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Move body generator for structs to its own module

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Mingun 2025-06-14 19:03:18 +05:00
parent 19956e6b8e
commit 2d607de146
5 changed files with 707 additions and 690 deletions
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688
serde_derive/src/de.rs
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@ -1,5 +1,5 @@
use crate::deprecated::allow_deprecated;
use crate::fragment::{Expr, Fragment, Match, Stmts};
use crate::fragment::{Expr, Fragment, Stmts};
use crate::internals::ast::{Container, Data, Field, Style, Variant};
use crate::internals::name::Name;
use crate::internals::{attr, replace_receiver, ungroup, Ctxt, Derive};
@ -17,6 +17,7 @@ mod enum_adjacently;
mod enum_externally;
mod enum_internally;
mod enum_untagged;
mod struct_;
pub fn expand_derive_deserialize(input: &mut syn::DeriveInput) -> syn::Result<TokenStream> {
replace_receiver(input);
@ -310,7 +311,7 @@ fn deserialize_body(cont: &Container, params: &Parameters) -> Fragment {
match &cont.data {
Data::Enum(variants) => enum_::deserialize_enum(params, variants, &cont.attrs),
Data::Struct(Style::Struct, fields) => {
deserialize_struct(params, fields, &cont.attrs, StructForm::Struct)
struct_::deserialize_struct(params, fields, &cont.attrs, StructForm::Struct)
}
Data::Struct(Style::Tuple, fields) | Data::Struct(Style::Newtype, fields) => {
deserialize_tuple(params, fields, &cont.attrs, TupleForm::Tuple)
@ -345,7 +346,7 @@ fn deserialize_in_place_body(cont: &Container, params: &Parameters) -> Option<St
let code = match &cont.data {
Data::Struct(Style::Struct, fields) => {
deserialize_struct_in_place(params, fields, &cont.attrs)?
struct_::deserialize_struct_in_place(params, fields, &cont.attrs)?
}
Data::Struct(Style::Tuple, fields) | Data::Struct(Style::Newtype, fields) => {
deserialize_tuple_in_place(params, fields, &cont.attrs)
@ -960,278 +961,6 @@ enum StructForm<'a> {
Untagged(&'a syn::Ident),
}
/// Generates `Deserialize::deserialize` body for a `struct Struct {...}`
fn deserialize_struct(
params: &Parameters,
fields: &[Field],
cattrs: &attr::Container,
form: StructForm,
) -> Fragment {
let this_type = &params.this_type;
let this_value = &params.this_value;
let (de_impl_generics, de_ty_generics, ty_generics, where_clause) = params.generics();
let delife = params.borrowed.de_lifetime();
// If there are getters (implying private fields), construct the local type
// and use an `Into` conversion to get the remote type. If there are no
// getters then construct the target type directly.
let construct = if params.has_getter {
let local = &params.local;
quote!(#local)
} else {
quote!(#this_value)
};
let type_path = match form {
StructForm::Struct => construct,
StructForm::ExternallyTagged(variant_ident)
| StructForm::InternallyTagged(variant_ident)
| StructForm::Untagged(variant_ident) => quote!(#construct::#variant_ident),
};
let expecting = match form {
StructForm::Struct => format!("struct {}", params.type_name()),
StructForm::ExternallyTagged(variant_ident)
| StructForm::InternallyTagged(variant_ident)
| StructForm::Untagged(variant_ident) => {
format!("struct variant {}::{}", params.type_name(), variant_ident)
}
};
let expecting = cattrs.expecting().unwrap_or(&expecting);
let deserialized_fields: Vec<_> = fields
.iter()
.enumerate()
// Skip fields that shouldn't be deserialized or that were flattened,
// so they don't appear in the storage in their literal form
.filter(|&(_, field)| !field.attrs.skip_deserializing() && !field.attrs.flatten())
.map(|(i, field)| FieldWithAliases {
ident: field_i(i),
aliases: field.attrs.aliases(),
})
.collect();
let has_flatten = has_flatten(fields);
let field_visitor = deserialize_field_identifier(&deserialized_fields, cattrs, has_flatten);
// untagged struct variants do not get a visit_seq method. The same applies to
// structs that only have a map representation.
