feat: add experimental iterator

iterator.go

@@ -0,0 +1,41 @@
+//go:build go1.22 && goexperiment.rangefunc
+// +build go1.22,goexperiment.rangefunc
+
+package gitlab
+
+import (
+	"iter"
+)
+
+// PageIterator is an EXPERIMENTAL iterator as defined in the "rangefunc" experiment for go 1.22.
+// See https://go.dev/wiki/RangefuncExperiment for more details.
+//
+// It can be used as:
+//
+//	for user, err := range gitlab.PageIterator(gl.Users.List, nil) {
+//		if err != nil {
+//			// handle error
+//		}
+//		// process individual user
+//	}
+func PageIterator[O, T any](f Paginatable[O, T], opt *O) iter.Seq2[*T, error] {
+	return func(yield func(*T, error) bool) {
+		nextLink := ""
+		for {
+			page, resp, err := f(opt, WithKeysetPaginationParameters(nextLink))
+			if err != nil {
+				yield(nil, err)
+				return
+			}
+			for _, p := range page {
+				if !yield(p, nil) {
+					return
+				}
+			}
+			if resp.NextLink == "" {
+				break
+			}
+			nextLink = resp.NextLink
+		}
+	}
+}