Class Operator

java.lang.Object
  |
  +--Operator

Direct Known Subclasses:

AdditionOperator, DivisionOperator, MultiplicationOperator, NegationOperator, SineOperator, SubtractionOperator

public abstract class Operator

extends java.lang.Object

Class representing the concept of an operator in an equation. For example, in X + 3 = Y X, 3 and Y are operands representing values whereas + and = are operators representing actions to be performed on the operands.

Field Summary

int	numberOperands The number of operands that the operator acts on.
int	precedence The precedence of the operator.
boolean	preceededByAnOperand Flag allowing for the contextualization of operators.
java.lang.String	token The token representing the operation in an equation.

Constructor Summary

Operator()

Method Summary

boolean	isHigherPrecedence(Operator o)
boolean	isLowerPrecedence(Operator o)
abstract int	operate(int[] x) Abstact method that all operators must implement.
java.lang.String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

token

public java.lang.String token

The token representing the operation in an equation.

precedence

public int precedence

The precedence of the operator. In equations different operators can have an order of operations defined; for instance in normal arithmetic operations there are the basic operators + (addition), - (subtraction), * (multiplication), and / (division). There is an order of operations which states that all multiplication and division is performed before any addition or subtraction. This is ignoring the concept of grouping symbols such as parenthesis. All multipliaction and division is performed left to right and then all addition and subtraction is performed left to right. This could be expanded to a more operators; each time the highest order of precedence is performed left to right until none of that operator remain, then the same is repeated for the next lower precedence until eventually there is but a single value left.

numberOperands

public int numberOperands

The number of operands that the operator acts on.

preceededByAnOperand

public boolean preceededByAnOperand

Flag allowing for the contextualization of operators. It is the case sometimes that in an equation the same symbol may represent more than one operator. For instance in arithmetic the - represents both subtration 3 - 5 and negation -2. Which action is intended by the writer is known by the reader of the equation based upon the context where it appears. In 3 - 5 = -2 it is known that the first - is a minus because it is preceeded by 3 and the second is negation becasue it is preceeded by a =.

Constructor Detail

Operator

public Operator()

Method Detail

operate

public abstract int operate(int[] x)

Abstact method that all operators must implement. This represents the operator acting upon a series of operands.

Returns:

the new operand produced by the operation

isHigherPrecedence

public boolean isHigherPrecedence(Operator o)

Parameters:

o - an operator to be compared to this one

Returns:

true if this operator is of higher precedence

isLowerPrecedence

public boolean isLowerPrecedence(Operator o)

Parameters:

o - an operator to be compared to this one

Returns:

true if this operator is of lower precedence

toString

public java.lang.String toString()

Returns:

the token for the current operator

Overrides:

toString in class java.lang.Object