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Macro attributes to specify From and Into trait types for structs and enums (#817)

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* serde macro support for type conversions through From and Into trait

* Revisions requested by dtolnay

* Additional changes requested by dtolnay
This commit is contained in:
John Baublitz
2017-03-18 12:22:27 -04:00
committed by David Tolnay
parent c488cec641
commit bc946e4fd7
8 changed files with 223 additions and 48 deletions
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serde_derive/src/de.rs
+39 -27
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@@ -85,36 +85,48 @@ fn requires_default(attrs: &attr::Field) -> bool {
}
fn deserialize_body(item: &Item, generics: &syn::Generics) -> Fragment {
match item.body {
Body::Enum(ref variants) => {
deserialize_item_enum(&item.ident, generics, variants, &item.attrs)
}
Body::Struct(Style::Struct, ref fields) => {
if fields.iter().any(|field| field.ident.is_none()) {
panic!("struct has unnamed fields");
if let Some(fr_ty) = item.attrs.from_type() {
deserialize_from(fr_ty)
} else {
match item.body {
Body::Enum(ref variants) => {
deserialize_item_enum(&item.ident, generics, variants, &item.attrs)
}
deserialize_struct(&item.ident,
None,
generics,
fields,
&item.attrs,
None)
}
Body::Struct(Style::Tuple, ref fields) |
Body::Struct(Style::Newtype, ref fields) => {
if fields.iter().any(|field| field.ident.is_some()) {
panic!("tuple struct has named fields");
Body::Struct(Style::Struct, ref fields) => {
if fields.iter().any(|field| field.ident.is_none()) {
panic!("struct has unnamed fields");
}
deserialize_struct(&item.ident,
None,
generics,
fields,
&item.attrs,
None)
}
deserialize_tuple(&item.ident,
None,
generics,
fields,
&item.attrs,
None)
Body::Struct(Style::Tuple, ref fields) |
Body::Struct(Style::Newtype, ref fields) => {
if fields.iter().any(|field| field.ident.is_some()) {
panic!("tuple struct has named fields");
}
deserialize_tuple(&item.ident,
None,
generics,
fields,
&item.attrs,
None)
}
Body::Struct(Style::Unit, _) => deserialize_unit_struct(&item.ident, &item.attrs),
}
}
}
fn deserialize_from(from_type: &syn::Ty) -> Fragment {
quote_block! {
let de_val = <#from_type as _serde::Deserialize>::deserialize(deserializer);
match de_val {
_serde::export::Result::Ok(from_in) => _serde::export::Result::Ok(_serde::export::convert::From::from(from_in)),
_serde::export::Result::Err(e) => _serde::export::Result::Err(e)
}
Body::Struct(Style::Unit, _) => deserialize_unit_struct(&item.ident, &item.attrs),
}
}