Source code
Revision control
Copy as Markdown
Other Tools
use quote::ToTokens;
use crate::{ast::Data, codegen::FromAttributesImpl, Error, Result};
use super::{OuterFrom, ParseAttribute, ParseData};
/// Receiver for derived `FromAttributes` impls.
pub struct FromAttributesOptions {
// Note: FromAttributes has no behaviors beyond those common
// to all the `OuterFrom` traits.
pub base: OuterFrom,
}
impl FromAttributesOptions {
pub fn new(di: &syn::DeriveInput) -> Result<Self> {
let opts = (Self {
base: OuterFrom::start(di)?,
})
.parse_attributes(&di.attrs)?
.parse_body(&di.data)?;
if !opts.is_newtype() && opts.base.attr_names.is_empty() {
Err(Error::custom(
"FromAttributes without attributes collects nothing",
))
} else {
Ok(opts)
}
}
fn is_newtype(&self) -> bool {
if let Data::Struct(ref data) = self.base.container.data {
data.is_newtype()
} else {
false
}
}
}
impl ParseAttribute for FromAttributesOptions {
fn parse_nested(&mut self, mi: &syn::Meta) -> Result<()> {
self.base.parse_nested(mi)
}
}
impl ParseData for FromAttributesOptions {
fn parse_variant(&mut self, variant: &syn::Variant) -> Result<()> {
self.base.parse_variant(variant)
}
fn parse_field(&mut self, field: &syn::Field) -> Result<()> {
self.base.parse_field(field)
}
fn validate_body(&self, errors: &mut crate::error::Accumulator) {
self.base.validate_body(errors);
}
}
impl<'a> From<&'a FromAttributesOptions> for FromAttributesImpl<'a> {
fn from(v: &'a FromAttributesOptions) -> Self {
FromAttributesImpl {
base: (&v.base.container).into(),
attr_names: &v.base.attr_names,
forward_attrs: v.base.as_forward_attrs(),
}
}
}
impl ToTokens for FromAttributesOptions {
fn to_tokens(&self, tokens: &mut proc_macro2::TokenStream) {
FromAttributesImpl::from(self).to_tokens(tokens)
}
}