tk.pratanumandal.expr4j.shuntingyard

Class ShuntingYardDualStack

java.lang.Object

tk.pratanumandal.expr4j.shuntingyard.ShuntingYard

tk.pratanumandal.expr4j.shuntingyard.ShuntingYardDualStack

public class ShuntingYardDualStack
extends ShuntingYard

The ShuntingYardDualStack class provides an implementation of the Shunting Yard algorithm using Dual Stacks.

Two stacks are used to immediately evaluate the expression without generating the postfix (or RPN) expression.
This is the recommended implementation since theoretically it should use less memory and require less time due to lesser complexity.

Since:

0.0.1

Author:

Pratanu Mandal

Field Summary

Fields

Modifier and Type	Field and Description
protected Stack<Operand>	operandStack Stack to hold the operands.
protected Stack<Operator>	operatorStack Stack to hold the operators.

Constructor Summary

Constructors

Constructor and Description
ShuntingYardDualStack() No-Argument Constructor.

Method Summary

Modifier and Type	Method and Description
double	evaluate(String expr) Method to evaluate an expression. This method acts as the single point of access for expression evaluation.
protected Operand	evaluateExpr(String expr) Method to evaluate the expression string and return the result as an operand.
protected void	evaluateParenthesis() Method to evaluate operators at the top of the operator stack until a left parenthesis is encountered.
protected void	evaluateTOS() Method to evaluate the operator at the top of the operator stack.

Methods inherited from class java.lang.Object

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

Field Detail

operandStack

protected Stack<Operand> operandStack

Stack to hold the operands.

operatorStack

protected Stack<Operator> operatorStack

Stack to hold the operators.

Constructor Detail

ShuntingYardDualStack

public ShuntingYardDualStack()

No-Argument Constructor.

Method Detail

evaluateExpr

protected Operand evaluateExpr(String expr)

Method to evaluate the expression string and return the result as an operand.

Parameters:

expr - Expression string

Returns:

Result of expression evaluation as an operand

evaluateTOS

protected void evaluateTOS()

Method to evaluate the operator at the top of the operator stack.

evaluateParenthesis

protected void evaluateParenthesis()

Method to evaluate operators at the top of the operator stack until a left parenthesis is encountered.

evaluate

public double evaluate(String expr)

Method to evaluate an expression.
This method acts as the single point of access for expression evaluation.

Specified by:

evaluate in class ShuntingYard

Parameters:

expr - Expression string

Returns:

Result of expression evaluation as a double