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https://github.com/elliotchance/orderedmap
🔃 An ordered map in Go with amortized O(1) for Set, Get, Delete and Len.
https://github.com/elliotchance/orderedmap
data-structures golang maps orderedmap
Last synced: 5 days ago
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🔃 An ordered map in Go with amortized O(1) for Set, Get, Delete and Len.
- Host: GitHub
- URL: https://github.com/elliotchance/orderedmap
- Owner: elliotchance
- License: mit
- Created: 2019-11-14T21:12:26.000Z (about 5 years ago)
- Default Branch: master
- Last Pushed: 2025-01-02T16:04:20.000Z (24 days ago)
- Last Synced: 2025-01-14T06:02:51.694Z (12 days ago)
- Topics: data-structures, golang, maps, orderedmap
- Language: Go
- Homepage:
- Size: 70.3 KB
- Stars: 890
- Watchers: 16
- Forks: 66
- Open Issues: 10
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# 🔃 github.com/elliotchance/orderedmap/v3 [](https://godoc.org/github.com/elliotchance/orderedmap/v3)
## Basic Usage
An `*OrderedMap` is a high performance ordered map that maintains amortized O(1)
for `Set`, `Get`, `Delete` and `Len`:
```go
import "github.com/elliotchance/orderedmap/v3"
func main() {
m := orderedmap.NewOrderedMap[string, any]()
m.Set("foo", "bar")
m.Set("qux", 1.23)
m.Set("123", true)
m.Delete("qux")
}
```
> [!NOTE]
>
> - _v3 requires Go v1.23_ - If you need to support Go 1.18-1.22, you can use v2.
> - _v2 requires Go v1.18 for generics_ - If you need to support Go 1.17 or below, you can use v1.
Internally an `*OrderedMap` uses the composite type
[map](https://go.dev/blog/maps) combined with a
trimmed down linked list to maintain the order.
## Iterating
The following methods all return
[iterators](https://go.dev/doc/go1.23#iterators) that can be used to loop over
elements in an ordered map:
- `AllFromFront()`
- `AllFromBack()`
- `Keys()`
- `Values()`
```go
// Iterate through all elements from oldest to newest:
for key, value := range m.AllFromFront() {
fmt.Println(key, value)
}
```
Iterators are safe to use bidirectionally, and will return `nil` once it goes
beyond the first or last item. If the map is changing while the iteration is
in-flight it may produce unexpected behavior.
If you want to get a slice of the map keys or values, you can use the standard
`slices.Collect` method with the iterator returned from `Keys()` or `Values()`:
```go
fmt.Println(slices.Collect(m.Keys())
// [A B C]
```
Likewise, calling `maps.Collect` on the iterator returned from `AllFromFront()`
will create a regular unordered map from the ordered one:
```go
fmt.Println(maps.Collect(m.AllFromFront())
// [A:1 B:2 C:3]
```
If you don't want to use iterators, you can also manually loop over the elements
using `Front()` or `Back()` with `Next()`:
```go
// Iterate through all elements from oldest to newest:
for el := m.Front(); el != nil; el = el.Next() {
fmt.Println(el.Key, el.Value)
}
// You can also use Back and Prev to iterate in reverse:
for el := m.Back(); el != nil; el = el.Prev() {
fmt.Println(el.Key, el.Value)
}
```