Package EDU.purdue.cs.bloat.tree

Class OperandStack

  • public class OperandStack
extends java.lang.Object
    OperandStack is used to simulate the JVM stack. A stack of expressions is maintained. OperandStack has methods to push and pop (both wide and non-wide) expressions, replace an expression at a given depth in the stack, peek into the stack, etc.
    See Also:
    Expr, Tree

    • Constructor Summary

      Constructors 
      Constructor Description
      OperandStack()
      Constructor.

    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      Expr get​(int index)
      Returns the expression at index from the bottom of the stack.
      int height()  
      boolean isEmpty()  
      Expr peek()
      Returns the expression at the top of the stack, but does not modify the stack.
      Expr peek​(int depth)
      Get the expression that is depth expressions from the top of the stack, but do not modify the stack.
      Expr pop​(Type type)
      Pops an operand off the stack.
      Expr pop1()
      Pops a non-wide expression off the stack.
      Expr[] pop2()
      Pops a (possibly) wide expression off of the stack and returns the result as an array of Expr.
      void push​(Expr expr)
      Push an expression onto the stack.
      void replace​(int depth, Expr expr)
      Replaces the expression that is depth expressions from the top of the stack.
      void set​(int index, Expr expr)
      Sets the entry at a specified index from the bottom of the stack
      int size()
      Returns the number of expressions on the stack.
      java.lang.String toString()
      Returns a String represntation of this stack.

      • Methods inherited from class java.lang.Object

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

    • Constructor Detail

      • OperandStack

        public OperandStack()
        Constructor.

    • Method Detail

      • isEmpty

        public boolean isEmpty()
        Returns:
        True, if the stack is empty.

      • pop

        public Expr pop​(Type type)
        Pops an operand off the stack. Checks to make sure the top of the stack is of the expected Type.
        Parameters:
        type - The expected Type of the top of the stack
        Returns:
        Expression on the top of the stack

      • peek

        public Expr peek()
        Returns the expression at the top of the stack, but does not modify the stack.

      • set

        public void set​(int index,
                Expr expr)
        Sets the entry at a specified index from the bottom of the stack
        Parameters:
        index - The position in the stack.
        expr - The new value of the expression.

      • height

        public int height()
        Returns:
        The number of elements in the stack.

      • replace

        public void replace​(int depth,
                    Expr expr)
        Replaces the expression that is depth expressions from the top of the stack.
        Parameters:
        depth - The number of expressions from the top of the stack.
        expr - The new expression

      • peek

        public Expr peek​(int depth)
        Get the expression that is depth expressions from the top of the stack, but do not modify the stack.
        Parameters:
        depth - Number of expressions deep to get.
        Returns:
        The expression that is depth expression from the top of the stack.

      • pop1

        public Expr pop1()
        Pops a non-wide expression off the stack.

      • pop2

        public Expr[] pop2()
        Pops a (possibly) wide expression off of the stack and returns the result as an array of Expr. If the expression at the top of the stack is indeed wide, it is returned in element [0] of the array. If the expression at the top of the stack is not wide, the top two expressions are returned in the array as elements 0 and 1.

      • size

        public int size()
        Returns the number of expressions on the stack.

      • get

        public Expr get​(int index)
        Returns the expression at index from the bottom of the stack.

      • toString

        public java.lang.String toString()
        Returns a String represntation of this stack.
        Overrides:
        toString in class java.lang.Object