commonMain.it.unibo.tuprolog.solve.streams.SolverStrategies.kt Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of solve-streams-jvm Show documentation

Experimental, functional-programming-based implementation of Prolog's SLDNF resolution principle

There is a newer version: 1.0.4

package it.unibo.tuprolog.solve.streams

import it.unibo.tuprolog.core.Clause
import it.unibo.tuprolog.core.Term
import it.unibo.tuprolog.solve.ExecutionContext

/**
 * Interface representing internal strategies used by the [Solver]
 *
 * @author Enrico
 */
interface SolverStrategies {
    /** Selects the predication to be solved first, from provided sequence */
    fun  predicationChoiceStrategy(
        predicationSequence: Sequence
,
        context: ExecutionContext,
    ): P

    /** Selects the clause to be expanded in place of unifying predication, from provided sequence */
    fun  clauseChoiceStrategy(
        unifiableClauses: Sequence,
        context: ExecutionContext,
    ): C

    /** Determines "when and what" is considered successfully demonstrated, during solution process */
    fun successCheckStrategy(
        term: Term,
        context: ExecutionContext,
    ): Boolean

    companion object {
        /** Returns a strategy object containing the key solution strategies used by a Standard Prolog solver */
        val prologStandard =
            object : SolverStrategies {
                /** The default implementation, following the Prolog Standard, selects the first predication found */
                override fun 
 predicationChoiceStrategy(
                    predicationSequence: Sequence,
                    context: ExecutionContext,
                ): P = predicationSequence.first()

                /** The default implementation, following the Prolog Standard, selects the first clause found */
                override fun  clauseChoiceStrategy(
                    unifiableClauses: Sequence,
                    context: ExecutionContext,
                ): C = unifiableClauses.first()

                override fun successCheckStrategy(
                    term: Term,
                    context: ExecutionContext,
                ): Boolean = term.isTrue
            }
    }
}