se.sics.jasper
Interface Term

All Known Implementing Classes:

SPTerm

public interface Term

Terms are Java representations of Prolog terms. See SPTerm for more information on the implementation.

Field Summary

static int	TYPE_ATOM The term is an atom.
static int	TYPE_COMPOUND The term is a compound term.
static int	TYPE_FLOAT The term is a float.
static int	TYPE_INTEGER The term is an integer.
static int	TYPE_VARIABLE The term is a variable.

Method Summary

int	compare(Term with) Compares two terms according to standard order.
void	delete() Invalidates the Term object and make the SP_term_ref available for re-use.
Term	getArg(int i, Term arg) Gets an argument from a compound term.
double	getDouble() Obtains the value of the Prolog float.
int	getFunctorArity() Obtains the arity of a functor.
java.lang.String	getFunctorName() Obtains the name of a functor.
long	getInteger() Obtains the integer value of the Prolog term.
Term	getList(Term head, Term tail) Gets the head and tail of a Prolog list.
java.lang.String	getListChars() Obtains the value of a list of characters as a string.
java.lang.String	getNumberChars() Obtains the value of a Prolog number as a string.
java.lang.Object	getObject() Not yet implemented in Multi threaded Jasper.
java.lang.String	getString() Obtains the value of the Prolog atom as a string.
boolean	isAtom() Tests if the term is an atom.
boolean	isAtomic() Tests if the term is atomic.
boolean	isCompound() Tests if the term is a compound term.
boolean	isEmptyList() Tests if the term is the empty list.
boolean	isFloat() Tests if the term is a float.
boolean	isInteger() Tests if the term is an integer.
boolean	isList() Tests if the term is a list cell.
boolean	isNumber() Tests if the term is a number.
boolean	isValid() Tests if the Prolog term referenced is still accessible through this object.
boolean	isVariable() Tests if the term is a variable.
Term[]	toPrologTermArray() Converts a list to an array of Terms.
java.lang.String	toString() Returns a string-respresentation of a term.
java.lang.String	toString(Term options) Returns a string-respresentation of a term.
int	type() Returns the type of this term.
boolean	unify(Term with) Unifies the term with another term.

Field Detail

TYPE_VARIABLE

public static final int TYPE_VARIABLE

The term is a variable.

See Also:

type()

TYPE_INTEGER

public static final int TYPE_INTEGER

The term is an integer.

See Also:

type()

TYPE_ATOM

public static final int TYPE_ATOM

The term is an atom.

See Also:

type()

TYPE_FLOAT

public static final int TYPE_FLOAT

The term is a float.

See Also:

type()

TYPE_COMPOUND

public static final int TYPE_COMPOUND

The term is a compound term.

See Also:

type()

Method Detail

compare

public int compare(Term with)
            throws IllegalTermException,
                   java.lang.Exception

Compares two terms according to standard order.

Parameters:

with - The term to compare with.

Returns:

-1 if x < y, 0 if x == y, and 1 if x > y.

delete

public void delete()
            throws java.lang.Exception

Invalidates the Term object and make the SP_term_ref available for re-use. Accessing an invalid Term object throws IllegalTermException.

getArg

public Term getArg(int i,
                   Term arg)
            throws java.lang.InterruptedException,
                   java.lang.Exception

Gets an argument from a compound term. Similar to calling arg/3 with the third argument unbound.

Parameters:

i - The number of the argument.

arg - The term to which the ith argument will be assigned.

Returns:

A reference to itself.

getDouble

public double getDouble()
                 throws ConversionFailedException,
                        IllegalTermException,
                        java.lang.Exception

Obtains the value of the Prolog float.

Returns:

The value of the Prolog float as a Java double.

Throws:

ConversionFailedException - The term could not be converted to a double.

getFunctorArity

public int getFunctorArity()
                    throws ConversionFailedException,
                           IllegalTermException,
                           java.lang.Exception

Obtains the arity of a functor.

Returns:

The arity of a functor as a Java int.

Throws:

ConversionFailedException - The term could not be converted to the arity of a functor.

getFunctorName

public java.lang.String getFunctorName()
                                throws ConversionFailedException,
                                       IllegalTermException,
                                       java.lang.Exception

Obtains the name of a functor.

Returns:

The functor as a Java String.

