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b908487476633a397685a5a5f5265d4e0a4cd3a4
serde/serde_derive/src/de.rs
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David Tolnay b908487476 Remove double nesting of first_attempt 
`expr` is of type serde_derive::fragment::Expr, which can be
interpolated directly in any expression position. It does not
need to be nested in another set of braces.
2023-10-12 19:18:42 -07:00

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107 KiB
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use crate::fragment::{Expr, Fragment, Match, Stmts};
use crate::internals::ast::{Container, Data, Field, Style, Variant};
use crate::internals::{attr, replace_receiver, ungroup, Ctxt, Derive};
use crate::{bound, dummy, pretend, this};
use proc_macro2::{Literal, Span, TokenStream};
use quote::{quote, quote_spanned, ToTokens};
use std::collections::BTreeSet;
use std::ptr;
use syn::punctuated::Punctuated;
use syn::spanned::Spanned;
use syn::{parse_quote, Ident, Index, Member};
pub fn expand_derive_deserialize(input: &mut syn::DeriveInput) -> syn::Result<TokenStream> {
replace_receiver(input);
let ctxt = Ctxt::new();
let cont = match Container::from_ast(&ctxt, input, Derive::Deserialize) {
Some(cont) => cont,
None => return Err(ctxt.check().unwrap_err()),
};
precondition(&ctxt, &cont);
ctxt.check()?;
let ident = &cont.ident;
let params = Parameters::new(&cont);
let (de_impl_generics, _, ty_generics, where_clause) = split_with_de_lifetime(&params);
let body = Stmts(deserialize_body(&cont, &params));
let delife = params.borrowed.de_lifetime();
let serde = cont.attrs.serde_path();
let impl_block = if let Some(remote) = cont.attrs.remote() {
let vis = &input.vis;
let used = pretend::pretend_used(&cont, params.is_packed);
quote! {
impl #de_impl_generics #ident #ty_generics #where_clause {
#vis fn deserialize<__D>(__deserializer: __D) -> #serde::__private::Result<#remote #ty_generics, __D::Error>
where
__D: #serde::Deserializer<#delife>,
{
#used
#body
}
}
}
} else {
let fn_deserialize_in_place = deserialize_in_place_body(&cont, &params);
quote! {
#[automatically_derived]
impl #de_impl_generics #serde::Deserialize<#delife> for #ident #ty_generics #where_clause {
fn deserialize<__D>(__deserializer: __D) -> #serde::__private::Result<Self, __D::Error>
where
__D: #serde::Deserializer<#delife>,
{
#body
}
#fn_deserialize_in_place
}
}
};
Ok(dummy::wrap_in_const(
cont.attrs.custom_serde_path(),
impl_block,
))
}
fn precondition(cx: &Ctxt, cont: &Container) {
precondition_sized(cx, cont);
precondition_no_de_lifetime(cx, cont);
}
fn precondition_sized(cx: &Ctxt, cont: &Container) {
if let Data::Struct(_, fields) = &cont.data {
if let Some(last) = fields.last() {
if let syn::Type::Slice(_) = ungroup(last.ty) {
cx.error_spanned_by(
cont.original,
"cannot deserialize a dynamically sized struct",
);
}
}
}
}
fn precondition_no_de_lifetime(cx: &Ctxt, cont: &Container) {
if let BorrowedLifetimes::Borrowed(_) = borrowed_lifetimes(cont) {
for param in cont.generics.lifetimes() {
if param.lifetime.to_string() == "'de" {
cx.error_spanned_by(
&param.lifetime,
"cannot deserialize when there is a lifetime parameter called 'de",
);
return;
}
}
}
}
struct Parameters {
/// Name of the type the `derive` is on.
local: syn::Ident,
/// Path to the type the impl is for. Either a single `Ident` for local
/// types (does not include generic parameters) or `some::remote::Path` for
/// remote types.
this_type: syn::Path,
/// Same as `this_type` but using `::<T>` for generic parameters for use in
/// expression position.
this_value: syn::Path,
/// Generics including any explicit and inferred bounds for the impl.
generics: syn::Generics,
/// Lifetimes borrowed from the deserializer. These will become bounds on
/// the `'de` lifetime of the deserializer.
borrowed: BorrowedLifetimes,
/// At least one field has a serde(getter) attribute, implying that the
/// remote type has a private field.
has_getter: bool,
/// Type has a repr(packed) attribute.