let visit_seq = match form {
StructForm::Untagged(_) => None,
_ if has_flatten => None,
_ => {
let mut_seq = if deserialized_fields.is_empty() {
quote!(_)
} else {
quote!(mut __seq)
};
let visit_seq = Stmts(deserialize_seq(
&type_path, params, fields, true, cattrs, expecting,
));
Some(quote! {
#[inline]
fn visit_seq<__A>(self, #mut_seq: __A) -> _serde::#private::Result<Self::Value, __A::Error>
where
__A: _serde::de::SeqAccess<#delife>,
{
#visit_seq
}
})
}
};
let visit_map = Stmts(deserialize_map(
&type_path,
params,
fields,
cattrs,
has_flatten,
));
let visitor_seed = match form {
StructForm::ExternallyTagged(..) if has_flatten => Some(quote! {
#[automatically_derived]
impl #de_impl_generics _serde::de::DeserializeSeed<#delife> for __Visitor #de_ty_generics #where_clause {
type Value = #this_type #ty_generics;
fn deserialize<__D>(self, __deserializer: __D) -> _serde::#private::Result<Self::Value, __D::Error>
where
__D: _serde::Deserializer<#delife>,
{
_serde::Deserializer::deserialize_map(__deserializer, self)
}
}
}),
_ => None,
};
let fields_stmt = if has_flatten {
None
} else {
let field_names = deserialized_fields.iter().flat_map(|field| field.aliases);
Some(quote! {
#[doc(hidden)]
const FIELDS: &'static [&'static str] = &[ #(#field_names),* ];
})
};
let visitor_expr = quote! {
__Visitor {
marker: _serde::#private::PhantomData::<#this_type #ty_generics>,
lifetime: _serde::#private::PhantomData,
}
};
let dispatch = match form {
StructForm::Struct if has_flatten => quote! {
_serde::Deserializer::deserialize_map(__deserializer, #visitor_expr)
},
StructForm::Struct => {
let type_name = cattrs.name().deserialize_name();
quote! {
_serde::Deserializer::deserialize_struct(__deserializer, #type_name, FIELDS, #visitor_expr)
}
}
StructForm::ExternallyTagged(_) if has_flatten => quote! {
_serde::de::VariantAccess::newtype_variant_seed(__variant, #visitor_expr)
},
StructForm::ExternallyTagged(_) => quote! {
_serde::de::VariantAccess::struct_variant(__variant, FIELDS, #visitor_expr)
},
StructForm::InternallyTagged(_) => quote! {
_serde::Deserializer::deserialize_any(__deserializer, #visitor_expr)
},
StructForm::Untagged(_) => quote! {
_serde::Deserializer::deserialize_any(__deserializer, #visitor_expr)
},
};
quote_block! {
#field_visitor
#[doc(hidden)]
struct __Visitor #de_impl_generics #where_clause {
marker: _serde::#private::PhantomData<#this_type #ty_generics>,
lifetime: _serde::#private::PhantomData<&#delife ()>,
}
#[automatically_derived]
impl #de_impl_generics _serde::de::Visitor<#delife> for __Visitor #de_ty_generics #where_clause {
type Value = #this_type #ty_generics;
fn expecting(&self, __formatter: &mut _serde::#private::Formatter) -> _serde::#private::fmt::Result {
_serde::#private::Formatter::write_str(__formatter, #expecting)
}
#visit_seq
#[inline]
fn visit_map<__A>(self, mut __map: __A) -> _serde::#private::Result<Self::Value, __A::Error>
where
__A: _serde::de::MapAccess<#delife>,
{
#visit_map
}
}
#visitor_seed
#fields_stmt
#dispatch
}
}
/// Generates `Deserialize::deserialize_in_place` body for a `struct Struct {...}`
#[cfg(feature = "deserialize_in_place")]
fn deserialize_struct_in_place(
params: &Parameters,
fields: &[Field],
cattrs: &attr::Container,
) -> Option<Fragment> {
// for now we do not support in_place deserialization for structs that
// are represented as map.
if has_flatten(fields) {
return None;
}
let this_type = &params.this_type;
let (de_impl_generics, de_ty_generics, ty_generics, where_clause) = params.generics();
let delife = params.borrowed.de_lifetime();
let expecting = format!("struct {}", params.type_name());
let expecting = cattrs.expecting().unwrap_or(&expecting);
let deserialized_fields: Vec<_> = fields
.iter()
.enumerate()
.filter(|&(_, field)| !field.attrs.skip_deserializing())
.map(|(i, field)| FieldWithAliases {
ident: field_i(i),
aliases: field.attrs.aliases(),
})
.collect();
let field_visitor = deserialize_field_identifier(&deserialized_fields, cattrs, false);
let mut_seq = if deserialized_fields.is_empty() {
quote!(_)
} else {
quote!(mut __seq)
};
let visit_seq = Stmts(deserialize_seq_in_place(params, fields, cattrs, expecting));
let visit_map = Stmts(deserialize_map_in_place(params, fields, cattrs));
let field_names = deserialized_fields.iter().flat_map(|field| field.aliases);
let type_name = cattrs.name().deserialize_name();
let in_place_impl_generics = de_impl_generics.in_place();
let in_place_ty_generics = de_ty_generics.in_place();
let place_life = place_lifetime();
Some(quote_block! {
#field_visitor
#[doc(hidden)]
struct __Visitor #in_place_impl_generics #where_clause {
place: &#place_life mut #this_type #ty_generics,
lifetime: _serde::#private::PhantomData<&#delife ()>,
}
#[automatically_derived]
impl #in_place_impl_generics _serde::de::Visitor<#delife> for __Visitor #in_place_ty_generics #where_clause {
type Value = ();
fn expecting(&self, __formatter: &mut _serde::#private::Formatter) -> _serde::#private::fmt::Result {
_serde::#private::Formatter::write_str(__formatter, #expecting)
}
#[inline]
fn visit_seq<__A>(self, #mut_seq: __A) -> _serde::#private::Result<Self::Value, __A::Error>
where
__A: _serde::de::SeqAccess<#delife>,
{
#visit_seq
}
#[inline]
fn visit_map<__A>(self, mut __map: __A) -> _serde::#private::Result<Self::Value, __A::Error>
where
__A: _serde::de::MapAccess<#delife>,
{
#visit_map
}
}
#[doc(hidden)]
const FIELDS: &'static [&'static str] = &[ #(#field_names),* ];
_serde::Deserializer::deserialize_struct(__deserializer, #type_name, FIELDS, __Visitor {
place: __place,
lifetime: _serde::#private::PhantomData,
})
})
}
struct FieldWithAliases<'a> {
ident: Ident,
aliases: &'a BTreeSet<Name>,
@ -1297,34 +1026,6 @@ fn deserialize_generated_identifier(
}
}
/// Generates enum and its `Deserialize` implementation that represents each
/// non-skipped field of the struct
fn deserialize_field_identifier(
deserialized_fields: &[FieldWithAliases],
cattrs: &attr::Container,
has_flatten: bool,
) -> Stmts {
let (ignore_variant, fallthrough) = if has_flatten {
let ignore_variant = quote!(__other(_serde::#private::de::Content<'de>),);
let fallthrough = quote!(_serde::#private::Ok(__Field::__other(__value)));
(Some(ignore_variant), Some(fallthrough))
} else if cattrs.deny_unknown_fields() {
(None, None)
} else {
let ignore_variant = quote!(__ignore,);
let fallthrough = quote!(_serde::#private::Ok(__Field::__ignore));
(Some(ignore_variant), Some(fallthrough))
};
Stmts(deserialize_generated_identifier(
deserialized_fields,
has_flatten,
false,
ignore_variant,
fallthrough,
))
}
// Generates `Deserialize::deserialize` body for an enum with
// `serde(field_identifier)` or `serde(variant_identifier)` attribute.
