79 lines
2.5 KiB
Rust
79 lines
2.5 KiB
Rust
use proc_macro2::TokenStream;
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fn derive_impl(s: &synstructure::Structure, parse_fields: TokenStream, format_fields: TokenStream) -> TokenStream {
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s.gen_impl(quote!{
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#[allow(unused_imports)]
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use dnsbox_base::_failure::ResultExt as _;
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#[allow(unused_imports)]
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use dnsbox_base::ser::text::DnsTextData as _;
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gen impl ::dnsbox_base::ser::text::DnsTextData for @Self {
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fn dns_parse(_context: &::dnsbox_base::ser::text::DnsTextContext, _data: &mut &str) -> ::dnsbox_base::errors::Result<Self> {
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Ok(#parse_fields)
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}
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fn dns_format(&self, f: &mut ::dnsbox_base::ser::text::DnsTextFormatter) -> ::std::fmt::Result {
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use std::fmt::{self, Write};
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#format_fields
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Ok(())
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}
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}
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})
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}
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fn derive_unit(s: &synstructure::Structure) -> TokenStream {
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let name = &s.ast().ident;
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derive_impl(s, quote!{#name}, quote!{})
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}
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fn derive_named(s: &synstructure::Structure, fields: &syn::FieldsNamed) -> TokenStream {
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let name = &s.ast().ident;
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let mut parse_fields = quote!{};
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let mut format_fields = quote!{};
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for field in &fields.named {
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let field_name = field.ident.as_ref().unwrap();
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parse_fields.extend(quote!{
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#field_name: DnsTextData::dns_parse(_context, _data)
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.with_context(|e| format!("failed parsing field {}::{}: {}", stringify!(#name), stringify!(#field_name), e))?,
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});
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format_fields.extend(quote!{
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DnsTextData::dns_format(&self.#field_name, f)?;
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});
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}
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derive_impl(s, quote!{#name{ #parse_fields }}, format_fields)
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}
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fn derive_unnamed(s: &synstructure::Structure, fields: &syn::FieldsUnnamed) -> TokenStream {
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let name = &s.ast().ident;
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let mut parse_fields = quote!{};
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let mut format_fields = quote!{};
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for field in 0..fields.unnamed.len() {
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parse_fields.extend(quote!{
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DnsTextData::dns_parse(_context, _data)
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.with_context(|e| format!("failed parsing field {}::{}: {}", stringify!(#name), #field, e))?,
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});
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format_fields.extend(quote!{
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DnsTextData::dns_format(&self.#field, f)?;
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});
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}
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derive_impl(s, quote!{#name(#parse_fields)}, format_fields)
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}
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pub fn derive(s: synstructure::Structure) -> TokenStream {
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let ast = s.ast();
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match &ast.data {
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syn::Data::Struct(syn::DataStruct{ fields: syn::Fields::Unit, .. }) => derive_unit(&s),
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syn::Data::Struct(syn::DataStruct{ fields: syn::Fields::Named(fields), .. }) => derive_named(&s, fields),
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syn::Data::Struct(syn::DataStruct{ fields: syn::Fields::Unnamed(fields), .. }) => derive_unnamed(&s, fields),
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_ => panic!("Deriving DnsTextData not supported for non struct types"),
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}
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}
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