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Code Issues Releases Wiki Activity

Implement #[align] in BinWrite

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This commit is contained in:
Nikita Strygin 2023-02-06 22:22:39 +03:00
commit f6e31f99d9
2 changed files with 110 additions and 6 deletions
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43
bitbuffer_derive/src/write.rs
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@ -7,7 +7,7 @@ use syn::{
parse_macro_input, parse_quote, parse_str, Attribute, Data, DataStruct, DeriveInput, Expr,
Fields, GenericParam, Ident, Index, Lit, LitInt, Member, Path, Type,
};
use syn_util::get_attribute_value;
use syn_util::{contains_attribute, get_attribute_value};
pub fn derive_bitwrite_trait(
input: proc_macro::TokenStream,
@ -87,6 +87,8 @@ pub fn derive_bitwrite_trait(
fn write(data: Data, struct_name: &Ident, attrs: &[Attribute]) -> TokenStream {
let span = struct_name.span();
let align = get_align(attrs);
match data {
Data::Struct(DataStruct { fields, .. }) => {
let expand = fields.iter().enumerate().map(|(i, field)| {
@ -114,6 +116,7 @@ fn write(data: Data, struct_name: &Ident, attrs: &[Attribute]) -> TokenStream {
let writes = fields.iter().enumerate().map(|(i, f)| {
// Get attributes `#[..]` on each field
let size = get_field_size(&f.attrs, f.span());
let align = get_align(&f.attrs);
let span = f.span();
let member = f.ident.clone().map(Member::Named).unwrap_or_else(|| {
Member::Unnamed(Index {
@ -125,6 +128,7 @@ fn write(data: Data, struct_name: &Ident, attrs: &[Attribute]) -> TokenStream {
Some(size) => {
quote_spanned! { span =>
{
#align;
let _size: usize = #size;
__target__stream.write_sized(&self.#member, _size)?;
}
@ -132,13 +136,17 @@ fn write(data: Data, struct_name: &Ident, attrs: &[Attribute]) -> TokenStream {
}
None => {
quote_spanned! { span => {
__target__stream.write(&self.#member)?;
{
#align;
__target__stream.write(&self.#member)?;
}
}}
}
}
});
quote_spanned! {span=>
#align;
#(#expand)*
#(#writes)*
Ok(())
@ -217,15 +225,24 @@ fn write(data: Data, struct_name: &Ident, attrs: &[Attribute]) -> TokenStream {
let variant_name = &variant.ident;
match &variant.fields {
Fields::Unit => quote_spanned! {span =>
#struct_name::#variant_name => {},
},
Fields::Unit => {
if contains_attribute(&variant.attrs, &["align"]) {
return quote_spanned! { span =>
compile_error!("'align' attribute is not allowed on unit variants");
};
}
quote_spanned! {span =>
#struct_name::#variant_name => {},
}
}
Fields::Unnamed(f) => {
let size = get_field_size(&variant.attrs, f.span());
let align = get_align(&variant.attrs);
match size {
Some(size) => {
quote_spanned! { span =>
#struct_name::#variant_name(inner) => {
#align;
let size:usize = #size;
__target__stream.write_sized(inner, size)?;
}
@ -233,7 +250,10 @@ fn write(data: Data, struct_name: &Ident, attrs: &[Attribute]) -> TokenStream {
}
None => {
quote_spanned! { span =>
#struct_name::#variant_name(inner) => { __target__stream.write(inner)?; }
#struct_name::#variant_name(inner) => {
#align;
__target__stream.write(inner)?;
}
}
}
}
@ -246,6 +266,7 @@ fn write(data: Data, struct_name: &Ident, attrs: &[Attribute]) -> TokenStream {
let repr = repr_for_bits(discriminant_bits);
quote_spanned! {span=>
#align;
let discriminant:#repr = match &self {
#(#discriminant_value),*
};
@ -300,3 +321,13 @@ fn type_is_int(ty: &Type) -> bool {
false
}
}
fn get_align(attrs: &[Attribute]) -> TokenStream {
if contains_attribute(attrs, &["align"]) {
quote! {
__target__stream.align()
}
} else {
quote! { () }
}
}