fn deserialize_custom_identifier(
@ -1731,387 +1432,6 @@ fn deserialize_identifier(
}
}
fn deserialize_map(
struct_path: &TokenStream,
params: &Parameters,
fields: &[Field],
cattrs: &attr::Container,
has_flatten: bool,
) -> Fragment {
// Create the field names for the fields.
let fields_names: Vec<_> = fields
.iter()
.enumerate()
.map(|(i, field)| (field, field_i(i)))
.collect();
// Declare each field that will be deserialized.
let let_values = fields_names
.iter()
.filter(|&&(field, _)| !field.attrs.skip_deserializing() && !field.attrs.flatten())
.map(|(field, name)| {
let field_ty = field.ty;
quote! {
let mut #name: _serde::#private::Option<#field_ty> = _serde::#private::None;
}
});
// Collect contents for flatten fields into a buffer
let let_collect = if has_flatten {
Some(quote! {
let mut __collect = _serde::#private::Vec::<_serde::#private::Option<(
_serde::#private::de::Content,
_serde::#private::de::Content
)>>::new();
})
} else {
None
};
// Match arms to extract a value for a field.
let value_arms = fields_names
.iter()
.filter(|&&(field, _)| !field.attrs.skip_deserializing() && !field.attrs.flatten())
.map(|(field, name)| {
let deser_name = field.attrs.name().deserialize_name();
let visit = match field.attrs.deserialize_with() {
None => {
let field_ty = field.ty;
let span = field.original.span();
let func =
quote_spanned!(span=> _serde::de::MapAccess::next_value::<#field_ty>);
quote! {
#func(&mut __map)?
}
}
Some(path) => {
let (wrapper, wrapper_ty) = wrap_deserialize_field_with(params, field.ty, path);
quote!({
#wrapper
match _serde::de::MapAccess::next_value::<#wrapper_ty>(&mut __map) {
_serde::#private::Ok(__wrapper) => __wrapper.value,
_serde::#private::Err(__err) => {
return _serde::#private::Err(__err);
}
}
})
}
};
quote! {
__Field::#name => {
if _serde::#private::Option::is_some(&#name) {
return _serde::#private::Err(<__A::Error as _serde::de::Error>::duplicate_field(#deser_name));
}
#name = _serde::#private::Some(#visit);
}
}
});
// Visit ignored values to consume them
let ignored_arm = if has_flatten {
Some(quote! {
__Field::__other(__name) => {
__collect.push(_serde::#private::Some((
__name,
_serde::de::MapAccess::next_value_seed(&mut __map, _serde::#private::de::ContentVisitor::new())?)));
}
})
} else if cattrs.deny_unknown_fields() {
None
} else {
Some(quote! {
_ => { let _ = _serde::de::MapAccess::next_value::<_serde::de::IgnoredAny>(&mut __map)?; }
})
};
let all_skipped = fields.iter().all(|field| field.attrs.skip_deserializing());
let match_keys = if cattrs.deny_unknown_fields() && all_skipped {
quote! {
// FIXME: Once feature(exhaustive_patterns) is stable:
// let _serde::#private::None::<__Field> = _serde::de::MapAccess::next_key(&mut __map)?;
_serde::#private::Option::map(
_serde::de::MapAccess::next_key::<__Field>(&mut __map)?,
|__impossible| match __impossible {});
}
} else {
quote! {
while let _serde::#private::Some(__key) = _serde::de::MapAccess::next_key::<__Field>(&mut __map)? {
match __key {
#(#value_arms)*
#ignored_arm
}
}
}
};
let extract_values = fields_names
.iter()
.filter(|&&(field, _)| !field.attrs.skip_deserializing() && !field.attrs.flatten())
.map(|(field, name)| {
let missing_expr = Match(expr_is_missing(field, cattrs));
quote! {
let #name = match #name {
_serde::#private::Some(#name) => #name,
_serde::#private::None => #missing_expr
};
}
});
let extract_collected = fields_names
.iter()
.filter(|&&(field, _)| field.attrs.flatten() && !field.attrs.skip_deserializing())
.map(|(field, name)| {
let field_ty = field.ty;
let func = match field.attrs.deserialize_with() {
None => {
let span = field.original.span();
quote_spanned!(span=> _serde::de::Deserialize::deserialize)
}
Some(path) => quote!(#path),
};
quote! {
let #name: #field_ty = #func(
_serde::#private::de::FlatMapDeserializer(
&mut __collect,
_serde::#private::PhantomData))?;
}
});
let collected_deny_unknown_fields = if has_flatten && cattrs.deny_unknown_fields() {
Some(quote! {
if let _serde::#private::Some(_serde::#private::Some((__key, _))) =
__collect.into_iter().filter(_serde::#private::Option::is_some).next()
{
if let _serde::#private::Some(__key) = _serde::#private::de::content_as_str(&__key) {
return _serde::#private::Err(
_serde::de::Error::custom(format_args!("unknown field `{}`", &__key)));
} else {
return _serde::#private::Err(
_serde::de::Error::custom(format_args!("unexpected map key")));
}
}
})
} else {
None
};
let result = fields_names.iter().map(|(field, name)| {
let member = &field.member;
if field.attrs.skip_deserializing() {
let value = Expr(expr_is_missing(field, cattrs));
quote!(#member: #value)
} else {
quote!(#member: #name)
}
});
let let_default = match cattrs.default() {
attr::Default::Default => Some(quote!(
let __default: Self::Value = _serde::#private::Default::default();
)),
// If #path returns wrong type, error will be reported here (^^^^^).
