ubc.cs.JLog.Parser
Class pPredicateEntry

java.lang.Object
  ubc.cs.JLog.Parser.pPredicateEntry

All Implemented Interfaces:

iName, iNameArity

Direct Known Subclasses:

pCallPredicateEntry, pDCGPredicateEntry, pGenericPredicateEntry, pOrPredicateEntry

public abstract class pPredicateEntry
extends Object
implements iNameArity

Abstract base class for entries in the pPredicateRegistry. Each predicate entry subclass represents a type of prolog predicate at the level needed for the parser (they are parse time representations). Predicate entries contain information about the corresponding predicate, such as name and arity. Predicate entries generate the corresponding real Prolog predicate objects.

Version:

%I%, %G%

Author:

Glendon Holst

Field Summary

protected int	arity
protected String	library
protected String	name
static int	NARY_ARITY

Constructor Summary

pPredicateEntry(String name, int arity)

Method Summary

iPredicate	createPredicate() Public interface for generating the real prolog term objects.
abstract iPredicate	createPredicate(jCompoundTerm cterm) The internal method for creating the iPredicate representation of this predicate representation.
iPredicate	createPredicate(ubc.cs.JLog.Parser.pToken pt, jCompoundTerm cterm) Public interface for generating the real prolog term objects.
int	getArity() Returns the arity of this instance.
String	getLibrary() Get the name of the library associated with this predicate.
String	getName() Returns the name of this instance.
boolean	isArity(int a) Tests the arity of this entry.
boolean	sameLibrary(String lib)
void	setLibrary(String lib) Set the name of the library associated with this predicate.
String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

NARY_ARITY

public static final int NARY_ARITY

See Also:

Constant Field Values

name

protected String name

arity

protected int arity

library

protected String library

Constructor Detail

pPredicateEntry

public pPredicateEntry(String name,
                       int arity)

Method Detail

getName

public String getName()

Description copied from interface: iName

Returns the name of this instance.

Specified by:

getName in interface iName

Returns:

String containing name of this instance.

getArity

public int getArity()

Description copied from interface: iNameArity

Returns the arity of this instance.

Specified by:

getArity in interface iNameArity

Returns:

int whose value is the arity of this instance.

isArity

public boolean isArity(int a)

Tests the arity of this entry. Most predicates entries will only return true if there is an exact match, however, for n-ary predicates, arity should be set to NARY_ARITY, and isArity should always return true for supported arities.

Parameters:

a - The arity to test this entry for.

Returns:

boolean which is true if entry can be of this arity.

setLibrary

public void setLibrary(String lib)

Set the name of the library associated with this predicate. Once an association is made it is an error to change it (throws InvalidLibraryEntryException in this case). Predicates default to a null valued library.

Parameters:

lib - The name of the library.

getLibrary

public String getLibrary()

Get the name of the library associated with this predicate.

Returns:

The name of the library. May be null.

sameLibrary

public boolean sameLibrary(String lib)

createPredicate

public iPredicate createPredicate(ubc.cs.JLog.Parser.pToken pt,
                                  jCompoundTerm cterm)

Public interface for generating the real prolog term objects. May generate syntax errors. Invokes internal createPredicate to perform actual construction of term.

Parameters:

pt - The parsing token representing the operator. Used for generating information about the location of the operator in the input stream.

cterm - A terms belonging to this predicate.

Returns:

iPredicat representing this predicate and its terms.

createPredicate

public iPredicate createPredicate()

Public interface for generating the real prolog term objects. May generate syntax errors. Invokes internal createPredicate to perform actual construction of term.

Returns:

iPredicat representing this predicate with given arity, with unamed variables for terms.

createPredicate

public abstract iPredicate createPredicate(jCompoundTerm cterm)

The internal method for creating the iPredicate representation of this predicate representation. Subclasses must override. The terms are provided, already created. The caller is responsible to ensure that arity and cterm.size match.

Parameters:

cterm - The collection of jTerms.

Returns:

iPredicate representing this predicate and its terms.

toString

public String toString()

Overrides:

toString in class Object