Throws:

ConversionFailedException - The term could not be converted to the name of a functor.

getInteger

public long getInteger()
                throws java.lang.Exception

Obtains the integer value of the Prolog term.

Returns:

The value of the Prolog term as a Java long.

getList

public Term getList(Term head,
                    Term tail)
             throws java.lang.InterruptedException,
                    java.lang.Exception

Gets the head and tail of a Prolog list.

Parameters:

head - The term which will be assigned the head

tail - The term which will be assigned the tail

Returns:

A reference to itself.

getListChars

public java.lang.String getListChars()
                              throws java.lang.Exception

Obtains the value of a list of characters as a string.

Returns:

The value of the list as a Java String.

getNumberChars

public java.lang.String getNumberChars()
                                throws java.lang.Exception

Obtains the value of a Prolog number as a string.

Returns:

The value of the number as a Java String.

getObject

public java.lang.Object getObject()
                           throws java.lang.Exception

Not yet implemented in Multi threaded Jasper. (I.e. it is a no-op in MT-Jasper).

See SPTerm.getObject() for documentation on the single threaded implementation.

getString

public java.lang.String getString()
                           throws java.lang.Exception

Obtains the value of the Prolog atom as a string.

Returns:

The value of the Prolog atom as a Java String.

isAtom

public boolean isAtom()
               throws java.lang.Exception

Tests if the term is an atom.

Returns:

true if the term is an atom; false otherwise

isAtomic

public boolean isAtomic()
                 throws java.lang.Exception

Tests if the term is atomic. A term is atomic if it is instantiated to an atom or a number.

Returns:

true if the term is atomic; false otherwise

isCompound

public boolean isCompound()
                   throws java.lang.Exception

Tests if the term is a compound term.

Returns:

true if the term is a compound term; false otherwise

isEmptyList

public boolean isEmptyList()
                    throws java.lang.Exception

Tests if the term is the empty list.

Returns:

true if the term is the atom []; false otherwise

isFloat

public boolean isFloat()
                throws java.lang.Exception

Tests if the term is a float.

Returns:

true if the term is a float; false otherwise

isInteger

public boolean isInteger()
                  throws java.lang.Exception

Tests if the term is an integer.

Returns:

true if the term is an integer; false otherwise

isList

public boolean isList()
               throws java.lang.Exception

Tests if the term is a list cell. Equivalent to the Prolog code isList(T) :- nonvar(T), T=[_|_].

Returns:

true if the term is a list cell; false otherwise

isNumber

public boolean isNumber()
                 throws java.lang.Exception

Tests if the term is a number. A number is a term instantiated to an integer or a float.

Returns:

true if the term is a number; false otherwise

isValid

public boolean isValid()
                throws java.lang.Exception

Tests if the Prolog term referenced is still accessible through this object. Term object becomes invalid as the result of of explicit delete, closing, cutting or asking for the nextSolution of an enclosing SPQuery.

Returns:

true if still valid; false otherwise.

isVariable

public boolean isVariable()
                   throws java.lang.Exception

Tests if the term is a variable.

Returns:

true if the term is a variable; false otherwise

toString

public java.lang.String toString()

Returns a string-respresentation of a term.

Overrides:

toString in class java.lang.Object

toString

public java.lang.String toString(Term options)
                          throws SPException,
                                 java.lang.Exception

Returns a string-respresentation of a term. This is an interface to write_term/3, which see.

toPrologTermArray

public Term[] toPrologTermArray()
                         throws java.lang.Exception

Converts a list to an array of Terms. Useful when examining lists returned from Prolog queries. This is of course only possible on a list.

Returns:

An array of the terms.

type

public int type()
         throws java.lang.Exception

Returns the type of this term. The return value is as defined by the constants TYPE_INTEGER, TYPE_FLOAT, TYPE_ATOM, TYPE_VARIABLE, and TYPE_COMPOUND

See Also:

TYPE_INTEGER, TYPE_ATOM, TYPE_FLOAT, TYPE_VARIABLE, TYPE_COMPOUND, isVariable(), isInteger(), isAtom(), isFloat(), isCompound(), isList(), isAtomic(), isNumber()

unify

public boolean unify(Term with)
              throws java.lang.Exception

Unifies the term with another term.

Parameters:

with - The term with which to unify.

Returns:

True/False depending on whether the unification succeeded.