// We attach span of the path to the function so it will be reported
// on the #[serde(default = "...")]
// ^^^^^
attr::Default::Path(path) => Some(quote_spanned!(path.span()=>
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
}
};
let mut result = quote!(#struct_path { #(#result),* });
if params.has_getter {
let this_type = &params.this_type;
let (_, ty_generics, _) = params.generics.split_for_impl();
result = quote! {
_serde::#private::Into::<#this_type #ty_generics>::into(#result)
};
}
quote_block! {
#(#let_values)*
#let_collect
#match_keys
#let_default
#(#extract_values)*
#(#extract_collected)*
#collected_deny_unknown_fields
_serde::#private::Ok(#result)
}
}
#[cfg(feature = "deserialize_in_place")]
fn deserialize_map_in_place(
params: &Parameters,
fields: &[Field],
cattrs: &attr::Container,
) -> Fragment {
assert!(
!has_flatten(fields),
"inplace deserialization of maps does not support flatten fields"
);
// Create the field names for the fields.
let fields_names: Vec<_> = fields
.iter()
.enumerate()
.map(|(i, field)| (field, field_i(i)))
.collect();
// For deserialize_in_place, declare booleans for each field that will be
// deserialized.
let let_flags = fields_names
.iter()
.filter(|&&(field, _)| !field.attrs.skip_deserializing())
.map(|(_, name)| {
quote! {
let mut #name: bool = false;
}
});
// Match arms to extract a value for a field.
let value_arms_from = fields_names
.iter()
.filter(|&&(field, _)| !field.attrs.skip_deserializing())
.map(|(field, name)| {
let deser_name = field.attrs.name().deserialize_name();
let member = &field.member;
let visit = match field.attrs.deserialize_with() {
None => {
quote! {
_serde::de::MapAccess::next_value_seed(&mut __map, _serde::#private::de::InPlaceSeed(&mut self.place.#member))?
}
}
Some(path) => {
let (wrapper, wrapper_ty) = wrap_deserialize_field_with(params, field.ty, path);
quote!({
#wrapper
self.place.#member = match _serde::de::MapAccess::next_value::<#wrapper_ty>(&mut __map) {
_serde::#private::Ok(__wrapper) => __wrapper.value,
_serde::#private::Err(__err) => {
return _serde::#private::Err(__err);
}
};
})
}
};
quote! {
__Field::#name => {
if #name {
return _serde::#private::Err(<__A::Error as _serde::de::Error>::duplicate_field(#deser_name));
}
#visit;
#name = true;
}
}
});
// Visit ignored values to consume them
let ignored_arm = if cattrs.deny_unknown_fields() {
None
} else {
Some(quote! {
_ => { let _ = _serde::de::MapAccess::next_value::<_serde::de::IgnoredAny>(&mut __map)?; }
})
};
let all_skipped = fields.iter().all(|field| field.attrs.skip_deserializing());
let match_keys = if cattrs.deny_unknown_fields() && all_skipped {
quote! {
// FIXME: Once feature(exhaustive_patterns) is stable:
// let _serde::#private::None::<__Field> = _serde::de::MapAccess::next_key(&mut __map)?;
_serde::#private::Option::map(
_serde::de::MapAccess::next_key::<__Field>(&mut __map)?,
|__impossible| match __impossible {});
}
} else {
quote! {
while let _serde::#private::Some(__key) = _serde::de::MapAccess::next_key::<__Field>(&mut __map)? {
match __key {
#(#value_arms_from)*
#ignored_arm
}
}
}
};
let check_flags = fields_names
.iter()
.filter(|&&(field, _)| !field.attrs.skip_deserializing())
.map(|(field, name)| {
let missing_expr = expr_is_missing(field, cattrs);
// If missing_expr unconditionally returns an error, don't try
// to assign its value to self.place.
if field.attrs.default().is_none()
&& cattrs.default().is_none()
&& field.attrs.deserialize_with().is_some()
{
let missing_expr = Stmts(missing_expr);
quote! {
if !#name {
#missing_expr;
}
}
} else {
let member = &field.member;
let missing_expr = Expr(missing_expr);
quote! {
if !#name {
self.place.#member = #missing_expr;
};
}
}
});
let this_type = &params.this_type;
let (_, _, ty_generics, _) = params.generics();
let let_default = match cattrs.default() {
attr::Default::Default => Some(quote!(
let __default: #this_type #ty_generics = _serde::#private::Default::default();
)),
// If #path returns wrong type, error will be reported here (^^^^^).
// We attach span of the path to the function so it will be reported
// on the #[serde(default = "...")]
