wk8/ go-ordered-map

Need help with go-ordered-map?

Click the “chat” button below for chat support from the developer who created it, or find similar developers for support.

About the developer

wk8

152 Stars

11 Forks

Apache License 2.0

8 Commits

1 Opened issues

Description

Optimal implementation of ordered maps for Golang - ie maps that remember the order in which keys were inserted.

Services available

Need anything else?

Contributors list

Jean Rougé wk8

# 211,808

Erlang

Rails

k8s-sig...

3 commits

Readme

Goland Ordered Maps

Name: go-ordered-map
Brand: go-ordered-map
SKU: //wk8/go-ordered-map
Rating: 2.13 (152 reviews)

Same as regular maps, but also remembers the order in which keys were inserted, akin to Python's

collections.OrderedDict

It offers the following features: * optimal runtime performance (all operations are constant time) * optimal memory usage (only one copy of values, no unnecessary memory allocation) * allows iterating from newest or oldest keys indifferently, without memory copy, allowing to

break

the iteration, and in time linear to the number of keys iterated over rather than the total length of the ordered map * takes and returns generic

interface{}

s * idiomatic API, akin to that of

container/list

Installation

go get -u github.com/wk8/go-ordered-map

Or use your favorite golang vendoring tool!

Documentation

The full documentation is available on godoc.org.

Example / usage

package main

import (
    "fmt"
"github.com/wk8/go-ordered-map"
)
func main() {
    om := orderedmap.New()
om.Set("foo", "bar")
om.Set("bar", "baz")
om.Set("coucou", "toi")

fmt.Println(om.Get("foo"))          // =&gt; bar, true
fmt.Println(om.Get("i dont exist")) // =&gt; <nil>, false

// iterating pairs from oldest to newest:
for pair := om.Oldest(); pair != nil; pair = pair.Next() {
    fmt.Printf("%s =&gt; %s\n", pair.Key, pair.Value)
} // prints:
// foo =&gt; bar
// bar =&gt; baz
// coucou =&gt; toi

// iterating over the 2 newest pairs:
i := 0
for pair := om.Newest(); pair != nil; pair = pair.Prev() {
    fmt.Printf("%s =&gt; %s\n", pair.Key, pair.Value)
    i++
    if i &gt;= 2 {
        break
    }
} // prints:
// coucou =&gt; toi
// bar =&gt; baz
}

All of

OrderedMap

's methods accept and return

interface{}

s, so you can use any type of keys that regular

map

s accept, as well pack/unpack arbitrary values, e.g.: ```go type myStruct struct { payload string }

func main() { om := orderedmap.New()

om.Set(12, &myStruct{"foo"})
om.Set(1, &myStruct{"bar"})

value, present := om.Get(12)
if !present {
    panic("should be there!")
}
fmt.Println(value.(*myStruct).payload) // => foo
for pair := om.Oldest(); pair != nil; pair = pair.Next() {
    fmt.Printf("%d => %s\n", pair.Key, pair.Value.(*myStruct).payload)
} // prints:
// 12 => foo
// 1 => bar

} ```

Alternatives

There are several other ordered map golang implementations out there, but I believe that at the time of writing none of them offer the same functionality as this library; more specifically: * iancoleman/orderedmap only accepts

string

keys, its

Delete

operations are linear * cevaris/ordered_map uses a channel for iterations, and leaks goroutines if the iteration is interrupted before fully traversing the map * mantyr/iterator also uses a channel for iterations, and its

Delete

operations are linear * samdolan/go-ordered-map adds unnecessary locking (users should add their own locking instead if they need it), its

Delete

and

Get

operations are linear, iterations trigger a linear memory allocation