sjm.examples.sling
Class FunctionComparison

java.lang.Object
  |
  +--sjm.engine.Structure
        |
        +--sjm.engine.Gateway
              |
              +--sjm.examples.sling.FunctionComparison

public class FunctionComparison

extends Gateway

implements BooleanTerm

This class's constructor accepts two functions and an operator, and can evaluate and compare the functions. An object of this class can say whether a comparison holds for two functions. A comparison must ultimately be between two numbers rather than two functions. This class actually compares the y components of functions at time zero.

Field Summary

protected SlingFunction	f0
protected SlingFunction	f1
protected java.lang.String	operator

Fields inherited from class sjm.engine.Gateway

open

Fields inherited from class sjm.engine.Structure

emptyList, functor, terms

Constructor Summary

FunctionComparison(java.lang.String operator, SlingFunction f0, SlingFunction f1)
Create a comparison with the specified operator and comparison functions.

Method Summary

boolean	canProveOnce() Returns true if the comparison operator holds true between the values of this comparison's terms.
java.lang.Object	eval() Returns Boolean.TRUE if the comparison operator holds true between the values of the two terms.
java.lang.String	toString() Returns a string representation of this comparison.

Methods inherited from class sjm.engine.Gateway

canFindNextProof, cleanup

Methods inherited from class sjm.engine.Structure

arity, copyForProof, equals, functorAndArityEquals, headAndTail, isList, list, list, list, listTailString, listTermsToString, terms, unify, unify, unify, variables

Methods inherited from class java.lang.Object

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

Field Detail

operator

protected java.lang.String operator

f0

protected SlingFunction f0

f1

protected SlingFunction f1

Constructor Detail

FunctionComparison

public FunctionComparison(java.lang.String operator,
                          SlingFunction f0,
                          SlingFunction f1)

Create a comparison with the specified operator and comparison functions.

Parameters:

String - the comparison operator

SlingFunction - the first function

SlingFunction - the second function

Method Detail

canProveOnce

public boolean canProveOnce()

Returns true if the comparison operator holds true between the values of this comparison's terms.

This method evaluates the two functions received in the constructor to fix any variable references. Then this method extracts the y components of the functions at time zero, and compares these values.

Overrides:

canProveOnce in class Gateway

Returns:

true if the comparison operator holds true between the values of this comparison's terms.

eval

public java.lang.Object eval()

Returns Boolean.TRUE if the comparison operator holds true between the values of the two terms.

Overrides:

eval in class Structure

Returns:

Boolean.TRUE if the comparison operator holds true between the values of the two terms.

toString

public java.lang.String toString()

Returns a string representation of this comparison.

Overrides:

toString in class Structure

Returns:

a string representation of this comparison