openethereum/util/rlp_derive/src/en.rs
Marek Kotewicz 407c8c3fb9 rlp_derive (#6125)
* rlp_derive

* RlpEncodableWrapper, RlpDecodableWrapper

* use rlp_derive in parity

* fixed broken transaction Action serialization
2017-08-20 12:01:46 +08:00

111 lines
3.2 KiB
Rust

use {syn, quote};
pub fn impl_encodable(ast: &syn::DeriveInput) -> quote::Tokens {
let body = match ast.body {
syn::Body::Struct(ref s) => s,
_ => panic!("#[derive(RlpEncodable)] is only defined for structs."),
};
let stmts: Vec<_> = match *body {
syn::VariantData::Struct(ref fields) | syn::VariantData::Tuple(ref fields) =>
fields.iter().enumerate().map(encodable_field_map).collect(),
syn::VariantData::Unit => panic!("#[derive(RlpEncodable)] is not defined for Unit structs."),
};
let name = &ast.ident;
let stmts_len = syn::Ident::new(stmts.len().to_string());
let dummy_const = syn::Ident::new(format!("_IMPL_RLP_ENCODABLE_FOR_{}", name));
let impl_block = quote! {
impl rlp::Encodable for #name {
fn rlp_append(&self, stream: &mut rlp::RlpStream) {
stream.begin_list(#stmts_len);
#(#stmts)*
}
}
};
quote! {
#[allow(non_upper_case_globals, unused_attributes, unused_qualifications)]
const #dummy_const: () = {
extern crate rlp;
#impl_block
};
}
}
pub fn impl_encodable_wrapper(ast: &syn::DeriveInput) -> quote::Tokens {
let body = match ast.body {
syn::Body::Struct(ref s) => s,
_ => panic!("#[derive(RlpEncodableWrapper)] is only defined for structs."),
};
let stmt = match *body {
syn::VariantData::Struct(ref fields) | syn::VariantData::Tuple(ref fields) => {
if fields.len() == 1 {
let field = fields.first().expect("fields.len() == 1; qed");
encodable_field(0, field)
} else {
panic!("#[derive(RlpEncodableWrapper)] is only defined for structs with one field.")
}
},
syn::VariantData::Unit => panic!("#[derive(RlpEncodableWrapper)] is not defined for Unit structs."),
};
let name = &ast.ident;
let dummy_const = syn::Ident::new(format!("_IMPL_RLP_ENCODABLE_FOR_{}", name));
let impl_block = quote! {
impl rlp::Encodable for #name {
fn rlp_append(&self, stream: &mut rlp::RlpStream) {
#stmt
}
}
};
quote! {
#[allow(non_upper_case_globals, unused_attributes, unused_qualifications)]
const #dummy_const: () = {
extern crate rlp;
#impl_block
};
}
}
fn encodable_field_map(tuple: (usize, &syn::Field)) -> quote::Tokens {
encodable_field(tuple.0, tuple.1)
}
fn encodable_field(index: usize, field: &syn::Field) -> quote::Tokens {
let ident = match field.ident {
Some(ref ident) => ident.to_string(),
None => index.to_string(),
};
let id = syn::Ident::new(format!("self.{}", ident));
match field.ty {
syn::Ty::Path(_, ref path) => {
let top_segment = path.segments.first().expect("there must be at least 1 segment");
let ident = &top_segment.ident;
if &ident.to_string() == "Vec" {
let inner_ident = match top_segment.parameters {
syn::PathParameters::AngleBracketed(ref angle) => {
let ty = angle.types.first().expect("Vec has only one angle bracketed type; qed");
match *ty {
syn::Ty::Path(_, ref path) => &path.segments.first().expect("there must be at least 1 segment").ident,
_ => panic!("rlp_derive not supported"),
}
},
_ => unreachable!("Vec has only one angle bracketed type; qed"),
};
quote! { stream.append_list::<#inner_ident, _>(&#id); }
} else {
quote! { stream.append(&#id); }
}
},
_ => panic!("rlp_derive not supported"),
}
}