forked from serde-rs/serde
/
receiver.rs
190 lines (172 loc) · 6.48 KB
/
receiver.rs
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use super::respan::respan;
use proc_macro2::{Group, Spacing, Span, TokenStream, TokenTree};
use quote::{quote, quote_spanned};
use std::{iter::FromIterator, mem};
use syn::{
parse_quote,
punctuated::Punctuated,
visit_mut::{self, VisitMut},
DeriveInput, ExprPath, Macro, Path, PathArguments, QSelf, Type, TypePath,
};
pub fn replace_receiver(input: &mut DeriveInput) {
let self_ty = {
let ident = &input.ident;
let ty_generics = input.generics.split_for_impl().1;
parse_quote!(#ident #ty_generics)
};
let mut visitor = ReplaceReceiver(&self_ty);
visitor.visit_generics_mut(&mut input.generics);
visitor.visit_data_mut(&mut input.data);
}
struct ReplaceReceiver<'a>(&'a TypePath);
impl ReplaceReceiver<'_> {
fn self_ty(&self, span: Span) -> TypePath {
respan(self.0, span)
}
fn self_to_qself(&self, qself: &mut Option<QSelf>, path: &mut Path) {
if path.leading_colon.is_some() {
return;
}
// Make borrow checker happy
{
let first = &path.segments[0];
if first.ident != "Self" || !first.arguments.is_empty() {
return;
}
}
if path.segments.len() == 1 {
self.self_to_expr_path(path);
return;
}
let span = path.segments[0].ident.span();
*qself = Some(QSelf {
lt_token: Token![<](span),
ty: Box::new(self.self_ty(span).into()),
position: 0,
as_token: None,
gt_token: Token![>](span),
});
path.leading_colon = Some(**path.segments.pairs().next().unwrap().punct().unwrap());
let segments = mem::replace(&mut path.segments, Punctuated::new());
path.segments = segments.into_pairs().skip(1).collect();
}
fn self_to_expr_path(&self, path: &mut Path) {
if path.leading_colon.is_some() {
return;
}
// Make borrow checker happy
{
let first = &path.segments[0];
if first.ident != "Self" || !first.arguments.is_empty() {
return;
}
}
let self_ty = self.self_ty(path.segments[0].ident.span());
let variant = mem::replace(path, self_ty.path);
for segment in &mut path.segments {
if let PathArguments::AngleBracketed(bracketed) = &mut segment.arguments {
if bracketed.colon2_token.is_none() && !bracketed.args.is_empty() {
bracketed.colon2_token = Some(<Token![::]>::default());
}
}
}
if variant.segments.len() > 1 {
path.segments.push_punct(<Token![::]>::default());
path.segments.extend(variant.segments.into_pairs().skip(1));
}
}
fn visit_token_stream(&self, tokens: &mut TokenStream) -> bool {
let mut out = Vec::new();
let mut modified = false;
let mut iter = tokens.clone().into_iter().peekable();
while let Some(tt) = iter.next() {
match tt {
TokenTree::Ident(ident) => {
if ident == "Self" {
modified = true;
let self_ty = self.self_ty(ident.span());
match iter.peek() {
Some(TokenTree::Punct(p))
if p.as_char() == ':' && p.spacing() == Spacing::Joint => {}
_ => {
out.extend(quote!(#self_ty));
continue;
}
}
let next = iter.next().unwrap();
match iter.peek() {
Some(TokenTree::Punct(p)) if p.as_char() == ':' => {
let span = ident.span();
out.extend(quote_spanned!(span=> <#self_ty>));
}
_ => out.extend(quote!(#self_ty)),
}
out.push(next);
} else {
out.push(TokenTree::Ident(ident));
}
}
TokenTree::Group(group) => {
let mut content = group.stream();
modified |= self.visit_token_stream(&mut content);
let mut new = Group::new(group.delimiter(), content);
new.set_span(group.span());
out.push(TokenTree::Group(new));
}
other => out.push(other),
}
}
if modified {
*tokens = TokenStream::from_iter(out);
}
modified
}
}
impl VisitMut for ReplaceReceiver<'_> {
// `Self` -> `Receiver`
fn visit_type_mut(&mut self, ty: &mut Type) {
let span = if let Type::Path(node) = ty {
if node.qself.is_none() && node.path.is_ident("Self") {
node.path.segments[0].ident.span()
} else {
self.visit_type_path_mut(node);
return;
}
} else {
visit_mut::visit_type_mut(self, ty);
return;
};
*ty = self.self_ty(span).into();
}
// `Self::Assoc` -> `<Receiver>::Assoc`
fn visit_type_path_mut(&mut self, ty: &mut TypePath) {
if ty.qself.is_none() {
self.self_to_qself(&mut ty.qself, &mut ty.path);
}
visit_mut::visit_type_path_mut(self, ty);
}
// `Self::method` -> `<Receiver>::method`
fn visit_expr_path_mut(&mut self, expr: &mut ExprPath) {
if expr.qself.is_none() {
self.self_to_qself(&mut expr.qself, &mut expr.path);
}
visit_mut::visit_expr_path_mut(self, expr);
}
fn visit_macro_mut(&mut self, mac: &mut Macro) {
// We can't tell in general whether `self` inside a macro invocation
// refers to the self in the argument list or a different self
// introduced within the macro. Heuristic: if the macro input contains
// `fn`, then `self` is more likely to refer to something other than the
// outer function's self argument.
if !contains_fn(mac.tokens.clone()) {
self.visit_token_stream(&mut mac.tokens);
}
}
}
fn contains_fn(tokens: TokenStream) -> bool {
tokens.into_iter().any(|tt| match tt {
TokenTree::Ident(ident) => ident == "fn",
TokenTree::Group(group) => contains_fn(group.stream()),
_ => false,
})
}