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use crate::repr::Repr;
use quote::ToTokens;
use syn::{AttrStyle, DeriveInput, Error, Ident, Lit, LitStr, Meta, NestedMeta, Path};
#[derive(Default)]
pub struct Attributes {
pub archive_as: Option<LitStr>,
pub archived: Option<Ident>,
pub resolver: Option<Ident>,
pub attrs: Vec<Meta>,
pub archived_repr: Repr,
pub compares: Option<(Path, Vec<Path>)>,
pub archive_bound: Option<LitStr>,
pub serialize_bound: Option<LitStr>,
pub deserialize_bound: Option<LitStr>,
pub copy_safe: Option<Path>,
pub rkyv_path: Option<Path>,
}
fn try_set_attribute<T: ToTokens>(
attribute: &mut Option<T>,
value: T,
name: &'static str,
) -> Result<(), Error> {
if attribute.is_none() {
*attribute = Some(value);
Ok(())
} else {
Err(Error::new_spanned(
value,
&format!("{} already specified", name),
))
}
}
fn parse_archive_attributes(attributes: &mut Attributes, meta: &Meta) -> Result<(), Error> {
match meta {
Meta::Path(path) => {
if path.is_ident("copy_safe") {
try_set_attribute(&mut attributes.copy_safe, path.clone(), "copy_safe")
} else {
Err(Error::new_spanned(meta, "unrecognized archive argument"))
}
}
Meta::List(list) => {
if list.path.is_ident("compare") {
if attributes.compares.is_none() {
let mut compares = Vec::new();
for compare in list.nested.iter() {
if let NestedMeta::Meta(Meta::Path(path)) = compare {
compares.push(path.clone());
} else {
return Err(Error::new_spanned(
compare,
"compare arguments must be compare traits to derive",
));
}
}
attributes.compares = Some((list.path.clone(), compares));
Ok(())
} else {
Err(Error::new_spanned(list, "compares already specified"))
}
} else if list.path.is_ident("bound") {
for bound in list.nested.iter() {
if let NestedMeta::Meta(Meta::NameValue(name_value)) = bound {
if let Lit::Str(ref lit_str) = name_value.lit {
if name_value.path.is_ident("archive") {
try_set_attribute(
&mut attributes.archive_bound,
lit_str.clone(),
"archive bound",
)?;
} else if name_value.path.is_ident("serialize") {
try_set_attribute(
&mut attributes.serialize_bound,
lit_str.clone(),
"serialize bound",
)?;
} else if name_value.path.is_ident("deserialize") {
try_set_attribute(
&mut attributes.deserialize_bound,
lit_str.clone(),
"deserialize bound",
)?;
} else {
return Err(Error::new_spanned(
bound,
"bound must be either serialize or deserialize",
));
}
} else {
return Err(Error::new_spanned(
bound,
"bound arguments must be a string",
));
}
} else {
return Err(Error::new_spanned(
bound,
"bound arguments must be serialize or deserialize bounds to apply",
));
}
}
Ok(())
} else if list.path.is_ident("repr") {
attributes.archived_repr.parse_args(list.nested.iter())
} else {
Err(Error::new_spanned(
&list.path,
"unrecognized archive argument",
))
}
}
Meta::NameValue(meta) => {
if meta.path.is_ident("archived") {
if let Lit::Str(ref lit_str) = meta.lit {
try_set_attribute(
&mut attributes.archived,
Ident::new(&lit_str.value(), lit_str.span()),
"archived",
)
} else {
Err(Error::new_spanned(meta, "archived must be a string"))
}
} else if meta.path.is_ident("resolver") {
if let Lit::Str(ref lit_str) = meta.lit {
try_set_attribute(
&mut attributes.resolver,
Ident::new(&lit_str.value(), lit_str.span()),
"resolver",
)
} else {
Err(Error::new_spanned(meta, "resolver must be a string"))
}
} else if meta.path.is_ident("as") {
if let Lit::Str(ref lit_str) = meta.lit {
try_set_attribute(&mut attributes.archive_as, lit_str.clone(), "archive as")
} else {
Err(Error::new_spanned(meta, "archive as must be a string"))
}
} else if meta.path.is_ident("crate") {
if let Lit::Str(ref lit_str) = meta.lit {
let stream = syn::parse_str(&lit_str.value())?;
let tokens = crate::serde::respan::respan(stream, lit_str.span());
let path = syn::parse2(tokens)?;
try_set_attribute(&mut attributes.rkyv_path, path, "crate")
} else {
Err(Error::new_spanned(meta, "crate must be a string"))
}
} else {
Err(Error::new_spanned(meta, "unrecognized archive argument"))
}
}
}
}
pub fn parse_attributes(input: &DeriveInput) -> Result<Attributes, Error> {
let mut result = Attributes::default();
for attr in input.attrs.iter() {
if let AttrStyle::Outer = attr.style {
if attr.path.is_ident("archive") || attr.path.is_ident("archive_attr") {
if let Meta::List(list) = attr.parse_meta()? {
if list.path.is_ident("archive") {
for nested in list.nested.iter() {
if let NestedMeta::Meta(meta) = nested {
parse_archive_attributes(&mut result, meta)?;
} else {
return Err(Error::new_spanned(
nested,
"archive arguments must be metas",
));
}
}
} else if list.path.is_ident("archive_attr") {
for nested in list.nested.iter() {
if let NestedMeta::Meta(meta) = nested {
if let Meta::List(list) = meta {
if list.path.is_ident("repr") {
result.archived_repr.parse_args(list.nested.iter())?;
} else {
result.attrs.push(meta.clone());
}
} else {
result.attrs.push(meta.clone());
}
} else {
return Err(Error::new_spanned(
nested,
"archive_attr arguments must be metas",
));
}
}
}
} else {
return Err(Error::new_spanned(
attr,
"archive and archive_attr may only be structured list attributes",
));
}
}
}
}
Ok(result)
}
