Package org.prolog4j

Class Solution<S>

java.lang.Object

org.prolog4j.Solution<S>

Type Parameters:

S - The type of the values of the variable that is of special interest

All Implemented Interfaces:

Iterable<S>

Direct Known Subclasses:

SWIPrologSolution, TuPrologSolution

public abstract class Solution<S>
extends Object
implements Iterable<S>

Represents the solutions of a query.

Field Summary

Fields

Modifier and Type	Field	Description
protected Class<S>	clazz	The values that get bound to the default output variable will be converted to this type.

Constructor Summary

Constructors

Constructor	Description
Solution()

Method Summary

Modifier and Type	Method	Description
<C extends Collection<? super S>> C	collect(C collection)	Collects the values of the primary variable into the given collection.
void	collect(String[] variables, Collection<?>[] collections)	Collects the values of the specified variables into the given collections.
abstract void	collect(Collection<?>... collections)	Collects the values of the variables into the given collections.
protected abstract boolean	fetch()	Fetches the next solution if there is one.
S	get()	Returns the value of the variable last occurring in the goal bound to by the first solution of the goal.
<A> A	get(Class<A> type)	Returns the value of the variable last occurring in the goal bound to by the first solution of the goal.
abstract <A> A	get(String variable)	Returns the value of the given variable bound to by the first solution of the goal.
abstract <A> A	get(String variable, Class<A> type)	Returns the value of the given variable bound by the first solution.
abstract boolean	isSuccess()	Returns whether there exists a solution or not.
SolutionIterator<S>	iterator()
<A> Solution<A>	on(String variable)	Changes the state of this solution object so that it supports traversing the solutions according to another variable.
<A> Solution<A>	on(String variable, Class<A> clazz)	Changes the state of this solution object so that it supports traversing the solutions according to another variable.
List<S>	toList()	Collects the values of the primary variable into a List.
abstract List<?>[]	toLists()	Collects the values of the variables into a List array.
Set<S>	toSet()	Collects the values of the primary variable into a Set.

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.lang.Iterable

forEach, spliterator

Field Detail

clazz

protected Class<S> clazz

The values that get bound to the default output variable will be converted to this type.

Constructor Detail

Solution

public Solution()

Method Detail

isSuccess

public abstract boolean isSuccess()

Returns whether there exists a solution or not. Does not depend on the state of the traversal, only one solution should exist.

Returns:

true if the goal can be satisfied, otherwise false

on

public <A> Solution<A> on(String variable)

Changes the state of this solution object so that it supports traversing the solutions according to another variable.

Type Parameters:

A - the type of the values of the variable that is of special interest

Parameters:

variable - the name of the variable

Returns:

the same object

on

public <A> Solution<A> on(String variable,
                          Class<A> clazz)

Changes the state of this solution object so that it supports traversing the solutions according to another variable. The returned object will convert the traversed elements to the specified type.

Type Parameters:

A - the type of the values of the variable that is of special interest

Parameters:

variable - the name of the variable

clazz - the type to which the elements have to be converted

Returns:

the same object

get

public S get()

Returns the value of the variable last occurring in the goal bound to by the first solution of the goal.

Returns:

the value of the last variable occurring in the goal

get

public <A> A get(Class<A> type)

Returns the value of the variable last occurring in the goal bound to by the first solution of the goal. The required type of the value can be specified explicitly. This is useful when not the default type is desired.

Type Parameters:

A - the type of the value

Parameters:

type - the type which the value should be converted to

Returns:

the value bound to the variable

get

public abstract <A> A get(String variable)

Returns the value of the given variable bound to by the first solution of the goal.

Type Parameters:

A - the type of the value

Parameters:

variable - the name of the variable

Returns:

the value bound to the variable

get

public abstract <A> A get(String variable,
                          Class<A> type)

Returns the value of the given variable bound by the first solution. The required type of the value can be specified explicitly. This is useful when not the default type is desired.

Type Parameters:

A - the type of the value

Parameters:

variable - the name of the variable

type - the type which the value should be converted to

Returns:

the value bound to the variable

fetch

protected abstract boolean fetch()

Fetches the next solution if there is one.

Returns:

true if there was another solution, otherwise false

iterator

public SolutionIterator<S> iterator()

Specified by:

iterator in interface Iterable<S>

collect

public final <C extends Collection<? super S>> C collect(C collection)

Collects the values of the primary variable into the given collection. Returns its parameter.

Type Parameters:

C - the type of the collection

Parameters:

collection - the collection which will store the solutions

Returns:

collection

collect

public final void collect(String[] variables,
                          Collection<?>[] collections)

Collects the values of the specified variables into the given collections. The size of the arrays is expected to be the same.

Parameters:

variables - the name of the output variables

collections - the collections where to store the solutions

collect

public abstract void collect(Collection<?>... collections)

Collects the values of the variables into the given collections.

Parameters:

collections - the collections which will store the solutions

toSet

public Set<S> toSet()

Collects the values of the primary variable into a Set.

Returns:

a set containing the values of the variable of interest

toList

public List<S> toList()

Collects the values of the primary variable into a List.

Returns:

a list containing the values of the variable of interest

toLists

public abstract List<?>[] toLists()

Collects the values of the variables into a List array.

Returns:

a list array containing the values of the variables