-
Notifications
You must be signed in to change notification settings - Fork 3
/
std_map.go
205 lines (180 loc) · 5.25 KB
/
std_map.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
package maps
import (
"bytes"
"encoding/gob"
"encoding/json"
"fmt"
"strings"
)
// StdMap wraps a standard go map with a standard set of functions shared with other MapI-like types.
//
// The zero value is NOT settable. Use NewStdMap to create a new StdMap object, or use standard
// map instantiation syntax like this:
// m := StdMap[string, int]{"a":1}
//
// StdMap is mostly a convenience type for making a standard Go map into a MapI interface.
// Generally, you should use Map instead, as it presents a consistent interface that allows you
// to swap the underlying type without changing implemented code.
type StdMap[K comparable, V any] map[K]V
// NewStdMap creates a new map that maps values of type K to values of type V.
// Pass in zero or more standard maps and the contents of those maps will be copied to the new StdMap.
// You can also create a new StdMap like this:
// m := StdMap[string, int]{"a":1}
func NewStdMap[K comparable, V any](sources ...map[K]V) StdMap[K, V] {
m := StdMap[K, V]{}
for _, i := range sources {
m.Merge(Cast(i))
}
return m
}
// Cast is a convenience method for casting a standard Go map to a StdMap type.
// Note that this is a cast, so the return value is the equivalent map of what
// was past in. Use this primarily to make a standard map into a MapI object.
func Cast[M ~map[K]V, K comparable, V any](m M) StdMap[K, V] {
return StdMap[K, V](m)
}
// Clear resets the map to an empty map
func (m StdMap[K, V]) Clear() {
for k := range m {
delete(m, k)
}
}
// Len returns the number of items in the map.
func (m StdMap[K, V]) Len() int {
return len(m)
}
// Merge copies the items from in to the map, overwriting any conflicting keys.
func (m StdMap[K, V]) Merge(in MapI[K, V]) {
if m == nil {
panic("cannot merge into a nil map")
}
in.Range(func(k K, v V) bool {
m[k] = v
return true
})
}
// Range calls the given function for each key,value pair in the map.
// This is the same interface as sync.Map.Range().
// While its safe to call methods of the map from within the Range function, its discouraged.
// If you ever switch to one of the SafeMap maps, it will cause a deadlock.
func (m StdMap[K, V]) Range(f func(k K, v V) bool) {
for k, v := range m {
if !f(k, v) {
break
}
}
}
// Load returns the value based on its key, and a boolean indicating whether it exists in the map.
// This is the same interface as sync.Map.Load()
func (m StdMap[K, V]) Load(k K) (v V, ok bool) {
if m == nil {
return
}
v, ok = m[k]
return
}
// Get returns the value for the given key. If the key does not exist, the zero value will be returned.
func (m StdMap[K, V]) Get(k K) (v V) {
v, _ = m.Load(k)
return
}
// Has returns true if the key exists.
func (m StdMap[K, V]) Has(k K) (exists bool) {
_, exists = m.Load(k)
return
}
// Set sets the given key to the given value.
func (m StdMap[K, V]) Set(k K, v V) {
if m == nil {
panic("cannot call Set() on a nil map")
}
m[k] = v
}
// Delete removes the key from the map. If the key does not exist, nothing happens.
func (m StdMap[K, V]) Delete(k K) {
delete(m, k)
}
// Keys returns a new slice containing the keys of the map.
func (m StdMap[K, V]) Keys() (keys []K) {
if m.Len() == 0 {
return
}
keys = make([]K, m.Len())
var i int
for k := range m {
keys[i] = k
i++
}
return keys
}
// Values returns a new slice containing the values of the map.
func (m StdMap[K, V]) Values() (values []V) {
if m.Len() == 0 {
return
}
values = make([]V, m.Len())
var i int
for _, v := range m {
values[i] = v
i++
}
return values
}
// Equal returns true if all the keys and values are equal.
//
// If the values are not comparable, you should implement the Equaler interface on the values.
// Otherwise you will get a runtime panic.
func (m StdMap[K, V]) Equal(m2 MapI[K, V]) bool {
if m.Len() != m2.Len() {
return false
}
ret := true
m2.Range(func(k K, v V) bool {
if v2, ok := m[k]; !ok || !equalValues(v, v2) {
ret = false
return false
}
return true
})
return ret
}
// String returns a string representation of the map.
func (m StdMap[K, V]) String() string {
s := fmt.Sprintf("%#v", m)
loc := strings.IndexRune(s, '{')
return s[loc:]
}
// MarshalBinary implements the BinaryMarshaler interface to convert the map to a byte stream.
func (m StdMap[K, V]) MarshalBinary() ([]byte, error) {
var b bytes.Buffer
enc := gob.NewEncoder(&b)
err := enc.Encode(map[K]V(m))
return b.Bytes(), err
}
// UnmarshalBinary implements the BinaryUnmarshaler interface to convert a byte stream to a Map.
//
// Note that you will likely need to register the unmarshaller at init time with gob like this:
// func init() {
// gob.Register(new(Map[K,V]))
// }
func (m *StdMap[K, V]) UnmarshalBinary(data []byte) (err error) {
b := bytes.NewBuffer(data)
dec := gob.NewDecoder(b)
var v map[K]V
err = dec.Decode(&v)
*m = v
return
}
// MarshalJSON implements the json.Marshaler interface to convert the map into a JSON object.
func (m StdMap[K, V]) MarshalJSON() (out []byte, err error) {
v := map[K]V(m)
return json.Marshal(v)
}
// UnmarshalJSON implements the json.Unmarshaler interface to convert a json object to a StdMap.
// The JSON must start with an object.
func (m *StdMap[K, V]) UnmarshalJSON(in []byte) (err error) {
var v map[K]V
err = json.Unmarshal(in, &v)
*m = v
return
}