Add ability to re-export parity-scale-codec crate (#325)

* use codec_crate_path for all derivable macros

* update README

* bump versions

* use `codec` attribute in tests

* remove redundant call to parse_quote

Cargo.toml

@@ -1,7 +1,7 @@
 [package]
 name = "parity-scale-codec"
 description = "SCALE - Simple Concatenating Aggregated Little Endians"
-version = "3.0.0"
+version = "3.1.0"
 authors = ["Parity Technologies <admin@parity.io>"]
 license = "Apache-2.0"
 repository = "https://github.com/paritytech/parity-scale-codec"
@@ -12,7 +12,7 @@ rust-version = "1.56.1"
 [dependencies]
 arrayvec = { version = "0.7", default-features = false }
 serde = { version = "1.0.102", optional = true }
-parity-scale-codec-derive = { path = "derive", version = "3.0.0", default-features = false, optional = true }
+parity-scale-codec-derive = { path = "derive", version = "3.1.0", default-features = false, optional = true }
 bitvec = { version = "1", default-features = false, features = [ "alloc" ], optional = true }
 bytes = { version = "1", default-features = false, optional = true }
 byte-slice-cast = { version = "1.0.0", default-features = false }

README.md

@@ -201,6 +201,9 @@ The derive implementation supports the following attributes:
 - `codec(index = 0)`: Needs to be placed above an enum variant to make the variant use the given
   index when encoded. By default the index is determined by counting from `0` beginning wth the
   first variant.
+- `codec(crate = path::to::crate)`: Specify a path to the parity-scale-codec crate instance to use
+  when referring to Codec APIs from generated code. This is normally only applicable when invoking
+  re-exported Codec derives from a public macro in a different crate.
 
 
 License: Apache-2.0

derive/Cargo.toml

@@ -1,7 +1,7 @@
 [package]
 name = "parity-scale-codec-derive"
 description = "Serialization and deserialization derive macro for Parity SCALE Codec"
-version = "3.0.0"
+version = "3.1.0"
 authors = ["Parity Technologies <admin@parity.io>"]
 license = "Apache-2.0"
 edition = "2021"

derive/src/decode.rs

@@ -31,7 +31,7 @@ pub fn quote(
 	type_name: &Ident,
 	type_generics: &TokenStream,
 	input: &TokenStream,
-	crate_ident: &TokenStream,
+	crate_path: &syn::Path,
 ) -> TokenStream {
 	match *data {
 		Data::Struct(ref data) => match data.fields {
@@ -40,7 +40,7 @@ pub fn quote(
 				&type_name.to_string(),
 				input,
 				&data.fields,
-				crate_ident,
+				crate_path,
 			),
 			Fields::Unit => {
 				quote_spanned! { data.fields.span() =>
@@ -67,7 +67,7 @@ pub fn quote(
 					&format!("{}::{}", type_name, name),
 					input,
 					&v.fields,
-					crate_ident,
+					crate_path,
 				);
 
 				quote_spanned! { v.span() =>
@@ -101,7 +101,7 @@ pub fn quote(
 	}
 }
 
-fn create_decode_expr(field: &Field, name: &str, input: &TokenStream, crate_ident: &TokenStream) -> TokenStream {
+fn create_decode_expr(field: &Field, name: &str, input: &TokenStream, crate_path: &syn::Path) -> TokenStream {
 	let encoded_as = utils::get_encoded_as_type(field);
 	let compact = utils::is_compact(field);
 	let skip = utils::should_skip(&field.attrs);
@@ -122,7 +122,7 @@ fn create_decode_expr(field: &Field, name: &str, input: &TokenStream, crate_iden
 		quote_spanned! { field.span() =>
 			{
 				let #res = <
-					<#field_type as #crate_ident::HasCompact>::Type as #crate_ident::Decode
+					<#field_type as #crate_path::HasCompact>::Type as #crate_path::Decode
 				>::decode(#input);
 				match #res {
 					::core::result::Result::Err(e) => return ::core::result::Result::Err(e.chain(#err_msg)),
@@ -133,7 +133,7 @@ fn create_decode_expr(field: &Field, name: &str, input: &TokenStream, crate_iden
 	} else if let Some(encoded_as) = encoded_as {
 		quote_spanned! { field.span() =>
 			{
-				let #res = <#encoded_as as #crate_ident::Decode>::decode(#input);
+				let #res = <#encoded_as as #crate_path::Decode>::decode(#input);
 				match #res {
 					::core::result::Result::Err(e) => return ::core::result::Result::Err(e.chain(#err_msg)),
 					::core::result::Result::Ok(#res) => #res.into(),
@@ -146,7 +146,7 @@ fn create_decode_expr(field: &Field, name: &str, input: &TokenStream, crate_iden
 		let field_type = &field.ty;
 		quote_spanned! { field.span() =>
 			{
-				let #res = <#field_type as #crate_ident::Decode>::decode(#input);
+				let #res = <#field_type as #crate_path::Decode>::decode(#input);
 				match #res {
 					::core::result::Result::Err(e) => return ::core::result::Result::Err(e.chain(#err_msg)),
 					::core::result::Result::Ok(#res) => #res,
@@ -161,7 +161,7 @@ fn create_instance(
 	name_str: &str,
 	input: &TokenStream,
 	fields: &Fields,
-	crate_ident: &TokenStream,
+	crate_path: &syn::Path,
 ) -> TokenStream {
 	match *fields {
 		Fields::Named(ref fields) => {
@@ -171,7 +171,7 @@ fn create_instance(
 					Some(a) => format!("{}::{}", name_str, a),
 					None => format!("{}", name_str), // Should never happen, fields are named.
 				};
-				let decode = create_decode_expr(f, &field_name, input, crate_ident);
+				let decode = create_decode_expr(f, &field_name, input, crate_path);
 
