interval: the IN operator can now check if an integer value is inlcuded in a range

types/interval/interval.go

@@ -8,6 +8,7 @@ import (
 	"fmt"
 
 	"git.portale-stac.it/go-pkg/expr/kern"
+	"git.portale-stac.it/go-pkg/expr/types"
 )
 
 const TypeName = "interval"
@@ -60,6 +61,17 @@ func (p *IntervalType) ToIntTriple() (b, e, s int) {
 	return
 }
 
+func (p *IntervalType) Contains(value any) (ok bool) {
+	if v, err := types.ToGoInt64(value, TypeName); err == nil {
+		if p.begin <= p.end {
+			ok = (v >= p.begin && v < p.end && (v-p.begin)%p.step == 0)
+		} else {
+			ok = (v <= p.begin && v > p.end && (v-p.begin)%p.step == 0)
+		}
+	}
+	return
+}
+
 // func (b *bool) EqualTo(other kern.Equaler) (equal bool) {
 // 	if otherBool, ok := other.(*bool); ok {
 // 		equal = b == otherBool