1// Copyright 2021 The Go Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style
3// license that can be found in the LICENSE file.
4
5// Package maps defines various functions useful with maps of any type.
6//
7// This package does not have any special handling for non-reflexive keys
8// (keys k where k != k), such as floating-point NaNs.
9package maps
10
11import (
12	_ "unsafe"
13)
14
15// Equal reports whether two maps contain the same key/value pairs.
16// Values are compared using ==.
17func Equal[M1, M2 ~map[K]V, K, V comparable](m1 M1, m2 M2) bool {
18	if len(m1) != len(m2) {
19		return false
20	}
21	for k, v1 := range m1 {
22		if v2, ok := m2[k]; !ok || v1 != v2 {
23			return false
24		}
25	}
26	return true
27}
28
29// EqualFunc is like Equal, but compares values using eq.
30// Keys are still compared with ==.
31func EqualFunc[M1 ~map[K]V1, M2 ~map[K]V2, K comparable, V1, V2 any](m1 M1, m2 M2, eq func(V1, V2) bool) bool {
32	if len(m1) != len(m2) {
33		return false
34	}
35	for k, v1 := range m1 {
36		if v2, ok := m2[k]; !ok || !eq(v1, v2) {
37			return false
38		}
39	}
40	return true
41}
42
43// clone is implemented in the runtime package.
44//
45//go:linkname clone maps.clone
46func clone(m any) any
47
48// Clone returns a copy of m.  This is a shallow clone:
49// the new keys and values are set using ordinary assignment.
50func Clone[M ~map[K]V, K comparable, V any](m M) M {
51	// Preserve nil in case it matters.
52	if m == nil {
53		return nil
54	}
55	return clone(m).(M)
56}
57
58// Copy copies all key/value pairs in src adding them to dst.
59// When a key in src is already present in dst,
60// the value in dst will be overwritten by the value associated
61// with the key in src.
62func Copy[M1 ~map[K]V, M2 ~map[K]V, K comparable, V any](dst M1, src M2) {
63	for k, v := range src {
64		dst[k] = v
65	}
66}
67
68// DeleteFunc deletes any key/value pairs from m for which del returns true.
69func DeleteFunc[M ~map[K]V, K comparable, V any](m M, del func(K, V) bool) {
70	for k, v := range m {
71		if del(k, v) {
72			delete(m, k)
73		}
74	}
75}
76