feat: move classifier to its own package

move the classifier to its own package. introduces a generic way of
classifying usages against thresholds.

pkg/framework/plugins/nodeutilization/classifier/classifier.go

@@ -0,0 +1,84 @@
+/*
+Copyright 2025 The Kubernetes Authors.
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+	http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package classifier
+
+// Classifier is a function that classifies a resource usage based on a limit.
+// The function should return true if the resource usage matches the classifier
+// intent.
+type Classifier[K comparable, V any] func(K, V, V) bool
+
+// Comparer is a function that compares two objects. This function should return
+// -1 if the first object is less than the second, 0 if they are equal, and 1 if
+// the first object is greater than the second. Of course this is a simplification
+// and any value between -1 and 1 can be returned.
+type Comparer[V any] func(V, V) int
+
+// Values is a map of values indexed by a comparable key. An example of this
+// can be a list of resources indexed by a node name.
+type Values[K comparable, V any] map[K]V
+
+// Limits is a map of list of limits indexed by a comparable key. Each limit
+// inside the list requires a classifier to evaluate.
+type Limits[K comparable, V any] map[K][]V
+
+// Classify is a function that classifies based on classifier functions. This
+// function receives Values, a list of n Limits (indexed by name), and a list
+// of n Classifiers. The classifier at n position is called to evaluate the
+// limit at n position. The first classifier to return true will receive the
+// value, at this point the loop will break and the next value will be
+// evaluated. This function returns a slice of maps, each position in the
+// returned slice correspond to one of the classifiers (e.g. if n limits
+// and classifiers are provided, the returned slice will have n maps).
+func Classify[K comparable, V any](
+	values Values[K, V], limits Limits[K, V], classifiers ...Classifier[K, V],
+) []map[K]V {
+	result := make([]map[K]V, len(classifiers))
+	for i := range classifiers {
+		result[i] = make(map[K]V)
+	}
+
+	for index, usage := range values {
+		for i, limit := range limits[index] {
+			if len(classifiers) <= i {
+				continue
+			}
+			if !classifiers[i](index, usage, limit) {
+				continue
+			}
+			result[i][index] = usage
+			break
+		}
+	}
+
+	return result
+}
+
+// ForMap is a function that returns a classifier that compares all values in a
+// map. The function receives a Comparer function that is used to compare all
+// the map values. The returned Classifier will return true only if the
+// provided Comparer function returns a value less than 0 for all the values.
+func ForMap[K, I comparable, V any, M ~map[I]V](cmp Comparer[V]) Classifier[K, M] {
+	return func(_ K, usages, limits M) bool {
+		for idx, usage := range usages {
+			if limit, ok := limits[idx]; ok {
+				if cmp(usage, limit) >= 0 {
+					return false
+				}
+			}
+		}
+		return true
+	}
+}