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Java example source code file (MethodVisitor.java)

This example Java source code file (MethodVisitor.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.

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Java - Java tags/keywords

annotationvisitor, label, methodvisitor, object, string

The MethodVisitor.java Java example source code

/*
 * Copyright (c) 2005, 2009, 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.
 */

/*
 * This file is available under and governed by the GNU General Public
 * License version 2 only, as published by the Free Software Foundation.
 * However, the following notice accompanied the original version of this
 * file:
 *
 * ASM: a very small and fast Java bytecode manipulation framework
 * Copyright (c) 2000-2007 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 com.sun.xml.internal.ws.org.objectweb.asm;

/**
 * A visitor to visit a Java method. The methods of this interface must be
 * called in the following order: [ <tt>visitAnnotationDefault ] (
 * <tt>visitAnnotation | visitParameterAnnotation |
 * <tt>visitAttribute )* [ visitCode ( visitFrame |
 * <tt>visitXInsn | visitLabel | visitTryCatchBlock |
 * <tt>visitLocalVariable | visitLineNumber)* visitMaxs ]
 * <tt>visitEnd. In addition, the visitXInsn
 * and <tt>visitLabel methods must be called in the sequential order of
 * the bytecode instructions of the visited code, <tt>visitTryCatchBlock
 * must be called <i>before the labels passed as arguments have been
 * visited, and the <tt>visitLocalVariable and visitLineNumber
 * methods must be called <i>after the labels passed as arguments have been
 * visited.
 *
 * @author Eric Bruneton
 */
public interface MethodVisitor {

    // -------------------------------------------------------------------------
    // Annotations and non standard attributes
    // -------------------------------------------------------------------------

    /**
     * Visits the default value of this annotation interface method.
     *
     * @return a visitor to the visit the actual default value of this
     *         annotation interface method, or <tt>null if this visitor
     *         is not interested in visiting this default value. The 'name'
     *         parameters passed to the methods of this annotation visitor are
     *         ignored. Moreover, exacly one visit method must be called on this
     *         annotation visitor, followed by visitEnd.
     */
    AnnotationVisitor visitAnnotationDefault();

    /**
     * Visits an annotation of this method.
     *
     * @param desc the class descriptor of the annotation class.
     * @param visible <tt>true if the annotation is visible at runtime.
     * @return a visitor to visit the annotation values, or <tt>null if
     *         this visitor is not interested in visiting this annotation.
     */
    AnnotationVisitor visitAnnotation(String desc, boolean visible);

    /**
     * Visits an annotation of a parameter this method.
     *
     * @param parameter the parameter index.
     * @param desc the class descriptor of the annotation class.
     * @param visible <tt>true if the annotation is visible at runtime.
     * @return a visitor to visit the annotation values, or <tt>null if
     *         this visitor is not interested in visiting this annotation.
     */
    AnnotationVisitor visitParameterAnnotation(
        int parameter,
        String desc,
        boolean visible);

    /**
     * Visits a non standard attribute of this method.
     *
     * @param attr an attribute.
     */
    void visitAttribute(Attribute attr);

    /**
     * Starts the visit of the method's code, if any (i.e. non abstract method).
     */
    void visitCode();

    /**
     * Visits the current state of the local variables and operand stack
     * elements. This method must(*) be called <i>just before any
     * instruction <b>i that follows an unconditionnal branch instruction
     * such as GOTO or THROW, that is the target of a jump instruction, or that
     * starts an exception handler block. The visited types must describe the
     * values of the local variables and of the operand stack elements <i>just
     * before</i> i is executed. 

