1package csync
2
3import (
4 "encoding/json"
5 "iter"
6 "maps"
7 "sync"
8)
9
10// Map is a concurrent map implementation that provides thread-safe access.
11type Map[K comparable, V any] struct {
12 inner map[K]V
13 mu sync.RWMutex
14}
15
16// NewMap creates a new thread-safe map with the specified key and value types.
17func NewMap[K comparable, V any]() *Map[K, V] {
18 return &Map[K, V]{
19 inner: make(map[K]V),
20 }
21}
22
23// NewMapFrom creates a new thread-safe map from an existing map.
24func NewMapFrom[K comparable, V any](m map[K]V) *Map[K, V] {
25 return &Map[K, V]{
26 inner: m,
27 }
28}
29
30// NewLazyMap creates a new lazy-loaded map. The provided load function is
31// executed in a separate goroutine to populate the map.
32func NewLazyMap[K comparable, V any](load func() map[K]V) *Map[K, V] {
33 m := &Map[K, V]{}
34 m.mu.Lock()
35 go func() {
36 m.inner = load()
37 m.mu.Unlock()
38 }()
39 return m
40}
41
42// Set sets the value for the specified key in the map.
43func (m *Map[K, V]) Set(key K, value V) {
44 m.mu.Lock()
45 defer m.mu.Unlock()
46 m.inner[key] = value
47}
48
49// Del deletes the specified key from the map.
50func (m *Map[K, V]) Del(key K) {
51 m.mu.Lock()
52 defer m.mu.Unlock()
53 delete(m.inner, key)
54}
55
56// Get gets the value for the specified key from the map.
57func (m *Map[K, V]) Get(key K) (V, bool) {
58 m.mu.RLock()
59 defer m.mu.RUnlock()
60 v, ok := m.inner[key]
61 return v, ok
62}
63
64// Len returns the number of items in the map.
65func (m *Map[K, V]) Len() int {
66 m.mu.RLock()
67 defer m.mu.RUnlock()
68 return len(m.inner)
69}
70
71// GetOrSet gets and returns the key if it exists, otherwise, it executes the
72// given function, set its return value for the given key, and returns it.
73func (m *Map[K, V]) GetOrSet(key K, fn func() V) V {
74 got, ok := m.Get(key)
75 if ok {
76 return got
77 }
78 value := fn()
79 m.Set(key, value)
80 return value
81}
82
83// Take gets an item and then deletes it.
84func (m *Map[K, V]) Take(key K) (V, bool) {
85 m.mu.Lock()
86 defer m.mu.Unlock()
87 v, ok := m.inner[key]
88 delete(m.inner, key)
89 return v, ok
90}
91
92// Seq2 returns an iter.Seq2 that yields key-value pairs from the map.
93func (m *Map[K, V]) Seq2() iter.Seq2[K, V] {
94 dst := make(map[K]V)
95 m.mu.RLock()
96 maps.Copy(dst, m.inner)
97 m.mu.RUnlock()
98 return func(yield func(K, V) bool) {
99 for k, v := range dst {
100 if !yield(k, v) {
101 return
102 }
103 }
104 }
105}
106
107// Seq returns an iter.Seq that yields values from the map.
108func (m *Map[K, V]) Seq() iter.Seq[V] {
109 return func(yield func(V) bool) {
110 for _, v := range m.Seq2() {
111 if !yield(v) {
112 return
113 }
114 }
115 }
116}
117
118var (
119 _ json.Unmarshaler = &Map[string, any]{}
120 _ json.Marshaler = &Map[string, any]{}
121)
122
123func (Map[K, V]) JSONSchemaAlias() any { //nolint
124 m := map[K]V{}
125 return m
126}
127
128// UnmarshalJSON implements json.Unmarshaler.
129func (m *Map[K, V]) UnmarshalJSON(data []byte) error {
130 m.mu.Lock()
131 defer m.mu.Unlock()
132 m.inner = make(map[K]V)
133 return json.Unmarshal(data, &m.inner)
134}
135
136// MarshalJSON implements json.Marshaler.
137func (m *Map[K, V]) MarshalJSON() ([]byte, error) {
138 m.mu.RLock()
139 defer m.mu.RUnlock()
140 return json.Marshal(m.inner)
141}