// ^^^^^
attr::Default::Path(path) => Some(quote_spanned!(path.span()=>
let __default: #this_type #ty_generics = #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_block! {
#(#let_flags)*
#match_keys
#let_default
#(#check_flags)*
_serde::#private::Ok(())
}
}
fn field_i(i: usize) -> Ident {
Ident::new(&format!("__field{}", i), Span::call_site())
}

5
serde_derive/src/de/enum_externally.rs
View File

@ -5,8 +5,9 @@
//! ```
use crate::de::enum_;
use crate::de::struct_;
use crate::de::{
deserialize_struct, deserialize_tuple, expr_is_missing, field_i,
deserialize_tuple, expr_is_missing, field_i,
unwrap_to_variant_closure, wrap_deserialize_field_with, wrap_deserialize_with, Parameters,
StructForm, TupleForm,
};
@ -148,7 +149,7 @@ fn deserialize_externally_tagged_variant(
cattrs,
TupleForm::ExternallyTagged(variant_ident),
),
Style::Struct => deserialize_struct(
Style::Struct => struct_::deserialize_struct(
params,
&variant.fields,
cattrs,

5
serde_derive/src/de/enum_internally.rs
View File

@ -7,8 +7,9 @@
use crate::de::enum_;
use crate::de::enum_untagged;
use crate::de::struct_;
use crate::de::{
deserialize_struct, effective_style, expr_is_missing, field_i,
effective_style, expr_is_missing, field_i,
unwrap_to_variant_closure, Parameters, StructForm,
};
use crate::fragment::{Expr, Fragment, Match};
@ -95,7 +96,7 @@ fn deserialize_internally_tagged_variant(
Style::Newtype => {
enum_untagged::deserialize_untagged_newtype_variant(variant_ident, params, &variant.fields[0])
}
Style::Struct => deserialize_struct(
Style::Struct => struct_::deserialize_struct(
params,
&variant.fields,
cattrs,

5
serde_derive/src/de/enum_untagged.rs
View File

@ -5,8 +5,9 @@
//! enum Enum {}
//! ```
use crate::de::struct_;
use crate::de::{
deserialize_struct, deserialize_tuple, effective_style, expr_is_missing,
deserialize_tuple, effective_style, expr_is_missing,
unwrap_to_variant_closure, Parameters, StructForm, TupleForm,
};
use crate::fragment::{Expr, Fragment};
@ -99,7 +100,7 @@ pub fn deserialize_untagged_variant(
cattrs,
TupleForm::Untagged(variant_ident),
),
Style::Struct => deserialize_struct(
Style::Struct => struct_::deserialize_struct(
params,
&variant.fields,
cattrs,

694
serde_derive/src/de/struct_.rs Normal file
View File

@ -0,0 +1,694 @@
use crate::de::{
deserialize_generated_identifier, deserialize_seq, expr_is_missing, field_i, has_flatten,
wrap_deserialize_field_with, FieldWithAliases, Parameters, StructForm,
};
#[cfg(feature = "deserialize_in_place")]
use crate::de::{deserialize_seq_in_place, place_lifetime};
use crate::fragment::{Expr, Fragment, Match, Stmts};
use crate::internals::ast::Field;
use crate::internals::attr;
use crate::private;
use proc_macro2::TokenStream;
use quote::{quote, quote_spanned};
use syn::spanned::Spanned;
/// Generates `Deserialize::deserialize` body for a `struct Struct {...}`
pub fn deserialize_struct(
params: &Parameters,
fields: &[Field],
cattrs: &attr::Container,
form: StructForm,
) -> Fragment {
let this_type = &params.this_type;
let this_value = &params.this_value;
let (de_impl_generics, de_ty_generics, ty_generics, where_clause) = params.generics();
let delife = params.borrowed.de_lifetime();
// If there are getters (implying private fields), construct the local type
// and use an `Into` conversion to get the remote type. If there are no
// getters then construct the target type directly.
let construct = if params.has_getter {
let local = &params.local;
quote!(#local)
} else {
quote!(#this_value)
};
let type_path = match form {
StructForm::Struct => construct,
StructForm::ExternallyTagged(variant_ident)
| StructForm::InternallyTagged(variant_ident)
| StructForm::Untagged(variant_ident) => quote!(#construct::#variant_ident),
};
let expecting = match form {
StructForm::Struct => format!("struct {}", params.type_name()),
StructForm::ExternallyTagged(variant_ident)
| StructForm::InternallyTagged(variant_ident)
| StructForm::Untagged(variant_ident) => {
format!("struct variant {}::{}", params.type_name(), variant_ident)
}
};
let expecting = cattrs.expecting().unwrap_or(&expecting);
let deserialized_fields: Vec<_> = fields
.iter()
.enumerate()
// Skip fields that shouldn't be deserialized or that were flattened,
// so they don't appear in the storage in their literal form
.filter(|&(_, field)| !field.attrs.skip_deserializing() && !field.attrs.flatten())
.map(|(i, field)| FieldWithAliases {
ident: field_i(i),
aliases: field.attrs.aliases(),
})
.collect();
let has_flatten = has_flatten(fields);
let field_visitor = deserialize_field_identifier(&deserialized_fields, cattrs, has_flatten);
// untagged struct variants do not get a visit_seq method. The same applies to
// structs that only have a map representation.
