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#![recursion_limit="256"]
extern crate proc_macro;
mod gen;
use quote::{quote, quote_spanned};
use proc_macro2::TokenStream;
use syn::{
GenericParam,
Generics,
Ident,
Item,
LifetimeDef,
TypeParam,
parse,
};
use syn::spanned::Spanned;
use gen::{gen_widget, gen_where_clause, parser::dummy_ident};
#[proc_macro_derive(Msg)]
pub fn msg(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
let ast: Item = parse(input).expect("msg > parse failed");
let gen = impl_msg(&ast, Ident::new("relm", ast.span()));
gen.into()
}
#[proc_macro_attribute]
pub fn widget(_attributes: proc_macro::TokenStream, input: proc_macro::TokenStream) -> proc_macro::TokenStream {
let ast: Item = parse(input).expect("widget.parse failed");
let tokens = quote! {
#ast
};
let expanded = gen_widget(tokens);
expanded.into()
}
fn impl_msg(ast: &Item, krate: Ident) -> TokenStream {
let display = derive_display_variant(ast, &krate);
let into_option = derive_into_option(ast, &krate);
quote! {
#display
#into_option
}
}
fn derive_display_variant(ast: &Item, krate: &Ident) -> TokenStream {
if let Item::Enum(ref enum_item) = *ast {
let generics = &enum_item.generics;
let name = &enum_item.ident;
let generics_without_bound = remove_generic_bounds(generics);
let typ = quote! {
#name #generics_without_bound
};
let variant_patterns = enum_item.variants.iter().map(|variant| {
let doc_ident = dummy_ident("doc");
let attrs = variant.attrs.iter().filter(|attr| !attr.path.is_ident(&doc_ident));
let ident = &variant.ident;
quote! {
#(#attrs)* #name::#ident { .. }
}
});
let variant_names = enum_item.variants.iter().map(|variant| {
variant.ident.to_string()
});
let where_clause = gen_where_clause(generics);
quote_spanned! { krate.span() =>
impl #generics ::#krate::DisplayVariant for #typ #where_clause {
#[allow(unused_qualifications)]
fn display_variant(&self) -> &'static str {
match *self {
#(#variant_patterns => #variant_names,)*
}
}
}
}
}
else {
panic!("Expected enum");
}
}
fn derive_into_option(ast: &Item, krate: &Ident) -> TokenStream {
if let Item::Enum(ref enum_item) = *ast {
let generics = &enum_item.generics;
let name = &enum_item.ident;
let generics_without_bound = remove_generic_bounds(generics);
let typ = quote! {
#name #generics_without_bound
};
let where_clause = gen_where_clause(generics);
quote_spanned! { krate.span() =>
impl #generics ::#krate::IntoOption<#typ> for #typ #where_clause {
fn into_option(self) -> Option<#typ> {
Some(self)
}
}
}
}
else {
panic!("Expecting enum");
}
}
fn remove_generic_bounds(generics: &Generics) -> Generics {
let mut generics = generics.clone();
for param in generics.params.iter_mut() {
match *param {
GenericParam::Lifetime(LifetimeDef { ref mut bounds, .. }) =>
while bounds.pop().is_some() {
},
GenericParam::Type(TypeParam { ref mut bounds, .. }) =>
while bounds.pop().is_some() {
},
_ => (),
}
}
generics.clone()
}