org.objectweb.asm
Interface CodeVisitor

All Known Implementing Classes:

CodeWriter

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 visitMaxs method must be called after all the instructions have been visited. The visitTryCatchBlock, visitLocalVariable and visitLineNumber methods may be called in any order, at any time (provided the labels passed as arguments have already been visited with visitLabel).

Method Summary

void	visitFieldInsn(int opcode, java.lang.String owner, java.lang.String name, java.lang.String desc) Visits a field instruction.
void	visitIincInsn(int var, int increment) Visits an IINC instruction.
void	visitInsn(int opcode) Visits a zero operand instruction.
void	visitIntInsn(int opcode, int operand) Visits an instruction with a single int operand.
void	visitJumpInsn(int opcode, Label label) Visits a jump instruction.
void	visitLabel(Label label) Visits a label.
void	visitLdcInsn(java.lang.Object cst) Visits a LDC instruction.
void	visitLineNumber(int line, Label start) Visits a line number declaration.
void	visitLocalVariable(java.lang.String name, java.lang.String desc, Label start, Label end, int index) Visits a local variable declaration.
void	visitLookupSwitchInsn(Label dflt, int[] keys, Label[] labels) Visits a LOOKUPSWITCH instruction.
void	visitMaxs(int maxStack, int maxLocals) Visits the maximum stack size and the maximum number of local variables of the method.
void	visitMethodInsn(int opcode, java.lang.String owner, java.lang.String name, java.lang.String desc) Visits a method instruction.
void	visitMultiANewArrayInsn(java.lang.String desc, int dims) Visits a MULTIANEWARRAY instruction.
void	visitTableSwitchInsn(int min, int max, Label dflt, Label[] labels) Visits a TABLESWITCH instruction.
void	visitTryCatchBlock(Label start, Label end, Label handler, java.lang.String type) Visits a try catch block.
void	visitTypeInsn(int opcode, java.lang.String desc) Visits a type instruction.
void	visitVarInsn(int opcode, int var) Visits a local variable instruction.

Method Detail

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.

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.

visitTypeInsn

public void visitTypeInsn(int opcode,
                          java.lang.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 Type).

visitFieldInsn

public void visitFieldInsn(int opcode,
                           java.lang.String owner,
                           java.lang.String name,
                           java.lang.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 getInternalName).

name - the field's name.

desc - the field's descriptor (see Type).

visitMethodInsn

public void visitMethodInsn(int opcode,
                            java.lang.String owner,
                            java.lang.String name,
                            java.lang.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 getInternalName).

name - the method's name.

desc - the method's descriptor (see Type).

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 Label object.

visitLdcInsn

public void visitLdcInsn(java.lang.Object cst)

Visits a LDC instruction.

Parameters:

cst - the constant to be loaded on the stack. This parameter must be a non null Integer, a Float, a Long, a Double or a String.

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.

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.

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.

visitMultiANewArrayInsn

public void visitMultiANewArrayInsn(java.lang.String desc,
                                    int dims)

Visits a MULTIANEWARRAY instruction.

Parameters:

desc - an array type descriptor (see Type).

dims - number of dimensions of the array to allocate.

visitTryCatchBlock

public void visitTryCatchBlock(Label start,
                               Label end,
                               Label handler,
                               java.lang.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:

java.lang.IllegalArgumentException - if one of the labels has not already been visited by this visitor (by the visitLabel method).

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.

visitLocalVariable

public void visitLocalVariable(java.lang.String name,
                               java.lang.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:

java.lang.IllegalArgumentException - if one of the labels has not already been visited by this visitor (by the visitLabel method).

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:

java.lang.IllegalArgumentException - if start has not already been visited by this visitor (by the visitLabel method).