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extern crate askama;
extern crate proc_macro;
extern crate syn;
use proc_macro::TokenStream;
fn get_path_from_attrs(attrs: &Vec<syn::Attribute>) -> String {
for attr in attrs {
if attr.name() == "template" {
match attr.value {
syn::MetaItem::List(_, ref inner) => {
match inner[0] {
syn::NestedMetaItem::MetaItem(ref item) => {
match item {
&syn::MetaItem::NameValue(ref key, ref val) => {
assert_eq!(key.as_ref(), "path");
match val {
&syn::Lit::Str(ref s, _) => { return s.clone(); },
_ => panic!("template path must be a string"),
}
},
_ => panic!("template annotation must contain key/value pair"),
}
},
_ => panic!("template annotation must contain item"),
}
},
_ => panic!("template annotation must be of List type"),
}
}
}
panic!("template annotation not found");
}
#[proc_macro_derive(Template, attributes(template))]
pub fn derive_template(input: TokenStream) -> TokenStream {
let source = input.to_string();
let ast = syn::parse_derive_input(&source).unwrap();
let _ctx = match ast.body {
syn::Body::Struct(ref data) => data,
_ => panic!("#[derive(Template)] can only be used with structs"),
};
let path = get_path_from_attrs(&ast.attrs);
askama::build_template(&path, &ast).parse().unwrap()
}
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