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|
use std::iter::FromIterator;
use proc_macro2::TokenStream;
use quote::quote;
use syn::{
parse_quote,
punctuated::Punctuated,
visit_mut::{self, visit_item_mut, visit_path_segment_mut, VisitMut},
Expr, ExprBlock, File, GenericArgument, GenericParam, Item, PathArguments, PathSegment, Type,
TypeParamBound, WherePredicate,
};
pub struct ReplaceGenericType<'a> {
generic_type: &'a str,
arg_type: &'a PathSegment,
}
impl<'a> ReplaceGenericType<'a> {
pub fn new(generic_type: &'a str, arg_type: &'a PathSegment) -> Self {
Self {
generic_type,
arg_type,
}
}
pub fn replace_generic_type(item: &mut Item, generic_type: &'a str, arg_type: &'a PathSegment) {
let mut s = Self::new(generic_type, arg_type);
s.visit_item_mut(item);
}
}
impl<'a> VisitMut for ReplaceGenericType<'a> {
fn visit_item_mut(&mut self, i: &mut Item) {
if let Item::Fn(item_fn) = i {
// remove generic type from generics <T, F>
let args = item_fn
.sig
.generics
.params
.iter()
.filter_map(|param| {
if let GenericParam::Type(type_param) = ¶m {
if type_param.ident.to_string().eq(self.generic_type) {
None
} else {
Some(param)
}
} else {
Some(param)
}
})
.collect::<Vec<_>>();
item_fn.sig.generics.params =
Punctuated::from_iter(args.into_iter().map(|p| p.clone()).collect::<Vec<_>>());
// remove generic type from where clause
if let Some(where_clause) = &mut item_fn.sig.generics.where_clause {
let new_where_clause = where_clause
.predicates
.iter()
.filter_map(|predicate| {
if let WherePredicate::Type(predicate_type) = predicate {
if let Type::Path(p) = &predicate_type.bounded_ty {
if p.path.segments[0].ident.to_string().eq(self.generic_type) {
None
} else {
Some(predicate)
}
} else {
Some(predicate)
}
} else {
Some(predicate)
}
})
.collect::<Vec<_>>();
where_clause.predicates = Punctuated::from_iter(
new_where_clause
.into_iter()
.map(|c| c.clone())
.collect::<Vec<_>>(),
);
};
}
visit_item_mut(self, i)
}
fn visit_path_segment_mut(&mut self, i: &mut PathSegment) {
// replace generic type with target type
if i.ident.to_string().eq(&self.generic_type) {
*i = self.arg_type.clone();
}
visit_path_segment_mut(self, i);
}
}
pub struct AsyncAwaitRemoval;
impl AsyncAwaitRemoval {
pub fn remove_async_await(&mut self, item: TokenStream) -> TokenStream {
let mut syntax_tree: File = syn::parse(item.into()).unwrap();
self.visit_file_mut(&mut syntax_tree);
quote!(#syntax_tree)
}
}
impl VisitMut for AsyncAwaitRemoval {
fn visit_expr_mut(&mut self, node: &mut Expr) {
// Delegate to the default impl to visit nested expressions.
visit_mut::visit_expr_mut(self, node);
match node {
Expr::Await(expr) => *node = (*expr.base).clone(),
Expr::Async(expr) => {
let inner = &expr.block;
let sync_expr = if inner.stmts.len() == 1 {
// remove useless braces when there is only one statement
let stmt = &inner.stmts.get(0).unwrap();
// convert statement to Expr
parse_quote!(#stmt)
} else {
Expr::Block(ExprBlock {
attrs: expr.attrs.clone(),
block: inner.clone(),
label: None,
})
};
*node = sync_expr;
}
_ => {}
}
}
fn visit_item_mut(&mut self, i: &mut Item) {
// find generic parameter of Future and replace it with its Output type
if let Item::Fn(item_fn) = i {
let mut inputs: Vec<(String, PathSegment)> = vec![];
// generic params: <T:Future<Output=()>, F>
for param in &item_fn.sig.generics.params {
// generic param: T:Future<Output=()>
if let GenericParam::Type(type_param) = param {
let generic_type_name = type_param.ident.to_string();
// bound: Future<Output=()>
for bound in &type_param.bounds {
inputs.extend(search_trait_bound(&generic_type_name, bound));
}
}
}
if let Some(where_clause) = &item_fn.sig.generics.where_clause {
for predicate in &where_clause.predicates {
if let WherePredicate::Type(predicate_type) = predicate {
let generic_type_name = if let Type::Path(p) = &predicate_type.bounded_ty {
p.path.segments[0].ident.to_string()
} else {
panic!("Please submit an issue");
};
for bound in &predicate_type.bounds {
inputs.extend(search_trait_bound(&generic_type_name, bound));
}
}
}
}
for (generic_type_name, path_seg) in &inputs {
ReplaceGenericType::replace_generic_type(i, generic_type_name, path_seg);
}
}
visit_item_mut(self, i);
}
}
fn search_trait_bound(
generic_type_name: &str,
bound: &TypeParamBound,
) -> Vec<(String, PathSegment)> {
let mut inputs = vec![];
if let TypeParamBound::Trait(trait_bound) = bound {
let segment = &trait_bound.path.segments[trait_bound.path.segments.len() - 1];
let name = segment.ident.to_string();
if name.eq("Future") {
// match Future<Output=Type>
if let PathArguments::AngleBracketed(args) = &segment.arguments {
// binding: Output=Type
if let GenericArgument::Binding(binding) = &args.args[0] {
if let Type::Path(p) = &binding.ty {
inputs.push((generic_type_name.to_owned(), p.path.segments[0].clone()));
}
}
}
}
}
inputs
}
|
