Merge pull request RustCrypto#1 from baloo/baloo/der_derive/error-type

Author: turbocool3r

der_derive/src/attributes.rs

@@ -2,11 +2,33 @@
 
 use crate::{Asn1Type, Tag, TagMode, TagNumber};
 use proc_macro2::{Span, TokenStream};
-use quote::quote;
+use quote::{quote, ToTokens};
 use std::{fmt::Debug, str::FromStr};
 use syn::punctuated::Punctuated;
 use syn::{parse::Parse, parse::ParseStream, Attribute, Ident, LitStr, Path, Token};
 
+/// Error type used by the structure
+#[derive(Debug, Clone, Default, Eq, PartialEq)]
+pub(crate) enum ErrorType {
+    /// Represents the ::der::Error type
+    #[default]
+    Der,
+    /// Represents an error designed by Path
+    Custom(Path),
+}
+
+impl ToTokens for ErrorType {
+    fn to_tokens(&self, tokens: &mut TokenStream) {
+        match self {
+            Self::Der => {
+                let err = quote! { ::der::Error };
+                err.to_tokens(tokens)
+            }
+            Self::Custom(path) => path.to_tokens(tokens),
+        }
+    }
+}
+
 /// Attribute name.
 pub(crate) const ATTR_NAME: &str = "asn1";
 
@@ -18,7 +40,7 @@ pub(crate) struct TypeAttrs {
     ///
     /// The default value is `EXPLICIT`.
     pub tag_mode: TagMode,
-    pub error: Option<Path>,
+    pub error: ErrorType,
 }
 
 impl TypeAttrs {
@@ -44,7 +66,7 @@ impl TypeAttrs {
                         abort!(attr, "duplicate ASN.1 `error` attribute");
                     }
 
-                    error = Some(meta.value()?.parse()?);
+                    error = Some(ErrorType::Custom(meta.value()?.parse()?));
                 } else {
                     return Err(syn::Error::new_spanned(
                         attr,
@@ -58,7 +80,7 @@ impl TypeAttrs {
 
         Ok(Self {
             tag_mode: tag_mode.unwrap_or_default(),
-            error,
+            error: error.unwrap_or_default(),
         })
     }
 }

der_derive/src/choice.rs

@@ -5,10 +5,10 @@
 mod variant;
 
 use self::variant::ChoiceVariant;
-use crate::{default_lifetime, TypeAttrs};
+use crate::{default_lifetime, ErrorType, TypeAttrs};
 use proc_macro2::TokenStream;
 use quote::{quote, ToTokens};
-use syn::{DeriveInput, GenericParam, Generics, Ident, LifetimeParam, Path};
+use syn::{DeriveInput, GenericParam, Generics, Ident, LifetimeParam};
 
 /// Derive the `Choice` trait for an enum.
 pub(crate) struct DeriveChoice {
@@ -22,7 +22,7 @@ pub(crate) struct DeriveChoice {
     variants: Vec<ChoiceVariant>,
 
     /// Error type for `DecodeValue` implementation.
-    error: Option<Path>,
+    error: ErrorType,
 }
 
 impl DeriveChoice {
@@ -36,7 +36,7 @@ impl DeriveChoice {
             ),
         };
 
-        let mut type_attrs = TypeAttrs::parse(&input.attrs)?;
+        let type_attrs = TypeAttrs::parse(&input.attrs)?;
         let variants = data
             .variants
             .iter()
@@ -47,7 +47,7 @@ impl DeriveChoice {
             ident: input.ident,
             generics: input.generics.clone(),
             variants,
-            error: type_attrs.error.take(),
+            error: type_attrs.error.clone(),
         })
     }
 
@@ -88,11 +88,7 @@ impl DeriveChoice {
             tagged_body.push(variant.to_tagged_tokens());
         }
 
-        let error = self
-            .error
-            .as_ref()
-            .map(ToTokens::to_token_stream)
-            .unwrap_or_else(|| quote! { ::der::Error });
+        let error = self.error.to_token_stream();
 
         quote! {
             impl #impl_generics ::der::Choice<#lifetime> for #ident #ty_generics #where_clause {

der_derive/src/lib.rs

@@ -144,7 +144,7 @@ mod value_ord;
 
 use crate::{
     asn1_type::Asn1Type,
-    attributes::{FieldAttrs, TypeAttrs, ATTR_NAME},
+    attributes::{ErrorType, FieldAttrs, TypeAttrs, ATTR_NAME},
     choice::DeriveChoice,
     enumerated::DeriveEnumerated,
     sequence::DeriveSequence,

der_derive/src/sequence.rs

@@ -3,11 +3,11 @@
 
 mod field;
 
-use crate::{default_lifetime, TypeAttrs};
+use crate::{default_lifetime, ErrorType, TypeAttrs};
 use field::SequenceField;
 use proc_macro2::TokenStream;
 use quote::{quote, ToTokens};
-use syn::{DeriveInput, GenericParam, Generics, Ident, LifetimeParam, Path};
+use syn::{DeriveInput, GenericParam, Generics, Ident, LifetimeParam};
 
 /// Derive the `Sequence` trait for a struct
 pub(crate) struct DeriveSequence {
@@ -21,7 +21,7 @@ pub(crate) struct DeriveSequence {
     fields: Vec<SequenceField>,
 
     /// Error type for `DecodeValue` implementation.
-    error: Option<Path>,
+    error: ErrorType,
 }
 
 impl DeriveSequence {
@@ -35,7 +35,7 @@ impl DeriveSequence {
             ),
         };
 
-        let mut type_attrs = TypeAttrs::parse(&input.attrs)?;
+        let type_attrs = TypeAttrs::parse(&input.attrs)?;
 
         let fields = data
             .fields
@@ -47,7 +47,7 @@ impl DeriveSequence {
             ident: input.ident,
             generics: input.generics.clone(),
             fields,
-            error: type_attrs.error.take(),
+            error: type_attrs.error.clone(),
         })
     }
 
@@ -88,11 +88,7 @@ impl DeriveSequence {
             encode_fields.push(quote!(#field.encode(writer)?;));
         }
 
-        let error = self
-            .error
-            .as_ref()
-            .map(ToTokens::to_token_stream)
-            .unwrap_or_else(|| quote! { ::der::Error });
+        let error = self.error.to_token_stream();
 
         quote! {
             impl #impl_generics ::der::DecodeValue<#lifetime> for #ident #ty_generics #where_clause {