 				quote_spanned! { f.span() =>
 					#name_ident: #decode
@@ -188,7 +188,7 @@ fn create_instance(
 			let recurse = fields.unnamed.iter().enumerate().map(|(i, f) | {
 				let field_name = format!("{}.{}", name_str, i);
 
-				create_decode_expr(f, &field_name, input, crate_ident)
+				create_decode_expr(f, &field_name, input, crate_path)
 			});
 
 			quote_spanned! { fields.span() =>

derive/src/encode.rs

@@ -30,7 +30,7 @@ type FieldsList = Punctuated<Field, Comma>;
 fn encode_single_field(
 	field: &Field,
 	field_name: TokenStream,
-	crate_ident: &TokenStream,
+	crate_path: &syn::Path,
 ) -> TokenStream {
 	let encoded_as = utils::get_encoded_as_type(field);
 	let compact = utils::is_compact(field);
@@ -53,16 +53,16 @@ fn encode_single_field(
 		let field_type = &field.ty;
 		quote_spanned! {
 			field.span() => {
-				<<#field_type as #crate_ident::HasCompact>::Type as
-				#crate_ident::EncodeAsRef<'_, #field_type>>::RefType::from(#field_name)
+				<<#field_type as #crate_path::HasCompact>::Type as
+				#crate_path::EncodeAsRef<'_, #field_type>>::RefType::from(#field_name)
 			}
 		}
 	} else if let Some(encoded_as) = encoded_as {
 		let field_type = &field.ty;
 		quote_spanned! {
 			field.span() => {
 				<#encoded_as as
-				#crate_ident::EncodeAsRef<'_, #field_type>>::RefType::from(#field_name)
+				#crate_path::EncodeAsRef<'_, #field_type>>::RefType::from(#field_name)
 			}
 		}
 	} else {
@@ -75,19 +75,19 @@ fn encode_single_field(
 	let i_self = quote! { self };
 
 	quote_spanned! { field.span() =>
-			fn encode_to<__CodecOutputEdqy: #crate_ident::Output + ?::core::marker::Sized>(
+			fn encode_to<__CodecOutputEdqy: #crate_path::Output + ?::core::marker::Sized>(
 				&#i_self,
 				__codec_dest_edqy: &mut __CodecOutputEdqy
 			) {
-				#crate_ident::Encode::encode_to(&#final_field_variable, __codec_dest_edqy)
+				#crate_path::Encode::encode_to(&#final_field_variable, __codec_dest_edqy)
 			}
 
-			fn encode(&#i_self) -> #crate_ident::alloc::vec::Vec<::core::primitive::u8> {
-				#crate_ident::Encode::encode(&#final_field_variable)
+			fn encode(&#i_self) -> #crate_path::alloc::vec::Vec<::core::primitive::u8> {
+				#crate_path::Encode::encode(&#final_field_variable)
 			}
 
 			fn using_encoded<R, F: ::core::ops::FnOnce(&[::core::primitive::u8]) -> R>(&#i_self, f: F) -> R {
-				#crate_ident::Encode::using_encoded(&#final_field_variable, f)
+				#crate_path::Encode::using_encoded(&#final_field_variable, f)
 			}
 	}
 }
@@ -96,7 +96,7 @@ fn encode_fields<F>(
 	dest: &TokenStream,
 	fields: &FieldsList,
 	field_name: F,
-	crate_ident: &TokenStream,
+	crate_path: &syn::Path,
 ) -> TokenStream where
 	F: Fn(usize, &Option<Ident>) -> TokenStream,
 {
@@ -119,10 +119,10 @@ fn encode_fields<F>(
 			let field_type = &f.ty;
 			quote_spanned! {
 				f.span() => {
-					#crate_ident::Encode::encode_to(
+					#crate_path::Encode::encode_to(
 						&<
-							<#field_type as #crate_ident::HasCompact>::Type as
-							#crate_ident::EncodeAsRef<'_, #field_type>
+							<#field_type as #crate_path::HasCompact>::Type as
+							#crate_path::EncodeAsRef<'_, #field_type>
 						>::RefType::from(#field),
 						#dest,
 					);
@@ -132,10 +132,10 @@ fn encode_fields<F>(
 			let field_type = &f.ty;
 			quote_spanned! {
 				f.span() => {
-					#crate_ident::Encode::encode_to(
+					#crate_path::Encode::encode_to(
 						&<
 							#encoded_as as
-							#crate_ident::EncodeAsRef<'_, #field_type>
+							#crate_path::EncodeAsRef<'_, #field_type>
 						>::RefType::from(#field),
 						#dest,
 					);
@@ -147,7 +147,7 @@ fn encode_fields<F>(
 			}
 		} else {
 			quote_spanned! { f.span() =>
-				#crate_ident::Encode::encode_to(#field, #dest);
+				#crate_path::Encode::encode_to(#field, #dest);
 			}
 		}
 	});
@@ -157,7 +157,7 @@ fn encode_fields<F>(
 	}
 }
 
