org.jpl7

Class Rational

java.lang.Object

org.jpl7.Term

org.jpl7.Rational

public class Rational
extends Term

Rational is a specialised Term representing a Prolog rational value.

 Rational r1 = new Rational(2,3);
 Rational r2 = new Rational(2r3);
 

A rational will be stored in its canonical form with gcd(numerator, denominator = 1 (not reducible) and denominator greater than 1. If the denominator reduces to 1, a JPLException is thrown. Once constructed, the value of an Rational instance cannot be altered. An Rational can be used (and re-used) as an argument of Compounds. Copyright (C) 2020 Sebastian Sardina

Copyright (C) 2004 Paul Singleton

Copyright (C) 1998 Fred Dushin

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

See Also:

Term, Compound

Field Summary

Fields

Modifier and Type	Field and Description
protected long	denominator
protected long	numerator the numerator and denominator in canonical form: gcd(numerator, denominator = 1 (not reducible) denominator greater than 1 rat is a String of the form "NrM"

Constructor Summary

Constructors

Constructor and Description
Rational(long numerator, long denominator) Creates a rational in canonical form
Rational(java.lang.String rat) Creates a rational in canonical form

Method Summary

Modifier and Type	Method and Description
Term[]	args() The arguments of this Term.
double	doubleValue() Returns the value of this Rational converted to a double
boolean	equals(java.lang.Object o) Two Rationals instances are equal if their numerator and denominator match (remember Rationals are stored in canonical form)
float	floatValue() Returns the value of this Rational converted to a float
long	getDenominator()
long	getNumerator()
boolean	hasFunctor(long val, int arity) whether this Rational's functor has (long) 'name' and 'arity' (c.f.
int	hashCode()
int	intValue() Returns the value of this Rational as an int if possible, else throws a JPLException
long	longValue() Returns the value of this org.jpl7.Rational as a long
protected void	put(java.util.Map<java.lang.String,term_t> varnames_to_vars, term_t term) To convert an Rational into a Prolog term, we put its value into the term_t.
java.lang.String	toString() a Prolog source text representation of this Rational's value
int	type() the type of this term, as "Prolog.RATIONAL"
java.lang.String	typeName() the name of the type of this term, as "Rational"

Methods inherited from class org.jpl7.Term

arg, arity, atomListToStringArray, atomType, bigValue, getSubst, getSubsts, getTerm, getTerm, hasFunctor, hasFunctor, hasFunctor, intArrayArrayToList, intArrayToList, isAtom, isAtomOfNameType, isBig, isBigInteger, isCompound, isFloat, isInteger, isJFalse, isJNull, isJRef, isJTrue, isJVoid, isList, isList, isListNil, isListPair, isVariable, jrefToObject, listLength, listLength, listToTermArray, listToTermArray, name, object, objectToJRef, put, putParams, putParams, putParams1, putParams2, putTerm, putTerms, ref, setName, stringArrayToList, termArrayToList, textParamsToTerm, textToTerm, toString, toTermArray

Methods inherited from class java.lang.Object

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

Field Detail

numerator

protected final long numerator

the numerator and denominator in canonical form: gcd(numerator, denominator = 1 (not reducible) denominator greater than 1 rat is a String of the form "NrM"

denominator

protected final long denominator

Constructor Detail

Rational

public Rational(long numerator,
                long denominator)

Creates a rational in canonical form

Parameters:

numerator - a long integer

denominator - a long integer

Rational

public Rational(java.lang.String rat)

Creates a rational in canonical form

Parameters:

rat - The rational number in format NrM

Method Detail

args

public Term[] args()

Description copied from class: Term

The arguments of this Term.

Note that a SWI Prolog 7.x compound term can have zero arguments.

This method returns an empty Term[] from an Atom, Float, Integer or JRef, approximating the behaviour of SWI Prolog's =../2

Overrides:

args in class Term

Returns:

the arguments of a Compound

equals

public boolean equals(java.lang.Object o)

Two Rationals instances are equal if their numerator and denominator match (remember Rationals are stored in canonical form)

Overrides:

equals in class java.lang.Object

Parameters:

o - The Object to compare (not necessarily an Rational)

Returns:

true if the Object satisfies the above condition

hashCode

public int hashCode()

Overrides:

hashCode in class java.lang.Object

getNumerator

public final long getNumerator()

getDenominator

public final long getDenominator()

hasFunctor

public final boolean hasFunctor(long val,
                                int arity)

whether this Rational's functor has (long) 'name' and 'arity' (c.f. traditional functor/3)

Overrides:

hasFunctor in class Term

Parameters:

val - a possible name for the functor of a term

arity - an arity 0+

Returns:

whether this Rational's functor has (long) 'name' and 'arity'

intValue

public final int intValue()

Returns the value of this Rational as an int if possible, else throws a JPLException

Overrides:

intValue in class Term

Returns:

the int value of this Rational

Throws:

JPLException - if the value of this Rational is too great to be represented as a Java int

longValue

public final long longValue()

Returns the value of this org.jpl7.Rational as a long

Overrides:

longValue in class Term

Returns:

the value of this org.jpl7.Rational as a long

floatValue

public final float floatValue()

Returns the value of this Rational converted to a float

Overrides:

floatValue in class Term

Returns:

the value of this Rational converted to a float

doubleValue

public final double doubleValue()

Returns the value of this Rational converted to a double

Overrides:

doubleValue in class Term

Returns:

the value of this Rational converted to a double

put

protected final void put(java.util.Map<java.lang.String,term_t> varnames_to_vars,
                         term_t term)

To convert an Rational into a Prolog term, we put its value into the term_t.

Specified by:

put in class Term

Parameters:

varnames_to_vars - A Map from variable names to Prolog variables.

term - A (previously created) term_t which is to be set to a Prolog integer

toString

public java.lang.String toString()

a Prolog source text representation of this Rational's value

Overrides:

toString in class java.lang.Object

Returns:

a Prolog source text representation of this Rational's value

type

public final int type()

the type of this term, as "Prolog.RATIONAL"

Specified by:

type in class Term

Returns:

the type of this term, as "Prolog.JPLException"

typeName

public java.lang.String typeName()

the name of the type of this term, as "Rational"

Specified by:

typeName in class Term

Returns:

the name of the type of this term, as "Rational"