is_packed: bool,
}
impl Parameters {
fn new(cont: &Container) -> Self {
let local = cont.ident.clone();
let this_type = this::this_type(cont);
let this_value = this::this_value(cont);
let borrowed = borrowed_lifetimes(cont);
let generics = build_generics(cont, &borrowed);
let has_getter = cont.data.has_getter();
let is_packed = cont.attrs.is_packed();
Parameters {
local,
this_type,
this_value,
generics,
borrowed,
has_getter,
is_packed,
}
}
/// Type name to use in error messages and `&'static str` arguments to
/// various Deserializer methods.
fn type_name(&self) -> String {
self.this_type.segments.last().unwrap().ident.to_string()
}
}
// All the generics in the input, plus a bound `T: Deserialize` for each generic
// field type that will be deserialized by us, plus a bound `T: Default` for
// each generic field type that will be set to a default value.
fn build_generics(cont: &Container, borrowed: &BorrowedLifetimes) -> syn::Generics {
let generics = bound::without_defaults(cont.generics);
let generics = bound::with_where_predicates_from_fields(cont, &generics, attr::Field::de_bound);
let generics =
bound::with_where_predicates_from_variants(cont, &generics, attr::Variant::de_bound);
match cont.attrs.de_bound() {
Some(predicates) => bound::with_where_predicates(&generics, predicates),
None => {
let generics = match *cont.attrs.default() {
attr::Default::Default => bound::with_self_bound(
cont,
&generics,
&parse_quote!(_serde::__private::Default),
),
attr::Default::None | attr::Default::Path(_) => generics,
};
let delife = borrowed.de_lifetime();
let generics = bound::with_bound(
cont,
&generics,
needs_deserialize_bound,
&parse_quote!(_serde::Deserialize<#delife>),
);
bound::with_bound(
cont,
&generics,
requires_default,
&parse_quote!(_serde::__private::Default),
)
}
}
}
// Fields with a `skip_deserializing` or `deserialize_with` attribute, or which
// belong to a variant with a `skip_deserializing` or `deserialize_with`
// attribute, are not deserialized by us so we do not generate a bound. Fields
// with a `bound` attribute specify their own bound so we do not generate one.
// All other fields may need a `T: Deserialize` bound where T is the type of the
// field.
fn needs_deserialize_bound(field: &attr::Field, variant: Option<&attr::Variant>) -> bool {
!field.skip_deserializing()
&& field.deserialize_with().is_none()
&& field.de_bound().is_none()
&& variant.map_or(true, |variant| {
!variant.skip_deserializing()
&& variant.deserialize_with().is_none()
&& variant.de_bound().is_none()
})
}
// Fields with a `default` attribute (not `default=...`), and fields with a
// `skip_deserializing` attribute that do not also have `default=...`.
fn requires_default(field: &attr::Field, _variant: Option<&attr::Variant>) -> bool {
if let attr::Default::Default = *field.default() {
true
} else {
false
}
}
enum BorrowedLifetimes {
Borrowed(BTreeSet<syn::Lifetime>),
Static,
}
impl BorrowedLifetimes {
fn de_lifetime(&self) -> syn::Lifetime {
match *self {
BorrowedLifetimes::Borrowed(_) => syn::Lifetime::new("'de", Span::call_site()),
BorrowedLifetimes::Static => syn::Lifetime::new("'static", Span::call_site()),
}
}
fn de_lifetime_param(&self) -> Option<syn::LifetimeParam> {
match self {
BorrowedLifetimes::Borrowed(bounds) => Some(syn::LifetimeParam {
attrs: Vec::new(),
lifetime: syn::Lifetime::new("'de", Span::call_site()),
colon_token: None,
bounds: bounds.iter().cloned().collect(),
}),
BorrowedLifetimes::Static => None,
}
}
}
// The union of lifetimes borrowed by each field of the container.
//
// These turn into bounds on the `'de` lifetime of the Deserialize impl. If
// lifetimes `'a` and `'b` are borrowed but `'c` is not, the impl is:
//
// impl<'de: 'a + 'b, 'a, 'b, 'c> Deserialize<'de> for S<'a, 'b, 'c>
//
// If any borrowed lifetime is `'static`, then `'de: 'static` would be redundant
// and we use plain `'static` instead of `'de`.
