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use std::borrow::Cow;
use crate::ast::Fields;
use crate::codegen;
use crate::options::{Core, InputField, ParseAttribute};
use crate::util::SpannedValue;
use crate::{Error, FromMeta, Result};
#[derive(Debug, Clone)]
pub struct InputVariant {
ident: syn::Ident,
attr_name: Option<String>,
data: Fields<InputField>,
skip: Option<bool>,
/// Whether or not the variant should be used to create an instance for
/// `FromMeta::from_word`.
pub word: Option<SpannedValue<bool>>,
/// Whether or not unknown fields are acceptable in this
allow_unknown_fields: Option<bool>,
}
impl InputVariant {
pub fn as_codegen_variant<'a>(&'a self, ty_ident: &'a syn::Ident) -> codegen::Variant<'a> {
codegen::Variant {
ty_ident,
variant_ident: &self.ident,
name_in_attr: self
.attr_name
.as_ref()
.map_or_else(|| Cow::Owned(self.ident.to_string()), Cow::Borrowed),
data: self.data.as_ref().map(InputField::as_codegen_field),
skip: self.skip.unwrap_or_default(),
word: *self.word.unwrap_or_default(),
allow_unknown_fields: self.allow_unknown_fields.unwrap_or_default(),
}
}
pub fn from_variant(v: &syn::Variant, parent: Option<&Core>) -> Result<Self> {
let mut starter = (InputVariant {
ident: v.ident.clone(),
attr_name: Default::default(),
data: Fields::empty_from(&v.fields),
skip: Default::default(),
word: Default::default(),
allow_unknown_fields: None,
})
.parse_attributes(&v.attrs)?;
starter.data.fields = match v.fields {
syn::Fields::Unit => vec![],
syn::Fields::Unnamed(ref fields) => {
let mut items = Vec::with_capacity(fields.unnamed.len());
for item in &fields.unnamed {
items.push(InputField::from_field(item, parent)?);
}
items
}
syn::Fields::Named(ref fields) => {
let mut items = Vec::with_capacity(fields.named.len());
for item in &fields.named {
items.push(InputField::from_field(item, parent)?);
}
items
}
};
Ok(if let Some(p) = parent {
starter.with_inherited(p)
} else {
starter
})
}
fn with_inherited(mut self, parent: &Core) -> Self {
if self.attr_name.is_none() {
self.attr_name = Some(parent.rename_rule.apply_to_variant(self.ident.to_string()));
}
if self.allow_unknown_fields.is_none() {
self.allow_unknown_fields = Some(parent.allow_unknown_fields.unwrap_or_default());
}
self
}
}
impl ParseAttribute for InputVariant {
fn parse_nested(&mut self, mi: &syn::Meta) -> Result<()> {
let path = mi.path();
if path.is_ident("rename") {
if self.attr_name.is_some() {
return Err(Error::duplicate_field_path(path).with_span(mi));
}
self.attr_name = FromMeta::from_meta(mi)?;
} else if path.is_ident("skip") {
if self.skip.is_some() {
return Err(Error::duplicate_field_path(path).with_span(mi));
}
self.skip = FromMeta::from_meta(mi)?;
} else if path.is_ident("word") {
if self.word.is_some() {
return Err(Error::duplicate_field_path(path).with_span(mi));
}
if !self.data.is_unit() {
let note = "`#[darling(word)]` can only be applied to a unit variant";
#[cfg(feature = "diagnostics")]
let error = Error::unknown_field_path(path).note(note);
#[cfg(not(feature = "diagnostics"))]
let error = Error::custom(format!("Unexpected field: `word`. {}", note));
return Err(error.with_span(mi));
}
self.word = FromMeta::from_meta(mi)?;
} else {
return Err(Error::unknown_field_path(path).with_span(mi));
}
Ok(())
}
}