README
¶
orderedmap
A generic, thread-safe ordered map for Go that preserves insertion order using linkedlist.
Installation
go get github.com/winebarrel/orderedmap/v2
Requires Go 1.27+.
Usage
package main
import (
"fmt"
"slices"
"github.com/winebarrel/orderedmap/v2"
)
func main() {
om := orderedmap.New[string, any]()
om.Set("foo", "bar")
om.Set("zoo", 100)
om.Set("baz", true)
fmt.Println(om)
//=> *orderedmap.Map[string,interface {}][foo:bar zoo:100 baz:true]
// Get a value
fmt.Println(om.Get("foo"))
//=> bar
// Get a value with existence check
v, ok := om.GetOk("foo")
fmt.Println(v, ok)
//=> bar true
// Iterate over key-value pairs in insertion order
for k, v := range om.All() {
fmt.Println(k, v)
}
//=> foo bar
// zoo 100
// baz true
// Iterate over keys
for k := range om.Keys() {
fmt.Println(k)
}
// Iterate over values
for v := range om.Values() {
fmt.Println(v)
}
// Push moves an existing key to the back
om.Push("foo", "new_bar")
for k, v := range om.All() {
fmt.Println(k, v)
}
//=> zoo 100
// baz true
// foo new_bar
// Get all key-value pairs as a slice
pairs := om.Entries()
fmt.Println(pairs)
//=> [{zoo 100} {baz true} {foo new_bar}]
// Delete a key
om.Delete("zoo")
// Get the number of entries
fmt.Println(om.Len())
//=> 2
// Clear all entries
om.Clear()
// Create from an iterator
om2 := orderedmap.From(slices.All([]string{"foo", "bar", "baz"}))
fmt.Println(om2)
//=> *orderedmap.Map[int,string][0:foo 1:bar 2:baz]
}
Filter
package main
import (
"fmt"
"github.com/winebarrel/orderedmap/v2"
)
func main() {
om := orderedmap.New[string, int]()
om.Set("foo", 1)
om.Set("bar", 2)
om.Set("baz", 3)
// Filter returns a new map containing only the entries that satisfy the predicate
om2 := om.Filter(func(k string, v int) bool {
return v != 2
})
fmt.Println(om2)
//=> *orderedmap.Map[string,int][foo:1 baz:3]
}
Transform
package main
import (
"fmt"
"github.com/winebarrel/orderedmap/v2"
)
func main() {
om := orderedmap.New[string, int]()
om.Set("foo", 1)
om.Set("bar", 2)
om.Set("baz", 3)
// Transform returns an iterator of transformed values
for s := range om.Transform(func(k string, v int) string {
return fmt.Sprintf("%s=%d", k, v)
}) {
fmt.Println(s)
}
//=> foo=1
// bar=2
// baz=3
// TransformSlice returns a slice of transformed values
ss := om.TransformSlice(func(k string, v int) string {
return fmt.Sprintf("%s=%d", k, v)
})
fmt.Println(ss)
//=> [foo=1 bar=2 baz=3]
}
JSON Marshal / Unmarshal
package main
import (
"encoding/json"
"fmt"
"github.com/winebarrel/orderedmap/v2"
)
func main() {
// Marshal: preserves insertion order
om := orderedmap.New[string, any]()
om.Set("z", 3)
om.Set("a", 1)
om.Set("m", 2)
b, _ := json.Marshal(om)
fmt.Println(string(b))
//=> {"z":3,"a":1,"m":2}
// Unmarshal: preserves key order from JSON
om2 := orderedmap.New[string, any]()
json.Unmarshal([]byte(`{"z":3,"a":1,"m":2}`), om2)
for k, v := range om2.All() {
fmt.Println(k, v)
}
//=> z 3
// a 1
// m 2
}
encoding/json/v2
Map implements MarshalerTo and
UnmarshalerFrom, so encoding/json/v2
options (indentation, HTML escaping, ...) are honored.