fn borrowed_lifetimes(cont: &Container) -> BorrowedLifetimes {
let mut lifetimes = BTreeSet::new();
for field in cont.data.all_fields() {
if !field.attrs.skip_deserializing() {
lifetimes.extend(field.attrs.borrowed_lifetimes().iter().cloned());
}
}
if lifetimes.iter().any(|b| b.to_string() == "'static") {
BorrowedLifetimes::Static
} else {
BorrowedLifetimes::Borrowed(lifetimes)
}
}
fn deserialize_body(cont: &Container, params: &Parameters) -> Fragment {
if cont.attrs.transparent() {
deserialize_transparent(cont, params)
} else if let Some(type_from) = cont.attrs.type_from() {
deserialize_from(type_from)
} else if let Some(type_try_from) = cont.attrs.type_try_from() {
deserialize_try_from(type_try_from)
} else if let attr::Identifier::No = cont.attrs.identifier() {
match &cont.data {
Data::Enum(variants) => deserialize_enum(params, variants, &cont.attrs),
Data::Struct(Style::Struct, fields) => {
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)
}
Data::Struct(Style::Unit, _) => deserialize_unit_struct(params, &cont.attrs),
}
} else {
match &cont.data {
Data::Enum(variants) => deserialize_custom_identifier(params, variants, &cont.attrs),
Data::Struct(_, _) => unreachable!("checked in serde_derive_internals"),
}
}
}
#[cfg(feature = "deserialize_in_place")]
fn deserialize_in_place_body(cont: &Container, params: &Parameters) -> Option<Stmts> {
// Only remote derives have getters, and we do not generate
// deserialize_in_place for remote derives.
assert!(!params.has_getter);
if cont.attrs.transparent()
|| cont.attrs.type_from().is_some()
|| cont.attrs.type_try_from().is_some()
|| cont.attrs.identifier().is_some()
|| cont
.data
.all_fields()
.all(|f| f.attrs.deserialize_with().is_some())
{
return None;
}
let code = match &cont.data {
Data::Struct(Style::Struct, fields) => {
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)
}
Data::Enum(_) | Data::Struct(Style::Unit, _) => {
return None;
}
};
let delife = params.borrowed.de_lifetime();
let stmts = Stmts(code);
let fn_deserialize_in_place = quote_block! {
fn deserialize_in_place<__D>(__deserializer: __D, __place: &mut Self) -> _serde::__private::Result<(), __D::Error>
where
__D: _serde::Deserializer<#delife>,
{
#stmts
}
};
Some(Stmts(fn_deserialize_in_place))
}
#[cfg(not(feature = "deserialize_in_place"))]
fn deserialize_in_place_body(_cont: &Container, _params: &Parameters) -> Option<Stmts> {
None
}
fn deserialize_transparent(cont: &Container, params: &Parameters) -> Fragment {
let fields = match &cont.data {
Data::Struct(_, fields) => fields,
Data::Enum(_) => unreachable!(),
};
let this_value = &params.this_value;
let transparent_field = fields.iter().find(|f| f.attrs.transparent()).unwrap();
let path = match transparent_field.attrs.deserialize_with() {
Some(path) => quote!(#path),
None => {
let span = transparent_field.original.span();
quote_spanned!(span=> _serde::Deserialize::deserialize)
}
};
let assign = fields.iter().map(|field| {
let member = &field.member;
if ptr::eq(field, transparent_field) {
quote!(#member: __transparent)
} else {
let value = match field.attrs.default() {
attr::Default::Default => quote!(_serde::__private::Default::default()),
attr::Default::Path(path) => quote!(#path()),
attr::Default::None => quote!(_serde::__private::PhantomData),
};
quote!(#member: #value)
}
});
quote_block! {
_serde::__private::Result::map(
#path(__deserializer),
|__transparent| #this_value { #(#assign),* })
}
}
fn deserialize_from(type_from: &syn::Type) -> Fragment {
quote_block! {
_serde::__private::Result::map(
<#type_from as _serde::Deserialize>::deserialize(__deserializer),
_serde::__private::From::from)
}
}
fn deserialize_try_from(type_try_from: &syn::Type) -> Fragment {
quote_block! {
_serde::__private::Result::and_then(
<#type_try_from as _serde::Deserialize>::deserialize(__deserializer),
|v| _serde::__private::TryFrom::try_from(v).map_err(_serde::de::Error::custom))
}
}
fn deserialize_unit_struct(params: &Parameters, cattrs: &attr::Container) -> Fragment {
let this_type = &params.this_type;
let this_value = &params.this_value;
let type_name = cattrs.name().deserialize_name();
let (de_impl_generics, de_ty_generics, ty_generics, where_clause) =
split_with_de_lifetime(params);
let delife = params.borrowed.de_lifetime();
