generatoradapter.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.commons;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

import org.objectweb.asm.ClassVisitor;
import org.objectweb.asm.Label;
import org.objectweb.asm.MethodVisitor;
import org.objectweb.asm.Opcodes;
import org.objectweb.asm.Type;

/**
 * A {@link org.objectweb.asm.MethodAdapter} with convenient methods to generate
 * code. For example, using this adapter, the class below
 * 
 * <pre>
 * public class Example {
 *     public static void main(String[] args) {
 *         System.out.println(&quot;Hello world!&quot;);
 *     }
 * }
 * </pre>
 * 
 * can be generated as follows:
 * 
 * <pre>
 * ClassWriter cw = new ClassWriter(true);
 * cw.visit(V1_1, ACC_PUBLIC, &quot;Example&quot;, null, &quot;java/lang/Object&quot;, null);
 * 
 * Method m = Method.getMethod(&quot;void &lt;init&gt; ()&quot;);
 * GeneratorAdapter mg = new GeneratorAdapter(ACC_PUBLIC, m, null, null, cw);
 * mg.loadThis();
 * mg.invokeConstructor(Type.getType(Object.class), m);
 * mg.returnValue();
 * mg.endMethod();
 * 
 * m = Method.getMethod(&quot;void main (String[])&quot;);
 * mg = new GeneratorAdapter(ACC_PUBLIC + ACC_STATIC, m, null, null, cw);
 * mg.getStatic(Type.getType(System.class), &quot;out&quot;, Type.getType(PrintStream.class));
 * mg.push(&quot;Hello world!&quot;);
 * mg.invokeVirtual(Type.getType(PrintStream.class), Method.getMethod(&quot;void println (String)&quot;));
 * mg.returnValue();
 * mg.endMethod();
 * 
 * cw.visitEnd();
 * </pre>
 * 
 * @author Juozas Baliuka
 * @author Chris Nokleberg
 * @author Eric Bruneton
 */
public class GeneratorAdapter extends LocalVariablesSorter {

    private final static Type BYTE_TYPE = Type.getObjectType("java/lang/Byte");

    private final static Type BOOLEAN_TYPE = Type.getObjectType("java/lang/Boolean");

    private final static Type SHORT_TYPE = Type.getObjectType("java/lang/Short");

    private final static Type CHARACTER_TYPE = Type.getObjectType("java/lang/Character");

    private final static Type INTEGER_TYPE = Type.getObjectType("java/lang/Integer");

    private final static Type FLOAT_TYPE = Type.getObjectType("java/lang/Float");

    private final static Type LONG_TYPE = Type.getObjectType("java/lang/Long");

    private final static Type DOUBLE_TYPE = Type.getObjectType("java/lang/Double");

    private final static Type NUMBER_TYPE = Type.getObjectType("java/lang/Number");

    private final static Type OBJECT_TYPE = Type.getObjectType("java/lang/Object");

    private final static Method BOOLEAN_VALUE = Method.getMethod("boolean booleanValue()");

    private final static Method CHAR_VALUE = Method.getMethod("char charValue()");

    private final static Method INT_VALUE = Method.getMethod("int intValue()");

    private final static Method FLOAT_VALUE = Method.getMethod("float floatValue()");

    private final static Method LONG_VALUE = Method.getMethod("long longValue()");

    private final static Method DOUBLE_VALUE = Method.getMethod("double doubleValue()");

    /**
     * Constant for the {@link #math math} method.
     */
    public final static int ADD = Opcodes.IADD;

    /**
     * Constant for the {@link #math math} method.
     */
    public final static int SUB = Opcodes.ISUB;

    /**
     * Constant for the {@link #math math} method.
     */
    public final static int MUL = Opcodes.IMUL;

    /**
     * Constant for the {@link #math math} method.
     */
    public final static int DIV = Opcodes.IDIV;

    /**
     * Constant for the {@link #math math} method.
     */
    public final static int REM = Opcodes.IREM;

    /**
     * Constant for the {@link #math math} method.
     */
    public final static int NEG = Opcodes.INEG;

    /**
     * Constant for the {@link #math math} method.
     */
    public final static int SHL = Opcodes.ISHL;

    /**
     * Constant for the {@link #math math} method.
     */
    public final static int SHR = Opcodes.ISHR;

    /**
     * Constant for the {@link #math math} method.
     */
    public final static int USHR = Opcodes.IUSHR;

    /**
     * Constant for the {@link #math math} method.
     */
    public final static int AND = Opcodes.IAND;

    /**
     * Constant for the {@link #math math} method.
     */
    public final static int OR = Opcodes.IOR;

    /**
     * Constant for the {@link #math math} method.
     */
    public final static int XOR = Opcodes.IXOR;

    /**
     * Constant for the {@link #ifCmp ifCmp} method.
     */
    public final static int EQ = Opcodes.IFEQ;