let visit_seq = match form {
StructForm::Untagged(_) => None,
_ if has_flatten => None,
_ => {
let mut_seq = if deserialized_fields.is_empty() {
quote!(_)
} else {
quote!(mut __seq)
};
let visit_seq = Stmts(deserialize_seq(
&type_path, params, fields, true, cattrs, expecting,
));
Some(quote! {
#[inline]
fn visit_seq<__A>(self, #mut_seq: __A) -> _serde::#private::Result<Self::Value, __A::Error>
where
__A: _serde::de::SeqAccess<#delife>,
{
#visit_seq
}
})
}
};
let visit_map = Stmts(deserialize_map(
&type_path,
params,
fields,
cattrs,
has_flatten,
));
let visitor_seed = match form {
StructForm::ExternallyTagged(..) if has_flatten => Some(quote! {
#[automatically_derived]
impl #de_impl_generics _serde::de::DeserializeSeed<#delife> for __Visitor #de_ty_generics #where_clause {
type Value = #this_type #ty_generics;
fn deserialize<__D>(self, __deserializer: __D) -> _serde::#private::Result<Self::Value, __D::Error>
where
__D: _serde::Deserializer<#delife>,
{
_serde::Deserializer::deserialize_map(__deserializer, self)
}
}
}),
_ => None,
};
let fields_stmt = if has_flatten {
None
} else {
let field_names = deserialized_fields.iter().flat_map(|field| field.aliases);
Some(quote! {
#[doc(hidden)]
const FIELDS: &'static [&'static str] = &[ #(#field_names),* ];
})
};
let visitor_expr = quote! {
__Visitor {
marker: _serde::#private::PhantomData::<#this_type #ty_generics>,
lifetime: _serde::#private::PhantomData,
}
};
let dispatch = match form {
StructForm::Struct if has_flatten => quote! {
_serde::Deserializer::deserialize_map(__deserializer, #visitor_expr)
},
StructForm::Struct => {
let type_name = cattrs.name().deserialize_name();
quote! {
_serde::Deserializer::deserialize_struct(__deserializer, #type_name, FIELDS, #visitor_expr)
}
}
StructForm::ExternallyTagged(_) if has_flatten => quote! {
_serde::de::VariantAccess::newtype_variant_seed(__variant, #visitor_expr)
},
StructForm::ExternallyTagged(_) => quote! {
_serde::de::VariantAccess::struct_variant(__variant, FIELDS, #visitor_expr)
},
StructForm::InternallyTagged(_) => quote! {
_serde::Deserializer::deserialize_any(__deserializer, #visitor_expr)
},
StructForm::Untagged(_) => quote! {
_serde::Deserializer::deserialize_any(__deserializer, #visitor_expr)
},
};
quote_block! {
#field_visitor
#[doc(hidden)]
struct __Visitor #de_impl_generics #where_clause {
marker: _serde::#private::PhantomData<#this_type #ty_generics>,
lifetime: _serde::#private::PhantomData<&#delife ()>,
}
#[automatically_derived]
impl #de_impl_generics _serde::de::Visitor<#delife> for __Visitor #de_ty_generics #where_clause {
type Value = #this_type #ty_generics;
fn expecting(&self, __formatter: &mut _serde::#private::Formatter) -> _serde::#private::fmt::Result {
_serde::#private::Formatter::write_str(__formatter, #expecting)
}
#visit_seq
#[inline]
fn visit_map<__A>(self, mut __map: __A) -> _serde::#private::Result<Self::Value, __A::Error>
where
__A: _serde::de::MapAccess<#delife>,
{
#visit_map
}
}
#visitor_seed
#fields_stmt
#dispatch
}
}
/// Generates `Deserialize::deserialize_in_place` body for a `struct Struct {...}`
#[cfg(feature = "deserialize_in_place")]
pub fn deserialize_struct_in_place(
params: &Parameters,
fields: &[Field],
cattrs: &attr::Container,
) -> Option<Fragment> {
// for now we do not support in_place deserialization for structs that
// are represented as map.
if has_flatten(fields) {
return None;
}
let this_type = &params.this_type;
let (de_impl_generics, de_ty_generics, ty_generics, where_clause) = params.generics();
let delife = params.borrowed.de_lifetime();
let expecting = format!("struct {}", params.type_name());
let expecting = cattrs.expecting().unwrap_or(&expecting);
let deserialized_fields: Vec<_> = fields
.iter()
.enumerate()
.filter(|&(_, field)| !field.attrs.skip_deserializing())
.map(|(i, field)| FieldWithAliases {
ident: field_i(i),
aliases: field.attrs.aliases(),
})
.collect();
let field_visitor = deserialize_field_identifier(&deserialized_fields, cattrs, false);
let mut_seq = if deserialized_fields.is_empty() {
quote!(_)
} else {
quote!(mut __seq)
};
let visit_seq = Stmts(deserialize_seq_in_place(params, fields, cattrs, expecting));
let visit_map = Stmts(deserialize_map_in_place(params, fields, cattrs));
let field_names = deserialized_fields.iter().flat_map(|field| field.aliases);
let type_name = cattrs.name().deserialize_name();
let in_place_impl_generics = de_impl_generics.in_place();
let in_place_ty_generics = de_ty_generics.in_place();
let place_life = place_lifetime();
Some(quote_block! {
#field_visitor
#[doc(hidden)]
struct __Visitor #in_place_impl_generics #where_clause {
place: &#place_life mut #this_type #ty_generics,
lifetime: _serde::#private::PhantomData<&#delife ()>,
}
#[automatically_derived]
impl #in_place_impl_generics _serde::de::Visitor<#delife> for __Visitor #in_place_ty_generics #where_clause {
type Value = ();
fn expecting(&self, __formatter: &mut _serde::#private::Formatter) -> _serde::#private::fmt::Result {
_serde::#private::Formatter::write_str(__formatter, #expecting)
}
#[inline]
fn visit_seq<__A>(self, #mut_seq: __A) -> _serde::#private::Result<Self::Value, __A::Error>
where
__A: _serde::de::SeqAccess<#delife>,
{
#visit_seq
}
#[inline]
fn visit_map<__A>(self, mut __map: __A) -> _serde::#private::Result<Self::Value, __A::Error>
where
__A: _serde::de::MapAccess<#delife>,
{
#visit_map
}
}
#[doc(hidden)]
const FIELDS: &'static [&'static str] = &[ #(#field_names),* ];
_serde::Deserializer::deserialize_struct(__deserializer, #type_name, FIELDS, __Visitor {
place: __place,
lifetime: _serde::#private::PhantomData,
})
})
}
/// Generates enum and its `Deserialize` implementation that represents each
/// non-skipped field of the struct
fn deserialize_field_identifier(
deserialized_fields: &[FieldWithAliases],
cattrs: &attr::Container,
has_flatten: bool,
) -> Stmts {
let (ignore_variant, fallthrough) = if has_flatten {
let ignore_variant = quote!(__other(_serde::#private::de::Content<'de>),);
let fallthrough = quote!(_serde::#private::Ok(__Field::__other(__value)));
(Some(ignore_variant), Some(fallthrough))
} else if cattrs.deny_unknown_fields() {
(None, None)
} else {
let ignore_variant = quote!(__ignore,);
let fallthrough = quote!(_serde::#private::Ok(__Field::__ignore));
(Some(ignore_variant), Some(fallthrough))
};
Stmts(deserialize_generated_identifier(
deserialized_fields,
has_flatten,
false,
ignore_variant,
fallthrough,
))
}
fn deserialize_map(
struct_path: &TokenStream,
params: &Parameters,
fields: &[Field],
cattrs: &attr::Container,
has_flatten: bool,
) -> Fragment {
// Create the field names for the fields.
