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use std::collections::{HashMap, HashSet};
use crate::{
default::DefaultValue,
util::{either_attribute_arg, kw, parse_comma_separated, UniffiAttributeArgs},
};
use proc_macro2::TokenStream;
use quote::ToTokens;
use syn::{
parenthesized,
parse::{Parse, ParseStream},
punctuated::Punctuated,
Attribute, Ident, LitStr, Meta, Path, PathArguments, PathSegment, Token,
};
use uniffi_meta::UniffiTraitDiscriminants;
#[derive(Default)]
pub struct ExportTraitArgs {
pub(crate) async_runtime: Option<AsyncRuntime>,
pub(crate) callback_interface: Option<kw::callback_interface>,
pub(crate) with_foreign: Option<kw::with_foreign>,
}
impl Parse for ExportTraitArgs {
fn parse(input: ParseStream<'_>) -> syn::Result<Self> {
parse_comma_separated(input)
}
}
impl UniffiAttributeArgs for ExportTraitArgs {
fn parse_one(input: ParseStream<'_>) -> syn::Result<Self> {
let lookahead = input.lookahead1();
if lookahead.peek(kw::async_runtime) {
let _: kw::async_runtime = input.parse()?;
let _: Token![=] = input.parse()?;
Ok(Self {
async_runtime: Some(input.parse()?),
..Self::default()
})
} else if lookahead.peek(kw::callback_interface) {
Ok(Self {
callback_interface: input.parse()?,
..Self::default()
})
} else if lookahead.peek(kw::with_foreign) {
Ok(Self {
with_foreign: input.parse()?,
..Self::default()
})
} else {
Ok(Self::default())
}
}
fn merge(self, other: Self) -> syn::Result<Self> {
let merged = Self {
async_runtime: either_attribute_arg(self.async_runtime, other.async_runtime)?,
callback_interface: either_attribute_arg(
self.callback_interface,
other.callback_interface,
)?,
with_foreign: either_attribute_arg(self.with_foreign, other.with_foreign)?,
};
if merged.callback_interface.is_some() && merged.with_foreign.is_some() {
return Err(syn::Error::new(
merged.callback_interface.unwrap().span,
"`callback_interface` and `with_foreign` are mutually exclusive",
));
}
Ok(merged)
}
}
/// Attribute arguments for function
///
/// This includes top-level functions, constructors, and methods.
#[derive(Clone, Default)]
pub struct ExportFnArgs {
pub(crate) async_runtime: Option<AsyncRuntime>,
pub(crate) name: Option<String>,
pub(crate) defaults: DefaultMap,
}
impl Parse for ExportFnArgs {
fn parse(input: ParseStream<'_>) -> syn::Result<Self> {
parse_comma_separated(input)
}
}
impl UniffiAttributeArgs for ExportFnArgs {
fn parse_one(input: ParseStream<'_>) -> syn::Result<Self> {
let lookahead = input.lookahead1();
if lookahead.peek(kw::async_runtime) {
let _: kw::async_runtime = input.parse()?;
let _: Token![=] = input.parse()?;
Ok(Self {
async_runtime: Some(input.parse()?),
..Self::default()
})
} else if lookahead.peek(kw::name) {
let _: kw::name = input.parse()?;
let _: Token![=] = input.parse()?;
let name = Some(input.parse::<LitStr>()?.value());
Ok(Self {
name,
..Self::default()
})
} else if lookahead.peek(kw::default) {
Ok(Self {
defaults: DefaultMap::parse(input)?,
..Self::default()
})
} else {
Err(syn::Error::new(
input.span(),
format!("attribute `{input}` is not supported here."),
))
}
}
fn merge(self, other: Self) -> syn::Result<Self> {
Ok(Self {
async_runtime: either_attribute_arg(self.async_runtime, other.async_runtime)?,
name: either_attribute_arg(self.name, other.name)?,
defaults: self.defaults.merge(other.defaults),
})
}
}
#[derive(Default)]
pub struct ExportImplArgs {
pub(crate) async_runtime: Option<AsyncRuntime>,
}
impl Parse for ExportImplArgs {
fn parse(input: ParseStream<'_>) -> syn::Result<Self> {
parse_comma_separated(input)
}
}
impl UniffiAttributeArgs for ExportImplArgs {
fn parse_one(input: ParseStream<'_>) -> syn::Result<Self> {
let lookahead = input.lookahead1();
if lookahead.peek(kw::async_runtime) {
let _: kw::async_runtime = input.parse()?;
let _: Token![=] = input.parse()?;
Ok(Self {
async_runtime: Some(input.parse()?),
})
} else {
Err(syn::Error::new(
input.span(),
format!("uniffi::export attribute `{input}` is not supported here."),
))
}
}
fn merge(self, other: Self) -> syn::Result<Self> {
Ok(Self {
async_runtime: either_attribute_arg(self.async_runtime, other.async_runtime)?,
})
}
}
#[derive(Default)]
pub struct ExportStructArgs {
pub(crate) traits: HashSet<UniffiTraitDiscriminants>,
}
impl Parse for ExportStructArgs {
fn parse(input: ParseStream<'_>) -> syn::Result<Self> {
parse_comma_separated(input)
}
}
impl UniffiAttributeArgs for ExportStructArgs {
