2021-10-08 12:49:13 +02:00

79 lines
2.1 KiB
Rust

//! Details of the `#[ruma_api(...)]` attributes.
use syn::{
parse::{Parse, ParseStream},
Ident, Lit, Token, Type,
};
/// Value type used for request and response struct attributes
#[allow(clippy::large_enum_variant)]
pub enum MetaValue {
Lit(Lit),
Type(Type),
}
impl Parse for MetaValue {
fn parse(input: ParseStream<'_>) -> syn::Result<Self> {
if input.peek(Lit) {
input.parse().map(Self::Lit)
} else {
input.parse().map(Self::Type)
}
}
}
/// Like syn::MetaNameValue, but expects an identifier as the value.
///
/// Also, we don't care about the the span of the equals sign, so we don't have the `eq_token` field
/// from syn::MetaNameValue.
pub struct MetaNameValue<V> {
/// The part left of the equals sign
pub name: Ident,
/// The part right of the equals sign
pub value: V,
}
impl<V: Parse> Parse for MetaNameValue<V> {
fn parse(input: ParseStream<'_>) -> syn::Result<Self> {
let ident = input.parse()?;
let _: Token![=] = input.parse()?;
Ok(MetaNameValue { name: ident, value: input.parse()? })
}
}
/// Like syn::Meta, but only parses ruma_api attributes
pub enum Meta {
/// A single word, like `query` in `#[ruma_api(query)]`
Word(Ident),
/// A name-value pair, like `header = CONTENT_TYPE` in `#[ruma_api(header = CONTENT_TYPE)]`
NameValue(MetaNameValue<Ident>),
}
impl Meta {
/// Check if the given attribute is a ruma_api attribute.
///
/// If it is, parse it.
pub fn from_attribute(attr: &syn::Attribute) -> syn::Result<Option<Self>> {
if attr.path.is_ident("ruma_api") {
attr.parse_args().map(Some)
} else {
Ok(None)
}
}
}
impl Parse for Meta {
fn parse(input: ParseStream<'_>) -> syn::Result<Self> {
let ident = input.parse()?;
if input.peek(Token![=]) {
let _: Token![=] = input.parse()?;
Ok(Meta::NameValue(MetaNameValue { name: ident, value: input.parse()? }))
} else {
Ok(Meta::Word(ident))
}
}
}