use quote::quote;
use syn::{punctuated::Punctuated, Data, DeriveInput, Field, Fields, Index, Meta, Type};
use super::models::{FieldAttribute, FieldAttributeBuilder, TypeAttributeBuilder};
use crate::{
common::where_predicates_bool::WherePredicates, supported_traits::Trait, TraitHandler,
};
pub(crate) struct CloneStructHandler;
impl TraitHandler for CloneStructHandler {
#[inline]
fn trait_meta_handler(
ast: &DeriveInput,
token_stream: &mut proc_macro2::TokenStream,
traits: &[Trait],
meta: &Meta,
) -> syn::Result<()> {
let type_attribute = TypeAttributeBuilder {
enable_flag: true, enable_bound: true
}
.build_from_clone_meta(meta)?;
let mut bound: WherePredicates = Punctuated::new();
let mut clone_token_stream = proc_macro2::TokenStream::new();
let mut clone_from_token_stream = proc_macro2::TokenStream::new();
if let Data::Struct(data) = &ast.data {
let mut fields: Vec<(&Field, FieldAttribute)> = Vec::new();
#[cfg(feature = "Copy")]
let contains_copy = traits.contains(&Trait::Copy);
#[cfg(not(feature = "Copy"))]
let contains_copy = false;
if contains_copy {
clone_token_stream.extend(quote!(*self));
}
for field in data.fields.iter() {
let field_attribute = FieldAttributeBuilder {
enable_method: !contains_copy
}
.build_from_attributes(&field.attrs, traits)?;
fields.push((field, field_attribute));
}
let mut clone_types: Vec<&Type> = Vec::new();
match &data.fields {
Fields::Unit => {
if !contains_copy {
clone_token_stream.extend(quote!(Self));
clone_from_token_stream.extend(quote!(let _ = source;));
}
},
Fields::Named(_) => {
let mut fields_token_stream = proc_macro2::TokenStream::new();
let mut clone_from_body_token_stream = proc_macro2::TokenStream::new();
if fields.is_empty() {
clone_from_body_token_stream.extend(quote!(let _ = source;));
} else {
for (field, field_attribute) in fields {
let field_name = field.ident.as_ref().unwrap();
if let Some(clone) = field_attribute.method.as_ref() {
fields_token_stream.extend(quote! {
#field_name: #clone(&self.#field_name),
});
clone_from_body_token_stream.extend(
quote!(self.#field_name = #clone(&source.#field_name);),
);
} else {
clone_types.push(&field.ty);
fields_token_stream.extend(quote! {
#field_name: ::core::clone::Clone::clone(&self.#field_name),
});
clone_from_body_token_stream.extend(
quote!( ::core::clone::Clone::clone_from(&mut self.#field_name, &source.#field_name); ),
);
}
}
}
if !contains_copy {
clone_token_stream.extend(quote! {
Self {
#fields_token_stream
}
});
clone_from_token_stream.extend(clone_from_body_token_stream);
}
},
Fields::Unnamed(_) => {
let mut fields_token_stream = proc_macro2::TokenStream::new();
let mut clone_from_body_token_stream = proc_macro2::TokenStream::new();
if fields.is_empty() {
clone_from_body_token_stream.extend(quote!(let _ = source;));
} else {
for (index, (field, field_attribute)) in fields.into_iter().enumerate() {
let field_name = Index::from(index);
if let Some(clone) = field_attribute.method.as_ref() {
fields_token_stream.extend(quote!(#clone(&self.#field_name),));
clone_from_body_token_stream.extend(
quote!(self.#field_name = #clone(&source.#field_name);),
);
} else {
clone_types.push(&field.ty);
fields_token_stream.extend(
quote! ( ::core::clone::Clone::clone(&self.#field_name), ),
);
clone_from_body_token_stream.extend(
quote!( ::core::clone::Clone::clone_from(&mut self.#field_name, &source.#field_name); ),
);
}
}
}
if !contains_copy {
clone_token_stream.extend(quote!(Self ( #fields_token_stream )));
clone_from_token_stream.extend(clone_from_body_token_stream);
}
},
}
bound = type_attribute.bound.into_where_predicates_by_generic_parameters_check_types(
&ast.generics.params,
&syn::parse2(if contains_copy {
quote!(::core::marker::Copy)
} else {
quote!(::core::clone::Clone)
})
.unwrap(),
&clone_types,
&[],
);
}
let clone_from_fn_token_stream = if clone_from_token_stream.is_empty() {
None
} else {
Some(quote! {
#[inline]
fn clone_from(&mut self, source: &Self) {
#clone_from_token_stream
}
})
};
let ident = &ast.ident;
let mut generics = ast.generics.clone();
let where_clause = generics.make_where_clause();
for where_predicate in bound {
where_clause.predicates.push(where_predicate);
}
let (impl_generics, ty_generics, where_clause) = generics.split_for_impl();
token_stream.extend(quote! {
impl #impl_generics ::core::clone::Clone for #ident #ty_generics #where_clause {
#[inline]
fn clone(&self) -> Self {
#clone_token_stream
}
#clone_from_fn_token_stream
}
});
#[cfg(feature = "Copy")]
if traits.contains(&Trait::Copy) {
token_stream.extend(quote! {
impl #impl_generics ::core::marker::Copy for #ident #ty_generics #where_clause {
}
});
}
Ok(())
}
}