commonMain.it.unibo.tuprolog.solve.stdlib.primitive.CurrentFlag.kt Maven / Gradle / Ivy

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Resolution-agnostic API for logic solvers

There is a newer version: 1.0.4

package it.unibo.tuprolog.solve.stdlib.primitive

import it.unibo.tuprolog.core.Atom
import it.unibo.tuprolog.core.Substitution
import it.unibo.tuprolog.core.Term
import it.unibo.tuprolog.core.Var
import it.unibo.tuprolog.solve.ExecutionContext
import it.unibo.tuprolog.solve.primitive.BinaryRelation
import it.unibo.tuprolog.solve.primitive.Solve

object CurrentFlag : BinaryRelation.WithoutSideEffects("current_flag") {
    override fun Solve.Request.computeAllSubstitutions(
        first: Term,
        second: Term,
    ): Sequence =
        when (first) {
            is Atom, is Var -> {
                context.flags.asSequence()
                    .map { (k, v) -> Atom.of(k) to v }
                    .map { (k, v) -> mgu(k, first) + mgu(v, second) }
                    .filter { it.isSuccess }
            }
            else -> {
                ensuringArgumentIsAtom(0)
                emptySequence()
            }
        }
}