org.objectweb.asm.commons
Class LocalVariablesSorter
- MethodVisitor
public class LocalVariablesSorter
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(Type)
on this adapter (this
requires a reference back to this
LocalVariablesSorter
).
- Chris Nokleberg
- Eugene Kuleshov
- Eric Bruneton
protected int | firstLocal - Index of the first local variable, after formal parameters.
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protected int | nextLocal - Index of the next local variable to be created by
newLocal(Type) .
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int | newLocal(Type type) - Creates a new local variable of the given type.
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protected int | newLocalMapping(Type type)
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protected void | setLocalType(int local, Type type) - Sets the current type of the given local variable.
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void | visitFrame(int type, int nLocal, Object[] local, int nStack, Object[] stack) - Visits the current state of the local variables and operand stack
elements.
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void | visitIincInsn(int var, int increment) - Visits an IINC instruction.
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void | visitLocalVariable(String name, String desc, String signature, Label start, Label end, int index) - Visits a local variable declaration.
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void | visitMaxs(int maxStack, int maxLocals) - Visits the maximum stack size and the maximum number of local variables
of the method.
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void | visitVarInsn(int opcode, int var) - Visits a local variable instruction.
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visitAnnotation , visitAnnotationDefault , visitAttribute , visitCode , visitEnd , visitFieldInsn , visitFrame , visitIincInsn , visitInsn , visitIntInsn , visitJumpInsn , visitLabel , visitLdcInsn , visitLineNumber , visitLocalVariable , visitLookupSwitchInsn , visitMaxs , visitMethodInsn , visitMultiANewArrayInsn , visitParameterAnnotation , visitTableSwitchInsn , visitTryCatchBlock , visitTypeInsn , visitVarInsn |
firstLocal
protected final int firstLocal
Index of the first local variable, after formal parameters.
nextLocal
protected int nextLocal
LocalVariablesSorter
public LocalVariablesSorter(int access,
String desc,
MethodVisitor mv)
access
- access flags of the adapted method.desc
- the method's descriptor (see Type
).mv
- the method visitor to which this adapter delegates calls.
newLocal
public int newLocal(Type type)
Creates a new local variable of the given type.
type
- the type of the local variable to be created.
- the identifier of the newly created local variable.
newLocalMapping
protected int newLocalMapping(Type type)
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.
local
- a local variable identifier, as returned by newLocal()
.type
- the type of the value being stored in the local variable
visitFrame
public void visitFrame(int type,
int nLocal,
Object[] local,
int nStack,
Object[] stack)
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 unconditionnal 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):
Opcodes.F_SAME
representing frame with exactly the same
locals as the previous frame and with the empty stack.Opcodes.F_SAME1
representing frame with exactly the same locals as the previous frame and
with single value on the stack (nStack
is 1 and
stack[0]
contains value for the type of the stack item).Opcodes.F_APPEND
representing frame with current locals are
the same as the locals in the previous frame, except that additional
locals are defined (nLocal
is 1, 2 or 3 and
local
elements contains values representing added types).Opcodes.F_CHOP
representing frame with current locals are
the same as the locals in the previous frame, except that the last 1-3
locals are absent and with the empty stack (nLocals
is 1,
2 or 3). Opcodes.F_FULL
representing complete frame
data.
- visitFrame in interface MethodVisitor
- visitFrame in interface MethodAdapter
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.
visitIincInsn
public void visitIincInsn(int var,
int increment)
Visits an IINC instruction.
- visitIincInsn in interface MethodVisitor
- visitIincInsn in interface MethodAdapter
var
- index of the local variable to be incremented.increment
- amount to increment the local variable by.
visitLocalVariable
public void visitLocalVariable(String name,
String desc,
String signature,
Label start,
Label end,
int index)
Visits a local variable declaration.
- visitLocalVariable in interface MethodVisitor
- visitLocalVariable in interface MethodAdapter
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.
visitMaxs
public void visitMaxs(int maxStack,
int maxLocals)
Visits the maximum stack size and the maximum number of local variables
of the method.
- visitMaxs in interface MethodVisitor
- visitMaxs in interface MethodAdapter
maxStack
- maximum stack size of the method.maxLocals
- maximum number of local variables for the method.
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.
- visitVarInsn in interface MethodVisitor
- visitVarInsn in interface MethodAdapter
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.