org.objectweb.asm.commons
Class LocalVariablesSorter

java.lang.Object
  extended by org.objectweb.asm.MethodAdapter
      extended by org.objectweb.asm.commons.LocalVariablesSorter
All Implemented Interfaces:
MethodVisitor
Direct Known Subclasses:
GeneratorAdapter, RemappingMethodAdapter

public class LocalVariablesSorter
extends MethodAdapter

A MethodAdapter that renumbers local variables in their order of appearance. This adapter allows one to easily add new local variables to a method. It may be used by inheriting from this class, but the preferred way of using it is via delegation: the next visitor in the chain can indeed add new locals when needed by calling newLocal(org.objectweb.asm.Type) on this adapter (this requires a reference back to this LocalVariablesSorter).

Author:
Chris Nokleberg, Eugene Kuleshov, Eric Bruneton

Field Summary
protected  int firstLocal
          Index of the first local variable, after formal parameters.
protected  int nextLocal
          Index of the next local variable to be created by newLocal(org.objectweb.asm.Type).
 
Fields inherited from class org.objectweb.asm.MethodAdapter
mv
 
Constructor Summary
LocalVariablesSorter(int access, String desc, MethodVisitor mv)
          Creates a new LocalVariablesSorter.
 
Method Summary
 int newLocal(Type type)
          Creates a new local variable of the given type.
protected  int newLocalMapping(Type type)
           
protected  void setLocalType(int local, Type type)
          Sets the current type of the given local variable.
 void visitFrame(int type, int nLocal, Object[] local, int nStack, Object[] stack)
          Visits the current state of the local variables and operand stack elements.
 void visitIincInsn(int var, int increment)
          Visits an IINC instruction.
 void visitLocalVariable(String name, String desc, String signature, Label start, Label end, int index)
          Visits a local variable declaration.
 void visitMaxs(int maxStack, int maxLocals)
          Visits the maximum stack size and the maximum number of local variables of the method.
 void visitVarInsn(int opcode, int var)
          Visits a local variable instruction.
 
Methods inherited from class org.objectweb.asm.MethodAdapter
visitAnnotation, visitAnnotationDefault, visitAttribute, visitCode, visitEnd, visitFieldInsn, visitInsn, visitIntInsn, visitJumpInsn, visitLabel, visitLdcInsn, visitLineNumber, visitLookupSwitchInsn, visitMethodInsn, visitMultiANewArrayInsn, visitParameterAnnotation, visitTableSwitchInsn, visitTryCatchBlock, visitTypeInsn
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

firstLocal

protected final int firstLocal
Index of the first local variable, after formal parameters.


nextLocal

protected int nextLocal
Index of the next local variable to be created by newLocal(org.objectweb.asm.Type).

Constructor Detail

LocalVariablesSorter

public LocalVariablesSorter(int access,
                            String desc,
                            MethodVisitor mv)
Creates a new LocalVariablesSorter.

Parameters:
access - access flags of the adapted method.
desc - the method's descriptor (see Type).
mv - the method visitor to which this adapter delegates calls.
Method Detail

visitVarInsn

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

Specified by:
visitVarInsn in interface MethodVisitor
Overrides:
visitVarInsn in class MethodAdapter
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.

visitIincInsn

public void visitIincInsn(int var,
                          int increment)
Description copied from interface: MethodVisitor
Visits an IINC instruction.

Specified by:
visitIincInsn in interface MethodVisitor
Overrides:
visitIincInsn in class MethodAdapter
Parameters:
var - index of the local variable to be incremented.
increment - amount to increment the local variable by.

visitMaxs

public void visitMaxs(int maxStack,
                      int maxLocals)
Description copied from interface: MethodVisitor
Visits the maximum stack size and the maximum number of local variables of the method.

Specified by:
visitMaxs in interface MethodVisitor
Overrides:
visitMaxs in class MethodAdapter
Parameters:
maxStack - maximum stack size of the method.
maxLocals - maximum number of local variables for the method.

visitLocalVariable

public void visitLocalVariable(String name,
                               String desc,
                               String signature,
                               Label start,
                               Label end,
                               int index)
Description copied from interface: MethodVisitor
Visits a local variable declaration.

Specified by:
visitLocalVariable in interface MethodVisitor
Overrides:
visitLocalVariable in class MethodAdapter
Parameters:
name - the name of a local variable.
desc - the type descriptor of this local variable.
signature - the type signature of this local variable. May be null if the local variable type does not use generic types.
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.

visitFrame

public void visitFrame(int type,
                       int nLocal,
                       Object[] local,
                       int nStack,
                       Object[] stack)
Description copied from interface: MethodVisitor
Visits the current state of the local variables and operand stack elements. This method must(*) be called just before any instruction i that follows an unconditional 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 just before i is executed.

(*) this is mandatory only for classes whose version is greater than or equal to V1_6.

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):

Specified by:
visitFrame in interface MethodVisitor
Overrides:
visitFrame in class MethodAdapter
Parameters:
type - the type of this stack map frame. Must be Opcodes.F_NEW for expanded frames, or Opcodes.F_FULL, Opcodes.F_APPEND, Opcodes.F_CHOP, Opcodes.F_SAME or Opcodes.F_APPEND, Opcodes.F_SAME1 for compressed frames.
nLocal - the number of local variables in the visited frame.
local - the local variable types in this frame. This array must not be modified. Primitive types are represented by Opcodes.TOP, Opcodes.INTEGER, Opcodes.FLOAT, Opcodes.LONG, Opcodes.DOUBLE,Opcodes.NULL or 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).
nStack - the number of operand stack elements in the visited frame.
stack - the operand stack types in this frame. This array must not be modified. Its content has the same format as the "local" array.

newLocal

public int newLocal(Type type)
Creates a new local variable of the given type.

Parameters:
type - the type of the local variable to be created.
Returns:
the identifier of the newly created local variable.

setLocalType

protected void setLocalType(int local,
                            Type type)
Sets the current type of the given local variable. The default implementation of this method does nothing.

Parameters:
local - a local variable identifier, as returned by newLocal().
type - the type of the value being stored in the local variable

newLocalMapping

protected int newLocalMapping(Type type)