-fn try_impl_encode_single_field_optimisation(data: &Data, crate_ident: &TokenStream) -> Option<TokenStream> {
+fn try_impl_encode_single_field_optimisation(data: &Data, crate_path: &syn::Path) -> Option<TokenStream> {
 	match *data {
 		Data::Struct(ref data) => {
 			match data.fields {
@@ -167,7 +167,7 @@ fn try_impl_encode_single_field_optimisation(data: &Data, crate_ident: &TokenStr
 					Some(encode_single_field(
 						field,
 						quote!(&self.#name),
-						crate_ident,
+						crate_path,
 					))
 				},
 				Fields::Unnamed(ref fields) if utils::filter_skip_unnamed(fields).count() == 1 => {
@@ -177,7 +177,7 @@ fn try_impl_encode_single_field_optimisation(data: &Data, crate_ident: &TokenStr
 					Some(encode_single_field(
 						field,
 						quote!(&self.#id),
-						crate_ident,
+						crate_path,
 					))
 				},
 				_ => None,
@@ -187,7 +187,7 @@ fn try_impl_encode_single_field_optimisation(data: &Data, crate_ident: &TokenStr
 	}
 }
 
-fn impl_encode(data: &Data, type_name: &Ident, crate_ident: &TokenStream) -> TokenStream {
+fn impl_encode(data: &Data, type_name: &Ident, crate_path: &syn::Path) -> TokenStream {
 	let self_ = quote!(self);
 	let dest = &quote!(__codec_dest_edqy);
 	let encoding = match *data {
@@ -197,7 +197,7 @@ fn impl_encode(data: &Data, type_name: &Ident, crate_ident: &TokenStream) -> Tok
 					dest,
 					&fields.named,
 					|_, name| quote!(&#self_.#name),
-					crate_ident,
+					crate_path,
 				),
 				Fields::Unnamed(ref fields) => encode_fields(
 					dest,
@@ -206,7 +206,7 @@ fn impl_encode(data: &Data, type_name: &Ident, crate_ident: &TokenStream) -> Tok
 						let i = syn::Index::from(i);
 						quote!(&#self_.#i)
 					},
-					crate_ident,
+					crate_path,
 				),
 				Fields::Unit => quote!(),
 			}
@@ -242,7 +242,7 @@ fn impl_encode(data: &Data, type_name: &Ident, crate_ident: &TokenStream) -> Tok
 							dest,
 							&fields.named,
 							|a, b| field_name(a, b),
-							crate_ident,
+							crate_path,
 						);
 
 						quote_spanned! { f.span() =>
@@ -268,7 +268,7 @@ fn impl_encode(data: &Data, type_name: &Ident, crate_ident: &TokenStream) -> Tok
 							dest,
 							&fields.unnamed,
 							|a, b| field_name(a, b),
-							crate_ident,
+							crate_path,
 						);
 
 						quote_spanned! { f.span() =>
@@ -301,7 +301,7 @@ fn impl_encode(data: &Data, type_name: &Ident, crate_ident: &TokenStream) -> Tok
 		).to_compile_error(),
 	};
 	quote! {
-		fn encode_to<__CodecOutputEdqy: #crate_ident::Output + ?::core::marker::Sized>(
+		fn encode_to<__CodecOutputEdqy: #crate_path::Output + ?::core::marker::Sized>(
 			&#self_,
 			#dest: &mut __CodecOutputEdqy
 		) {
@@ -310,11 +310,11 @@ fn impl_encode(data: &Data, type_name: &Ident, crate_ident: &TokenStream) -> Tok
 	}
 }
 
-pub fn quote(data: &Data, type_name: &Ident, crate_ident: &TokenStream) -> TokenStream {
-	if let Some(implementation) = try_impl_encode_single_field_optimisation(data, crate_ident) {
+pub fn quote(data: &Data, type_name: &Ident, crate_path: &syn::Path) -> TokenStream {
+	if let Some(implementation) = try_impl_encode_single_field_optimisation(data, crate_path) {
 		implementation
 	} else {
-		impl_encode(data, type_name, crate_ident)
+		impl_encode(data, type_name, crate_path)
 	}
 }