org.projog.core.term

Class TermUtils

java.lang.Object

org.projog.core.term.TermUtils

public final class TermUtils
extends Object

Helper methods for performing common tasks on Term instances.

Field Summary

Fields

Modifier and Type	Field and Description
static Term[]	EMPTY_ARRAY A Term array of length 0.

Method Summary

Modifier and Type	Method and Description
static void	assertType(Term t, TermType type)
static void	backtrack(Term[] terms) Backtracks all Terms in the specified array.
static Numeric	castToNumeric(Term t) Return the Numeric represented by the specified Term.
static Term[]	copy(Term... input) Returns copies of the specified {link Term}s
static Set<Variable>	getAllVariablesInTerm(Term argument) Returns all Variables contained in the specified term.
static String	getAtomName(Term t) Return the name of the Atom represented by the specified Atom.
static boolean	termsEqual(Term a, Term b)
static int	toInt(Term t) Returns the integer value of the Numeric represented by the specified Term.
static long	toLong(ArithmeticOperators operators, Term t) Return the long value represented by the specified term.
static boolean	unify(Term[] queryArgs, Term[] consequentArgs) Attempts to unify all corresponding Terms in the specified arrays.

Methods inherited from class java.lang.Object

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

Field Detail

EMPTY_ARRAY

public static final Term[] EMPTY_ARRAY

A Term array of length 0.

Should be used wherever a zero-length Term array is required in order to minimise object creation.

Method Detail

copy

public static Term[] copy(Term... input)

Returns copies of the specified {link Term}s

Parameters:

input - Terms to copy

Returns:

copies of the specified {link Term}s

backtrack

public static void backtrack(Term[] terms)

Backtracks all Terms in the specified array.

Parameters:

terms - Terms to backtrack

See Also:

Term.backtrack()

unify

public static boolean unify(Term[] queryArgs,
                            Term[] consequentArgs)

Attempts to unify all corresponding Terms in the specified arrays.

Note: If the attempt to unify the corresponding terms is unsuccessful only the terms in queryArgs will get backtracked.

Parameters:

queryArgs - terms to unify with consequentArgs

consequentArgs - terms to unify with queryArgs

Returns:

true if the attempt to unify all corresponding terms was successful

getAllVariablesInTerm

public static Set<Variable> getAllVariablesInTerm(Term argument)

Returns all Variables contained in the specified term.

Parameters:

argument - the term to find variables for

Returns:

all Variables contained in the specified term.

castToNumeric

public static Numeric castToNumeric(Term t)

Return the Numeric represented by the specified Term.

Parameters:

t - the term representing a Numeric

Returns:

the Numeric represented by the specified Term

Throws:

ProjogException - if the specified Term does not represent a Numeric

toInt

public static int toInt(Term t)

Returns the integer value of the Numeric represented by the specified Term.

Parameters:

t - the term representing a Numeric

Returns:

the int value represented by t

Throws:

ProjogException - if the specified Term cannot be represented as an int.

toLong

public static long toLong(ArithmeticOperators operators,
                          Term t)

Return the long value represented by the specified term.

Parameters:

t - the term representing a long value

Returns:

the long value represented by t

Throws:

ProjogException - if the specified Term does not represent a term of type TermType.INTEGER

getAtomName

public static String getAtomName(Term t)

Return the name of the Atom represented by the specified Atom.

Parameters:

t - the term representing an Atom

Returns:

the name of Atom represented by the specified Term

Throws:

ProjogException - if the specified Term does not represent an Atom

assertType

public static void assertType(Term t,
                              TermType type)

termsEqual

public static boolean termsEqual(Term a,
                                 Term b)