| // Copyright 2023 The Go Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style |
| // license that can be found in the LICENSE file. |
| |
| package maps |
| |
| // Group returns a new non-nil map containing the elements of s grouped by the |
| // keys returned from the key func. |
| func Group[K comparable, V any](s []V, key func(V) K) map[K][]V { |
| m := make(map[K][]V) |
| for _, v := range s { |
| k := key(v) |
| m[k] = append(m[k], v) |
| } |
| return m |
| } |
| |
| // Keys returns the keys of the map M. |
| func Keys[M ~map[K]V, K comparable, V any](m M) []K { |
| r := make([]K, 0, len(m)) |
| for k := range m { |
| r = append(r, k) |
| } |
| return r |
| } |
| |
| // SameKeys reports whether x and y have equal sets of keys. |
| func SameKeys[K comparable, V1, V2 any](x map[K]V1, y map[K]V2) bool { |
| if len(x) != len(y) { |
| return false |
| } |
| for k := range x { |
| if _, ok := y[k]; !ok { |
| return false |
| } |
| } |
| return true |
| } |