org.objectweb.asm

Interface CodeVisitor

public interface CodeVisitor

A visitor to visit the bytecode instructions of a Java method. The methods of this visitor must be called in the sequential order of the bytecode instructions of the visited code. The {@link #visitMaxs visitMaxs} method must be called after all the instructions have been visited. The {@link #visitTryCatchBlock visitTryCatchBlock}, {@link #visitLocalVariable visitLocalVariable} and {@link #visitLineNumber visitLineNumber} methods may be called in any order, at any time (provided the labels passed as arguments have already been visited with {@link #visitLabel visitLabel}).

Author: Eric Bruneton

Method Summary
voidvisitAttribute(Attribute attr)
Visits a non standard attribute of the code.
voidvisitFieldInsn(int opcode, String owner, String name, String desc)
Visits a field instruction.
voidvisitIincInsn(int var, int increment)
Visits an IINC instruction.
voidvisitInsn(int opcode)
Visits a zero operand instruction.
voidvisitIntInsn(int opcode, int operand)
Visits an instruction with a single int operand.
voidvisitJumpInsn(int opcode, Label label)
Visits a jump instruction.
voidvisitLabel(Label label)
Visits a label.
voidvisitLdcInsn(Object cst)
Visits a LDC instruction.
voidvisitLineNumber(int line, Label start)
Visits a line number declaration.
voidvisitLocalVariable(String name, String desc, Label start, Label end, int index)
Visits a local variable declaration.
voidvisitLookupSwitchInsn(Label dflt, int[] keys, Label[] labels)
Visits a LOOKUPSWITCH instruction.
voidvisitMaxs(int maxStack, int maxLocals)
Visits the maximum stack size and the maximum number of local variables of the method.
voidvisitMethodInsn(int opcode, String owner, String name, String desc)
Visits a method instruction.
voidvisitMultiANewArrayInsn(String desc, int dims)
Visits a MULTIANEWARRAY instruction.
voidvisitTableSwitchInsn(int min, int max, Label dflt, Label[] labels)
Visits a TABLESWITCH instruction.
voidvisitTryCatchBlock(Label start, Label end, Label handler, String type)
Visits a try catch block.
voidvisitTypeInsn(int opcode, String desc)
Visits a type instruction.
voidvisitVarInsn(int opcode, int var)
Visits a local variable instruction.

Method Detail

visitAttribute

public void visitAttribute(Attribute attr)
Visits a non standard attribute of the code. This method must visit only the first attribute in the given attribute list.

Parameters: attr a non standard code attribute. Must not be null.

visitFieldInsn

public void visitFieldInsn(int opcode, String owner, String name, String desc)
Visits a field instruction. A field instruction is an instruction that loads or stores the value of a field of an object.

Parameters: opcode the opcode of the type instruction to be visited. This opcode is either GETSTATIC, PUTSTATIC, GETFIELD or PUTFIELD. owner the internal name of the field's owner class (see {@link Type#getInternalName() getInternalName}). name the field's name. desc the field's descriptor (see {@link Type Type}).

visitIincInsn

public void visitIincInsn(int var, int increment)
Visits an IINC instruction.

Parameters: var index of the local variable to be incremented. increment amount to increment the local variable by.

visitInsn

public void visitInsn(int opcode)
Visits a zero operand instruction.

Parameters: 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.

visitIntInsn

public void visitIntInsn(int opcode, int operand)
Visits an instruction with a single int operand.

Parameters: opcode the opcode of the instruction to be visited. This opcode is either BIPUSH, SIPUSH or NEWARRAY. operand the operand of the instruction to be visited.

visitJumpInsn

public void visitJumpInsn(int opcode, Label label)
Visits a jump instruction. A jump instruction is an instruction that may jump to another instruction.

Parameters: 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. 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.

visitLabel

public void visitLabel(Label label)
Visits a label. A label designates the instruction that will be visited just after it.