let expecting = format!("unit struct {}", params.type_name());
let expecting = cattrs.expecting().unwrap_or(&expecting);
quote_block! {
#[doc(hidden)]
struct __Visitor #de_impl_generics #where_clause {
marker: _serde::__private::PhantomData<#this_type #ty_generics>,
lifetime: _serde::__private::PhantomData<&#delife ()>,
}
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)
}
#[inline]
fn visit_unit<__E>(self) -> _serde::__private::Result<Self::Value, __E>
where
__E: _serde::de::Error,
{
_serde::__private::Ok(#this_value)
}
}
_serde::Deserializer::deserialize_unit_struct(
__deserializer,
#type_name,
__Visitor {
marker: _serde::__private::PhantomData::<#this_type #ty_generics>,
lifetime: _serde::__private::PhantomData,
},
)
}
}
enum TupleForm<'a> {
Tuple,
/// Contains a variant name
ExternallyTagged(&'a syn::Ident),
/// Contains a variant name and an intermediate deserializer from which actual
/// deserialization will be performed
Untagged(&'a syn::Ident, TokenStream),
}
fn deserialize_tuple(
params: &Parameters,
fields: &[Field],
cattrs: &attr::Container,
form: TupleForm,
) -> Fragment {
assert!(!cattrs.has_flatten());
let field_count = fields
.iter()
.filter(|field| !field.attrs.skip_deserializing())
.count();
let this_type = &params.this_type;
let this_value = &params.this_value;
let (de_impl_generics, de_ty_generics, ty_generics, where_clause) =
split_with_de_lifetime(params);
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 {
TupleForm::Tuple => construct,
TupleForm::ExternallyTagged(variant_ident) | TupleForm::Untagged(variant_ident, _) => {
quote!(#construct::#variant_ident)
}
};
let expecting = match form {
TupleForm::Tuple => format!("tuple struct {}", params.type_name()),
TupleForm::ExternallyTagged(variant_ident) | TupleForm::Untagged(variant_ident, _) => {
format!("tuple variant {}::{}", params.type_name(), variant_ident)
}
};
let expecting = cattrs.expecting().unwrap_or(&expecting);
let nfields = fields.len();
let visit_newtype_struct = match form {
TupleForm::Tuple if nfields == 1 => {
Some(deserialize_newtype_struct(&type_path, params, &fields[0]))
}
_ => None,
};
let visit_seq = Stmts(deserialize_seq(
&type_path, params, fields, false, cattrs, expecting,
));
let visitor_expr = quote! {
__Visitor {
marker: _serde::__private::PhantomData::<#this_type #ty_generics>,
lifetime: _serde::__private::PhantomData,
}
};
let dispatch = match form {
TupleForm::Tuple if nfields == 1 => {
let type_name = cattrs.name().deserialize_name();
quote! {
_serde::Deserializer::deserialize_newtype_struct(__deserializer, #type_name, #visitor_expr)
}
}
TupleForm::Tuple => {
let type_name = cattrs.name().deserialize_name();
quote! {
_serde::Deserializer::deserialize_tuple_struct(__deserializer, #type_name, #field_count, #visitor_expr)
}
}
TupleForm::ExternallyTagged(_) => quote! {
_serde::de::VariantAccess::tuple_variant(__variant, #field_count, #visitor_expr)
},
TupleForm::Untagged(_, deserializer) => quote! {
_serde::Deserializer::deserialize_tuple(#deserializer, #field_count, #visitor_expr)
},
};
let visitor_var = if field_count == 0 {
quote!(_)
} else {
quote!(mut __seq)
};
quote_block! {
#[doc(hidden)]
struct __Visitor #de_impl_generics #where_clause {
marker: _serde::__private::PhantomData<#this_type #ty_generics>,
lifetime: _serde::__private::PhantomData<&#delife ()>,
}
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_newtype_struct
#[inline]
fn visit_seq<__A>(self, #visitor_var: __A) -> _serde::__private::Result<Self::Value, __A::Error>
where
__A: _serde::de::SeqAccess<#delife>,
{
#visit_seq
}
}
#dispatch
}
}
#[cfg(feature = "deserialize_in_place")]
fn deserialize_tuple_in_place(
params: &Parameters,
fields: &[Field],
cattrs: &attr::Container,
) -> Fragment {
assert!(!cattrs.has_flatten());
let field_count = fields
.iter()
.filter(|field| !field.attrs.skip_deserializing())
.count();
let this_type = &params.this_type;
let (de_impl_generics, de_ty_generics, ty_generics, where_clause) =
split_with_de_lifetime(params);
let delife = params.borrowed.de_lifetime();
let expecting = format!("tuple struct {}", params.type_name());
let expecting = cattrs.expecting().unwrap_or(&expecting);
let nfields = fields.len();
let visit_newtype_struct = if nfields == 1 {
// We do not generate deserialize_in_place if every field has a
// deserialize_with.