(*) this is mandatory only * for classes whose version is greater than or equal to * {@link Opcodes#V1_6 V1_6}. <br>
Packed frames are basically * "deltas" from the state of the previous frame (very first frame is * implicitly defined by the method's parameters and access flags): <ul> * <li>{@link Opcodes#F_SAME} representing frame with exactly the same * locals as the previous frame and with the empty stack.</li>
  • {@link Opcodes#F_SAME1} * representing frame with exactly the same locals as the previous frame and * with single value on the stack (<code>nStack is 1 and * <code>stack[0] contains value for the type of the stack item).
  • * <li>{@link Opcodes#F_APPEND} representing frame with current locals are * the same as the locals in the previous frame, except that additional * locals are defined (<code>nLocal is 1, 2 or 3 and * <code>local elements contains values representing added types). * <li>{@link Opcodes#F_CHOP} representing frame with current locals are * the same as the locals in the previous frame, except that the last 1-3 * locals are absent and with the empty stack (<code>nLocals is 1, * 2 or 3). </li>
  • {@link Opcodes#F_FULL} representing complete frame * data.</li>
  • * * @param type the type of this stack map frame. Must be * {@link Opcodes#F_NEW} for expanded frames, or * {@link Opcodes#F_FULL}, {@link Opcodes#F_APPEND}, * {@link Opcodes#F_CHOP}, {@link Opcodes#F_SAME} or * {@link Opcodes#F_APPEND}, {@link Opcodes#F_SAME1} for compressed * frames. * @param nLocal the number of local variables in the visited frame. * @param local the local variable types in this frame. This array must not * be modified. Primitive types are represented by * {@link Opcodes#TOP}, {@link Opcodes#INTEGER}, * {@link Opcodes#FLOAT}, {@link Opcodes#LONG}, * {@link Opcodes#DOUBLE},{@link Opcodes#NULL} or * {@link Opcodes#UNINITIALIZED_THIS} (long and double are * represented by a single element). Reference types are represented * by String objects (representing internal names), and uninitialized * types by Label objects (this label designates the NEW instruction * that created this uninitialized value). * @param nStack the number of operand stack elements in the visited frame. * @param stack the operand stack types in this frame. This array must not * be modified. Its content has the same format as the "local" array. */ void visitFrame( int type, int nLocal, Object[] local, int nStack, Object[] stack); // ------------------------------------------------------------------------- // Normal instructions // ------------------------------------------------------------------------- /** * Visits a zero operand instruction. * * @param opcode the opcode of the instruction to be visited. This opcode is * either NOP, ACONST_NULL, ICONST_M1, ICONST_0, ICONST_1, ICONST_2, * ICONST_3, ICONST_4, ICONST_5, LCONST_0, LCONST_1, FCONST_0, * FCONST_1, FCONST_2, DCONST_0, DCONST_1, IALOAD, LALOAD, FALOAD, * DALOAD, AALOAD, BALOAD, CALOAD, SALOAD, IASTORE, LASTORE, FASTORE, * DASTORE, AASTORE, BASTORE, CASTORE, SASTORE, POP, POP2, DUP, * DUP_X1, DUP_X2, DUP2, DUP2_X1, DUP2_X2, SWAP, IADD, LADD, FADD, * DADD, ISUB, LSUB, FSUB, DSUB, IMUL, LMUL, FMUL, DMUL, IDIV, LDIV, * FDIV, DDIV, IREM, LREM, FREM, DREM, INEG, LNEG, FNEG, DNEG, ISHL, * LSHL, ISHR, LSHR, IUSHR, LUSHR, IAND, LAND, IOR, LOR, IXOR, LXOR, * I2L, I2F, I2D, L2I, L2F, L2D, F2I, F2L, F2D, D2I, D2L, D2F, I2B, * I2C, I2S, LCMP, FCMPL, FCMPG, DCMPL, DCMPG, IRETURN, LRETURN, * FRETURN, DRETURN, ARETURN, RETURN, ARRAYLENGTH, ATHROW, * MONITORENTER, or MONITOREXIT. */ void visitInsn(int opcode); /** * Visits an instruction with a single int operand. * * @param opcode the opcode of the instruction to be visited. This opcode is * either BIPUSH, SIPUSH or NEWARRAY. * @param operand the operand of the instruction to be visited.<br> When * opcode is BIPUSH, operand value should be between Byte.MIN_VALUE * and Byte.MAX_VALUE.<br> When opcode is SIPUSH, operand value * should be between Short.MIN_VALUE and Short.MAX_VALUE.<br> When * opcode is NEWARRAY, operand value should be one of * {@link Opcodes#T_BOOLEAN}, {@link Opcodes#T_CHAR}, * {@link Opcodes#T_FLOAT}, {@link Opcodes#T_DOUBLE}, * {@link Opcodes#T_BYTE}, {@link Opcodes#T_SHORT}, * {@link Opcodes#T_INT} or {@link Opcodes#T_LONG}. */ void visitIntInsn(int opcode, int operand); /** * Visits a local variable instruction. A local variable instruction is an * instruction that loads or stores the value of a local variable. * * @param opcode the opcode of the local variable instruction to be visited. * This opcode is either ILOAD, LLOAD, FLOAD, DLOAD, ALOAD, ISTORE, * LSTORE, FSTORE, DSTORE, ASTORE or RET. * @param var the operand of the instruction to be visited. This operand is * the index of a local variable. */ void visitVarInsn(int opcode, int var); /** * Visits a type instruction. A type instruction is an instruction that * takes the internal name of a class as parameter. * * @param opcode the opcode of the type instruction to be visited. This * opcode is either NEW, ANEWARRAY, CHECKCAST or INSTANCEOF. * @param type the operand of the instruction to be visited. This operand * must be the internal name of an object or array class (see {@link * Type#getInternalName() getInternalName}). */ void visitTypeInsn(int opcode, String type); /** * Visits a field instruction. A field instruction is an instruction that * loads or stores the value of a field of an object. * * @param opcode the opcode of the type instruction to be visited. This * opcode is either GETSTATIC, PUTSTATIC, GETFIELD or PUTFIELD. * @param owner the internal name of the field's owner class (see {@link * Type#getInternalName() getInternalName}). * @param