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#![warn(clippy::all)]
#![warn(clippy::cargo_common_metadata)]
mod attr;
mod replacement;
use self::attr::MetaforAttr;
use self::attr::TemplateValues;
use self::replacement::IdentReplacer;
use proc_macro::TokenStream;
use proc_macro2::TokenStream as TokenStream2;
use quote::ToTokens;
use std::collections::HashMap;
use syn::parse_macro_input;
use syn::visit_mut::VisitMut;
use syn::Ident;
use syn::Item;
#[proc_macro_attribute]
pub fn metafor(attr: TokenStream, input: TokenStream) -> TokenStream {
let input = parse_macro_input!(input as Item);
let attr = parse_macro_input!(attr as MetaforAttr);
impl_metafor(input, attr)
.into_iter()
.map(|item| item.to_token_stream())
.collect::<TokenStream2>()
.into()
}
fn impl_metafor(input: Item, attr: MetaforAttr) -> Vec<Item> {
generate_mappings(&attr)
.map(|mapping| {
let mut dup_input = input.clone();
let mut ident_replacer = IdentReplacer::new(mapping);
ident_replacer.visit_item_mut(&mut dup_input);
dup_input
})
.collect()
}
fn generate_mappings<'a>(attr: &'a MetaforAttr) -> impl Iterator<Item = HashMap<Ident, &'a Ident>> {
let replacements = &attr.replacements;
let mut counters = HashMap::new();
for (template_ident, _) in replacements.iter() {
counters.insert(template_ident, 0usize);
}
let mut has_next_combo = true;
core::iter::from_fn(move || {
if !has_next_combo {
return None;
}
let mut mapping = HashMap::new();
for (temp_ident, counter) in counters.iter() {
match &replacements[*temp_ident] {
TemplateValues::Idents(idents) => {
let replacement_ident = &idents[*counter];
let string = format!("__{}__", temp_ident);
let temp_ident = Ident::new(&string, temp_ident.span());
mapping.insert(temp_ident, replacement_ident);
}
TemplateValues::Tuples(tuples) => {
let temp_tuple = &tuples[*counter];
for (i, temp_tuple_value) in temp_tuple.values().enumerate() {
let string = format!("__{}__{}__", temp_ident, i);
let temp_ident = Ident::new(&string, temp_ident.span());
mapping.insert(temp_ident, temp_tuple_value);
}
}
TemplateValues::Structs(structs) => {
let temp_struct = &structs[*counter];
for (struct_field, temp_struct_value) in temp_struct.fields() {
let string = format!("__{}__{}__", temp_ident, struct_field);
let temp_ident = Ident::new(&string, temp_ident.span());
mapping.insert(temp_ident, temp_struct_value);
}
}
};
}
has_next_combo = false;
for (template_ident, counter) in counters.iter_mut() {
let max_count = replacements[template_ident].len();
*counter += 1;
if *counter >= max_count {
*counter = 0;
} else {
has_next_combo = true;
break;
}
}
Some(mapping)
})
}
#[cfg(test)]
mod tests {
use super::*;
use pretty_assertions::assert_eq;
use syn::parse_quote;
#[test]
fn impl_metafor_test() {
let input = parse_quote! {
impl MyTrait for __i__ {}
};
let attr = parse_quote! {
i = [u8, u16]
};
let actual = impl_metafor(input, attr);
let expected = vec![
parse_quote!(impl MyTrait for u8 {}),
parse_quote!(impl MyTrait for u16 {}),
];
assert_eq!(actual, expected)
}
}