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#![feature(associated_consts)]
extern crate rocket;
use rocket::request::{FromForm, FormItems};
pub trait NamedFields {
const FIELDS: &'static [&'static str];
}
pub struct QueryParamGroup<T>(T);
impl<T> QueryParamGroup<T> {
pub fn get(&self) -> &T {
&self.0
}
pub fn get_owned(self) -> T {
self.0
}
}
macro_rules! peel {
($name:ident, $($other:ident,)*) => (query_param_group! { $($other,)* })
}
macro_rules! query_param_group {
() => {};
($($name:ident,)+) => {
impl<'f, $($name),*> FromForm<'f> for QueryParamGroup<($($name,)*)>
where $($name: for<'x> FromForm<'x> + NamedFields),*
{
type Error = ();
fn from_form_items(form_items: &mut FormItems<'f>) -> Result<Self, ()> {
$(
let query_string_items: Vec<String> = FormItems::from(form_items.inner_str())
.filter(|&(ref k, _)| $name::FIELDS.contains(k))
.map(|(k,v)| format!("{}={}", k, v))
.collect();
let query_string = query_string_items.join("&");
let mut items: FormItems = FormItems::from(query_string.as_str());
#[allow(non_snake_case)]
let $name = $name::from_form_items(&mut items).map_err(|_| ())?;
)*
Ok(QueryParamGroup(($($name,)*)))
}
}
peel! { $($name,)* }
}
}
query_param_group! { T0, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, }