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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
use crate::fnsig::FnSignature;
use proc_macro2::{Ident, Span};
use quote::ToTokens;
use super::attributes::{ExportAttributeArguments, ExportedImplFnAttributes};
use uniffi_meta::UniffiTraitDiscriminants;
pub(super) enum ExportItem {
Function {
sig: FnSignature,
},
Impl {
self_ident: Ident,
items: Vec<ImplItem>,
},
Trait {
self_ident: Ident,
items: Vec<ImplItem>,
callback_interface: bool,
},
Struct {
self_ident: Ident,
uniffi_traits: Vec<UniffiTraitDiscriminants>,
},
}
impl ExportItem {
pub fn new(item: syn::Item, args: &ExportAttributeArguments) -> syn::Result<Self> {
match item {
syn::Item::Fn(item) => {
let sig = FnSignature::new_function(item.sig)?;
Ok(Self::Function { sig })
}
syn::Item::Impl(item) => Self::from_impl(item, args.constructor.is_some()),
syn::Item::Trait(item) => Self::from_trait(item, args.callback_interface.is_some()),
syn::Item::Struct(item) => Self::from_struct(item, args),
// FIXME: Support const / static?
_ => Err(syn::Error::new(
Span::call_site(),
"unsupported item: only functions and impl \
blocks may be annotated with this attribute",
)),
}
}
pub fn from_impl(item: syn::ItemImpl, force_constructor: bool) -> syn::Result<Self> {
if !item.generics.params.is_empty() || item.generics.where_clause.is_some() {
return Err(syn::Error::new_spanned(
&item.generics,
"generic impls are not currently supported by uniffi::export",
));
}
let type_path = type_as_type_path(&item.self_ty)?;
if type_path.qself.is_some() {
return Err(syn::Error::new_spanned(
type_path,
"qualified self types are not currently supported by uniffi::export",
));
}
let self_ident = match type_path.path.get_ident() {
Some(id) => id,
None => {
return Err(syn::Error::new_spanned(
type_path,
"qualified paths in self-types are not currently supported by uniffi::export",
));
}
};
let items = item
.items
.into_iter()
.map(|item| {
let impl_fn = match item {
syn::ImplItem::Fn(m) => m,
_ => {
return Err(syn::Error::new_spanned(
item,
"only fn's are supported in impl blocks annotated with uniffi::export",
));
}
};
let attrs = ExportedImplFnAttributes::new(&impl_fn.attrs)?;
let item = if force_constructor || attrs.constructor {
ImplItem::Constructor(FnSignature::new_constructor(
self_ident.clone(),
impl_fn.sig,
)?)
} else {
ImplItem::Method(FnSignature::new_method(self_ident.clone(), impl_fn.sig)?)
};
Ok(item)
})
.collect::<syn::Result<_>>()?;
Ok(Self::Impl {
items,
self_ident: self_ident.to_owned(),
})
}
fn from_trait(item: syn::ItemTrait, callback_interface: bool) -> syn::Result<Self> {
if !item.generics.params.is_empty() || item.generics.where_clause.is_some() {
return Err(syn::Error::new_spanned(
&item.generics,
"generic impls are not currently supported by uniffi::export",
));
}
let self_ident = item.ident.to_owned();
let items = item
.items
.into_iter()
.enumerate()
.map(|(i, item)| {
let tim = match item {
syn::TraitItem::Fn(tim) => tim,
_ => {
return Err(syn::Error::new_spanned(
item,
"only fn's are supported in traits annotated with uniffi::export",
));
}
};
let attrs = ExportedImplFnAttributes::new(&tim.attrs)?;
let item = if attrs.constructor {
return Err(syn::Error::new_spanned(
tim,
"exported traits can not have constructors",
));
} else {
ImplItem::Method(FnSignature::new_trait_method(
self_ident.clone(),
tim.sig,
i as u32,
)?)
};
Ok(item)
})
.collect::<syn::Result<_>>()?;
Ok(Self::Trait {
items,
self_ident,
callback_interface,
})
}
fn from_struct(item: syn::ItemStruct, args: &ExportAttributeArguments) -> syn::Result<Self> {
let mut uniffi_traits = Vec::new();
if args.trait_debug.is_some() {
uniffi_traits.push(UniffiTraitDiscriminants::Debug);
}
if args.trait_display.is_some() {
uniffi_traits.push(UniffiTraitDiscriminants::Display);
}
if args.trait_hash.is_some() {
uniffi_traits.push(UniffiTraitDiscriminants::Hash);
}
if args.trait_eq.is_some() {
uniffi_traits.push(UniffiTraitDiscriminants::Eq);
}
Ok(Self::Struct {
self_ident: item.ident,
uniffi_traits,
})
}
}
pub(super) enum ImplItem {
Constructor(FnSignature),
Method(FnSignature),
}
fn type_as_type_path(ty: &syn::Type) -> syn::Result<&syn::TypePath> {
match ty {
syn::Type::Group(g) => type_as_type_path(&g.elem),
syn::Type::Paren(p) => type_as_type_path(&p.elem),
syn::Type::Path(p) => Ok(p),
_ => Err(type_not_supported(ty)),
}
}
fn type_not_supported(ty: &impl ToTokens) -> syn::Error {
syn::Error::new_spanned(
ty,
"this type is not currently supported by uniffi::export in this position",
)
}
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