Crate doku[−][src]

Expand description

fn(Code) -> Docs

Overview

Doku is a framework for building textual, aesthetic documentation directly from the code; it allows to generate docs for configuration files, HTTP endpoints, and so on.

Say goodbye to stale, hand-written documentation - with Doku, code is the documentation!

Example

Say, you’re writing a tool that requires some JSON configuration to work:

use serde::Deserialize;

#[derive(Deserialize)]
struct Config {
    /// Database's engine
    db_engine: DbEngine,

    /// Database's host
    db_host: String,

    /// Database's port
    db_port: usize,
}

#[derive(Deserialize)]
enum DbEngine {
    #[serde(rename = "pgsql")]
    PostgreSQL,

    #[serde(rename = "mysql")]
    MySQL,
}

Now, with Doku, generating a documentation for your users is as simple as adding #[derive(Document)]:

use doku::Document;

#[derive(Deserialize, Document)]
struct Config {
    /* ... */
}

#[derive(Deserialize, Document)]
enum DbEngine {
    /* ... */
}

… and calling doku::to_json():

let doc = doku::to_json::<Config>();

println!("{}", doc); // says:

  {
    // Database's engine
    "db_engine": "pgsql" | "mysql",
    // Database's host
    "db_host": "string",
    // Database's port
    "db_port": 123
  }

The documentation can be then further fine-tuned e.g. by providing examples:

#[derive(Deserialize, Document)]
struct Config {
    /// Database's engine
    db_engine: DbEngine,

    /// Database's host
    #[doku(example = "localhost")]
    db_host: String,

    /// Database's port
    #[doku(example = "5432")]
    db_port: usize,
}

#[derive(Deserialize, Document)]
enum DbEngine {
    #[serde(rename = "pgsql")]
    PostgreSQL,

    #[serde(rename = "mysql")]
    MySQL,
}

let doc = doku::to_json::<Config>();

println!("{}", doc); // says:

  {
    // Database's engine
    "db_engine": "pgsql" | "mysql",
    // Database's host
    "db_host": "localhost",
    // Database's port
    "db_port": 5432
  }

And voilà, ready to deploy!

Also, because doku::to_json() returns a good-old String, it’s easy to e.g. create a test ensuring that docs stay in sync with the code:

use std::fs;

#[test]
fn docs() {
    let actual_docs = doku::to_json::<Config>();
    let current_docs = fs::read_to_string("config.example.json").unwrap();

    if current_docs != actual_docs {
        fs::write("config.example.json.new", actual_docs);
        panic!("`config.example.json` is stale; please see: `config.example.json.new`");
    }
}

Let go & let the pipelines worry about your docs!

Doku has been made with the plug-and-play approach in mind - it understands the most common Serde annotations and comes with a predefined formatting settings, so adding #[derive(Document)] here and there should get you started quickly & painlessly.

At the same time, Doku is extensible - if the formatting settings don’t match your taste, there is a way to tune them; if the derive macro doesn’t work because you use custom impl Serialize, you can write impl Document by hand, too.

So - come join the doc side!

Limits

Supported formats

Currently Doku provides functions for generating JSON docs; more formats, such as TOML, are on their way.

If you wanted, you could even implement a pretty-printer for your own format - all of the required types are public, so getting started is as easy as:

fn to_my_own_format<T>() -> String
where
    T: doku::Document
{
   match T::ty().kind {
       doku::TypeKind::String => "got a string!".to_string(),
       doku::TypeKind::Struct { .. } => "got a struct!".to_string(),
       _ => todo!(),
   }
}

println!("{}", to_my_own_format::<String>());

Supported Serde annotations

Legend:

❌ = not supported (the derive macro will return an error)
✅ = supported
✅ + no-op = supported, but doesn’t affect the documentation

#[serde] for containers:

