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Merge pull request #780 from Thomasdezeeuw/default_container

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Add support for `#[serde(default)]` on structs
This commit is contained in:
David Tolnay
2017-02-20 16:10:28 -08:00
committed by GitHub
parent dff919a926 7bee779514
commit ad480d2b04
5 changed files with 97 additions and 4 deletions
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serde_derive/src/de.rs
+28 -4
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@@ -235,7 +235,7 @@ 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);
let default = expr_is_missing(&field.attrs, false, "");
quote! {
let #var = #default;
}
@@ -1012,7 +1012,11 @@ fn deserialize_map(ident: &syn::Ident,
let extract_values = fields_names.iter()
.filter(|&&(field, _)| !field.attrs.skip_deserializing())
.map(|&(field, ref name)| {
let missing_expr = expr_is_missing(&field.attrs);
// 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());
quote! {
let #name = match #name {
@@ -1026,18 +1030,30 @@ 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)
expr_is_missing(&field.attrs, item_attrs.default(), ident.as_ref())
} 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!()
};
quote! {
#(#let_values)*
#match_keys
#default
#(#extract_values)*
_serde::export::Ok(#struct_path { #(#result),* })
@@ -1081,7 +1097,7 @@ fn wrap_deserialize_with(ident: &syn::Ident,
(wrapper, wrapper_ty)
}
fn expr_is_missing(attrs: &attr::Field) -> Tokens {
fn expr_is_missing(attrs: &attr::Field, use_default: bool, field_name: &str) -> Tokens {
match *attrs.default() {
attr::FieldDefault::Default => {
return quote!(_serde::export::Default::default());
@@ -1092,6 +1108,14 @@ fn expr_is_missing(attrs: &attr::Field) -> Tokens {
attr::FieldDefault::None => { /* below */ }
}
if use_default {
// Field name without the qoutes.
let field_name = quote::Ident::new(field_name);
return quote!(
default.#field_name
)
}
let name = attrs.name().deserialize_name();
match attrs.deserialize_with() {
None => {