Method evalDiamondPlus

engine/temporal.go:336–372

evalDiamondPlus implements the diamond-plus operator (<+). It returns true if the atom will be true at SOME point in the future interval. Syntax: <+[d1, d2] p(X) means "p(X) will be true at some point between d1 and d2 from now"

(
	atom ast.Atom,
	opInterval ast.Interval,
	interval *ast.Interval,
	subst unionfind.UnionFind,
)

// It returns true if the atom will be true at SOME point in the future interval.
// Syntax: <+[d1, d2] p(X) means "p(X) will be true at some point between d1 and d2 from now"
func (te *TemporalEvaluator) evalDiamondPlus(
	atom ast.Atom,
	opInterval ast.Interval,
	interval *ast.Interval,
	subst unionfind.UnionFind,
) ([]unionfind.UnionFind, error) {
	// Calculate the query interval based on the operator's interval
	queryInterval, err := te.resolveFutureOperatorInterval(opInterval)
	if err != nil {
		return nil, err
	}

	var solutions []unionfind.UnionFind

	// Query facts that overlap with the future query interval
	err = te.temporalStore.GetFactsDuring(atom, queryInterval, func(tf factstore.TemporalFact) error {
		// Unify the fact with the query atom
		newSubst, err := unionfind.UnifyTermsExtend(atom.Args, tf.Atom.Args, subst)
		if err != nil {
			return nil // No match, continue
		}

		// Bind interval variables if present
		if interval != nil {
			newSubst = te.bindIntervalVariables(*interval, tf.Interval, newSubst)
		}

		solutions = append(solutions, newSubst)
		return nil
	})

	if err != nil {
		return nil, err
	}

	return solutions, nil
}

// evalBoxPlus implements the box-plus operator ([+).
// It returns true if the atom will be true CONTINUOUSLY throughout the future interval.