assert!(fields[0].attrs.deserialize_with().is_none());
Some(quote! {
#[inline]
fn visit_newtype_struct<__E>(self, __e: __E) -> _serde::__private::Result<Self::Value, __E::Error>
where
__E: _serde::Deserializer<#delife>,
{
_serde::Deserialize::deserialize_in_place(__e, &mut self.place.0)
}
})
} else {
None
};
let visit_seq = Stmts(deserialize_seq_in_place(params, fields, cattrs, expecting));
let visitor_expr = quote! {
__Visitor {
place: __place,
lifetime: _serde::__private::PhantomData,
}
};
let type_name = cattrs.name().deserialize_name();
let dispatch = if nfields == 1 {
quote!(_serde::Deserializer::deserialize_newtype_struct(__deserializer, #type_name, #visitor_expr))
} else {
quote!(_serde::Deserializer::deserialize_tuple_struct(__deserializer, #type_name, #field_count, #visitor_expr))
};
let visitor_var = if field_count == 0 {
quote!(_)
} else {
quote!(mut __seq)
};
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();
quote_block! {
#[doc(hidden)]
struct __Visitor #in_place_impl_generics #where_clause {
place: &#place_life mut #this_type #ty_generics,
lifetime: _serde::__private::PhantomData<&#delife ()>,
}
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)
}
#visit_newtype_struct
#[inline]
fn visit_seq<__A>(self, #visitor_var: __A) -> _serde::__private::Result<Self::Value, __A::Error>
where
__A: _serde::de::SeqAccess<#delife>,
{
#visit_seq
}
}
#dispatch
}
}
fn deserialize_seq(
type_path: &TokenStream,
params: &Parameters,
fields: &[Field],
is_struct: bool,
cattrs: &attr::Container,
expecting: &str,
) -> Fragment {
let vars = (0..fields.len()).map(field_i as fn(_) -> _);
let deserialized_count = fields
.iter()
.filter(|field| !field.attrs.skip_deserializing())
.count();
let expecting = if deserialized_count == 1 {
format!("{} with 1 element", expecting)
} else {
format!("{} with {} elements", expecting, deserialized_count)
};
let expecting = cattrs.expecting().unwrap_or(&expecting);
let mut index_in_seq = 0_usize;
let let_values = vars.clone().zip(fields).map(|(var, field)| {
if field.attrs.skip_deserializing() {
let default = Expr(expr_is_missing(field, cattrs));
quote! {
let #var = #default;
}
} else {
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::SeqAccess::next_element::<#field_ty>);
quote!(#func(&mut __seq)?)
}
Some(path) => {
let (wrapper, wrapper_ty) = wrap_deserialize_field_with(params, field.ty, path);
quote!({
#wrapper
_serde::__private::Option::map(
_serde::de::SeqAccess::next_element::<#wrapper_ty>(&mut __seq)?,
|__wrap| __wrap.value)
})
}
};
let value_if_none = expr_is_missing_seq(None, index_in_seq, field, cattrs, expecting);
let assign = quote! {
let #var = match #visit {
_serde::__private::Some(__value) => __value,
_serde::__private::None => #value_if_none,
};
};
index_in_seq += 1;
assign
}
});
let mut result = if is_struct {
let names = fields.iter().map(|f| &f.member);
quote! {
#type_path { #( #names: #vars ),* }
}
} else {
quote! {
#type_path ( #(#vars),* )
}
};
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)
};
}
let let_default = match cattrs.default() {
attr::Default::Default => Some(quote!(
let __default: Self::Value = _serde::__private::Default::default();
)),
attr::Default::Path(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_block! {
#let_default
#(#let_values)*
_serde::__private::Ok(#result)
}
}
#[cfg(feature = "deserialize_in_place")]
fn deserialize_seq_in_place(
params: &Parameters,
fields: &[Field],
cattrs: &attr::Container,
expecting: &str,
) -> Fragment {
let deserialized_count = fields
.iter()
.filter(|field| !field.attrs.skip_deserializing())
.count();
let expecting = if deserialized_count == 1 {
format!("{} with 1 element", expecting)
} else {
format!("{} with {} elements", expecting, deserialized_count)
};
let expecting = cattrs.expecting().unwrap_or(&expecting);
let mut index_in_seq = 0usize;
let write_values = fields.iter().map(|field| {
let member = &field.member;
if field.attrs.skip_deserializing() {
let default = Expr(expr_is_missing(field, cattrs));
quote! {
self.place.#member = #default;
}
} else {
let value_if_none = expr_is_missing_seq(Some(quote!(self.place.#member = )), index_in_seq, field, cattrs, expecting);
let write = match field.attrs.deserialize_with() {
None => {
quote! {
if let _serde::__private::None = _serde::de::SeqAccess::next_element_seed(&mut __seq,
_serde::__private::de::InPlaceSeed(&mut self.place.#member))?
