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use crate::pallet::{parse::helper::get_doc_literals, Def};
pub fn expand_error(def: &mut Def) -> proc_macro2::TokenStream {
let error = if let Some(error) = &def.error { error } else { return Default::default() };
let error_ident = &error.error;
let frame_support = &def.frame_support;
let frame_system = &def.frame_system;
let type_impl_gen = &def.type_impl_generics(error.attr_span);
let type_use_gen = &def.type_use_generics(error.attr_span);
let config_where_clause = &def.config.where_clause;
let phantom_variant: syn::Variant = syn::parse_quote!(
#[doc(hidden)]
__Ignore(
#frame_support::sp_std::marker::PhantomData<(#type_use_gen)>,
#frame_support::Never,
)
);
let as_u8_matches = error.variants.iter().enumerate().map(
|(i, (variant, _))| quote::quote_spanned!(error.attr_span => Self::#variant => #i as u8,),
);
let as_str_matches = error.variants.iter().map(|(variant, _)| {
let variant_str = format!("{}", variant);
quote::quote_spanned!(error.attr_span => Self::#variant => #variant_str,)
});
let metadata = error.variants.iter().map(|(variant, doc)| {
let variant_str = format!("{}", variant);
quote::quote_spanned!(error.attr_span =>
#frame_support::error::ErrorMetadata {
name: #frame_support::error::DecodeDifferent::Encode(#variant_str),
documentation: #frame_support::error::DecodeDifferent::Encode(&[ #( #doc, )* ]),
},
)
});
let error_item = {
let item = &mut def.item.content.as_mut().expect("Checked by def parser").1[error.index];
if let syn::Item::Enum(item) = item {
item
} else {
unreachable!("Checked by error parser")
}
};
error_item.variants.insert(0, phantom_variant);
if get_doc_literals(&error_item.attrs).is_empty() {
error_item.attrs.push(syn::parse_quote!(
#[doc = r"
Custom [dispatch errors](https://substrate.dev/docs/en/knowledgebase/runtime/errors)
of this pallet.
"]
));
}
quote::quote_spanned!(error.attr_span =>
impl<#type_impl_gen> #frame_support::sp_std::fmt::Debug for #error_ident<#type_use_gen>
#config_where_clause
{
fn fmt(&self, f: &mut #frame_support::sp_std::fmt::Formatter<'_>)
-> #frame_support::sp_std::fmt::Result
{
f.write_str(self.as_str())
}
}
impl<#type_impl_gen> #error_ident<#type_use_gen> #config_where_clause {
pub fn as_u8(&self) -> u8 {
match &self {
Self::__Ignore(_, _) => unreachable!("`__Ignore` can never be constructed"),
#( #as_u8_matches )*
}
}
pub fn as_str(&self) -> &'static str {
match &self {
Self::__Ignore(_, _) => unreachable!("`__Ignore` can never be constructed"),
#( #as_str_matches )*
}
}
}
impl<#type_impl_gen> From<#error_ident<#type_use_gen>> for &'static str
#config_where_clause
{
fn from(err: #error_ident<#type_use_gen>) -> &'static str {
err.as_str()
}
}
impl<#type_impl_gen> From<#error_ident<#type_use_gen>>
for #frame_support::sp_runtime::DispatchError
#config_where_clause
{
fn from(err: #error_ident<#type_use_gen>) -> Self {
let index = <
<T as #frame_system::Config>::PalletInfo
as #frame_support::traits::PalletInfo
>::index::<Pallet<#type_use_gen>>()
.expect("Every active module has an index in the runtime; qed") as u8;
#frame_support::sp_runtime::DispatchError::Module {
index,
error: err.as_u8(),
message: Some(err.as_str()),
}
}
}
impl<#type_impl_gen> #frame_support::error::ModuleErrorMetadata
for #error_ident<#type_use_gen>
#config_where_clause
{
fn metadata() -> &'static [#frame_support::error::ErrorMetadata] {
&[ #( #metadata )* ]
}
}
)
}