fn parse_one(input: ParseStream<'_>) -> syn::Result<Self> {
let lookahead = input.lookahead1();
if lookahead.peek(kw::Debug) {
input.parse::<Option<kw::Debug>>()?;
Ok(Self {
traits: HashSet::from([UniffiTraitDiscriminants::Debug]),
})
} else if lookahead.peek(kw::Display) {
input.parse::<Option<kw::Display>>()?;
Ok(Self {
traits: HashSet::from([UniffiTraitDiscriminants::Display]),
})
} else if lookahead.peek(kw::Hash) {
input.parse::<Option<kw::Hash>>()?;
Ok(Self {
traits: HashSet::from([UniffiTraitDiscriminants::Hash]),
})
} else if lookahead.peek(kw::Eq) {
input.parse::<Option<kw::Eq>>()?;
Ok(Self {
traits: HashSet::from([UniffiTraitDiscriminants::Eq]),
})
} else {
Err(syn::Error::new(
input.span(),
format!(
"uniffi::export struct attributes must be builtin trait names; `{input}` is invalid"
),
))
}
}
fn merge(self, other: Self) -> syn::Result<Self> {
let mut traits = self.traits;
traits.extend(other.traits);
Ok(Self { traits })
}
}
#[derive(Clone)]
pub enum AsyncRuntime {
Tokio(LitStr),
}
impl Parse for AsyncRuntime {
fn parse(input: ParseStream<'_>) -> syn::Result<Self> {
let lit: LitStr = input.parse()?;
match lit.value().as_str() {
"tokio" => Ok(Self::Tokio(lit)),
_ => Err(syn::Error::new_spanned(
lit,
"unknown async runtime, currently only `tokio` is supported",
)),
}
}
}
impl ToTokens for AsyncRuntime {
fn to_tokens(&self, tokens: &mut TokenStream) {
match self {
AsyncRuntime::Tokio(lit) => lit.to_tokens(tokens),
}
}
}
#[derive(Default)]
pub(super) struct ExportedImplFnAttributes {
pub constructor: bool,
pub args: ExportFnArgs,
}
impl ExportedImplFnAttributes {
pub fn new(attrs: &[Attribute]) -> syn::Result<Self> {
let mut this = Self::default();
for attr in attrs {
let path = attr.path();
if is_uniffi_path(path) {
this.process_path(path, attr, &attr.meta)?;
} else if is_cfg_attr(attr) {
if let Ok(nested) =
attr.parse_args_with(Punctuated::<Meta, Token![,]>::parse_terminated)
{
for meta in &nested {
if let Meta::Path(path) = meta {
this.process_path(path, attr, meta)?
}
}
};
}
}
Ok(this)
}
fn process_path(&mut self, path: &Path, attr: &Attribute, meta: &Meta) -> syn::Result<()> {
let segs = &path.segments;
let fst = segs
.first()
.expect("attributes have at least one path segment");
if fst.ident != "uniffi" {
return Ok(());
}
ensure_no_path_args(fst)?;
let args = match meta {
Meta::List(_) => attr.parse_args::<ExportFnArgs>()?,
_ => Default::default(),
};
self.args = args;
if segs.len() != 2 {
return Err(syn::Error::new_spanned(
segs,
"unsupported uniffi attribute",
));
}
let snd = &segs[1];
ensure_no_path_args(snd)?;
match snd.ident.to_string().as_str() {
"constructor" => {
if self.constructor {
return Err(syn::Error::new_spanned(
attr,
"duplicate constructor attribute",
));
}
self.constructor = true;
}
"method" => {
if self.constructor {
return Err(syn::Error::new_spanned(
attr,
"confused constructor/method attributes",
));
}
}
_ => return Err(syn::Error::new_spanned(snd, "unknown uniffi attribute")),
}
Ok(())
}
}
fn is_uniffi_path(path: &Path) -> bool {
path.segments
.first()
.map(|segment| segment.ident == "uniffi")
.unwrap_or(false)
}
fn is_cfg_attr(attr: &Attribute) -> bool {
attr.meta
.path()
.get_ident()
.is_some_and(|ident| *ident == "cfg_attr")
}
fn ensure_no_path_args(seg: &PathSegment) -> syn::Result<()> {
if matches!(seg.arguments, PathArguments::None) {
Ok(())
} else {
Err(syn::Error::new_spanned(&seg.arguments, "unexpected syntax"))
}
}
/// Maps arguments to defaults for functions
#[derive(Clone, Default)]
pub struct DefaultMap {
map: HashMap<Ident, DefaultValue>,
}
impl DefaultMap {
pub fn merge(self, other: Self) -> Self {
let mut map = self.map;
map.extend(other.map);
Self { map }
}
pub fn remove(&mut self, ident: &Ident) -> Option<DefaultValue> {
self.map.remove(ident)
}
pub fn idents(&self) -> Vec<&Ident> {
self.map.keys().collect()
}
}
impl Parse for DefaultMap {
fn parse(input: ParseStream<'_>) -> syn::Result<Self> {
let _: kw::default = input.parse()?;
let content;
let _ = parenthesized!(content in input);
let pairs = content.parse_terminated(DefaultPair::parse, Token![,])?;
Ok(Self {
map: pairs.into_iter().map(|p| (p.name, p.value)).collect(),
})
}
}
pub struct DefaultPair {
pub name: Ident,
pub eq_token: Token![=],
pub value: DefaultValue,
}
impl Parse for DefaultPair {
fn parse(input: ParseStream<'_>) -> syn::Result<Self> {
Ok(Self {
name: input.parse()?,
eq_token: input.parse()?,
value: input.parse()?,
})
}
}