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Resolution-agnostic API for logic solvers

There is a newer version: 1.0.4

package it.unibo.tuprolog.solve.primitive

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

/** A base class to implement predicates with one argument */
abstract class UnaryPredicate(operator: String) : PrimitiveWrapper(operator, 1) {
    /** Template method aimed at computing the application of this predicate to a [Term] */
    protected abstract fun Solve.Request.computeAll(first: Term): Sequence

    final override fun uncheckedImplementation(request: Solve.Request): Sequence {
        return request.computeAll(request.arguments[0])
    }

    abstract class WithoutSideEffects(operator: String) : UnaryPredicate(operator) {
        protected abstract fun Solve.Request.computeAllSubstitutions(first: Term): Sequence

        final override fun Solve.Request.computeAll(first: Term): Sequence {
            return computeAllSubstitutions(first).map { replyWith(it) }
        }
    }

    abstract class NonBacktrackable(operator: String) : UnaryPredicate(operator) {
        protected abstract fun Solve.Request.computeOne(first: Term): Solve.Response

        final override fun Solve.Request.computeAll(first: Term): Sequence {
            return sequenceOf(computeOne(first))
        }
    }

    abstract class Functional(operator: String) : NonBacktrackable(operator) {
        protected abstract fun Solve.Request.computeOneSubstitution(first: Term): Substitution

        final override fun Solve.Request.computeOne(first: Term): Solve.Response {
            return replyWith(computeOneSubstitution(first))
        }
    }

    abstract class Predicative(operator: String) : NonBacktrackable(operator) {
        protected abstract fun Solve.Request.compute(first: Term): Boolean

        final override fun Solve.Request.computeOne(first: Term): Solve.Response {
            return if (compute(first)) replySuccess() else replyFail()
        }
    }
}