Source code
Revision control
Copy as Markdown
Other Tools
use proc_macro2::TokenStream;
use quote::ToTokens;
use syn::{DeriveInput, Field, Ident, Meta};
use crate::codegen::FromVariantImpl;
use crate::options::{DataShape, OuterFrom, ParseAttribute, ParseData};
use crate::{FromMeta, Result};
#[derive(Debug, Clone)]
pub struct FromVariantOptions {
pub base: OuterFrom,
/// The field on the deriving struct into which the discriminant expression
/// should be placed by the derived `FromVariant` impl.
pub discriminant: Option<Ident>,
pub fields: Option<Ident>,
pub supports: Option<DataShape>,
}
impl FromVariantOptions {
pub fn new(di: &DeriveInput) -> Result<Self> {
(FromVariantOptions {
base: OuterFrom::start(di)?,
discriminant: Default::default(),
fields: Default::default(),
supports: Default::default(),
})
.parse_attributes(&di.attrs)?
.parse_body(&di.data)
}
}
impl<'a> From<&'a FromVariantOptions> for FromVariantImpl<'a> {
fn from(v: &'a FromVariantOptions) -> Self {
FromVariantImpl {
base: (&v.base.container).into(),
ident: v.base.ident.as_ref(),
discriminant: v.discriminant.as_ref(),
fields: v.fields.as_ref(),
attr_names: &v.base.attr_names,
forward_attrs: v.base.as_forward_attrs(),
from_ident: v.base.from_ident,
supports: v.supports.as_ref(),
}
}
}
impl ParseAttribute for FromVariantOptions {
fn parse_nested(&mut self, mi: &Meta) -> Result<()> {
if mi.path().is_ident("supports") {
self.supports = FromMeta::from_meta(mi)?;
Ok(())
} else {
self.base.parse_nested(mi)
}
}
}
impl ParseData for FromVariantOptions {
fn parse_field(&mut self, field: &Field) -> Result<()> {
match field.ident.as_ref().map(|v| v.to_string()).as_deref() {
Some("discriminant") => {
self.discriminant.clone_from(&field.ident);
Ok(())
}
Some("fields") => {
self.fields.clone_from(&field.ident);
Ok(())
}
_ => self.base.parse_field(field),
}
}
fn validate_body(&self, errors: &mut crate::error::Accumulator) {
self.base.validate_body(errors);
}
}
impl ToTokens for FromVariantOptions {
fn to_tokens(&self, tokens: &mut TokenStream) {
FromVariantImpl::from(self).to_tokens(tokens)
}
}