Class Frame

java.lang.Object
org.objectweb.asm.tree.analysis.Frame
public class Frame extends 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.
Author:
Eric Bruneton

  • Constructor Summary

    Constructors
    Constructor
    Description
    Frame(int nLocals, int nStack)
    Constructs a new frame with the given size.
    Frame(Frame src)
    Constructs a new frame that is identical to the given frame.

  • Method Summary

    Modifier and Type
    Method
    Description
    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.
    void
    setReturn(Value v)
    Sets the expected return type of the analyzed method.
    String
    toString()
    Returns a string representation of this frame.

    Methods inherited from class Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

  • Constructor Details

    • 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 Details

    • init

      public Frame init(Frame src)
      Copies the state of the given frame into this frame.
      Parameters:
      src - a frame.
      Returns:
      this frame.

    • setReturn

      public void setReturn(Value v)
      Sets the expected return type of the analyzed method.
      Parameters:
      v - the expected return type of the analyzed method, or null if the method returns void.

    • 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 IndexOutOfBoundsException
      Returns the value of the given local variable.
      Parameters:
      i - a local variable index.
      Returns:
      the value of the given local variable.
      Throws:
      IndexOutOfBoundsException - if the variable does not exist.

    • setLocal

      public void setLocal(int i, Value value) throws IndexOutOfBoundsException
      Sets the value of the given local variable.
      Parameters:
      i - a local variable index.
      value - the new value of this local variable.
      Throws:
      IndexOutOfBoundsException - 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 IndexOutOfBoundsException
      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:
      IndexOutOfBoundsException - if the operand stack slot does not exist.

    • clearStack

      public void clearStack()
      Clears the operand stack of this frame.

    • pop

      public Value pop() throws IndexOutOfBoundsException
      Pops a value from the operand stack of this frame.
      Returns:
      the value that has been popped from the stack.
      Throws:
      IndexOutOfBoundsException - if the operand stack is empty.

    • push

      public void push(Value value) throws IndexOutOfBoundsException
      Pushes a value into the operand stack of this frame.
      Parameters:
      value - the value that must be pushed into the stack.
      Throws:
      IndexOutOfBoundsException - 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 String toString()
      Returns a string representation of this frame.
      Overrides:
      toString in class Object
      Returns:
      a string representation of this frame.