tenua.symbol
Class Symbol

java.lang.Object
  tenua.symbol.Symbol

Direct Known Subclasses:

Assignment, Binary, Interpreted, Power, Unary, Value

public abstract class Symbol
extends java.lang.Object

Represents something (numbers, id's, operators) that can be part of an Expression

Author:

Daniel Wachsstock

Field Summary

static Symbol	CLEAR_STACK a Symbol that clears the stack
static java.lang.Integer	maxPrecedence the maximum precedence.

Method Summary

abstract void	eval(DoubleStack s, VariableMemento v) evaluate the Symbol
void	toString(java.util.Stack stringStack, java.util.Stack precedenceStack, SymbolTable st) pushes a StringBuffer that reflects this Symbol, with all its arguments

Methods inherited from class java.lang.Object

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

Field Detail

maxPrecedence

public static final java.lang.Integer maxPrecedence

the maximum precedence. Just Integer.MAX_VALUE

CLEAR_STACK

public static final Symbol CLEAR_STACK

a Symbol that clears the stack

Method Detail

eval

public abstract void eval(DoubleStack s,
                          VariableMemento v)

evaluate the Symbol

Parameters:

s - the stack from which to pop arguments and to which to push results

v - the memento representing the current values of variables. If v is null, then use the default values

toString

public void toString(java.util.Stack stringStack,
                     java.util.Stack precedenceStack,
                     SymbolTable st)

pushes a StringBuffer that reflects this Symbol, with all its arguments

Parameters:

stringStack - the stack of StringBuffer from which to pop arguments and to which to push results

precedenceStack - a stack to be push'ed and pop'ed in parallel with stringStack that contains Integers, corresponding to the precedence of the arguments onstringStack. This is used to determine placement of parentheses. Anything other than a binary operation should push maxPrecedence

st - the SymbolTable to get Symbol names from Note: the name is a misnomer; it uses StringBuffer's, not String's