URN

A Rust crate for handling URNs. Parsing and comparison is done according to the spec (meaning only part of the URN is used for equality checks). Some RFCs define per-namespace lexical equivalence rules, those aren't taken into account here. no_std support is available if you disable the default "std" feature. alloc is needed, but the Urn type is a wrapper around String and should only use a single allocation (but I haven't checked). You can even construct a Urn from your own String by using TryFrom<String>, that way it shouldn't allocate at all.

URNs have a surprising amount of obscure details to the point I'm not sure if other URN parsers can be trusted! Granted, there's very little of them because almost nobody really needs URNs...

Changelog

• 0.1.0 - initial release
• 0.1.1 - add FromStr impl
• 0.2.0 - remove Urn::parse function in favor of FromStr, improved docs
• 0.2.1 - remove files left over from 0.1
• 0.3.0 - major implementation changes, remove Namespace (thanks to u/chris-morgan for help)
• 0.3.1 - fix a panic on empty NSS and add "?=" terminator to r-component (both "?" and "=" can be part of r-component, but together they terminate it)
• 0.3.2 - add Clone impl for Urn
• 0.3.3 - more precise builder errors; reduce memory footprint by up to 15 bytes (but increase it by 5 bytes on 16-bit platforms)
• 0.3.4 - Serde support by @callym
• 0.4.0 - UrnBuilder::namespace -> UrnBuilder::nid
• 0.5.0 - changed builder API to accept options for optional components, minor cleanup, fixed a couple potential minor bugs
• 0.5.1 - fix a panic in case there wasn't a valid utf-8 char boundary 4 bytes into the string
• 0.6.0 - add alloc feature, add UrnSlice type, add percent module, don't impl Deref<Target = str>. The crate is getting close to 1.0.

License

TL;DR do whatever you want.

Licensed under either the BSD Zero Clause License (https://opensource.org/licenses/0BSD), the Apache 2.0 License (http://www.apache.org/licenses/LICENSE-2.0) or the MIT License (http://opensource.org/licenses/MIT), at your choice.