Package jason.stdlib

Class nth

java.lang.Object

jason.asSemantics.DefaultInternalAction

jason.stdlib.nth

All Implemented Interfaces:

InternalAction, Serializable

@Manual(literal=".nth(index,list,term)",
        hint="gets the nth term of a list",
        argsHint={"the position of the term (the first term is at position 0)","the list where to get the term from","the term at referred position of the list."},
        argsType={"integer","list","term"},
        examples={".nth(0,[a,b,c],X): unifies X with a",".nth(2,[a,b,c],X): unifies X with c",".nth(0,[a,b,c],d): false",".nth(0,[a,b,c],a): true",".nth(5,[a,b,c],X): error",".nth(X,[a,b,c,a,e],a): unifies X with 0 (and 3 if it backtracks)"},
        seeAlso={"jason.stdlib.concat","jason.stdlib.delete","jason.stdlib.length","jason.stdlib.member","jason.stdlib.sort","jason.stdlib.max","jason.stdlib.min","jason.stdlib.reverse","jason.stdlib.difference","jason.stdlib.intersection","jason.stdlib.union"})
public class nth
extends DefaultInternalAction

Internal action: .nth.

Description: gets the nth term of a list.

Parameters:

• -/+ index (integer): the position of the term (the first term is at position 0)
  
• + list (list or string): the list/string where to get the term from.
  
• -/+ term (term): the term at position index in the list.
  

Examples:

• .nth(0,[a,b,c],X): unifies X with a.
• .nth(2,[a,b,c],X): unifies X with c.
• .nth(2,"abc",X): unifies X with c.
• .nth(0,[a,b,c],d): false.
• .nth(0,[a,b,c],a): true.
• .nth(5,[a,b,c],X): error.
• .nth(X,[a,b,c,a,e],a): unifies X with 0 (and 3 if it backtracks).

See Also:

• concat
• delete
• length
• member
• sort
• max
• min
• reverse
• difference
• intersection
• union
• Serialized Form

Constructor Summary

Constructors

Constructor	Description
nth()

Method Summary

Modifier and Type	Method	Description
protected void	checkArguments(Term[] args)
static InternalAction	create()
Object	execute(TransitionSystem ts, Unifier un, Term[] args)	Executes the internal action.
int	getMaxArgs()
int	getMinArgs()

Methods inherited from class jason.asSemantics.DefaultInternalAction

canBeUsedInContext, destroy, prepareArguments, suspendIntention

Methods inherited from class java.lang.Object

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

Constructor Details

nth

public nth()

Method Details

create

public static InternalAction create()

getMinArgs

public int getMinArgs()

Overrides:

getMinArgs in class DefaultInternalAction

getMaxArgs

public int getMaxArgs()

Overrides:

getMaxArgs in class DefaultInternalAction

checkArguments

protected void checkArguments(Term[] args)
                       throws JasonException

Overrides:

checkArguments in class DefaultInternalAction

Throws:

JasonException

execute

public Object execute(TransitionSystem ts,
 Unifier un,
 Term[] args)
               throws Exception

Description copied from interface: InternalAction

Executes the internal action. It should return a Boolean or an Iterator. A true boolean return means that the IA was successfully executed. An Iterator result means that there is more than one answer for this IA (e.g. see member internal action).

Specified by:

execute in interface InternalAction

Overrides:

execute in class DefaultInternalAction

Throws:

Exception