❌ #[serde(rename = "...")]
❌ #[serde(rename(serialize = "..."))]
❌ #[serde(rename(deserialize = "..."))]
❌ #[serde(rename(serialize = "...", deserialize = "..."))]
❌ #[serde(rename_all = "...")]
❌ #[serde(rename_all(serialize = "..."))]
❌ #[serde(rename_all(deserialize = "..."))]
❌ #[serde(rename_all(serialize = "...", deserialize = "..."))]
✅ #[serde(deny_unknown_fields)] (no-op)
✅ #[serde(tag = "...")]
✅ #[serde(tag = "...", content = "...")]
✅ #[serde(untagged)]
❌ #[serde(bound = "...")]
❌ #[serde(bound(serialize = "..."))]
❌ #[serde(bound(deserialize = "..."))]
❌ #[serde(bound(serialize = "...", deserialize = "..."))]
✅ #[serde(default)] (no-op)
✅ #[serde(default = "...")] (no-op)
❌ #[serde(remote = "...")]
✅ #[serde(transparent)]
❌ #[serde(from = "...")]
❌ #[serde(try_from = "...")]
❌ #[serde(into = "...")]
✅ #[serde(crate = "...")] (no-op)

#[serde] for variants:

✅ #[serde(rename = "...")]
❌ #[serde(rename(serialize = "..."))]
❌ #[serde(rename(deserialize = "..."))]
❌ #[serde(rename(serialize = "...", deserialize = "..."))]
❌ #[serde(alias = "...")]
❌ #[serde(rename_all = "...")]
✅ #[serde(skip)]
✅ #[serde(skip_serializing)]
✅ #[serde(skip_deserializing)]
✅ #[serde(serialize_with = "...")] (no-op)
✅ #[serde(deserialize_with = "...")] (no-op)
✅ #[serde(with = "...")] (no-op)
❌ #[serde(bound = "...")]
❌ #[serde(borrow)]
❌ #[serde(borrow = "...")]
✅ #[serde(other)] (no-op)

#[serde] for fields:

✅ #[serde(rename = "...")]
❌ #[serde(rename(serialize = "..."))]
❌ #[serde(rename(deserialize = "..."))]
❌ #[serde(rename(serialize = "...", deserialize = "..."))]
❌ #[serde(alias = "...")]
✅ #[serde(default)] (no-op)
✅ #[serde(default = "...'")] (no-op)
✅ #[serde(skip)]
✅ #[serde(skip_serializing)]
✅ #[serde(skip_deserializing)]
✅ #[serde(skip_serializing_if = "...")] (no-op)
✅ #[serde(serialize_with = "...")] (no-op)
✅ #[serde(deserialize_with = "...")] (no-op)
✅ #[serde(with = "...")] (no-op)
❌ #[serde(borrow)] (no-op)
❌ #[serde(borrow = "...")] (no-op)
❌ #[serde(getter = "...")]

Supported language features

❌ generic types (https://github.com/anixe/doku/issues/3)
❌ recursive types (https://github.com/anixe/doku/issues/10)

How does it work?

When you wrap a type with #[derive(Document)]:

#[derive(Document)]
struct User {
    /// Who? Who?
    #[doku(example = "alan.turing")]
    login: String,
}

… this derive macro generates an impl doku::Document:

impl doku::Document for User {
    fn ty() -> doku::Type {
        let login = doku::Field {
            ty: doku::Type {
                comment: Some("Who? Who?"),
                example: Some(doku::Example::Simple("alan.turing")),
                ..String::ty()
            },
            flattened: false,
        };

        doku::Type::from(doku::TypeKind::Struct {
            fields: doku::Fields::Named {
                fields: vec![
                    ("login", login)
                ],
            },
            transparent: false,
        })
    }
}

… and later, when you invoke doku::to_json<...>(), it just calls this fn ty() method:

fn to_json<T>() -> String
where
    T: doku::Document
{
    match T::ty().kind {
        doku::TypeKind::String => print_string(/* ... */),
        doku::TypeKind::Struct { .. } => print_struct(/* ... */),
        /* ... */
    }
}

There’s no magic, no RTTI hacks, no unsafety - it’s all just Rust.