rust/doc/rustdoc.md

% Rust Documentation

rustdoc is the built-in tool for generating documentation. It integrates with the compiler to provide accurate hyperlinking between usage of types and their documentation. Furthermore, by not using a separate parser, it will never reject your valid Rust code.

Creating Documentation

Documenting Rust APIs is quite simple. To document a given item, we have "doc comments":

// the "link" crate attribute is currently required for rustdoc, but normally
// isn't needed.
#[link(name="universe")];
#[crate_type="lib"];

//! Tools for dealing with universes (this is a doc comment, and is shown on
//! the crate index page. The ! makes it apply to the parent of the comment,
//! rather than what follows).

/// Widgets are very common (this is a doc comment, and will show up on
/// Widget's documentation).
pub struct Widget {
	/// All widgets have a purpose (this is a doc comment, and will show up
	/// the field's documentation).
	purpose: ~str,
	/// Humans are not allowed to understand some widgets
	understandable: bool
}

pub fn recalibrate() {
	//! Recalibrate a pesky universe (this is also a doc comment, like above,
	//! the documentation will be applied to the *parent* item, so
	//! `recalibrate`).
	/* ... */
}

Then, one can run rustdoc universe.rs. By default, it generates a directory called doc, with the documentation for universe being in doc/universe/index.html. If you are using other crates with extern mod, rustdoc will even link to them when you use their types, as long as their documentation has already been generated by a previous run of rustdoc, or the crate advertises that its documentation is hosted at a given URL.

The generated output can be controlled with the doc crate attribute, which is how the above advertisement works. An example from the libstd documentation:

#[doc(html_logo_url = "http://www.rust-lang.org/logos/rust-logo-128x128-blk.png",
      html_favicon_url = "http://www.rust-lang.org/favicon.ico",
      html_root_url = "http://static.rust-lang.org/doc/master")];

The html_root_url is the prefix that rustdoc will apply to any references to that crate's types etc.

rustdoc can also generate JSON, for consumption by other tools, with rustdoc --output-format json, and also consume already-generated JSON with rustdoc --input-format json.

Using the Documentation

The web pages generated by rustdoc present the same logical heirarchy that one writes a library with. Every kind of item (function, struct, etc) has its own color, and one can always click on a colored type to jump to its documentation. There is a search bar at the top, which is powered by some javascript and a statically-generated search index. No special web server is required for the search.