chore: import upstream snapshot with attribution

utils/slice_to_map.go

@@ -0,0 +1,34 @@
+// Copyright 2023 Dolthub, Inc.
+//
+// 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 utils
+
+// SliceToMapKeys converts the given slice into a map where all of the keys are represented by all of the slice's values.
+func SliceToMapKeys[T comparable](slice []T) map[T]struct{} {
+	m := make(map[T]struct{})
+	for _, val := range slice {
+		m[val] = struct{}{}
+	}
+	return m
+}
+
+// SliceToMapValues converts the given slice into a map where all of the slice's values are keyed by the output of the
+// `getKey` function, which takes a value and returns a key. It is up to the caller to return a unique key.
+func SliceToMapValues[K comparable, V any](slice []V, getKey func(V) K) map[K]V {
+	m := make(map[K]V)
+	for _, val := range slice {
+		m[getKey(val)] = val
+	}
+	return m
+}