ruwuma/src/lib.rs
2018-05-04 18:53:03 -07:00

208 lines
6.8 KiB
Rust

//! Crate `ruma-api-macros` provides a procedural macro for easily generating
//! [ruma-api](https://github.com/ruma/ruma-api)-compatible endpoints.
//!
//! See the documentation for the `ruma_api!` macro for usage details.
#![deny(missing_debug_implementations)]
#![feature(proc_macro, try_from)]
#![recursion_limit="256"]
#![allow(warnings)]
extern crate proc_macro;
#[macro_use] extern crate quote;
extern crate ruma_api;
#[macro_use] extern crate syn;
use proc_macro::TokenStream;
use std::convert::TryFrom;
use quote::{ToTokens, Tokens};
use api::{Api, Exprs};
mod api;
/// Generates a `ruma_api::Endpoint` from a concise definition.
///
/// The macro expects the following structure as input:
///
/// ```text
/// ruma_api! {
/// metadata {
/// description: &'static str
/// method: hyper::Method,
/// name: &'static str,
/// path: &'static str,
/// rate_limited: bool,
/// requires_authentication: bool,
/// }
///
/// request {
/// // Struct fields for each piece of data required
/// // to make a request to this API endpoint.
/// }
///
/// response {
/// // Struct fields for each piece of data expected
/// // in the response from this API endpoint.
/// }
/// }
/// # }
/// ```
///
/// This will generate a `ruma_api::Metadata` value to be used for the `ruma_api::Endpoint`'s
/// associated constant, single `Request` and `Response` structs, and the necessary trait
/// implementations to convert the request into a `hyper::Request` and to create a response from a
/// `hyper::response`.
///
/// The details of each of the three sections of the macros are documented below.
///
/// ## Metadata
///
/// * `description`: A short description of what the endpoint does.
/// * `method`: The HTTP method used for requests to the endpoint.
/// It's not necessary to import `hyper::Method`, you just write the value as if it was
/// imported, e.g. `Method::Get`.
/// * `name`: A unique name for the endpoint.
/// Generally this will be the same as the containing module.
/// * `path`: The path component of the URL for the endpoint, e.g. "/foo/bar".
/// Components of the path that are parameterized can indicate a varible by using a Rust
/// identifier prefixed with a colon, e.g. `/foo/:some_parameter`.
/// A corresponding query string parameter will be expected in the request struct (see below
/// for details).
/// * `rate_limited`: Whether or not the endpoint enforces rate limiting on requests.
/// * `requires_authentication`: Whether or not the endpoint requires a valid access token.
///
/// ## Request
///
/// The request block contains normal struct field definitions.
/// Doc comments and attributes are allowed as normal.
/// There are also a few special attributes available to control how the struct is converted into a
/// `hyper::Request`:
///
/// * `#[ruma_api(header)]`: Fields with this attribute will be treated as HTTP headers on the
/// request.
/// The value must implement `hyper::header::Header`.
/// * `#[ruma_api(path)]`: Fields with this attribute will be inserted into the matching path
/// component of the request URL.
/// * `#[ruma_api(query)]`: Fields with this attribute will be inserting into the URL's query
/// string.
///
/// Any field that does not include one of these attributes will be part of the request's JSON
/// body.
///
/// ## Response
///
/// Like the request block, the response block consists of normal struct field definitions.
/// Doc comments and attributes are allowed as normal.
/// There is also a special attribute available to control how the struct is created from a
/// `hyper::Request`:
///
/// * `#[ruma_api(header)]`: Fields with this attribute will be treated as HTTP headers on the
/// response.
/// The value must implement `hyper::header::Header`.
///
/// Any field that does not include the above attribute will be expected in the response's JSON
/// body.
///
/// ## Newtype bodies
///
/// Both the request and response block also support "newtype bodies" by using the
/// `#[ruma_api(body)]` attribute on a field. If present on a field, the entire request or response
/// body will be treated as the value of the field. This allows you to treat the entire request or
/// response body as a specific type, rather than a JSON object with named fields. Only one field in
/// each struct can be marked with this attribute. It is an error to have a newtype body field and
/// normal body fields within the same struct.
///
/// # Examples
///
/// ```rust,no_run
/// #![feature(associated_consts, proc_macro, try_from)]
///
/// extern crate futures;
/// extern crate hyper;
/// extern crate ruma_api;
/// extern crate ruma_api_macros;
/// extern crate serde;
/// #[macro_use] extern crate serde_derive;
/// extern crate serde_json;
/// extern crate serde_urlencoded;
/// extern crate url;
///
/// # fn main() {
/// pub mod some_endpoint {
/// use hyper::header::ContentType;
/// use ruma_api_macros::ruma_api;
///
/// ruma_api! {
/// metadata {
/// description: "Does something.",
/// method: Method::Get,
/// name: "some_endpoint",
/// path: "/_matrix/some/endpoint/:baz",
/// rate_limited: false,
/// requires_authentication: false,
/// }
///
/// request {
/// pub foo: String,
/// #[ruma_api(header)]
/// pub content_type: ContentType,
/// #[ruma_api(query)]
/// pub bar: String,
/// #[ruma_api(path)]
/// pub baz: String,
/// }
///
/// response {
/// #[ruma_api(header)]
/// pub content_type: ContentType,
/// pub value: String,
/// }
/// }
/// }
///
/// pub mod newtype_body_endpoint {
/// use ruma_api_macros::ruma_api;
///
/// #[derive(Debug, Deserialize)]
/// pub struct MyCustomType {
/// pub foo: String,
/// }
///
/// ruma_api! {
/// metadata {
/// description: "Does something.",
/// method: Method::Get,
/// name: "newtype_body_endpoint",
/// path: "/_matrix/some/newtype/body/endpoint",
/// rate_limited: false,
/// requires_authentication: false,
/// }
///
/// request {
/// #[ruma_api(body)]
/// pub file: Vec<u8>,
/// }
///
/// response {
/// #[ruma_api(body)]
/// pub my_custom_type: MyCustomType,
/// }
/// }
/// }
/// # }
/// ```
#[proc_macro]
pub fn ruma_api(input: TokenStream) -> TokenStream {
let exprs: Exprs = syn::parse(input).expect("ruma_api! failed to parse input");
let api = Api::from(exprs.inner);
let mut tokens = Tokens::new();
api.to_tokens(&mut tokens);
tokens.into()
}