{
#value_if_none;
}
}
}
Some(path) => {
let (wrapper, wrapper_ty) = wrap_deserialize_field_with(params, field.ty, path);
quote!({
#wrapper
match _serde::de::SeqAccess::next_element::<#wrapper_ty>(&mut __seq)? {
_serde::__private::Some(__wrap) => {
self.place.#member = __wrap.value;
}
_serde::__private::None => {
#value_if_none;
}
}
})
}
};
index_in_seq += 1;
write
}
});
let this_type = &params.this_type;
let (_, ty_generics, _) = params.generics.split_for_impl();
let let_default = match cattrs.default() {
attr::Default::Default => Some(quote!(
let __default: #this_type #ty_generics = _serde::__private::Default::default();
)),
attr::Default::Path(path) => Some(quote!(
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_default
#(#write_values)*
_serde::__private::Ok(())
}
}
fn deserialize_newtype_struct(
type_path: &TokenStream,
params: &Parameters,
field: &Field,
) -> TokenStream {
let delife = params.borrowed.de_lifetime();
let field_ty = field.ty;
let value = match field.attrs.deserialize_with() {
None => {
let span = field.original.span();
let func = quote_spanned!(span=> <#field_ty as _serde::Deserialize>::deserialize);
quote! {
#func(__e)?
}
}
Some(path) => {
quote! {
#path(__e)?
}
}
};
let mut result = quote!(#type_path(__field0));
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! {
#[inline]
fn visit_newtype_struct<__E>(self, __e: __E) -> _serde::__private::Result<Self::Value, __E::Error>
where
__E: _serde::Deserializer<#delife>,
{
let __field0: #field_ty = #value;
_serde::__private::Ok(#result)
}
}
}
enum StructForm<'a> {
Struct,
/// Contains a variant name
ExternallyTagged(&'a syn::Ident),
/// Contains a variant name and an intermediate deserializer from which actual
/// deserialization will be performed
InternallyTagged(&'a syn::Ident, TokenStream),
/// Contains a variant name and an intermediate deserializer from which actual
/// deserialization will be performed
Untagged(&'a syn::Ident, TokenStream),
}
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) =
split_with_de_lifetime(params);
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 field_names_idents: 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)| {
(
field.attrs.name().deserialize_name(),
field_i(i),
field.attrs.aliases(),
)
})
.collect();
let field_visitor = deserialize_field_identifier(&field_names_idents, cattrs);
// 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 cattrs.has_flatten() => None,
_ => {
let mut_seq = if field_names_idents.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));
let visitor_seed = match form {
StructForm::ExternallyTagged(..) if cattrs.has_flatten() => Some(quote! {
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 cattrs.has_flatten() {
None
} else {
let field_names = field_names_idents
.iter()
.flat_map(|&(_, _, aliases)| 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 cattrs.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 cattrs.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(_, deserializer) => quote! {
_serde::Deserializer::deserialize_any(#deserializer, #visitor_expr)
},
StructForm::Untagged(_, deserializer) => 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 ()>,
}
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
}
}
#[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 cattrs.has_flatten() {
return None;
}
let this_type = &params.this_type;
let (de_impl_generics, de_ty_generics, ty_generics, where_clause) =
split_with_de_lifetime(params);
let delife = params.borrowed.de_lifetime();
let expecting = format!("struct {}", params.type_name());
let expecting = cattrs.expecting().unwrap_or(&expecting);
let field_names_idents: Vec<_> = fields
.iter()
.enumerate()
.filter(|&(_, field)| !field.attrs.skip_deserializing())
