// FILE. . . . . d:/hak/hlt/src/hlt/fot/Functor.java
// EDIT BY . . . Hassan Ait-Kaci
// ON MACHINE. . Hak-Laptop
// STARTED ON. . Sat Jul 14 07:23:44 2018
package hlt.fot;
import hlt.language.util.ArrayList;
/**
* This is a class for a term-constructor functor (element of a Signature).
*
* @see Signature
*
* @version Last modified on Tue Apr 30 06:36:23 2019 by hak
* @author Hassan Aït-Kaci
* @copyright © by the author
*/
public class Functor
{ /* ************************************************************************ */
/**
* Name of this functor.
*/
protected String name;
/**
* Returns the name of this functor.
*/
public String name ()
{
return this.name;
}
// The following method is commented out since setting the name of a
// functor is only done in the Functor constructor (and this make no
// sense anyway).
//
// /**
// * Sets the name of this functor to the given string and returns this functor.
// */
// public Functor setName (String name)
// {
// this.name = name;
// return this;
// }
/* ************************************************************************ */
/**
* Number of arguments for a term with this functor as root symbol.
*/
protected int arity;
/**
* Returns the number of arguments taken by this functor.
*/
public int arity ()
{
return this.arity;
}
// The following method is commented out since setting the arity of a
// functor is only done in the Functor constructor (and this make no
// sense anyway).
//
// /**
// * Sets the arity of this functor to the given int and
// * returns this functor.
// */
// public Functor setArity (int arity)
// {
// this.arity = arity;
// return this;
// }
/* ************************************************************************ */
/**
* Signature where this functor belongs.
*/
protected Signature signature;
/**
* Returns the signature where this functor belongs.
*/
public Signature signature ()
{
return signature;
}
/**
* Index of this functor in its signature (starting at 0 and
* at most signature.size()); i.e., this.index =
* signature.functor(index).
*/
protected int index;
/**
* Returns the index of this functor in its signature (starting at
* 0 and at most signature.size()-1) and is equal to
* signature.functor(index()).
*/
public int index ()
{
return index;
}
/**
* Returns the position of this functor in its signature (starting at
* 1 and at most signature.size()) that is such that
* this.position() = this.index()+1.
*/
public int position ()
{
return index+1;
}
/* ************************************************************************ */
/**
* Constructs a functor object name/arity at
* position index in signature.
*/
public Functor (int index, String name, int arity, Signature signature)
{
this.index = index;
this.name = name;
this.arity = arity;
this.signature = signature;
}
/* ************************************************************************ */
public boolean equal (Functor functor)
{
return this == functor;
}
/* ************************************************************************ */
public String toString ()
{
return name; // +"/"+arity;
}
/* ************************************************************************ */
/**
* Static facilities.
*/
/**
* This is an ArrayList, initially empty, of
* ArrayLists of Integer objects of the form
* [1,...,n], 0 &\le; n, denoting the list of
* argument positions of a functor of arity n. Such a list is
* to serve as a unique reference list for a SetOf positions
* denoting a partial argument map between the arguments of two
* functors.
*/
static private ArrayList argumentLists = new ArrayList();
/**
* This returns the unique list of ArrayLists of
* Integer objects denoting argument positions for the
* specified arity. It is defined such that each list
* [1,...,arity] is created by need, stored in
* argumentLists at index arity, and will never
* change once created.
*/
static public ArrayList argumentList (int arity)
{
ArrayList argumentList = (ArrayList)argumentLists.get(arity);
if (argumentList != null)
return argumentList;
argumentLists.set(arity,argumentList = new ArrayList(arity));
for (int i = 0; i < arity; i++)
// i+1 because argument positions go from 1 to arity
argumentList.set(i,Integer.valueOf(i+1));
return argumentList;
}
}