package main
import (
"encoding/json/jsontext"
json "encoding/json/v2"
"fmt"
"github.com/winebarrel/orderedmap/v2"
)
func main() {
// Marshal: preserves insertion order
om := orderedmap.New[string, any]()
om.Set("z", 3)
om.Set("a", 1)
om.Set("m", 2)
b, _ := json.Marshal(om, jsontext.WithIndent(" "))
fmt.Println(string(b))
//=> {
// "z": 3,
// "a": 1,
// "m": 2
// }
// Unmarshal: preserves key order from JSON
om2 := orderedmap.New[string, any]()
json.Unmarshal([]byte(`{"z":3,"a":1,"m":2}`), om2)
for k, v := range om2.All() {
fmt.Println(k, v)
}
//=> z 3
// a 1
// m 2
}
Documentation
¶
Index ¶
- func Transform[K comparable, V any, R any](om *Map[K, V], f func(k K, v V) R) iter.Seq[R]
- func TransformSlice[K comparable, V any, R any](om *Map[K, V], f func(k K, v V) R) []R
- type Map
- func (om *Map[K, V]) All() iter.Seq2[K, V]
- func (om *Map[K, V]) Clear()
- func (om *Map[K, V]) Clone() *Map[K, V]
- func (om *Map[K, V]) CollectKeys() []K
- func (om *Map[K, V]) CollectValues() []V
- func (om *Map[K, V]) Delete(k K) V
- func (om *Map[K, V]) DeleteOk(k K) (V, bool)
- func (om *Map[K, V]) Entries() []Pair[K, V]
- func (om *Map[K, V]) Filter(f func(k K, v V) bool) *Map[K, V]
- func (om *Map[K, V]) Get(k K) V
- func (om *Map[K, V]) GetOk(k K) (V, bool)
- func (om *Map[K, V]) Keys() iter.Seq[K]
- func (om *Map[K, V]) Len() int
- func (om *Map[K, V]) MarshalJSON() ([]byte, error)
- func (om *Map[K, V]) MarshalJSONTo(enc *jsontext.Encoder) error
- func (om *Map[K, V]) Push(k K, v V)
- func (om *Map[K, V]) Set(k K, v V)
- func (om *Map[K, V]) String() string
- func (om *Map[K, V]) Transform[R any](f func(k K, v V) R) iter.Seq[R]
- func (om *Map[K, V]) TransformSlice[R any](f func(k K, v V) R) []R
- func (om *Map[K, V]) UnmarshalJSON(data []byte) error
- func (om *Map[K, V]) UnmarshalJSONFrom(dec *jsontext.Decoder) error
- func (om *Map[K, V]) Values() iter.Seq[V]
- type Pair
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
func TransformSlice ¶
func TransformSlice[K comparable, V any, R any](om *Map[K, V], f func(k K, v V) R) []R
Types ¶
type Map ¶
type Map[K comparable, V any] struct { // contains filtered or unexported fields }
func New ¶
func New[K comparable, V any]() *Map[K, V]
func (*Map[K, V]) CollectKeys ¶
func (om *Map[K, V]) CollectKeys() []K
func (*Map[K, V]) CollectValues ¶
func (om *Map[K, V]) CollectValues() []V
func (*Map[K, V]) MarshalJSON ¶
MarshalJSON implements jsonv1.Marshaler with encoding/json v1 semantics. Encoders aware of jsonv2.MarshalerTo call Map.MarshalJSONTo instead.
func (*Map[K, V]) MarshalJSONTo ¶ added in v2.2.0
MarshalJSONTo implements jsonv2.MarshalerTo. It encodes the map as a JSON object, preserving insertion order.
func (*Map[K, V]) TransformSlice ¶ added in v2.1.0
func (*Map[K, V]) UnmarshalJSON ¶
UnmarshalJSON implements jsonv1.Unmarshaler with encoding/json v1 semantics. Decoders aware of jsonv2.UnmarshalerFrom call Map.UnmarshalJSONFrom instead.
func (*Map[K, V]) UnmarshalJSONFrom ¶ added in v2.2.0
UnmarshalJSONFrom implements jsonv2.UnmarshalerFrom. It decodes a JSON object, preserving the order of its members. Entries already held by the map are discarded.
type Pair ¶
type Pair[K comparable, V any] struct { Key K Value V }
Source Files
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