    /**
     * Constant for the {@link #ifCmp ifCmp} method.
     */
    public final static int NE = Opcodes.IFNE;

    /**
     * Constant for the {@link #ifCmp ifCmp} method.
     */
    public final static int LT = Opcodes.IFLT;

    /**
     * Constant for the {@link #ifCmp ifCmp} method.
     */
    public final static int GE = Opcodes.IFGE;

    /**
     * Constant for the {@link #ifCmp ifCmp} method.
     */
    public final static int GT = Opcodes.IFGT;

    /**
     * Constant for the {@link #ifCmp ifCmp} method.
     */
    public final static int LE = Opcodes.IFLE;

    /**
     * Access flags of the method visited by this adapter.
     */
    private final int access;

    /**
     * Return type of the method visited by this adapter.
     */
    private final Type returnType;

    /**
     * Argument types of the method visited by this adapter.
     */
    private final Type[] argumentTypes;

    /**
     * Types of the local variables of the method visited by this adapter.
     */
    private final List localTypes = new ArrayList();

    /**
     * Creates a new {@link GeneratorAdapter}.
     * 
     * @param mv the method visitor to which this adapter delegates calls.
     * @param access the method's access flags (see {@link Opcodes}).
     * @param name the method's name.
     * @param desc the method's descriptor (see {@link Type Type}).
     */
    public GeneratorAdapter(
        final MethodVisitor mv,
        final int access,
        final String name,
        final String desc)
    {
        super(access, desc, mv);
        this.access = access;
        this.returnType = Type.getReturnType(desc);
        this.argumentTypes = Type.getArgumentTypes(desc);
    }

    /**
     * Creates a new {@link GeneratorAdapter}.
     * 
     * @param access access flags of the adapted method.
     * @param method the adapted method.
     * @param mv the method visitor to which this adapter delegates calls.
     */
    public GeneratorAdapter(
        final int access,
        final Method method,
        final MethodVisitor mv)
    {
        super(access, method.getDescriptor(), mv);
        this.access = access;
        this.returnType = method.getReturnType();
        this.argumentTypes = method.getArgumentTypes();
    }

    /**
     * Creates a new {@link GeneratorAdapter}.
     * 
     * @param access access flags of the adapted method.
     * @param method the adapted method.
     * @param signature the signature of the adapted method (may be
     *        <tt>null</tt>).
     * @param exceptions the exceptions thrown by the adapted method (may be
     *        <tt>null</tt>).
     * @param cv the class visitor to which this adapter delegates calls.
     */
    public GeneratorAdapter(
        final int access,
        final Method method,
        final String signature,
        final Type[] exceptions,
        final ClassVisitor cv)
    {
        this(access, method, cv.visitMethod(access,
                method.getName(),
                method.getDescriptor(),
                signature,
                getInternalNames(exceptions)));
    }

    /**
     * Returns the internal names of the given types.
     * 
     * @param types a set of types.
     * @return the internal names of the given types.
     */
    private static String[] getInternalNames(final Type[] types) {
        if (types == null) {
            return null;
        }
        String[] names = new String[types.length];
        for (int i = 0; i < names.length; ++i) {
            names[i] = types[i].getInternalName();
        }
        return names;
    }

    // ------------------------------------------------------------------------
    // Instructions to push constants on the stack
    // ------------------------------------------------------------------------

    /**
     * Generates the instruction to push the given value on the stack.
     * 
     * @param value the value to be pushed on the stack.
     */
    public void push(final boolean value) {
        push(value ? 1 : 0);
    }

    /**
     * Generates the instruction to push the given value on the stack.
     * 
     * @param value the value to be pushed on the stack.
     */
    public void push(final int value) {
        if (value >= -1 && value <= 5) {
            mv.visitInsn(Opcodes.ICONST_0 + value);
        } else if (value >= Byte.MIN_VALUE && value <= Byte.MAX_VALUE) {
            mv.visitIntInsn(Opcodes.BIPUSH, value);
        } else if (value >= Short.MIN_VALUE && value <= Short.MAX_VALUE) {
            mv.visitIntInsn(Opcodes.SIPUSH, value);
        } else {
            mv.visitLdcInsn(new Integer(value));
        }
    }

    /**
     * Generates the instruction to push the given value on the stack.
     * 
     * @param value the value to be pushed on the stack.
     */
    public void push(final long value) {
        if (value == 0L || value == 1L) {
            mv.visitInsn(Opcodes.LCONST_0 + (int) value);
        } else {
            mv.visitLdcInsn(new Long(value));
        }
    }

    /**
     * Generates the instruction to push the given value on the stack.
     * 
     * @param value the value to be pushed on the stack.
     */
    public void push(final float value) {
        int bits = Float.floatToIntBits(value);
        if (bits == 0L || bits == 0x3f800000 || bits == 0x40000000) { // 0..2
            mv.visitInsn(Opcodes.FCONST_0 + (int) value);
        } else {
            mv.visitLdcInsn(new Float(value));