opendial.datastructs

Class MathExpression

java.lang.Object

opendial.datastructs.MathExpression

public final class MathExpression
extends java.lang.Object

Representation of a mathematical expression whose value can be evaluated. The expression may contain unknown variables. In this case, one can evaluate the value of the expression given a particular assignment of values. The class builds on the exp4j package, see http://www.objecthunter.net/exp4j/.

Field Summary

Fields

Modifier and Type	Field and Description
static java.util.List<java.lang.String>	fixedFunctions

Constructor Summary

Constructors

Constructor and Description
MathExpression(MathExpression existing) Creates a new mathematical expression that is a copy from another one
MathExpression(java.lang.String expression) Creates a new mathematical expression from the string

Method Summary

Modifier and Type	Method and Description
MathExpression	combine(char operator, MathExpression... elements) Combines the current expression with one or more other expressions and a binary operator (such as +,* or -).
boolean	equals(java.lang.Object o) Returns true if the expressions are identical, false otherwise
double	evaluate() Evaluates the result of the expression
double	evaluate(Assignment input) Evaluates the result of the expression, given an assignment of values to the unknown variables
java.util.Set<java.lang.String>	getVariables() Returns the unknown variable labels in the expression
int	hashCode() Returns the hashcode for the expression
java.lang.String	toString() Returns a string representation of the expression

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

fixedFunctions

public static final java.util.List<java.lang.String> fixedFunctions

Constructor Detail

MathExpression

public MathExpression(java.lang.String expression)

Creates a new mathematical expression from the string

Parameters:

expression - the expression

MathExpression

public MathExpression(MathExpression existing)

Creates a new mathematical expression that is a copy from another one

Parameters:

existing - the expression to copy

Method Detail

getVariables

public java.util.Set<java.lang.String> getVariables()

Returns the unknown variable labels in the expression

Returns:

the variable labels

evaluate

public double evaluate()

Evaluates the result of the expression

Returns:

the result

evaluate

public double evaluate(Assignment input)

Evaluates the result of the expression, given an assignment of values to the unknown variables

Parameters:

input - the assignment

Returns:

the result

combine

public MathExpression combine(char operator,
                              MathExpression... elements)

Combines the current expression with one or more other expressions and a binary operator (such as +,* or -).

Parameters:

operator - the operator between the expression

elements - the elements to add

Returns:

the expression corresponding to the combination

toString

public java.lang.String toString()

Returns a string representation of the expression

Overrides:

toString in class java.lang.Object

equals

public boolean equals(java.lang.Object o)

Returns true if the expressions are identical, false otherwise

Overrides:

equals in class java.lang.Object

hashCode

public int hashCode()

Returns the hashcode for the expression

Overrides:

hashCode in class java.lang.Object