let fields_names: Vec<_> = fields
.iter()
.enumerate()
.map(|(i, field)| (field, field_i(i)))
.collect();
// Declare each field that will be deserialized.
let let_values = fields_names
.iter()
.filter(|&&(field, _)| !field.attrs.skip_deserializing() && !field.attrs.flatten())
.map(|(field, name)| {
let field_ty = field.ty;
quote! {
let mut #name: _serde::#private::Option<#field_ty> = _serde::#private::None;
}
});
// Collect contents for flatten fields into a buffer
let let_collect = if has_flatten {
Some(quote! {
let mut __collect = _serde::#private::Vec::<_serde::#private::Option<(
_serde::#private::de::Content,
_serde::#private::de::Content
)>>::new();
})
} else {
None
};
// Match arms to extract a value for a field.
let value_arms = fields_names
.iter()
.filter(|&&(field, _)| !field.attrs.skip_deserializing() && !field.attrs.flatten())
.map(|(field, name)| {
let deser_name = field.attrs.name().deserialize_name();
let visit = match field.attrs.deserialize_with() {
None => {
let field_ty = field.ty;
let span = field.original.span();
let func =
quote_spanned!(span=> _serde::de::MapAccess::next_value::<#field_ty>);
quote! {
#func(&mut __map)?
}
}
Some(path) => {
let (wrapper, wrapper_ty) = wrap_deserialize_field_with(params, field.ty, path);
quote!({
#wrapper
match _serde::de::MapAccess::next_value::<#wrapper_ty>(&mut __map) {
_serde::#private::Ok(__wrapper) => __wrapper.value,
_serde::#private::Err(__err) => {
return _serde::#private::Err(__err);
}
}
})
}
};
quote! {
__Field::#name => {
if _serde::#private::Option::is_some(&#name) {
return _serde::#private::Err(<__A::Error as _serde::de::Error>::duplicate_field(#deser_name));
}
#name = _serde::#private::Some(#visit);
}
}
});
// Visit ignored values to consume them
let ignored_arm = if has_flatten {
Some(quote! {
__Field::__other(__name) => {
__collect.push(_serde::#private::Some((
__name,
_serde::de::MapAccess::next_value_seed(&mut __map, _serde::#private::de::ContentVisitor::new())?)));
}
})
} else if cattrs.deny_unknown_fields() {
None
} else {
Some(quote! {
_ => { let _ = _serde::de::MapAccess::next_value::<_serde::de::IgnoredAny>(&mut __map)?; }
})
};
let all_skipped = fields.iter().all(|field| field.attrs.skip_deserializing());
let match_keys = if cattrs.deny_unknown_fields() && all_skipped {
quote! {
// FIXME: Once feature(exhaustive_patterns) is stable:
// let _serde::#private::None::<__Field> = _serde::de::MapAccess::next_key(&mut __map)?;
_serde::#private::Option::map(
_serde::de::MapAccess::next_key::<__Field>(&mut __map)?,
|__impossible| match __impossible {});
}
} else {
quote! {
while let _serde::#private::Some(__key) = _serde::de::MapAccess::next_key::<__Field>(&mut __map)? {
match __key {
#(#value_arms)*
#ignored_arm
}
}
}
};
let extract_values = fields_names
.iter()
.filter(|&&(field, _)| !field.attrs.skip_deserializing() && !field.attrs.flatten())
.map(|(field, name)| {
let missing_expr = Match(expr_is_missing(field, cattrs));
quote! {
let #name = match #name {
_serde::#private::Some(#name) => #name,
_serde::#private::None => #missing_expr
};
}
});
let extract_collected = fields_names
.iter()
.filter(|&&(field, _)| field.attrs.flatten() && !field.attrs.skip_deserializing())
.map(|(field, name)| {
let field_ty = field.ty;
let func = match field.attrs.deserialize_with() {
None => {
let span = field.original.span();
quote_spanned!(span=> _serde::de::Deserialize::deserialize)
}
Some(path) => quote!(#path),
};
quote! {
let #name: #field_ty = #func(
_serde::#private::de::FlatMapDeserializer(
&mut __collect,
_serde::#private::PhantomData))?;
}
});
let collected_deny_unknown_fields = if has_flatten && cattrs.deny_unknown_fields() {
Some(quote! {
if let _serde::#private::Some(_serde::#private::Some((__key, _))) =
__collect.into_iter().filter(_serde::#private::Option::is_some).next()
{
if let _serde::#private::Some(__key) = _serde::#private::de::content_as_str(&__key) {
return _serde::#private::Err(
_serde::de::Error::custom(format_args!("unknown field `{}`", &__key)));
} else {
return _serde::#private::Err(
_serde::de::Error::custom(format_args!("unexpected map key")));
}
}
})
} else {
None
};
let result = fields_names.iter().map(|(field, name)| {
let member = &field.member;
if field.attrs.skip_deserializing() {
let value = Expr(expr_is_missing(field, cattrs));
quote!(#member: #value)
} else {
quote!(#member: #name)
}
});
let let_default = match cattrs.default() {
attr::Default::Default => Some(quote!(
let __default: Self::Value = _serde::#private::Default::default();
)),
// If #path returns wrong type, error will be reported here (^^^^^).
