Package jason.stdlib

Class if_then_else

java.lang.Object

jason.asSemantics.DefaultInternalAction

jason.stdlib.if_then_else

All Implemented Interfaces:

InternalAction, Serializable

@Manual(literal="if (formula) { plan_body1 } else { plan_body2 }",
        hint="implementation of \"if then, elif then, and else\"",
        argsHint="the formula that when true makes the plan_body1 be executed, otherwise plan_body2 will be executed",
        argsType="logical formula",
        examples={"if (vl(X) & X > 10) { .print(\"value > 10\"); }: where vl(X) is a belief","if (e(1)) { .print(a); } elif (e(2)) { .print(b); } elif (e(3)) { .print(c); } else { .print(d); }"},
        seeAlso="")
public class if_then_else
extends DefaultInternalAction

Implementation of if.

Syntax:

  if ( logical formula ) {
     plan_body1
  [ } else { plan_body2 ]
  [ } elif ( logical formula  ) { plan_body3 ]
  }

if logical formula holds, plan_body1 is executed; otherwise, plan_body2/3 is executed.

Example:

+event : context
  invalid input: '<'- ...
     if (vl(X) invalid input: '&' X > 10) { // where vl(X) is a belief
       .print("value > 10");
     }
     ...
     if   (e(1)) { .print(a); }
     elif (e(2)) { .print(b); }
     elif (e(3)) { .print(c); }
     else        { .print(d); }
     ...

The unification is changed by the evaluation of the logical formula, i.e., X might have a value after if.

See Also:

• Serialized Form

Constructor Summary

Constructors

Constructor	Description
if_then_else()

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()
Term[]	prepareArguments(Literal body, Unifier un)	Prepare body's terms to be used in 'execute', normally it consist of cloning and applying each term

Methods inherited from class jason.asSemantics.DefaultInternalAction

canBeUsedInContext, destroy, suspendIntention

Methods inherited from class java.lang.Object

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

Constructor Details

if_then_else

public if_then_else()

Method Details

create

public static InternalAction create()

prepareArguments

public Term[] prepareArguments(Literal body,
 Unifier un)

Description copied from interface: InternalAction

Prepare body's terms to be used in 'execute', normally it consist of cloning and applying each term

Specified by:

prepareArguments in interface InternalAction

Overrides:

prepareArguments in class DefaultInternalAction

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