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remove panics from FromBody

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Dominic 2020-04-08 21:53:57 +02:00
parent 2b8ad48504
commit f677789747
Signed by: msrd0
GPG key ID: DCC8C247452E98F9
1 changed files with 15 additions and 6 deletions
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21
gotham_restful_derive/src/from_body.rs
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@ -1,15 +1,25 @@
use proc_macro::TokenStream; use proc_macro::TokenStream;
use proc_macro2::TokenStream as TokenStream2;
use quote::quote; use quote::quote;
use syn::{ use syn::{
spanned::Spanned,
Error,
Fields, Fields,
ItemStruct, ItemStruct,
parse_macro_input parse_macro_input
}; };
pub fn expand_from_body(tokens : TokenStream) -> TokenStream pub fn expand_from_body(tokens : TokenStream) -> TokenStream
{
expand(tokens)
.unwrap_or_else(|err| err.to_compile_error())
.into()
}
fn expand(tokens : TokenStream) -> Result<TokenStream2, Error>
{ {
let krate = super::krate(); let krate = super::krate();
let input = parse_macro_input!(tokens as ItemStruct); let input = parse_macro_input::parse::<ItemStruct>(tokens)?;
let ident = input.ident; let ident = input.ident;
let generics = input.generics; let generics = input.generics;
@ -24,7 +34,7 @@ pub fn expand_from_body(tokens : TokenStream) -> TokenStream
let field_ty = &field.ty; let field_ty = &field.ty;
(quote!(where #field_ty : for<'a> From<&'a [u8]>), quote!(Self { #field_ident: body.into() })) (quote!(where #field_ty : for<'a> From<&'a [u8]>), quote!(Self { #field_ident: body.into() }))
}, },
_ => panic!("FromBody can only be derived for structs with at most one field") _ => return Err(Error::new(fields.into_iter().nth(1).unwrap().span(), "FromBody can only be derived for structs with at most one field"))
} }
}, },
Fields::Unnamed(unnamed) => { Fields::Unnamed(unnamed) => {
@ -36,13 +46,13 @@ pub fn expand_from_body(tokens : TokenStream) -> TokenStream
let field_ty = &field.ty; let field_ty = &field.ty;
(quote!(where #field_ty : for<'a> From<&'a [u8]>), quote!(Self(body.into()))) (quote!(where #field_ty : for<'a> From<&'a [u8]>), quote!(Self(body.into())))
}, },
_ => panic!("FromBody can only be derived for structs with at most one field") _ => return Err(Error::new(fields.into_iter().nth(1).unwrap().span(), "FromBody can only be derived for structs with at most one field"))
} }
}, },
Fields::Unit => (quote!(), quote!(Self{})) Fields::Unit => (quote!(), quote!(Self{}))
}; };
let output = quote! { Ok(quote! {
impl #generics #krate::FromBody for #ident #generics impl #generics #krate::FromBody for #ident #generics
#were #were
{ {
@ -54,6 +64,5 @@ pub fn expand_from_body(tokens : TokenStream) -> TokenStream
Ok(#body) Ok(#body)
} }
} }
}; })
output.into()
} }