Coverage Summary for Class: MetaCall (it.unibo.tuprolog.argumentation.core.engine.fsm)

 package it.unibo.tuprolog.argumentation.core.engine.fsm
 
 import it.unibo.tuprolog.argumentation.core.engine.PrologExecutionContext
 import it.unibo.tuprolog.argumentation.core.engine.stdlib.rule.Call
 import it.unibo.tuprolog.argumentation.core.engine.stdlib.rule.NegationAsFailure
 import it.unibo.tuprolog.core.Rule
 import it.unibo.tuprolog.core.Struct
 import it.unibo.tuprolog.core.Truth
 import it.unibo.tuprolog.core.Tuple
 import it.unibo.tuprolog.core.prepareForExecution
 import it.unibo.tuprolog.solve.Signature
 import it.unibo.tuprolog.solve.TimeInstant
 import it.unibo.tuprolog.solve.exception.ResolutionException
 import it.unibo.tuprolog.solve.stdlib.magic.MagicCut
 import it.unibo.tuprolog.solve.stdlib.primitive.EnsureExecutable
 import it.unibo.tuprolog.utils.Cursor
 
 /**
  * A meta-call of its single argument, a goal: checked executable as ensure_executable/1 does, then solved in a frame
  * of its own, opaque to cut, whose goals and choice point are given by [frame].
  */
 internal abstract class MetaCall(
     functor: String,
 ) : ControlConstruct {
     final override val signature: Signature = Signature(functor, 1)
 
     /** The frame solving [goal], from [frame], the frame of its own whose current goal is [goal] */
     protected abstract fun frame(
         goal: Struct,
         frame: PrologExecutionContext,
     ): PrologExecutionContext
 
     final override fun select(
         context: PrologExecutionContext,
         goal: Struct,
         time: TimeInstant,
     ): State {
         val frame = context.createChild(goal)
         val check = frame.copy(goals = Struct.of(EnsureExecutable.functor, goal[0]).toGoals()).createChild()
         return try {
             ensureExecutable(check, time)
             StateGoalSelection(frame(goal, frame).copy(step = context.step + 1))
         } catch (exception: ResolutionException) {
             StateException(exception.updateLastContext(check.skipThrow()), context.copy(step = context.step + 1))
         }
     }
 
     // Runs ensure_executable/1, the current goal of [check], raising its errors
     private fun ensureExecutable(
         check: PrologExecutionContext,
         time: TimeInstant,
     ) {
         val request = check.toRequest(check.currentGoal!!.castToStruct(), EnsureExecutable.signature, time)
         EnsureExecutable.implementation.solve(request).first()
     }
 }
 
 /**
  * call/1, as its clause `call(G) :- ensure_executable(G), G`: the frame solves the goal, its choice point (with no
  * alternatives) is the one a cut in the goal finds.
  */
 internal object CallConstruct : MetaCall(Call.functor) {
     override fun frame(
         goal: Struct,
         frame: PrologExecutionContext,
     ): PrologExecutionContext {
         val body = Rule.of(goal, goal[0]).prepareForExecution().body
         return frame.copy(goals = body.toBodyGoals()).appendChoicePoint(Cursor.empty())
     }
 }
 
 /**
  * \+/1, as its clauses `\+ G :- ensure_executable(G), call(G), '$cut', fail` and `\+ G :- true`: the frame tries the
  * goal, cutting its own choice point and failing if the goal succeeds; the choice point goes on with the second
  * clause.
  */
 internal object NegationConstruct : MetaCall(NegationAsFailure.FUNCTOR) {
     override fun frame(
         goal: Struct,
         frame: PrologExecutionContext,
     ): PrologExecutionContext =
         frame
             .appendChoicePoint(RuleCursor.of(listOf(Rule.of(goal, Truth.TRUE))))
             .copy(goals = Tuple.of(Struct.of(Call.functor, goal[0]), MagicCut, Truth.FAIL).toGoals())
 }