.map(|(i, field)| {
(
field.attrs.name().deserialize_name(),
field_i(i),
field.attrs.aliases(),
)
})
.collect();
let field_visitor = deserialize_field_identifier(&field_names_idents, cattrs);
let mut_seq = if field_names_idents.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 = field_names_idents
.iter()
.flat_map(|&(_, _, aliases)| 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 ()>,
}
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,
})
})
}
fn deserialize_enum(
params: &Parameters,
variants: &[Variant],
cattrs: &attr::Container,
) -> Fragment {
// The variants have already been checked (in ast.rs) that all untagged variants appear at the end
match variants.iter().position(|var| var.attrs.untagged()) {
Some(variant_idx) => {
let (tagged, untagged) = variants.split_at(variant_idx);
let tagged_frag = Expr(deserialize_homogeneous_enum(params, tagged, cattrs));
deserialize_untagged_enum_after(params, untagged, cattrs, Some(tagged_frag))
}
None => deserialize_homogeneous_enum(params, variants, cattrs),
}
}
fn deserialize_homogeneous_enum(
params: &Parameters,
variants: &[Variant],
cattrs: &attr::Container,
) -> Fragment {
match cattrs.tag() {
attr::TagType::External => deserialize_externally_tagged_enum(params, variants, cattrs),
attr::TagType::Internal { tag } => {
deserialize_internally_tagged_enum(params, variants, cattrs, tag)
}
attr::TagType::Adjacent { tag, content } => {
deserialize_adjacently_tagged_enum(params, variants, cattrs, tag, content)
}
attr::TagType::None => deserialize_untagged_enum(params, variants, cattrs),
}
}
fn prepare_enum_variant_enum(
variants: &[Variant],
cattrs: &attr::Container,
) -> (TokenStream, Stmts) {
let mut deserialized_variants = variants
.iter()
.enumerate()
.filter(|&(_, variant)| !variant.attrs.skip_deserializing());
let variant_names_idents: Vec<_> = deserialized_variants
.clone()
.map(|(i, variant)| {
(
variant.attrs.name().deserialize_name(),
field_i(i),
variant.attrs.aliases(),
)
})
.collect();
let fallthrough = deserialized_variants
.position(|(_, variant)| variant.attrs.other())
.map(|other_idx| {
let ignore_variant = variant_names_idents[other_idx].1.clone();
quote!(_serde::__private::Ok(__Field::#ignore_variant))
});
let variants_stmt = {
let variant_names = variant_names_idents.iter().map(|(name, _, _)| name);
quote! {
#[doc(hidden)]
const VARIANTS: &'static [&'static str] = &[ #(#variant_names),* ];
}
};
let variant_visitor = Stmts(deserialize_generated_identifier(
&variant_names_idents,
cattrs,
true,
None,
fallthrough,
));
(variants_stmt, variant_visitor)
}
fn deserialize_externally_tagged_enum(
params: &Parameters,
variants: &[Variant],
cattrs: &attr::Container,
) -> Fragment {
let this_type = &params.this_type;
let (de_impl_generics, de_ty_generics, ty_generics, where_clause) =
split_with_de_lifetime(params);
let delife = params.borrowed.de_lifetime();
let type_name = cattrs.name().deserialize_name();
let expecting = format!("enum {}", params.type_name());
let expecting = cattrs.expecting().unwrap_or(&expecting);
let (variants_stmt, variant_visitor) = prepare_enum_variant_enum(variants, cattrs);
// Match arms to extract a variant from a string
let variant_arms = variants
.iter()
.enumerate()
.filter(|&(_, variant)| !variant.attrs.skip_deserializing())
.map(|(i, variant)| {
let variant_name = field_i(i);
let block = Match(deserialize_externally_tagged_variant(
params, variant, cattrs,
));
quote! {
(__Field::#variant_name, __variant) => #block
}
});
let all_skipped = variants
.iter()
.all(|variant| variant.attrs.skip_deserializing());
let match_variant = if all_skipped {
// This is an empty enum like `enum Impossible {}` or an enum in which
// all variants have `#[serde(skip_deserializing)]`.
