Java tutorial
/*** * 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.google.gwt.dev.asm; /** * A visitor to visit a Java method. The methods of this interface must be * called in the following order: [ <tt>visitAnnotationDefault</tt> ] ( * <tt>visitAnnotation</tt> | <tt>visitParameterAnnotation</tt> | * <tt>visitAttribute</tt> )* [ <tt>visitCode</tt> ( <tt>visitFrame</tt> | * <tt>visit</tt><i>X</i>Insn</tt> | <tt>visitLabel</tt> | <tt>visitTryCatchBlock</tt> | * <tt>visitLocalVariable</tt> | <tt>visitLineNumber</tt>)* <tt>visitMaxs</tt> ] * <tt>visitEnd</tt>. In addition, the <tt>visit</tt><i>X</i>Insn</tt> * and <tt>visitLabel</tt> methods must be called in the sequential order of * the bytecode instructions of the visited code, <tt>visitTryCatchBlock</tt> * must be called <i>before</i> the labels passed as arguments have been * visited, and the <tt>visitLocalVariable</tt> and <tt>visitLineNumber</tt> * methods must be called <i>after</i> 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</tt> 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</tt> if the annotation is visible at runtime. * @return a visitor to visit the annotation values, or <tt>null</tt> 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</tt> if the annotation is visible at runtime. * @return a visitor to visit the annotation values, or <tt>null</tt> 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</i> any * instruction <b>i</b> 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> <b>i</b> is executed. <br> <br> (*) this is mandatory only * for classes whose version is greater than or equal to * {@link Opcodes#V1_6 V1_6}. <br> <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> <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</code> is 1 and * <code>stack[0]</code> contains value for the type of the stack item).</li> * <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</code> is 1, 2 or 3 and * <code>local</code> elements contains values representing added types).</li> * <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</code> is 1, * 2 or 3). </li> <li>{@link Opcodes#F_FULL} representing complete frame * data.</li> </li> </ul> * * @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</tt> 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]</tt> is * the beginning of the handler block for the <tt>min + i</tt> 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]</tt> is * the beginning of the handler block for the <tt>keys[i]</tt> 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</tt> 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</tt> 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</tt> 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(); }