2020-06-05 01:59:26 +02:00

636 lines
23 KiB
Rust

//! Details of the `ruma_api` procedural macro.
use std::convert::{TryFrom, TryInto as _};
use proc_macro2::{Span, TokenStream};
use quote::{quote, ToTokens};
use syn::{
braced,
parse::{Parse, ParseStream},
Field, FieldValue, Ident, Token, Type,
};
mod attribute;
mod metadata;
mod request;
mod response;
use self::{metadata::Metadata, request::Request, response::Response};
/// Removes `serde` attributes from struct fields.
pub fn strip_serde_attrs(field: &Field) -> Field {
let mut field = field.clone();
field.attrs.retain(|attr| !attr.path.is_ident("serde"));
field
}
/// The result of processing the `ruma_api` macro, ready for output back to source code.
pub struct Api {
/// The `metadata` section of the macro.
metadata: Metadata,
/// The `request` section of the macro.
request: Request,
/// The `response` section of the macro.
response: Response,
/// The `error` section of the macro.
error: Type,
}
impl TryFrom<RawApi> for Api {
type Error = syn::Error;
fn try_from(raw_api: RawApi) -> syn::Result<Self> {
let res = Self {
metadata: raw_api.metadata.try_into()?,
request: raw_api.request.try_into()?,
response: raw_api.response.try_into()?,
error: raw_api
.error
.map_or(syn::parse_str::<Type>("ruma_api::error::Void").unwrap(), |err| err.ty),
};
let newtype_body_field = res.request.newtype_body_field();
if res.metadata.method == "GET"
&& (res.request.has_body_fields() || newtype_body_field.is_some())
{
let mut combined_error: Option<syn::Error> = None;
let mut add_error = |field| {
let error = syn::Error::new_spanned(field, "GET endpoints can't have body fields");
if let Some(combined_error_ref) = &mut combined_error {
combined_error_ref.combine(error);
} else {
combined_error = Some(error);
}
};
for field in res.request.body_fields() {
add_error(field);
}
if let Some(field) = newtype_body_field {
add_error(field);
}
Err(combined_error.unwrap())
} else {
Ok(res)
}
}
}
impl ToTokens for Api {
fn to_tokens(&self, tokens: &mut TokenStream) {
let description = &self.metadata.description;
let method = &self.metadata.method;
// We don't (currently) use this literal as a literal in the generated code. Instead we just
// put it into doc comments, for which the span information is irrelevant. So we can work
// with only the literal's value from here on.
let name = &self.metadata.name.value();
let path = &self.metadata.path;
let rate_limited = &self.metadata.rate_limited;
let requires_authentication = &self.metadata.requires_authentication;
let non_auth_endpoint_impl = if requires_authentication.value {
quote! {
impl ruma_api::NonAuthEndpoint for Request {}
}
} else {
TokenStream::new()
};
let request_type = &self.request;
let response_type = &self.response;
let request_try_from_type = if self.request.uses_wrap_incoming() {
quote!(IncomingRequest)
} else {
quote!(Request)
};
let response_try_from_type = if self.response.uses_wrap_incoming() {
quote!(IncomingResponse)
} else {
quote!(Response)
};
let extract_request_path = if self.request.has_path_fields() {
quote! {
let path_segments: Vec<&str> = request.uri().path()[1..].split('/').collect();
}
} else {
TokenStream::new()
};
let (request_path_string, parse_request_path) = if self.request.has_path_fields() {
let path_string = path.value();
assert!(path_string.starts_with('/'), "path needs to start with '/'");
assert!(
path_string.chars().filter(|c| *c == ':').count()
== self.request.path_field_count(),
"number of declared path parameters needs to match amount of placeholders in path"
);
let format_call = {
let mut format_string = path_string.clone();
let mut format_args = Vec::new();
while let Some(start_of_segment) = format_string.find(':') {
// ':' should only ever appear at the start of a segment
assert_eq!(&format_string[start_of_segment - 1..start_of_segment], "/");
let end_of_segment = match format_string[start_of_segment..].find('/') {
Some(rel_pos) => start_of_segment + rel_pos,
None => format_string.len(),
};
let path_var = Ident::new(
&format_string[start_of_segment + 1..end_of_segment],
Span::call_site(),
);
format_args.push(quote! {
ruma_api::exports::percent_encoding::utf8_percent_encode(
&request.#path_var.to_string(),
ruma_api::exports::percent_encoding::NON_ALPHANUMERIC,
)
});
format_string.replace_range(start_of_segment..end_of_segment, "{}");
}
quote! {
format!(#format_string, #(#format_args),*)
}
};
let path_fields = path_string[1..]
