orderedmap

Overview

A Go map that preserves insertion order for manual operations and JSON marshalling. Nested JSON objects are unmarshalled as ordered maps too.

Installation

go get github.com/cornelk/orderedmap

Requires Go 1.24 or later.

Usage

package main

import (
	"encoding/json"
	"fmt"

	"github.com/cornelk/orderedmap"
)

func main() {
	var m orderedmap.Map

	m.Set("name", "Alice")
	m.Set("age", 30)

	if value, ok := m.Get("name"); ok {
		fmt.Println(value)
	}

	m.Range(func(key string, value any) bool {
		fmt.Printf("%s: %v\n", key, value)
		return true
	})

	data, _ := json.Marshal(&m)
	fmt.Println(string(data))
}

JSON input order is preserved when unmarshalling and marshalling:

var m orderedmap.Map
input := `{"423":"abc","231":"dbh","152":"xyz"}`

json.Unmarshal([]byte(input), &m)
output, _ := json.Marshal(&m)
// Output: {"423":"abc","231":"dbh","152":"xyz"}

API

• Set(key string, value any) adds or updates a value without moving existing keys.
• Get(key string) (any, bool) retrieves a value.
• Delete(key string) bool removes a value.
• GetAndDelete(key string) (any, bool) retrieves and removes a value.
• Clear() removes all values.
• Len() int returns the number of entries.
• Range(func(key string, value any) bool) iterates in insertion order.

License

Apache-2.0 License - See LICENSE file for details.