mini-yaml-rs

A minimalist, zero-copy YAML parser for Rust. Supports sequences, mappings, and custom tags.

Features

- Zero-copy parsing (returns references to input)
- Sequences and mappings (flow and block styles)
- Custom tag support: !tagname becomes __type: "tagname"
- Works in both Rust backend (Tauri) and WebAssembly

Installation

$3

``toml
[dependencies]
mini-yaml-rs = "0.2"
`

$3

`bash
npm install mini-yaml-rs
`

Building

`bash


Build Rust library (for Tauri/backend)

make build-rust

Build WASM for bundlers (Vite, webpack)

make build

Build WASM for direct browser use

make build-web

Build WASM for Node.js

make build-node
`

Usage

$3

`rust
use mini_yaml_rs::parse;

let yaml = parse(r#"
+setupSettings:
title: Settings
authors[]:
- !mod +@Me{}
- !mod +@Boby at Unix Group

signature:
pubkey: |
MCowBQYDK2VwAyEAGb9F2CMlxqLDB3rrzBVwC7aB...

created: 2024-06-01T12:00:00Z
modified: 2024-06-01T12:00:00Z
"#).unwrap();

// Returns Yaml<'_> enum - use to_json() for serde_json::Value
let json = yaml.to_json();
println!("{}", json);
`

Output:
`json
{
"+setupSettings": {
"title": "Settings",
"authors":
{
"__type": "mod",
"+@[Me"
},
{
"__type": "mod",
"+@Boby at Unix Group"
}
],
"signature": {
"pubkey": "MCowBQYDK2VwAyEAGb9F2CMlxqLDB3rrzBVwC7aB..."
},
"created": "2024-06-01T12:00:00Z",
"modified": "2024-06-01T12:00:00Z"
}
}
`

$3

The to_mx() method transforms keys in +namelabel format:

`rust
use mini_yaml_rs::parse;

let yaml = parse(r#"
+setupSettings:
title: Settings
enabled: true
"#).unwrap();

let mx = yaml.to_mx();
println!("{}", mx);
`

Output:
`json
{
"+setup": {
"__name": "Settings",
"__value": "db://settings",
"title": "Settings",
"enabled": true
}
}
`

The key +setupSettings becomes +setup with:
- __name = bracket content (Settings)
- __value = paren content (db://settings, optional)

$3

Tags are converted to __type fields:

`yaml
!person {name: John} # → {__type: "person", name: "John"}
!custom_tag [1, 2, 3] # → {__type: "custom_tag", __value: [1, 2, 3]}
`

$3

Unquoted scalar values are automatically converted to native types:

`yaml
42 # → 42 (as integer)
-123 # → -123 (as integer)
3.14 # → 3.14 (as float)
1.0e10 # → 1.0e10 (as float)
true # → true (as boolean)
false # → false (as boolean)
yes/no # → true/false (as boolean)
on/off # → true/false (as boolean)

Keep these as strings by quoting:


"42" # → "42" (string, quotes stripped)
'true' # → "true" (string, quotes stripped)
`

$3

All functions return plain JavaScript objects (not Map objects), making them easy to use with standard JS object syntax.

`typescript
import init, { parseYaml, parseYamlToMx, printYaml } from 'mini-yaml-rs';

// Initialize WASM module
await init();

// Parse YAML → JavaScript object (no JSON.parse needed)
const obj = parseYaml(
name: hello
value: 42
items:
- one
- two
);
console.log(obj.name); // "hello"
console.log(obj.value); // 42
console.log(obj.items); // ["one", "two"]

// Convert JavaScript object → YAML string
const yaml = printYaml({
title: "My Config",
enabled: true,
settings: {
theme: "dark",
fontSize: 14
}
});
console.log(yaml);
// title: My Config
// enabled: true
// settings:
// theme: dark
// fontSize: 14

// Parse with mx transformation
const mx = parseYamlToMx(
+setupSettings:
title: Settings
);
console.log(mx["+setup"].__name); // "Settings"
console.log(mx["+setup"].__value); // "db://settings"
``

License

Apache-2.0. See LICENSE.

Acknowledgments

Based on minimal-yaml by Nathan Whitaker.