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Code Issues Releases Wiki Activity

fix size expressions

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This commit is contained in:
Robin Appelman 2021-07-13 19:10:09 +02:00
commit b7fa549e79
3 changed files with 58 additions and 22 deletions
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52
bitbuffer_derive/src/write.rs
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@ -5,7 +5,7 @@ use quote::{quote, quote_spanned};
use syn::spanned::Spanned;
use syn::{
parse_macro_input, parse_quote, parse_str, Attribute, Data, DataStruct, DeriveInput, Expr,
Fields, GenericParam, Ident, Index, Lit, Member, Path,
Fields, GenericParam, Ident, Index, Lit, Member, Path, Type,
};
use syn_util::get_attribute_value;
@ -100,8 +100,14 @@ fn write(data: Data, struct_name: &Ident, attrs: &[Attribute]) -> TokenStream {
span: field.span(),
})
});
quote_spanned! { field.span() =>
let #name = &self.#member;
// extract int fields to be used in size expressions
if type_is_int(&field.ty) {
quote_spanned! { field.span() =>
#[allow(unused_variables)]
let #name = self.#member;
}
} else {
quote! {}
}
});
@ -109,22 +115,24 @@ fn write(data: Data, struct_name: &Ident, attrs: &[Attribute]) -> TokenStream {
// Get attributes `#[..]` on each field
let size = get_field_size(&f.attrs, f.span());
let span = f.span();
let name = f
.ident
.clone()
.unwrap_or_else(|| Ident::new(&format!("__{}", i), span));
let member = f.ident.clone().map(Member::Named).unwrap_or_else(|| {
Member::Unnamed(Index {
index: i as u32,
span,
})
});
match size {
Some(size) => {
quote_spanned! { span =>
{
let _size: usize = #size;
__target__stream.write_sized(#name, _size)?;
__target__stream.write_sized(&self.#member, _size)?;
}
}
}
None => {
quote_spanned! { span => {
__target__stream.write(#name)?;
__target__stream.write(&self.#member)?;
}}
}
}
@ -258,14 +266,8 @@ fn get_field_size(attrs: &[Attribute], span: Span) -> Option<TokenStream> {
}
Lit::Str(size_field) => {
let size = parse_str::<Expr>(&size_field.value()).expect("size");
if size_field.value() == "input_size" {
quote_spanned! {span =>
(#size) as usize
}
} else {
quote_spanned! {span =>
(*#size) as usize
}
quote_spanned! {span =>
(#size) as usize
}
}
_ => panic!("Unsupported value for size attribute"),
@ -278,3 +280,19 @@ fn get_field_size(attrs: &[Attribute], span: Span) -> Option<TokenStream> {
})
})
}
fn type_is_int(ty: &Type) -> bool {
if let Type::Path(path) = ty {
if let Some(ident) = path.path.get_ident() {
let name = ident.to_string();
matches!(
name.as_str(),
"u8" | "u16" | "u32" | "u64" | "usize" | "i8" | "i16" | "i32" | "i64" | "isize"
)
} else {
false
}
} else {
false
}
}