aertje / keepcase

Go module that provides a case-insensitive map - while keeping the key's casing

KeepCase

This module provides you with a map[string]T-like struct with some pretty specific behaviour.

You shouldn't need to use this. My very particular use case is to override HTTP headers while not affecting the existing casing.

Behaviour

It fulfills the following requirements:

• Set key and value, maintaining the casing of the key.
• If a key is already set, setting it again maintains the existing casing of the key.
• Retrieve the value for a key in a case-insensitive way.

The implementation is thead-safe.

Sample

Its behaviour is probably best demonstrated with an example. Note how:

• The Content-Type key casing is kept intact.
• The value for the Content-Type key is overwritten, even though the input key is content-type.
• The value can be retrieved with both Content-Type and content-type.

import "github.com/aertje/keepcase"

m := keepcase.NewMap[string]()

v, ok := m.Get("content-type") // => "", false
l := m.Len() // => 0
mm := m.AsMap() // => {}

m.Set("Content-Type", "application/json")
v, ok = m.Get("content-type") // => "application/json", true
l = m.Len() // => 1
mm = m.AsMap() // => {"Content-Type": "application/json"}

m.Set("content-type", "text/html")

v, ok = m.Get("content-type") // => "text/html", true
v, ok = m.Get("Content-Type") // => "text/html", true
mm = m.AsMap() // => {"Content-Type": "text/html"}
l = m.Len() // => 1

Use it

Since it uses generics, Go 1.18 is required.

go get github.com/aertje/keepcase