.split('/')
.enumerate()
.filter(|(_, s)| s.starts_with(':'))
.map(|(i, segment)| {
let path_var = &segment[1..];
let path_var_ident = Ident::new(path_var, Span::call_site());
quote! {
#path_var_ident: {
use std::ops::Deref as _;
use ruma_api::error::RequestDeserializationError;
let segment = path_segments.get(#i).unwrap().as_bytes();
let decoded = match ruma_api::exports::percent_encoding::percent_decode(
segment
).decode_utf8() {
Ok(x) => x,
Err(err) => {
return Err(
RequestDeserializationError::new(err, request).into()
);
}
};
match std::convert::TryFrom::try_from(decoded.deref()) {
Ok(val) => val,
Err(err) => {
return Err(
RequestDeserializationError::new(err, request).into()
);
}
}
}
}
});
(format_call, quote! { #(#path_fields,)* })
} else {
(quote! { metadata.path.to_owned() }, TokenStream::new())
};
let request_query_string = if let Some(field) = self.request.query_map_field() {
let field_name = field.ident.as_ref().expect("expected field to have identifier");
let field_type = &field.ty;
quote!({
// This function exists so that the compiler will throw an
// error when the type of the field with the query_map
// attribute doesn't implement IntoIterator<Item = (String, String)>
//
// This is necessary because the ruma_serde::urlencoded::to_string
// call will result in a runtime error when the type cannot be
// encoded as a list key-value pairs (?key1=value1&key2=value2)
//
// By asserting that it implements the iterator trait, we can
// ensure that it won't fail.
fn assert_trait_impl<T>()
where
T: std::iter::IntoIterator<Item = (std::string::String, std::string::String)>,
{}
assert_trait_impl::<#field_type>();
let request_query = RequestQuery(request.#field_name);
format!("?{}", ruma_api::exports::ruma_serde::urlencoded::to_string(request_query)?)
})
} else if self.request.has_query_fields() {
let request_query_init_fields = self.request.request_query_init_fields();
quote!({
let request_query = RequestQuery {
#request_query_init_fields
};
format!("?{}", ruma_api::exports::ruma_serde::urlencoded::to_string(request_query)?)
})
} else {
quote! {
String::new()
}
};
let extract_request_query = if self.request.query_map_field().is_some() {
quote! {
let request_query = match ruma_api::exports::ruma_serde::urlencoded::from_str(
&request.uri().query().unwrap_or("")
) {
Ok(query) => query,
Err(err) => {
return Err(
ruma_api::error::RequestDeserializationError::new(err, request).into()
);
}
};
}
} else if self.request.has_query_fields() {
quote! {
let request_query: RequestQuery =
match ruma_api::exports::ruma_serde::urlencoded::from_str(
&request.uri().query().unwrap_or("")
) {
Ok(query) => query,
Err(err) => {
return Err(
ruma_api::error::RequestDeserializationError::new(err, request)
.into()
);
}
};
}
} else {
TokenStream::new()
};
let parse_request_query = if let Some(field) = self.request.query_map_field() {
let field_name = field.ident.as_ref().expect("expected field to have an identifier");
quote! {
#field_name: request_query
}
} else {
self.request.request_init_query_fields()
};
let add_headers_to_request = if self.request.has_header_fields() {
let add_headers = self.request.add_headers_to_request();
quote! {
let headers = http_request.headers_mut();
#add_headers
}
} else {
TokenStream::new()
};
let extract_request_headers = if self.request.has_header_fields() {
quote! {
let headers = request.headers();
}
} else {
TokenStream::new()
};
let extract_request_body =
if self.request.has_body_fields() || self.request.newtype_body_field().is_some() {
quote! {
let request_body: RequestBody =
match ruma_api::exports::serde_json::from_slice(request.body().as_slice()) {
Ok(body) => body,
Err(err) => {
return Err(
ruma_api::error::RequestDeserializationError::new(err, request)
.into()
);
}
};
}
} else {
TokenStream::new()
};
let parse_request_headers = if self.request.has_header_fields() {
self.request.parse_headers_from_request()
} else {
TokenStream::new()
};
let request_body = if let Some(field) = self.request.newtype_raw_body_field() {
let field_name = field.ident.as_ref().expect("expected field to have an identifier");
quote!(request.#field_name)
} else if self.request.has_body_fields() || self.request.newtype_body_field().is_some() {
let request_body_initializers = if let Some(field) = self.request.newtype_body_field() {
let field_name =
field.ident.as_ref().expect("expected field to have an identifier");
quote! { (request.#field_name) }
} else {
let initializers = self.request.request_body_init_fields();
quote! { { #initializers } }
};
quote! {
{
let request_body = RequestBody #request_body_initializers;
ruma_api::exports::serde_json::to_vec(&request_body)?
