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Support custom paths in container attribute serde(default="...")

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This commit is contained in:
David Tolnay
2017-02-20 17:03:38 -08:00
parent ad480d2b04
commit 3d6e086d3e
4 changed files with 131 additions and 55 deletions
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serde_derive/src/de.rs
+46 -33
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@@ -46,11 +46,19 @@ fn build_generics(item: &Item) -> syn::Generics {
match item.attrs.de_bound() {
Some(predicates) => bound::with_where_predicates(&generics, predicates),
None => {
let generics = match *item.attrs.default() {
attr::Default::Default => {
bound::with_self_bound(item, &generics, &path!(_serde::export::Default))
}
attr::Default::None | attr::Default::Path(_) => generics,
};
let generics =
bound::with_bound(item,
&generics,
needs_deserialize_bound,
&path!(_serde::Deserialize));
bound::with_bound(item,
&generics,
requires_default,
@@ -70,7 +78,7 @@ fn needs_deserialize_bound(attrs: &attr::Field) -> bool {
// Fields with a `default` attribute (not `default=...`), and fields with a
// `skip_deserializing` attribute that do not also have `default=...`.
fn requires_default(attrs: &attr::Field) -> bool {
attrs.default() == &attr::FieldDefault::Default
attrs.default() == &attr::Default::Default
}
fn deserialize_body(item: &Item, generics: &syn::Generics) -> Tokens {
@@ -168,7 +176,7 @@ fn deserialize_tuple(ident: &syn::Ident,
None
};
let visit_seq = deserialize_seq(ident, &type_path, generics, fields, false);
let visit_seq = deserialize_seq(ident, &type_path, generics, fields, false, item_attrs);
let visitor_expr = quote! {
__Visitor { marker: _serde::export::PhantomData::<#ident #ty_generics> }
@@ -222,7 +230,8 @@ fn deserialize_seq(ident: &syn::Ident,
type_path: &Tokens,
generics: &syn::Generics,
fields: &[Field],
is_struct: bool)
is_struct: bool,
item_attrs: &attr::Item)
-> Tokens {
let vars = (0..fields.len()).map(field_i as fn(_) -> _);
@@ -235,7 +244,7 @@ fn deserialize_seq(ident: &syn::Ident,
let let_values = vars.clone().zip(fields)
.map(|(var, field)| {
if field.attrs.skip_deserializing() {
let default = expr_is_missing(&field.attrs, false, "");
let default = expr_is_missing(&field, item_attrs);
quote! {
let #var = #default;
}
@@ -337,7 +346,7 @@ fn deserialize_struct(ident: &syn::Ident,
None => format!("struct {}", ident),
};
let visit_seq = deserialize_seq(ident, &type_path, generics, fields, true);
let visit_seq = deserialize_seq(ident, &type_path, generics, fields, true, item_attrs);
let (field_visitor, fields_stmt, visit_map) =
deserialize_struct_visitor(ident, type_path, generics, fields, item_attrs);
@@ -1012,11 +1021,7 @@ fn deserialize_map(ident: &syn::Ident,
let extract_values = fields_names.iter()
.filter(|&&(field, _)| !field.attrs.skip_deserializing())
.map(|&(field, ref name)| {
// Use the ident as field name, since the user can rename the field
// in the attributes using `#[serde(rename = "name")]`, but we need
// the original (in code) name of the field.
let ident = field.ident.clone().expect("struct contains unnamed fields");
let missing_expr = expr_is_missing(&field.attrs, item_attrs.default(), ident.as_ref());
let missing_expr = expr_is_missing(&field, item_attrs);
quote! {
let #name = match #name {
@@ -1030,21 +1035,29 @@ fn deserialize_map(ident: &syn::Ident,
.map(|&(field, ref name)| {
let ident = field.ident.clone().expect("struct contains unnamed fields");
let value = if field.attrs.skip_deserializing() {
expr_is_missing(&field.attrs, item_attrs.default(), ident.as_ref())
expr_is_missing(&field, item_attrs)
} else {
quote!(#name)
};
quote!(#ident: #value)
});
let default = if item_attrs.default() {
quote!(
let default: #struct_path = _serde::export::Default::default();
)
} else {
// We don't need the default value, to prevent an unused variable warning
// we'll leave the line empty.
quote!()
let let_default = match *item_attrs.default() {
attr::Default::Default => {
Some(quote!(
let __default: Self::Value = _serde::export::Default::default();
))
}
attr::Default::Path(ref path) => {
Some(quote!(
let __default: Self::Value = #path();
))
}
attr::Default::None => {
// We don't need the default value, to prevent an unused variable warning
// we'll leave the line empty.
None
}
};
quote! {
@@ -1052,7 +1065,7 @@ fn deserialize_map(ident: &syn::Ident,
#match_keys
#default
#let_default
#(#extract_values)*
@@ -1097,27 +1110,27 @@ fn wrap_deserialize_with(ident: &syn::Ident,
(wrapper, wrapper_ty)
}
fn expr_is_missing(attrs: &attr::Field, use_default: bool, field_name: &str) -> Tokens {
match *attrs.default() {
attr::FieldDefault::Default => {
fn expr_is_missing(field: &Field, item_attrs: &attr::Item) -> Tokens {
match *field.attrs.default() {
attr::Default::Default => {
return quote!(_serde::export::Default::default());
}
attr::FieldDefault::Path(ref path) => {
attr::Default::Path(ref path) => {
return quote!(#path());
}
attr::FieldDefault::None => { /* below */ }
attr::Default::None => { /* below */ }
}
if use_default {
// Field name without the qoutes.
let field_name = quote::Ident::new(field_name);
return quote!(
default.#field_name
)
match *item_attrs.default() {
attr::Default::Default | attr::Default::Path(_) => {
let ident = &field.ident;
return quote!(__default.#ident);
}
attr::Default::None => { /* below */ }
}
let name = attrs.name().deserialize_name();
match attrs.deserialize_with() {
let name = field.attrs.name().deserialize_name();
match field.attrs.deserialize_with() {
None => {
quote! {
try!(_serde::de::private::missing_field(#name))