name the field's name. * @param desc the field's descriptor (see {@link Type Type}). */ void visitFieldInsn(int opcode, String owner, String name, String desc); /** * Visits a method instruction. A method instruction is an instruction that * invokes a method. * * @param opcode the opcode of the type instruction to be visited. This * opcode is either INVOKEVIRTUAL, INVOKESPECIAL, INVOKESTATIC or * INVOKEINTERFACE. * @param owner the internal name of the method's owner class (see {@link * Type#getInternalName() getInternalName}). * @param name the method's name. * @param desc the method's descriptor (see {@link Type Type}). */ void visitMethodInsn(int opcode, String owner, String name, String desc); /** * Visits a jump instruction. A jump instruction is an instruction that may * jump to another instruction. * * @param opcode the opcode of the type instruction to be visited. This * opcode is either IFEQ, IFNE, IFLT, IFGE, IFGT, IFLE, IF_ICMPEQ, * IF_ICMPNE, IF_ICMPLT, IF_ICMPGE, IF_ICMPGT, IF_ICMPLE, IF_ACMPEQ, * IF_ACMPNE, GOTO, JSR, IFNULL or IFNONNULL. * @param label the operand of the instruction to be visited. This operand * is a label that designates the instruction to which the jump * instruction may jump. */ void visitJumpInsn(int opcode, Label label); /** * Visits a label. A label designates the instruction that will be visited * just after it. * * @param label a {@link Label Label} object. */ void visitLabel(Label label); // ------------------------------------------------------------------------- // Special instructions // ------------------------------------------------------------------------- /** * Visits a LDC instruction. * * @param cst the constant to be loaded on the stack. This parameter must be * a non null {@link Integer}, a {@link Float}, a {@link Long}, a * {@link Double} a {@link String} (or a {@link Type} for * <tt>.class constants, for classes whose version is 49.0 or * more). */ void visitLdcInsn(Object cst); /** * Visits an IINC instruction. * * @param var index of the local variable to be incremented. * @param increment amount to increment the local variable by. */ void visitIincInsn(int var, int increment); /** * Visits a TABLESWITCH instruction. * * @param min the minimum key value. * @param max the maximum key value. * @param dflt beginning of the default handler block. * @param labels beginnings of the handler blocks. <tt>labels[i] is * the beginning of the handler block for the <tt>min + i key. */ void visitTableSwitchInsn(int min, int max, Label dflt, Label[] labels); /** * Visits a LOOKUPSWITCH instruction. * * @param dflt beginning of the default handler block. * @param keys the values of the keys. * @param labels beginnings of the handler blocks. <tt>labels[i] is * the beginning of the handler block for the <tt>keys[i] key. */ void visitLookupSwitchInsn(Label dflt, int[] keys, Label[] labels); /** * Visits a MULTIANEWARRAY instruction. * * @param desc an array type descriptor (see {@link Type Type}). * @param dims number of dimensions of the array to allocate. */ void visitMultiANewArrayInsn(String desc, int dims); // ------------------------------------------------------------------------- // Exceptions table entries, debug information, max stack and max locals // ------------------------------------------------------------------------- /** * Visits a try catch block. * * @param start beginning of the exception handler's scope (inclusive). * @param end end of the exception handler's scope (exclusive). * @param handler beginning of the exception handler's code. * @param type internal name of the type of exceptions handled by the * handler, or <tt>null to catch any exceptions (for "finally" * blocks). * @throws IllegalArgumentException if one of the labels has already been * visited by this visitor (by the {@link #visitLabel visitLabel} * method). */ void visitTryCatchBlock(Label start, Label end, Label handler, String type); /** * Visits a local variable declaration. * * @param name the name of a local variable. * @param desc the type descriptor of this local variable. * @param signature the type signature of this local variable. May be * <tt>null if the local variable type does not use generic * types. * @param start the first instruction corresponding to the scope of this * local variable (inclusive). * @param end the last instruction corresponding to the scope of this local * variable (exclusive). * @param index the local variable's index. * @throws IllegalArgumentException if one of the labels has not already * been visited by this visitor (by the * {@link #visitLabel visitLabel} method). */ void visitLocalVariable( String name, String desc, String signature, Label start, Label end, int index); /** * Visits a line number declaration. * * @param line a line number. This number refers to the source file from * which the class was compiled. * @param start the first instruction corresponding to this line number. * @throws IllegalArgumentException if <tt>start has not already been * visited by this visitor (by the {@link #visitLabel visitLabel} * method). */ void visitLineNumber(int line, Label start); /** * Visits the maximum stack size and the maximum number of local variables * of the method. * * @param maxStack maximum stack size of the method. * @param maxLocals maximum number of local variables for the method. */ void visitMaxs(int maxStack, int maxLocals); /** * Visits the end of the method. This method, which is the last one to be * called, is used to inform the visitor that all the annotations and * attributes of the method have been visited. */ void visitEnd(); }

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