// We attach span of the path to the function so it will be reported
// on the #[serde(default = "...")]
// ^^^^^
attr::Default::Path(path) => Some(quote_spanned!(path.span()=>
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
}
};
let mut result = quote!(#struct_path { #(#result),* });
if params.has_getter {
let this_type = &params.this_type;
let (_, ty_generics, _) = params.generics.split_for_impl();
result = quote! {
_serde::#private::Into::<#this_type #ty_generics>::into(#result)
};
}
quote_block! {
#(#let_values)*
#let_collect
#match_keys
#let_default
#(#extract_values)*
#(#extract_collected)*
#collected_deny_unknown_fields
_serde::#private::Ok(#result)
}
}
#[cfg(feature = "deserialize_in_place")]
fn deserialize_map_in_place(
params: &Parameters,
fields: &[Field],
cattrs: &attr::Container,
) -> Fragment {
assert!(
!has_flatten(fields),
"inplace deserialization of maps does not support flatten fields"
);
// Create the field names for the fields.
let fields_names: Vec<_> = fields
.iter()
.enumerate()
.map(|(i, field)| (field, field_i(i)))
.collect();
// For deserialize_in_place, declare booleans for each field that will be
// deserialized.
let let_flags = fields_names
.iter()
.filter(|&&(field, _)| !field.attrs.skip_deserializing())
.map(|(_, name)| {
quote! {
let mut #name: bool = false;
}
});
// Match arms to extract a value for a field.
let value_arms_from = fields_names
.iter()
.filter(|&&(field, _)| !field.attrs.skip_deserializing())
.map(|(field, name)| {
let deser_name = field.attrs.name().deserialize_name();
let member = &field.member;
let visit = match field.attrs.deserialize_with() {
None => {
quote! {
_serde::de::MapAccess::next_value_seed(&mut __map, _serde::#private::de::InPlaceSeed(&mut self.place.#member))?
}
}
Some(path) => {
let (wrapper, wrapper_ty) = wrap_deserialize_field_with(params, field.ty, path);
quote!({
#wrapper
self.place.#member = match _serde::de::MapAccess::next_value::<#wrapper_ty>(&mut __map) {
_serde::#private::Ok(__wrapper) => __wrapper.value,
_serde::#private::Err(__err) => {
return _serde::#private::Err(__err);
}
};
})
}
};
quote! {
__Field::#name => {
if #name {
return _serde::#private::Err(<__A::Error as _serde::de::Error>::duplicate_field(#deser_name));
}
#visit;
#name = true;
}
}
});
// Visit ignored values to consume them
let ignored_arm = if cattrs.deny_unknown_fields() {
None
} else {
Some(quote! {
_ => { let _ = _serde::de::MapAccess::next_value::<_serde::de::IgnoredAny>(&mut __map)?; }
})
};
let all_skipped = fields.iter().all(|field| field.attrs.skip_deserializing());
let match_keys = if cattrs.deny_unknown_fields() && all_skipped {
quote! {
// FIXME: Once feature(exhaustive_patterns) is stable:
// let _serde::#private::None::<__Field> = _serde::de::MapAccess::next_key(&mut __map)?;
_serde::#private::Option::map(
_serde::de::MapAccess::next_key::<__Field>(&mut __map)?,
|__impossible| match __impossible {});
}
} else {
quote! {
while let _serde::#private::Some(__key) = _serde::de::MapAccess::next_key::<__Field>(&mut __map)? {
match __key {
#(#value_arms_from)*
#ignored_arm
}
}
}
};
let check_flags = fields_names
.iter()
.filter(|&&(field, _)| !field.attrs.skip_deserializing())
.map(|(field, name)| {
let missing_expr = expr_is_missing(field, cattrs);
// If missing_expr unconditionally returns an error, don't try
// to assign its value to self.place.
if field.attrs.default().is_none()
&& cattrs.default().is_none()
&& field.attrs.deserialize_with().is_some()
{
let missing_expr = Stmts(missing_expr);
quote! {
if !#name {
#missing_expr;
}
}
} else {
let member = &field.member;
let missing_expr = Expr(missing_expr);
quote! {
if !#name {
self.place.#member = #missing_expr;
};
}
}
});
let this_type = &params.this_type;
let (_, _, ty_generics, _) = params.generics();
let let_default = match cattrs.default() {
attr::Default::Default => Some(quote!(
let __default: #this_type #ty_generics = _serde::#private::Default::default();
)),
// If #path returns wrong type, error will be reported here (^^^^^).
// We attach span of the path to the function so it will be reported
// on the #[serde(default = "...")]
// ^^^^^
attr::Default::Path(path) => Some(quote_spanned!(path.span()=>
let __default: #this_type #ty_generics = #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_block! {
#(#let_flags)*
#match_keys
#let_default
#(#check_flags)*
_serde::#private::Ok(())
}
}