[chore] add some more slice related utility functions + remove duplicated functions (#3149)

internal/util/unique.go

@@ -17,48 +17,57 @@
 
 package util
 
-import "net/url"
+// Set represents a hashmap of only keys,
+// useful for deduplication / key checking.
+type Set[T comparable] map[T]struct{}
 
-// UniqueStrings returns a deduplicated version of the given
-// slice of strings, without changing the order of the entries.
-func UniqueStrings(strings []string) []string {
-	var (
-		l      = len(strings)
-		keys   = make(map[string]any, l) // Use map to dedupe items.
-		unique = make([]string, 0, l)    // Return slice.
-	)
-
-	for _, str := range strings {
-		// Check if already set as a key in the map;
-		// if not, add to return slice + mark key as set.
-		if _, set := keys[str]; !set {
-			keys[str] = nil // Value doesn't matter.
-			unique = append(unique, str)
-		}
+// ToSet creates a Set[T] from given values,
+// noting that this does not maintain any order.
+func ToSet[T comparable](in []T) Set[T] {
+	set := make(Set[T], len(in))
+	for _, v := range in {
+		set[v] = struct{}{}
 	}
-
-	return unique
+	return set
 }
 
-// UniqueURIs returns a deduplicated version of the given
-// slice of URIs, without changing the order of the entries.
-func UniqueURIs(uris []*url.URL) []*url.URL {
-	var (
-		l      = len(uris)
-		keys   = make(map[string]any, l) // Use map to dedupe items.
-		unique = make([]*url.URL, 0, l)  // Return slice.
-	)
+// FromSet extracts the values from set to slice,
+// noting that this does not maintain any order.
+func FromSet[T comparable](in Set[T]) []T {
+	out := make([]T, len(in))
+	var i int
+	for v := range in {
+		out[i] = v
+		i++
+	}
+	return out
+}
 
-	for _, uri := range uris {
-		uriStr := uri.String()
-
-		// Check if already set as a key in the map;
-		// if not, add to return slice + mark key as set.
-		if _, set := keys[uriStr]; !set {
-			keys[uriStr] = nil // Value doesn't matter.
-			unique = append(unique, uri)
+// In returns input slice filtered to
+// only contain those in receiving set.
+func (s Set[T]) In(vs []T) []T {
+	out := make([]T, 0, len(vs))
+	for _, v := range vs {
+		if _, ok := s[v]; ok {
+			out = append(out, v)
 		}
 	}
-
-	return unique
+	return out
+}
+
+// NotIn is the functional inverse of In().
+func (s Set[T]) NotIn(vs []T) []T {
+	out := make([]T, 0, len(vs))
+	for _, v := range vs {
+		if _, ok := s[v]; !ok {
+			out = append(out, v)
+		}
+	}
+	return out
+}
+
+// Has returns if value is in Set.
+func (s Set[T]) Has(v T) bool {
+	_, ok := s[v]
+	return ok
 }