org.jpl7

Class Atom

java.lang.Object

org.jpl7.Term

org.jpl7.Atom

public class Atom
extends Term

Atom is a specialised Term, representing a Prolog atom with the same name. An Atom is constructed with a String parameter (its name, unquoted), which cannot thereafter be changed.

 Atom a = new Atom("hello");
 

An Atom can be used (and re-used) as an argument of Compound Terms. Two Atom instances are equal (by equals()) iff they are of the same type and have equal values. 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 java.lang.String	name the name of this Atom
protected java.lang.String	type the type of this Atom (e.g.

Constructor Summary

Constructors

Constructor and Description
Atom(java.lang.String name) This constructs a "text" Atom, and is equivalent to
Atom(java.lang.String name, java.lang.String type)

Method Summary

Modifier and Type	Method and Description
Term[]	args() The arguments of this Term.
java.lang.String	atomType()
boolean	equals(java.lang.Object o) Two Atoms are equal if they are identical (same object) or their respective names and blobTypes are equal
boolean	hasFunctor(java.lang.String name, int arity) Tests whether this Compound's functor has (String) 'name' and 'arity'.
int	hashCode()
protected boolean	isAtomOfNameType(java.lang.String name, java.lang.String type) for internal use only
boolean	isListNil() whether this Term denotes (syntax-specifically) an empty list
java.lang.String	name() the name (unquoted) of this Compound
protected void	put(java.util.Map<java.lang.String,term_t> varnames_to_vars, term_t term) To put an Atom in a term, we create a sequence of term_t references from the Term.terms_to_term_ts() method, and then use the Prolog.cons_functor_v() method to create a Prolog compound term.
java.lang.String	toString() an Atom's name is quoted if it is not a simple identifier.
int	type() returns the type of this term, as "Prolog.ATOM"
java.lang.String	typeName() returns the name of the type of this term, as "Atom"

Methods inherited from class org.jpl7.Term

arg, arity, atomListToStringArray, bigValue, doubleValue, floatValue, getSubst, getSubsts, getTerm, getTerm, hasFunctor, hasFunctor, hasFunctor, intArrayArrayToList, intArrayToList, intValue, isAtom, isBig, isBigInteger, isCompound, isFloat, isInteger, isJFalse, isJNull, isJRef, isJTrue, isJVoid, isList, isList, isListPair, isVariable, jrefToObject, listLength, listLength, listToTermArray, listToTermArray, longValue, 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

name

protected final java.lang.String name

the name of this Atom

type

protected final java.lang.String type

the type of this Atom (e.g. "text", "string", "reserved_symbol")

Constructor Detail

Atom

public Atom(java.lang.String name)

This constructs a "text" Atom, and is equivalent to

new Atom(name, "text")

Parameters:

name - the Atom's name (unquoted)

Throws:

JPLException - if name is null

Atom

public Atom(java.lang.String name,
            java.lang.String type)

Parameters:

name - the Atom's name (unquoted)

type - the required Atom type, e.g. "text" or "string"

Throws:

JPLException - if name or type is null, or if type is "jref"

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

atomType

public final java.lang.String atomType()

Overrides:

atomType in class Term

Returns:

the type ("text", "string", "reserved_symbol", "jref" etc.) of an Atom

equals

public boolean equals(java.lang.Object o)

Two Atoms are equal if they are identical (same object) or their respective names and blobTypes are equal

Overrides:

equals in class java.lang.Object

Parameters:

o - the Object to compare (not necessarily another Atom)

Returns:

true if the Object satisfies the above condition

hashCode

public int hashCode()

Overrides:

hashCode in class java.lang.Object

hasFunctor

public final boolean hasFunctor(java.lang.String name,
                                int arity)

Tests whether this Compound's functor has (String) 'name' and 'arity'.

Overrides:

hasFunctor in class Term

Parameters:

name - a possible name for the functor of a term

arity - an arity 0+

Returns:

whether this Compound's functor has (String) 'name' and 'arity'

isAtomOfNameType

protected final boolean isAtomOfNameType(java.lang.String name,
                                         java.lang.String type)

for internal use only

Overrides:

isAtomOfNameType in class Term

Parameters:

name - an Atom name

type - an Atom (blob) type, e.g. "text", "reserved_symbol"

Returns:

whether this Term instance is an Atom with name and type

isListNil

public final boolean isListNil()

whether this Term denotes (syntax-specifically) an empty list

Overrides:

isListNil in class Term

Returns:

whether this Term denotes an empty list within the current syntax ("traditional" or "modern").

See Also:

JPL.getSyntax()

name

public final java.lang.String name()

the name (unquoted) of this Compound

Overrides:

name in class Term

Returns:

the name (unquoted) of this Compound

put

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

To put an Atom in a term, we create a sequence of term_t references from the Term.terms_to_term_ts() method, and then use the Prolog.cons_functor_v() method to create a Prolog compound term.

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 term corresponding to the Term subtype (Atom, Variable, Compound, etc.) on which the method is invoked.

toString

public java.lang.String toString()

an Atom's name is quoted if it is not a simple identifier.

Overrides:

toString in class java.lang.Object

Returns:

string representation of an Atom

type

public final int type()

returns the type of this term, as "Prolog.ATOM"

Specified by:

type in class Term

Returns:

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

typeName

public java.lang.String typeName()

returns the name of the type of this term, as "Atom"

Specified by:

typeName in class Term

Returns:

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