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#![recursion_limit = "256"]
extern crate proc_macro;
extern crate proc_macro2;
extern crate syn;
#[macro_use]
extern crate quote;
use proc_macro::TokenStream;
use proc_macro2::Span;
use syn::{DeriveInput, Ident};
#[proc_macro_derive(AsJsonb)]
pub fn hello_macro_derive(input: TokenStream) -> TokenStream {
let ast: DeriveInput = syn::parse(input).unwrap();
let name = &ast.ident;
let scope = Ident::new(&format!("{}_as_jsonb", name), Span::call_site());
let proxy = Ident::new(&format!("{}ValueProxy", name), Span::call_site());
let gen = quote! {
mod #scope {
use diesel::sql_types::Jsonb;
use std::io::Write;
use diesel::pg::Pg;
use diesel::serialize::{self, IsNull, Output, ToSql};
use diesel::deserialize::{self, FromSql};
#[derive(FromSqlRow, AsExpression)]
#[diesel(foreign_derive)]
#[sql_type = "Jsonb"]
struct #proxy(#name);
impl FromSql<Jsonb, Pg> for #name {
fn from_sql(bytes: Option<&[u8]>) -> deserialize::Result<Self> {
let bytes = not_none!(bytes);
if bytes[0] != 1 {
return Err("Unsupported JSONB encoding version".into());
}
serde_json::from_slice(&bytes[1..]).map_err(Into::into)
}
}
impl ToSql<Jsonb, Pg> for #name {
fn to_sql<W: Write>(&self, out: &mut Output<W, Pg>) -> serialize::Result {
try!(out.write_all(&[1]));
serde_json::to_writer(out, self)
.map(|_| IsNull::No)
.map_err(Into::into)
}
}
}
};
gen.into()
}