mirror of
https://github.com/pezkuwichain/pezkuwi-subxt.git
synced 2026-06-27 21:01:04 +00:00
Shawn Tabrizi
102 lines
3.0 KiB
Rust
102 lines
3.0 KiB
Rust
// Copyright 2019-2020 Parity Technologies (UK) Ltd.
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// This file is part of Substrate.
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// Substrate is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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// Substrate is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// You should have received a copy of the GNU General Public License
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// along with Substrate. If not, see <http://www.gnu.org/licenses/>.
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//! Derive macro implementation of `PassBy` with the associated type set to `Enum`.
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//!
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//! Besides `PassBy`, `TryFrom<u8>` and `From<Self> for u8` are implemented for the type.
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use crate::utils::{generate_crate_access, generate_runtime_interface_include};
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use syn::{DeriveInput, Result, Data, Fields, Error, Ident};
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use quote::quote;
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use proc_macro2::{TokenStream, Span};
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/// The derive implementation for `PassBy` with `Enum`.
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pub fn derive_impl(input: DeriveInput) -> Result<TokenStream> {
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let crate_include = generate_runtime_interface_include();
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let crate_ = generate_crate_access();
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let ident = input.ident;
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let enum_fields = get_enum_field_idents(&input.data)?
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.enumerate()
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.map(|(i, v)| {
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let i = i as u8;
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v.map(|v| (quote!(#i => Ok(#ident::#v)), quote!(#ident::#v => #i)))
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})
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.collect::<Result<Vec<_>>>()?;
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let try_from_variants = enum_fields.iter().map(|i| &i.0);
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let into_variants = enum_fields.iter().map(|i| &i.1);
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let res = quote! {
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const _: () = {
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#crate_include
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impl #crate_::pass_by::PassBy for #ident {
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type PassBy = #crate_::pass_by::Enum<#ident>;
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}
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impl #crate_::sp_std::convert::TryFrom<u8> for #ident {
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type Error = ();
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fn try_from(inner: u8) -> #crate_::sp_std::result::Result<Self, ()> {
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match inner {
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#( #try_from_variants, )*
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_ => Err(()),
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}
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}
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}
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impl From<#ident> for u8 {
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fn from(var: #ident) -> u8 {
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match var {
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#( #into_variants ),*
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}
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}
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}
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};
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};
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Ok(res)
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}
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/// Get the enum fields idents of the given `data` object as iterator.
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///
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/// Returns an error if the number of variants is greater than `256`, the given `data` is not an
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/// enum or a variant is not an unit.
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fn get_enum_field_idents<'a>(data: &'a Data) -> Result<impl Iterator<Item = Result<&'a Ident>>> {
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match data {
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Data::Enum(d) => {
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if d.variants.len() <= 256 {
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Ok(
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d.variants.iter().map(|v| if let Fields::Unit = v.fields {
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Ok(&v.ident)
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} else {
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Err(Error::new(
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Span::call_site(),
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"`PassByEnum` only supports unit variants.",
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))
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})
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)
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} else {
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Err(Error::new(Span::call_site(), "`PassByEnum` only supports `256` variants."))
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}
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},
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_ => Err(Error::new(Span::call_site(), "`PassByEnum` only supports enums as input type."))
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}
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}
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