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use proc_macro2::TokenTree;
use quote::quote;
use std::collections::HashSet;
use syn::export::TokenStream2;
use syn::{GenericArgument, ItemFn, PathArguments, ReturnType, Type, TypeParamBound};
#[derive(Debug, Hash, Ord, PartialOrd, Eq, PartialEq)]
pub enum ExternArgs {
Immutable,
Strict,
Stable,
Volatile,
Raw,
NoGuard,
ParallelSafe,
ParallelUnsafe,
ParallelRestricted,
Error(String),
}
#[derive(Debug)]
pub enum CategorizedType {
Iterator(Vec<String>),
OptionalIterator(Vec<String>),
Default,
}
pub fn parse_extern_attributes(attr: TokenStream2) -> HashSet<ExternArgs> {
let mut args = HashSet::<ExternArgs>::new();
let mut itr = attr.into_iter();
while let Some(t) = itr.next() {
match t {
TokenTree::Group(g) => {
for arg in parse_extern_attributes(g.stream()).into_iter() {
args.insert(arg);
}
}
TokenTree::Ident(i) => {
let name = i.to_string();
match name.as_str() {
"immutable" => args.insert(ExternArgs::Immutable),
"strict" => args.insert(ExternArgs::Strict),
"stable" => args.insert(ExternArgs::Stable),
"volatile" => args.insert(ExternArgs::Volatile),
"raw" => args.insert(ExternArgs::Raw),
"no_guard" => args.insert(ExternArgs::NoGuard),
"parallel_safe" => args.insert(ExternArgs::ParallelSafe),
"parallel_unsafe" => args.insert(ExternArgs::ParallelUnsafe),
"parallel_restricted" => args.insert(ExternArgs::ParallelRestricted),
"error" => {
let _punc = itr.next().unwrap();
let literal = itr.next().unwrap();
let message = literal.to_string();
let message = unescape::unescape(&message).expect("failed to unescape");
let message = message[1..message.len() - 1].to_string();
args.insert(ExternArgs::Error(message.to_string()))
}
_ => false,
};
}
TokenTree::Punct(_) => {}
TokenTree::Literal(_) => {}
}
}
args
}
pub fn categorize_return_type(func: &ItemFn) -> CategorizedType {
let rt = &func.sig.output;
match rt {
ReturnType::Default => CategorizedType::Default,
ReturnType::Type(_, ty) => categorize_type(ty),
}
}
pub fn categorize_type(ty: &Type) -> CategorizedType {
match ty {
Type::Path(ty) => {
let segments = &ty.path.segments;
for segment in segments {
if segment.ident.to_string() == "Option" {
match &segment.arguments {
PathArguments::AngleBracketed(a) => match a.args.first().unwrap() {
GenericArgument::Type(ty) => {
let result = categorize_type(ty);
return match result {
CategorizedType::Iterator(i) => {
CategorizedType::OptionalIterator(i)
}
_ => result,
};
}
_ => {
break;
}
},
_ => {
break;
}
}
}
}
CategorizedType::Default
}
Type::ImplTrait(ty) => {
for bound in &ty.bounds {
match bound {
TypeParamBound::Trait(trait_bound) => {
let segments = &trait_bound.path.segments;
let mut ident = String::new();
for segment in segments {
if !ident.is_empty() {
ident.push_str("::")
}
ident.push_str(segment.ident.to_string().as_str());
}
match ident.as_str() {
"Iterator" | "std::iter::Iterator" => {
let segment = segments.last().unwrap();
match &segment.arguments {
PathArguments::None => {
panic!("Iterator must have at least one generic type")
}
PathArguments::Parenthesized(_) => {
panic!("Unsupported arguments to Iterator")
}
PathArguments::AngleBracketed(a) => {
let args = &a.args;
if args.len() > 1 {
panic!("Only one generic type is supported when returning an Iterator")
}
match args.first().unwrap() {
GenericArgument::Binding(b) => {
let mut types = Vec::new();
let ty = &b.ty;
match ty {
Type::Tuple(tuple) => {
for e in &tuple.elems {
types.push(quote! {#e}.to_string());
}
},
_ => {
types.push(quote! {#ty}.to_string())
}
}
return CategorizedType::Iterator(types);
}
_ => panic!("Only binding type arguments are supported when returning an Iterator")
}
}
}
}
_ => panic!("Unsupported trait return type"),
}
}
TypeParamBound::Lifetime(_) => {
panic!("Functions can't return traits with lifetime bounds")
}
}
}
panic!("Unsupported trait return type");
}
_ => CategorizedType::Default,
}
}
#[cfg(test)]
mod tests {
use crate::{parse_extern_attributes, ExternArgs};
use std::str::FromStr;
use syn::export::TokenStream2;
#[test]
fn parse_args() {
let s = "error = \"syntax error at or near \\\"THIS\\\"\"";
let ts = TokenStream2::from_str(s).unwrap();
let args = parse_extern_attributes(ts);
assert!(args.contains(&ExternArgs::Error(
"syntax error at or near \"THIS\"".to_string()
)));
}
}