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allow wildcard in enum parsing

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This commit is contained in:
Robin Appelman 2019-03-01 23:07:20 +01:00
commit c571326ed7
3 changed files with 49 additions and 8 deletions
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26
bitstream_reader_derive/src/lib.rs
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@ -138,9 +138,10 @@ extern crate proc_macro;
use proc_macro2::{Span, TokenStream};
use quote::{quote, quote_spanned};
use syn::spanned::Spanned;
use syn::token::Token;
use syn::{
parse_macro_input, parse_quote, parse_str, Attribute, Data, DeriveInput, Expr, Fields, Ident,
Lit, LitStr, Meta, Path,
Lit, LitStr, Meta, Pat, Path,
};
/// See the [crate documentation](index.html) for details
@ -273,7 +274,7 @@ fn parse(data: &Data, struct_name: &Ident, attrs: &Vec<Attribute>) -> TokenStrea
let mut last_discriminant = -1;
let mut discriminants = Vec::with_capacity(data.variants.len());
for variant in &data.variants {
let discriminant = variant
let discriminant: Option<usize> = variant
.discriminant
.clone()
.map(|(_, expr)| match expr {
@ -282,12 +283,19 @@ fn parse(data: &Data, struct_name: &Ident, attrs: &Vec<Attribute>) -> TokenStrea
})
.or_else(|| get_attr(&variant.attrs, "discriminant"))
.map(|lit| match lit {
Lit::Int(lit) => lit.value(),
_ => panic!("discriminant is required to be an integer literal"),
Lit::Int(lit) => Some(lit.value() as usize),
Lit::Str(lit) => match lit.value().as_str() {
"_" => None,
_ => {
panic!("discriminant is required to be an integer literal or \"_\"")
}
},
_ => panic!("discriminant is required to be an integer literal or \"_\""),
})
.unwrap_or_else(|| (last_discriminant + 1) as u64)
as usize;
last_discriminant = discriminant as isize;
.unwrap_or_else(|| Some((last_discriminant + 1) as usize));
if let Some(disc) = discriminant {
last_discriminant = disc as isize;
}
discriminants.push(discriminant)
}
let match_arms =
@ -297,6 +305,10 @@ fn parse(data: &Data, struct_name: &Ident, attrs: &Vec<Attribute>) -> TokenStrea
.map(|(variant, discriminant)| {
let span = variant.span();
let variant_name = &variant.ident;
let discriminant_string = discriminant
.map(|value| value.to_string())
.unwrap_or("_".to_string());
let discriminant = parse_str::<Pat>(discriminant_string.as_str()).unwrap();
let read_fields = match &variant.fields {
Fields::Unit => quote_spanned! {span=>
#struct_name::#variant_name