commonMain.it.unibo.tuprolog.solve.stdlib.primitive.AtomLength.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.Integer
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 AtomLength : BinaryRelation.Functional("atom_length") {
    override fun Solve.Request.computeOneSubstitution(
        first: Term,
        second: Term,
    ): Substitution =
        when {
            first is Var -> {
                ensuringAllArgumentsAreInstantiated()
                Substitution.failed()
            }
            second is Var -> {
                ensuringArgumentIsAtom(0)
                val atomLength = (first as Atom).value.length
                Substitution.of(second, Integer.of(atomLength))
            }
            else -> {
                ensuringArgumentIsAtom(0)
                ensuringArgumentIsNonNegativeInteger(1)
                val atomLength = Integer.of((first as Atom).value.length)
                mgu(atomLength, second)
            }
        }
}