items.
     */
    final static int STR = 8;

    /**
     * The type of CONSTANT_Integer constant pool items.
     */
    final static int INT = 3;

    /**
     * The type of CONSTANT_Float constant pool items.
     */
    final static int FLOAT = 4;

    /**
     * The type of CONSTANT_Long constant pool items.
     */
    final static int LONG = 5;

    /**
     * The type of CONSTANT_Double constant pool items.
     */
    final static int DOUBLE = 6;

    /**
     * The type of CONSTANT_NameAndType constant pool items.
     */
    final static int NAME_TYPE = 12;

    /**
     * The type of CONSTANT_Utf8 constant pool items.
     */
    final static int UTF8 = 1;

    /**
     * Normal type Item stored in the ClassWriter {@link ClassWriter#typeTable},
     * instead of the constant pool, in order to avoid clashes with normal
     * constant pool items in the ClassWriter constant pool's hash table.
     */
    final static int TYPE_NORMAL = 13;

    /**
     * Uninitialized type Item stored in the ClassWriter
     * {@link ClassWriter#typeTable}, instead of the constant pool, in order to
     * avoid clashes with normal constant pool items in the ClassWriter constant
     * pool's hash table.
     */
    final static int TYPE_UNINIT = 14;

    /**
     * Merged type Item stored in the ClassWriter {@link ClassWriter#typeTable},
     * instead of the constant pool, in order to avoid clashes with normal
     * constant pool items in the ClassWriter constant pool's hash table.
     */
    final static int TYPE_MERGED = 15;

    /**
     * The class reader from which this class writer was constructed, if any.
     */
    ClassReader cr;

    /**
     * Minor and major version numbers of the class to be generated.
     */
    int version;

    /**
     * Index of the next item to be added in the constant pool.
     */
    int index;

    /**
     * The constant pool of this class.
     */
    ByteVector pool;

    /**
     * The constant pool's hash table data.
     */
    Item[] items;

    /**
     * The threshold of the constant pool's hash table.
     */
    int threshold;

    /**
     * A reusable key used to look for items in the {@link #items} hash table.
     */
    Item key;

    /**
     * A reusable key used to look for items in the {@link #items} hash table.
     */
    Item key2;

    /**
     * A reusable key used to look for items in the {@link #items} hash table.
     */
    Item key3;

    /**
     * A type table used to temporarily store internal names that will not
     * necessarily be stored in the constant pool. This type table is used by
     * the control flow and data flow analysis algorithm used to compute stack
     * map frames from scratch. This array associates to each index <tt>i</tt>
     * the Item whose index is <tt>i</tt>. All Item objects stored in this
     * array are also stored in the {@link #items} hash table. These two arrays
     * allow to retrieve an Item from its index or, conversly, to get the index
     * of an Item from its value. Each Item stores an internal name in its
     * {@link Item#strVal1} field.
     */
    Item[] typeTable;

    /**
     * Number of elements in the {@link #typeTable} array.
     */
    private short typeCount; // TODO int?

    /**
     * The access flags of this class.
     */
    private int access;

    /**
     * The constant pool item that contains the internal name of this class.
     */
    private int name;

    /**
     * The internal name of this class.
     */
    String thisName;

    /**
     * The constant pool item that contains the signature of this class.
     */
    private int signature;

    /**
     * The constant pool item that contains the internal name of the super class
     * of this class.
     */
    private int superName;

    /**
     * Number of interfaces implemented or extended by this class or interface.
     */
    private int interfaceCount;

    /**
     * The interfaces implemented or extended by this class or interface. More
     * precisely, this array contains the indexes of the constant pool items
     * that contain the internal names of these interfaces.
     */
    private int[] interfaces;

    /**