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use proc_macro2::Span;
use syn::visit_mut::{self, VisitMut};
use syn::{Block, GenericArgument, Item, Lifetime, Receiver, Signature, TypeReference};
pub fn has_async_lifetime(sig: &mut Signature, block: &mut Block) -> bool {
let mut visitor = HasAsyncLifetime(false);
visitor.visit_signature_mut(sig);
visitor.visit_block_mut(block);
visitor.0
}
struct HasAsyncLifetime(bool);
impl VisitMut for HasAsyncLifetime {
fn visit_lifetime_mut(&mut self, life: &mut Lifetime) {
self.0 |= life.to_string() == "'async_trait";
}
fn visit_item_mut(&mut self, _: &mut Item) {
}
}
pub struct CollectLifetimes {
pub elided: Vec<Lifetime>,
pub explicit: Vec<Lifetime>,
}
impl CollectLifetimes {
pub fn new() -> Self {
CollectLifetimes {
elided: Vec::new(),
explicit: Vec::new(),
}
}
fn visit_opt_lifetime(&mut self, lifetime: &mut Option<Lifetime>) {
match lifetime {
None => *lifetime = Some(self.next_lifetime()),
Some(lifetime) => self.visit_lifetime(lifetime),
}
}
fn visit_lifetime(&mut self, lifetime: &mut Lifetime) {
if lifetime.ident == "_" {
*lifetime = self.next_lifetime();
} else {
self.explicit.push(lifetime.clone());
}
}
fn next_lifetime(&mut self) -> Lifetime {
let name = format!("'life{}", self.elided.len());
let life = Lifetime::new(&name, Span::call_site());
self.elided.push(life.clone());
life
}
}
impl VisitMut for CollectLifetimes {
fn visit_receiver_mut(&mut self, arg: &mut Receiver) {
if let Some((_, lifetime)) = &mut arg.reference {
self.visit_opt_lifetime(lifetime);
}
}
fn visit_type_reference_mut(&mut self, ty: &mut TypeReference) {
self.visit_opt_lifetime(&mut ty.lifetime);
visit_mut::visit_type_reference_mut(self, ty);
}
fn visit_generic_argument_mut(&mut self, gen: &mut GenericArgument) {
if let GenericArgument::Lifetime(lifetime) = gen {
self.visit_lifetime(lifetime);
}
visit_mut::visit_generic_argument_mut(self, gen);
}
}