1 files changed, 111 insertions, 0 deletions
diff --git a/src/codegen/from_attributes_impl.rs b/src/codegen/from_attributes_impl.rs
new file mode 100644
index 0000000..72da349
--- /dev/null
+++ b/src/codegen/from_attributes_impl.rs
@@ -0,0 +1,111 @@
+use proc_macro2::TokenStream;
+use quote::{quote, ToTokens};
+
+use crate::{
+    ast::Data,
+    codegen::{ExtractAttribute, OuterFromImpl, TraitImpl},
+    util::PathList,
+};
+
+use super::ForwardAttrs;
+
+pub struct FromAttributesImpl<'a> {
+    pub base: TraitImpl<'a>,
+    pub attr_names: &'a PathList,
+    pub forward_attrs: ForwardAttrs<'a>,
+}
+
+impl ToTokens for FromAttributesImpl<'_> {
+    fn to_tokens(&self, tokens: &mut TokenStream) {
+        let ty_ident = self.base.ident;
+        let input = self.param_name();
+        let post_transform = self.base.post_transform_call();
+
+        if let Data::Struct(ref data) = self.base.data {
+            if data.is_newtype() {
+                self.wrap(
+                    quote! {
+                        fn from_attributes(#input: &[::darling::export::syn::Attribute]) -> ::darling::Result<Self> {
+                            ::darling::export::Ok(
+                                #ty_ident(::darling::FromAttributes::from_attributes(#input)?)
+                            ) #post_transform
+                        }
+                    },
+                    tokens,
+                );
+
+                return;
+            }
+        }
+
+        let inits = self.base.initializers();
+        let default = self.base.fallback_decl();
+
+        let grab_attrs = self.extractor();
+
+        let declare_errors = self.base.declare_errors();
+        let require_fields = self.base.require_fields();
+        let check_errors = self.base.check_errors();
+
+        self.wrap(
+            quote! {
+                fn from_attributes(#input: &[::darling::export::syn::Attribute]) -> ::darling::Result<Self> {
+                    #declare_errors
+
+                    #grab_attrs
+
+                    #require_fields
+
+                    #check_errors
+
+                    #default
+
+                    ::darling::export::Ok(#ty_ident {
+                        #inits
+                    }) #post_transform
+                }
+            },
+            tokens,
+        );
+    }
+}
+
+impl<'a> ExtractAttribute for FromAttributesImpl<'a> {
+    fn local_declarations(&self) -> TokenStream {
+        self.base.local_declarations()
+    }
+
+    fn attr_names(&self) -> &PathList {
+        self.attr_names
+    }
+
+    fn forward_attrs(&self) -> &super::ForwardAttrs {
+        &self.forward_attrs
+    }
+
+    fn param_name(&self) -> TokenStream {
+        quote!(__di)
+    }
+
+    fn attrs_accessor(&self) -> TokenStream {
+        self.param_name()
+    }
+
+    fn core_loop(&self) -> TokenStream {
+        self.base.core_loop()
+    }
+}
+
+impl<'a> OuterFromImpl<'a> for FromAttributesImpl<'a> {
+    fn trait_path(&self) -> syn::Path {
+        path!(::darling::FromAttributes)
+    }
+
+    fn trait_bound(&self) -> syn::Path {
+        path!(::darling::FromMeta)
+    }
+
+    fn base(&'a self) -> &'a TraitImpl<'a> {
+        &self.base
+    }
+}