}
}
} else {
quote!(Vec::new())
};
let parse_request_body = if let Some(field) = self.request.newtype_body_field() {
let field_name = field.ident.as_ref().expect("expected field to have an identifier");
quote! {
#field_name: request_body.0,
}
} else if let Some(field) = self.request.newtype_raw_body_field() {
let field_name = field.ident.as_ref().expect("expected field to have an identifier");
quote! {
#field_name: request.into_body(),
}
} else {
self.request.request_init_body_fields()
};
let extract_response_headers = if self.response.has_header_fields() {
quote! {
let mut headers = response.headers().clone();
}
} else {
TokenStream::new()
};
let typed_response_body_decl = if self.response.has_body_fields()
|| self.response.newtype_body_field().is_some()
{
quote! {
let response_body: ResponseBody =
match ruma_api::exports::serde_json::from_slice(response.body().as_slice()) {
Ok(body) => body,
Err(err) => {
return Err(
ruma_api::error::ResponseDeserializationError::new(err, response)
.into()
);
}
};
}
} else {
TokenStream::new()
};
let response_init_fields = self.response.init_fields();
let serialize_response_headers = self.response.apply_header_fields();
let body = self.response.to_body();
let request_doc = format!(
"Data for a request to the `{}` API endpoint.\n\n{}",
name,
description.value()
);
let response_doc = format!("Data in the response from the `{}` API endpoint.", name);
let error = &self.error;
let api = quote! {
use ruma_api::exports::serde::de::Error as _;
use ruma_api::exports::serde::Deserialize as _;
use ruma_api::Endpoint as _;
use std::convert::TryInto as _;
#[doc = #request_doc]
#request_type
impl std::convert::TryFrom<ruma_api::exports::http::Request<Vec<u8>>> for #request_try_from_type {
type Error = ruma_api::error::FromHttpRequestError;
#[allow(unused_variables)]
fn try_from(request: ruma_api::exports::http::Request<Vec<u8>>) -> Result<Self, Self::Error> {
#extract_request_path
#extract_request_query
#extract_request_headers
#extract_request_body
Ok(Self {
#parse_request_path
#parse_request_query
#parse_request_headers
#parse_request_body
})
}
}
impl std::convert::TryFrom<Request> for ruma_api::exports::http::Request<Vec<u8>> {
type Error = ruma_api::error::IntoHttpError;
#[allow(unused_mut, unused_variables)]
fn try_from(request: Request) -> Result<Self, Self::Error> {
let metadata = Request::METADATA;
let path_and_query = #request_path_string + &#request_query_string;
let mut http_request = ruma_api::exports::http::Request::new(#request_body);
*http_request.method_mut() = ruma_api::exports::http::Method::#method;
*http_request.uri_mut() = ruma_api::exports::http::uri::Builder::new()
.path_and_query(path_and_query.as_str())
.build()
// The only way this can fail is if the path given in the API definition is
// invalid. It is okay to panic in that case.
.unwrap();
{ #add_headers_to_request }
Ok(http_request)
}
}
#[doc = #response_doc]
#response_type
impl std::convert::TryFrom<Response> for ruma_api::exports::http::Response<Vec<u8>> {
type Error = ruma_api::error::IntoHttpError;
#[allow(unused_variables)]
fn try_from(response: Response) -> Result<Self, Self::Error> {
let response = ruma_api::exports::http::Response::builder()
.header(ruma_api::exports::http::header::CONTENT_TYPE, "application/json")
#serialize_response_headers
.body(#body)
// Since we require header names to come from the `http::header` module,
// this cannot fail.
