io.github.prolobjectlink.prolog

Interface PrologList

All Superinterfaces:

Comparable<PrologTerm>, Iterable<PrologTerm>, PrologElement, PrologTerm

All Known Subinterfaces:

PrologMap

public interface PrologList
extends PrologTerm, Iterable<PrologTerm>

Represent prolog list compound term. List are an special compound term that have like functor a dot (.) and arity equals 2. Prolog list are recursively defined. The first item in the list is referred like list head and the second item list tail. The list tail can be another list that contains head and tail. An special list case is the empty list denoted by no items brackets ([]). The arity for this empty list is zero.

The Prolog Provider is the mechanism to create a new Prolog structures invoking PrologProvider.newList() for empty list or PrologProvider.newList(PrologTerm) for one item list or PrologProvider.newList(PrologTerm[]) for many items.

Two list are equals if and only if are list and have equals arguments. List terms unify only with the same arguments list, with free variable or with lists where your arguments unify.

 PrologList empty = provider.newList();
 

 PrologInteger one = provider.newInteger(1);
 PrologInteger two = provider.newInteger(2);
 PrologInteger three = provider.newInteger(3);
 PrologList list = provider.newList(new PrologTerm[] { one, two, three });
 

PrologList implement Iterable interface to be used in for each sentence iterating over every element present in the list.

 for (PrologTerm prologTerm : list) {
        System.out.println(prologTerm);
 }
 

 Iterator<PrologTerm> i = list.iterator();
 while (i.hasNext()) {
        PrologTerm prologTerm = i.next();
        System.out.println(prologTerm);
 }
 

 for (Iterator<PrologTerm> i = list.iterator(); i.hasNext();) {
        PrologTerm prologTerm = i.next();
        System.out.println(prologTerm);
 }
 

Since:

1.0

Author:

Jose Zalacain

Method Summary

Modifier and Type	Method and Description
void	clear() Clear the current list removing all contained prolog term.
PrologTerm	getHead() Return the head term of the current list if the current list have at least one element.
PrologTerm	getTail() Return the tail term of the current list if the current list have tail.
boolean	isEmpty() Return true if the current list don't have any elements, false in other case.
int	size() Returns the number of elements in this list.

Methods inherited from interface io.github.prolobjectlink.prolog.PrologTerm

cast, getArgument, getArguments, getArity, getFunctor, getIndicator, getObject, getProvider, getTerm, getType, hasIndicator, isAtom, isAtomic, isClass, isCompound, isDouble, isEmptyList, isEntry, isEvaluable, isFalseType, isField, isFloat, isInteger, isList, isLong, isMap, isMixin, isNil, isNullType, isNumber, isObjectType, isParameter, isReference, isResult, isStructure, isTrueType, isVariable, isVariableBound, isVariableNotBound, isVoidType, match, unify

Methods inherited from interface java.lang.Comparable

compareTo

Methods inherited from interface io.github.prolobjectlink.prolog.PrologElement

isClause, isTerm

Methods inherited from interface java.lang.Iterable

forEach, iterator, spliterator

Method Detail

getHead

PrologTerm getHead()

Return the head term of the current list if the current list have at least one element. If the list is an instance of Prolog empty list term, the result for invoke get head is the empty list term properly.

Returns:

the head term of the current list if the current list have at least one element.

Since:

1.0

getTail

PrologTerm getTail()

Return the tail term of the current list if the current list have tail. If the list is a sole term list, the result for invoke get tail is the empty list term.

Returns:

the tail term of the current list if the current list have tail.

Since:

1.0

isEmpty

boolean isEmpty()

Return true if the current list don't have any elements, false in other case. More formally return #size()==0

Returns:

true if the current list don't have any elements, false in other case.

Since:

1.0

clear

void clear()

Clear the current list removing all contained prolog term. After clear the list the resulting list is equal and unify with empty list.

Since:

1.0

size

int size()

Returns the number of elements in this list.

Returns:

the number of elements in this list.

Since:

1.0