oracle.toplink.libraries.asm.tree.analysis
Class Frame

java.lang.Object
  oracle.toplink.libraries.asm.tree.analysis.Frame

public class Frame
extends java.lang.Object

A symbolic execution stack frame. A stack frame contains a set of local variable slots, and an operand stack. Warning: long and double values are represented by two slots in local variables, and by one slot in the operand stack.

Constructor Summary

Frame(Frame src)
Constructs a new frame that is identical to the given frame.

Frame(int nLocals, int nStack)
Constructs a new frame with the given size.

Method Summary

void	clearStack() Clears the operand stack of this frame.
void	execute(AbstractInsnNode insn, Interpreter interpreter)
Value	getLocal(int i) Returns the value of the given local variable.
int	getLocals() Returns the maximum number of local variables of this frame.
Value	getStack(int i) Returns the value of the given operand stack slot.
int	getStackSize() Returns the number of values in the operand stack of this frame.
Frame	init(Frame src) Copies the state of the given frame into this frame.
boolean	merge(Frame frame, boolean[] access) Merges this frame with the given frame (case of a RET instruction).
boolean	merge(Frame frame, Interpreter interpreter) Merges this frame with the given frame.
Value	pop() Pops a value from the operand stack of this frame.
void	push(Value value) Pushes a value into the operand stack of this frame.
void	setLocal(int i, Value value) Sets the value of the given local variable.
java.lang.String	toString() Returns a string representation of this frame.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

Frame

public Frame(int nLocals,
             int nStack)

Constructs a new frame with the given size.

Parameters:

nLocals - the maximum number of local variables of the frame.

nStack - the maximum stack size of the frame.

Frame

public Frame(Frame src)

Constructs a new frame that is identical to the given frame.

Parameters:

src - a frame.

Method Detail

init

public Frame init(Frame src)

Copies the state of the given frame into this frame.

Parameters:

src - a frame.

Returns:

this frame.

getLocals

public int getLocals()

Returns the maximum number of local variables of this frame.

Returns:

the maximum number of local variables of this frame.

getLocal

public Value getLocal(int i)
               throws AnalyzerException

Returns the value of the given local variable.

Parameters:

i - a local variable index.

Returns:

the value of the given local variable.

Throws:

AnalyzerException - if the variable does not exist.

setLocal

public void setLocal(int i,
                     Value value)
              throws AnalyzerException

Sets the value of the given local variable.

Parameters:

i - a local variable index.

value - the new value of this local variable.

Throws:

AnalyzerException - if the variable does not exist.

getStackSize

public int getStackSize()

Returns the number of values in the operand stack of this frame. Long and double values are treated as single values.

Returns:

the number of values in the operand stack of this frame.

getStack

public Value getStack(int i)
               throws AnalyzerException

Returns the value of the given operand stack slot.

Parameters:

i - the index of an operand stack slot.

Returns:

the value of the given operand stack slot.

Throws:

AnalyzerException - if the operand stack slot does not exist.

clearStack

public void clearStack()

Clears the operand stack of this frame.

pop

public Value pop()
          throws AnalyzerException

Pops a value from the operand stack of this frame.

Returns:

the value that has been popped from the stack.

Throws:

AnalyzerException - if the operand stack is empty.

push

public void push(Value value)
          throws AnalyzerException

Pushes a value into the operand stack of this frame.

Parameters:

value - the value that must be pushed into the stack.

Throws:

AnalyzerException - if the operand stack is full.

execute

public void execute(AbstractInsnNode insn,
                    Interpreter interpreter)
             throws AnalyzerException

Throws:

AnalyzerException

merge

public boolean merge(Frame frame,
                     Interpreter interpreter)
              throws AnalyzerException

Merges this frame with the given frame.

Parameters:

frame - a frame.

interpreter - the interpreter used to merge values.

Returns:

true if this frame has been changed as a result of the merge operation, or false otherwise.

Throws:

AnalyzerException - if the frames have incompatible sizes.

merge

public boolean merge(Frame frame,
                     boolean[] access)

Merges this frame with the given frame (case of a RET instruction).

Parameters:

frame - a frame

access - the local variables that have been accessed by the subroutine to which the RET instruction corresponds.

Returns:

true if this frame has been changed as a result of the merge operation, or false otherwise.

toString

public java.lang.String toString()

Returns a string representation of this frame.

Overrides:

toString in class java.lang.Object

Returns:

a string representation of this frame.