.unwrap();
Ok(response)
}
}
impl std::convert::TryFrom<ruma_api::exports::http::Response<Vec<u8>>> for #response_try_from_type {
type Error = ruma_api::error::FromHttpResponseError<#error>;
#[allow(unused_variables)]
fn try_from(
response: ruma_api::exports::http::Response<Vec<u8>>,
) -> Result<Self, Self::Error> {
if response.status().as_u16() < 400 {
#extract_response_headers
#typed_response_body_decl
Ok(Self {
#response_init_fields
})
} else {
match <#error as ruma_api::EndpointError>::try_from_response(response) {
Ok(err) => Err(ruma_api::error::ServerError::Known(err).into()),
Err(response_err) => Err(ruma_api::error::ServerError::Unknown(response_err).into())
}
}
}
}
impl ruma_api::Endpoint for Request {
type Response = Response;
type ResponseError = #error;
/// Metadata for the `#name` endpoint.
const METADATA: ruma_api::Metadata = ruma_api::Metadata {
description: #description,
method: ruma_api::exports::http::Method::#method,
name: #name,
path: #path,
rate_limited: #rate_limited,
requires_authentication: #requires_authentication,
};
}
#non_auth_endpoint_impl
};
api.to_tokens(tokens);
}
}
/// Custom keyword macros for syn.
mod kw {
use syn::custom_keyword;
custom_keyword!(metadata);
custom_keyword!(request);
custom_keyword!(response);
custom_keyword!(error);
}
/// The entire `ruma_api!` macro structure directly as it appears in the source code..
pub struct RawApi {
/// The `metadata` section of the macro.
pub metadata: RawMetadata,
/// The `request` section of the macro.
pub request: RawRequest,
/// The `response` section of the macro.
pub response: RawResponse,
/// The `error` section of the macro.
pub error: Option<RawErrorType>,
}
impl Parse for RawApi {
fn parse(input: ParseStream<'_>) -> syn::Result<Self> {
Ok(Self {
metadata: input.parse()?,
request: input.parse()?,
response: input.parse()?,
error: input.parse().ok(),
})
}
}
pub struct RawMetadata {
pub metadata_kw: kw::metadata,
pub field_values: Vec<FieldValue>,
}
impl Parse for RawMetadata {
fn parse(input: ParseStream<'_>) -> syn::Result<Self> {
let metadata_kw = input.parse::<kw::metadata>()?;
let field_values;
braced!(field_values in input);
Ok(Self {
metadata_kw,
field_values: field_values
.parse_terminated::<FieldValue, Token![,]>(FieldValue::parse)?
.into_iter()
.collect(),
})
}
}
pub struct RawRequest {
pub request_kw: kw::request,
pub fields: Vec<Field>,
}
impl Parse for RawRequest {
fn parse(input: ParseStream<'_>) -> syn::Result<Self> {
let request_kw = input.parse::<kw::request>()?;
let fields;
braced!(fields in input);
Ok(Self {
request_kw,
fields: fields
.parse_terminated::<Field, Token![,]>(Field::parse_named)?
.into_iter()
.collect(),
})
}
}
pub struct RawResponse {
pub response_kw: kw::response,
pub fields: Vec<Field>,
}
impl Parse for RawResponse {
fn parse(input: ParseStream<'_>) -> syn::Result<Self> {
let response_kw = input.parse::<kw::response>()?;
let fields;
braced!(fields in input);
Ok(Self {
response_kw,
fields: fields
.parse_terminated::<Field, Token![,]>(Field::parse_named)?
.into_iter()
.collect(),
})
}
}
pub struct RawErrorType {
pub error_kw: kw::error,
pub ty: Type,
}
impl Parse for RawErrorType {
fn parse(input: ParseStream<'_>) -> syn::Result<Self> {
let error_kw = input.parse::<kw::error>()?;
input.parse::<Token![:]>()?;
let ty = input.parse()?;
Ok(Self { error_kw, ty })
}
}