org.objectweb.asm
Interface CodeVisitor

All Known Implementing Classes:
ASMifierCodeVisitor, CheckCodeAdapter, CodeAdapter, CodeWriter, PrintCodeVisitor, SAXCodeAdapter, TraceCodeVisitor, TreeCodeAdapter

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).

Author:
Eric Bruneton

Method Summary
 void visitAttribute(Attribute attr)
          Visits a non standard attribute of the code.
 void visitFieldInsn(int opcode, String owner, String name, 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(Object cst)
          Visits a LDC instruction.
 void visitLineNumber(int line, Label start)
          Visits a line number declaration.
 void visitLocalVariable(String name, 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, String owner, String name, String desc)
          Visits a method instruction.
 void visitMultiANewArrayInsn(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, String type)
          Visits a try catch block.
 void visitTypeInsn(int opcode, String desc)
          Visits a type instruction.
 void visitVarInsn(int opcode, int var)
          Visits a local variable instruction.
 

Method Detail

visitInsn

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

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

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

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 Type).

visitFieldInsn

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

visitMethodInsn

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

visitJumpInsn

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

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

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 Integer, a Float, a Long, a Double a String (or a Type for .class constants, for classes whose version is 49.0 or more).

visitIincInsn

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

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

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

void visitMultiANewArrayInsn(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

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 visitLabel method).

visitMaxs

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

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 visitLabel method).

visitLineNumber

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 visitLabel method).

visitAttribute

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.