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enum_messages.rs
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enum_messages.rs
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use quote;
use syn;
use helpers::{unique_attr, extract_attrs, extract_meta, is_disabled};
pub fn enum_message_inner(ast: &syn::DeriveInput) -> quote::Tokens {
let name = &ast.ident;
let (impl_generics, ty_generics, where_clause) = ast.generics.split_for_impl();
let variants = match ast.data {
syn::Data::Enum(ref v) => &v.variants,
_ => panic!("EnumMessage only works on Enums"),
};
let mut arms = Vec::new();
let mut detailed_arms = Vec::new();
let mut serializations = Vec::new();
for variant in variants {
let meta = extract_meta(&variant.attrs);
let messages = unique_attr(&meta, "strum", "message");
let detailed_messages = unique_attr(&meta, "strum", "detailed_message");
let ident = &variant.ident;
use syn::Fields::*;
let params = match variant.fields {
Unit => quote!{},
Unnamed(..) => quote!{ (..) },
Named(..) => quote!{ {..} },
};
// You can't disable getting the serializations.
{
let mut serialization_variants = extract_attrs(&meta, "strum", "serialize");
if serialization_variants.len() == 0 {
serialization_variants.push(ident.to_string());
}
let count = serialization_variants.len();
serializations.push(quote!{
&#name::#ident #params => {
static ARR: [&'static str; #count] = [#(#serialization_variants),*];
&ARR
}
});
}
// But you can disable the messages.
if is_disabled(&meta) {
continue;
}
if let Some(msg) = messages {
let params = params.clone();
// Push the simple message.
let tokens = quote!{ &#name::#ident #params => ::std::option::Option::Some(#msg) };
arms.push(tokens.clone());
if detailed_messages.is_none() {
detailed_arms.push(tokens);
}
}
if let Some(msg) = detailed_messages {
let params = params.clone();
// Push the simple message.
detailed_arms
.push(quote!{ &#name::#ident #params => ::std::option::Option::Some(#msg) });
}
}
if arms.len() < variants.len() {
arms.push(quote!{ _ => ::std::option::Option::None });
}
if detailed_arms.len() < variants.len() {
detailed_arms.push(quote!{ _ => ::std::option::Option::None });
}
quote!{
impl #impl_generics ::strum::EnumMessage for #name #ty_generics #where_clause {
fn get_message(&self) -> ::std::option::Option<&str> {
match self {
#(#arms),*
}
}
fn get_detailed_message(&self) -> ::std::option::Option<&str> {
match self {
#(#detailed_arms),*
}
}
fn get_serializations(&self) -> &[&str] {
match self {
#(#serializations),*
}
}
}
}
}