Parameters: label a {@link Label Label} object.

visitLdcInsn

public void visitLdcInsn(Object cst)
Visits a LDC instruction.

Parameters: cst the constant to be loaded on the stack. This parameter must be a non null {@link java.lang.Integer Integer}, a {@link java.lang.Float Float}, a {@link java.lang.Long Long}, a {@link java.lang.Double Double} a {@link String String} (or a {@link Type Type} for .class constants, for classes whose version is 49.0 or more).

visitLineNumber

public void visitLineNumber(int line, Label start)
Visits a line number declaration.

Parameters: line a line number. This number refers to the source file from which the class was compiled. start the first instruction corresponding to this line number.

Throws: IllegalArgumentException if start has not already been visited by this visitor (by the {@link #visitLabel visitLabel} method).

visitLocalVariable

public void visitLocalVariable(String name, String desc, Label start, Label end, int index)
Visits a local variable declaration.

Parameters: name the name of a local variable. desc the type descriptor of this local variable. start the first instruction corresponding to the scope of this local variable (inclusive). end the last instruction corresponding to the scope of this local variable (exclusive). 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).

visitLookupSwitchInsn

public void visitLookupSwitchInsn(Label dflt, int[] keys, Label[] labels)
Visits a LOOKUPSWITCH instruction.

Parameters: dflt beginning of the default handler block. keys the values of the keys. labels beginnings of the handler blocks. labels[i] is the beginning of the handler block for the keys[i] key.

visitMaxs

public void visitMaxs(int maxStack, int maxLocals)
Visits the maximum stack size and the maximum number of local variables of the method.

Parameters: maxStack maximum stack size of the method. maxLocals maximum number of local variables for the method.

visitMethodInsn

public void visitMethodInsn(int opcode, String owner, String name, String desc)
Visits a method instruction. A method instruction is an instruction that invokes a method.

Parameters: opcode the opcode of the type instruction to be visited. This opcode is either INVOKEVIRTUAL, INVOKESPECIAL, INVOKESTATIC or INVOKEINTERFACE. owner the internal name of the method's owner class (see {@link Type#getInternalName() getInternalName}). name the method's name. desc the method's descriptor (see {@link Type Type}).

visitMultiANewArrayInsn

public void visitMultiANewArrayInsn(String desc, int dims)
Visits a MULTIANEWARRAY instruction.

Parameters: desc an array type descriptor (see {@link Type Type}). dims number of dimensions of the array to allocate.

visitTableSwitchInsn

public void visitTableSwitchInsn(int min, int max, Label dflt, Label[] labels)
Visits a TABLESWITCH instruction.

Parameters: min the minimum key value. max the maximum key value. dflt beginning of the default handler block. labels beginnings of the handler blocks. labels[i] is the beginning of the handler block for the min + i key.

visitTryCatchBlock

public void visitTryCatchBlock(Label start, Label end, Label handler, String type)
Visits a try catch block.

Parameters: start beginning of the exception handler's scope (inclusive). end end of the exception handler's scope (exclusive). handler beginning of the exception handler's code. type internal name of the type of exceptions handled by the handler, or null to catch any exceptions (for "finally" blocks).

Throws: IllegalArgumentException if one of the labels has not already been visited by this visitor (by the {@link #visitLabel visitLabel} method).

visitTypeInsn

public void visitTypeInsn(int opcode, String desc)
Visits a type instruction. A type instruction is an instruction that takes a type descriptor as parameter.

Parameters: opcode the opcode of the type instruction to be visited. This opcode is either NEW, ANEWARRAY, CHECKCAST or INSTANCEOF. desc the operand of the instruction to be visited. This operand is must be a fully qualified class name in internal form, or the type descriptor of an array type (see {@link Type Type}).

visitVarInsn

public void visitVarInsn(int opcode, int var)
Visits a local variable instruction. A local variable instruction is an instruction that loads or stores the value of a local variable.

Parameters: 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. var the operand of the instruction to be visited. This operand is the index of a local variable.