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use core::convert::TryFrom;
use proc_macro2::{Span, TokenStream as TokenStream2};
use quote::quote;
use syn::{Fields, Ident, Index, ItemStruct, WhereClause};
use crate::attribute_helpers::contains_skip;
pub fn struct_ser(input: &ItemStruct, cratename: Ident) -> syn::Result<TokenStream2> {
let name = &input.ident;
let (impl_generics, ty_generics, where_clause) = input.generics.split_for_impl();
let mut where_clause = where_clause.map_or_else(
|| WhereClause {
where_token: Default::default(),
predicates: Default::default(),
},
Clone::clone,
);
let mut body = TokenStream2::new();
match &input.fields {
Fields::Named(fields) => {
for field in &fields.named {
if contains_skip(&field.attrs) {
continue;
}
let field_name = field.ident.as_ref().unwrap();
let delta = quote! {
#cratename::BorshSerialize::serialize(&self.#field_name, writer)?;
};
body.extend(delta);
let field_type = &field.ty;
where_clause.predicates.push(
syn::parse2(quote! {
#field_type: #cratename::ser::BorshSerialize
})
.unwrap(),
);
}
}
Fields::Unnamed(fields) => {
for field_idx in 0..fields.unnamed.len() {
let field_idx = Index {
index: u32::try_from(field_idx).expect("up to 2^32 fields are supported"),
span: Span::call_site(),
};
let delta = quote! {
#cratename::BorshSerialize::serialize(&self.#field_idx, writer)?;
};
body.extend(delta);
}
}
Fields::Unit => {}
}
Ok(quote! {
impl #impl_generics #cratename::ser::BorshSerialize for #name #ty_generics #where_clause {
fn serialize<W: #cratename::maybestd::io::Write>(&self, writer: &mut W) -> ::core::result::Result<(), #cratename::maybestd::io::Error> {
#body
Ok(())
}
}
})
}
#[rustfmt::skip]
#[cfg(test)]
mod tests {
use super::*;
fn assert_eq(expected: TokenStream2, actual: TokenStream2) {
assert_eq!(expected.to_string(), actual.to_string())
}
#[test]
fn simple_struct() {
let item_struct: ItemStruct = syn::parse2(quote!{
struct A {
x: u64,
y: String,
}
}).unwrap();
let actual = struct_ser(&item_struct, Ident::new("borsh", Span::call_site())).unwrap();
let expected = quote!{
impl borsh::ser::BorshSerialize for A
where
u64: borsh::ser::BorshSerialize,
String: borsh::ser::BorshSerialize
{
fn serialize<W: borsh::maybestd::io::Write>(&self, writer: &mut W) -> ::core::result::Result<(), borsh::maybestd::io::Error> {
borsh::BorshSerialize::serialize(&self.x, writer)?;
borsh::BorshSerialize::serialize(&self.y, writer)?;
Ok(())
}
}
};
assert_eq(expected, actual);
}
#[test]
fn simple_generics() {
let item_struct: ItemStruct = syn::parse2(quote!{
struct A<K, V> {
x: HashMap<K, V>,
y: String,
}
}).unwrap();
let actual = struct_ser(&item_struct, Ident::new("borsh", Span::call_site())).unwrap();
let expected = quote!{
impl<K, V> borsh::ser::BorshSerialize for A<K, V>
where
HashMap<K, V>: borsh::ser::BorshSerialize,
String: borsh::ser::BorshSerialize
{
fn serialize<W: borsh::maybestd::io::Write>(&self, writer: &mut W) -> ::core::result::Result<(), borsh::maybestd::io::Error> {
borsh::BorshSerialize::serialize(&self.x, writer)?;
borsh::BorshSerialize::serialize(&self.y, writer)?;
Ok(())
}
}
};
assert_eq(expected, actual);
}
#[test]
fn bound_generics() {
let item_struct: ItemStruct = syn::parse2(quote!{
struct A<K: Key, V> where V: Value {
x: HashMap<K, V>,
y: String,
}
}).unwrap();
let actual = struct_ser(&item_struct, Ident::new("borsh", Span::call_site())).unwrap();
let expected = quote!{
impl<K: Key, V> borsh::ser::BorshSerialize for A<K, V>
where
V: Value,
HashMap<K, V>: borsh::ser::BorshSerialize,
String: borsh::ser::BorshSerialize
{
fn serialize<W: borsh::maybestd::io::Write>(&self, writer: &mut W) -> ::core::result::Result<(), borsh::maybestd::io::Error> {
borsh::BorshSerialize::serialize(&self.x, writer)?;
borsh::BorshSerialize::serialize(&self.y, writer)?;
Ok(())
}
}
};
assert_eq(expected, actual);
}
}