org.objectweb.asm

Interface CodeVisitor

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, keys[] , 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, 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 Details

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.

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 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 Integer, a Float, a Long, a Double a String (or a 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.

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.

visitLookupSwitchInsn

public void visitLookupSwitchInsn(Label dflt,
                                  keys[] ,
                                  labels[] )
Visits a LOOKUPSWITCH instruction.
Parameters:
dflt - beginning of the default handler block.

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.

visitMultiANewArrayInsn

public 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.

visitTableSwitchInsn

public void visitTableSwitchInsn(int min,
                                 int max,
                                 Label dflt,
                                 labels[] )
Visits a TABLESWITCH instruction.
Parameters:
min - the minimum key value.
max - the maximum key value.
dflt - beginning of the default handler block.

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).

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.

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.