quote! {
// FIXME: Once feature(exhaustive_patterns) is stable:
// let _serde::__private::Err(__err) = _serde::de::EnumAccess::variant::<__Field>(__data);
// _serde::__private::Err(__err)
_serde::__private::Result::map(
_serde::de::EnumAccess::variant::<__Field>(__data),
|(__impossible, _)| match __impossible {})
}
} else {
quote! {
match _serde::de::EnumAccess::variant(__data)? {
#(#variant_arms)*
}
}
};
quote_block! {
#variant_visitor
#[doc(hidden)]
struct __Visitor #de_impl_generics #where_clause {
marker: _serde::__private::PhantomData<#this_type #ty_generics>,
lifetime: _serde::__private::PhantomData<&#delife ()>,
}
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)
}
fn visit_enum<__A>(self, __data: __A) -> _serde::__private::Result<Self::Value, __A::Error>
where
__A: _serde::de::EnumAccess<#delife>,
{
#match_variant
}
}
#variants_stmt
_serde::Deserializer::deserialize_enum(
__deserializer,
#type_name,
VARIANTS,
__Visitor {
marker: _serde::__private::PhantomData::<#this_type #ty_generics>,
lifetime: _serde::__private::PhantomData,
},
)
}
}
fn deserialize_internally_tagged_enum(
params: &Parameters,
variants: &[Variant],
cattrs: &attr::Container,
tag: &str,
) -> Fragment {
let (variants_stmt, variant_visitor) = prepare_enum_variant_enum(variants, cattrs);
// Match arms to extract a variant from a string
let variant_arms = variants
.iter()
.enumerate()
.filter(|&(_, variant)| !variant.attrs.skip_deserializing())
.map(|(i, variant)| {
let variant_name = field_i(i);
let block = Match(deserialize_internally_tagged_variant(
params,
variant,
cattrs,
quote!(__deserializer),
));
quote! {
__Field::#variant_name => #block
}
});
let expecting = format!("internally tagged enum {}", params.type_name());
let expecting = cattrs.expecting().unwrap_or(&expecting);
quote_block! {
#variant_visitor
#variants_stmt
let (__tag, __content) = _serde::Deserializer::deserialize_any(
__deserializer,
_serde::__private::de::TaggedContentVisitor::<__Field>::new(#tag, #expecting))?;
let __deserializer = _serde::__private::de::ContentDeserializer::<__D::Error>::new(__content);
match __tag {
#(#variant_arms)*
}
}
}
fn deserialize_adjacently_tagged_enum(
params: &Parameters,
variants: &[Variant],
cattrs: &attr::Container,
tag: &str,
content: &str,
) -> Fragment {
let this_type = &params.this_type;
let this_value = &params.this_value;
let (de_impl_generics, de_ty_generics, ty_generics, where_clause) =
split_with_de_lifetime(params);
let delife = params.borrowed.de_lifetime();
let (variants_stmt, variant_visitor) = prepare_enum_variant_enum(variants, cattrs);
let variant_arms: &Vec<_> = &variants
.iter()
.enumerate()
.filter(|&(_, variant)| !variant.attrs.skip_deserializing())
.map(|(i, variant)| {
let variant_index = field_i(i);
let block = Match(deserialize_untagged_variant(
params,
variant,
cattrs,
quote!(__deserializer),
));
quote! {
__Field::#variant_index => #block
}
})
.collect();
let rust_name = params.type_name();
let expecting = format!("adjacently tagged enum {}", rust_name);
let expecting = cattrs.expecting().unwrap_or(&expecting);
let type_name = cattrs.name().deserialize_name();
let deny_unknown_fields = cattrs.deny_unknown_fields();
// If unknown fields are allowed, we pick the visitor that can step over
// those. Otherwise we pick the visitor that fails on unknown keys.
let field_visitor_ty = if deny_unknown_fields {
quote! { _serde::__private::de::TagOrContentFieldVisitor }
} else {
quote! { _serde::__private::de::TagContentOtherFieldVisitor }
};
let tag_or_content = quote! {
#field_visitor_ty {
tag: #tag,
content: #content,
}
};
let variant_seed = quote! {
_serde::__private::de::AdjacentlyTaggedEnumVariantSeed::<__Field> {
enum_name: #rust_name,
variants: VARIANTS,
fields_enum: _serde::__private::PhantomData
}
};
let mut missing_content = quote! {
_serde::__private::Err(<__A::Error as _serde::de::Error>::missing_field(#content))
};
let mut missing_content_fallthrough = quote!();
let missing_content_arms = variants
.iter()
.enumerate()
.filter(|&(_, variant)| !variant.attrs.skip_deserializing())
.filter_map(|(i, variant)| {
let variant_index = field_i(i);
let variant_ident = &variant.ident;
let arm = match variant.style {
Style::Unit => quote! {
_serde::__private::Ok(#this_value::#variant_ident)
},
Style::Newtype if variant.attrs.deserialize_with().is_none() => {
let span = variant.original.span();
let func = quote_spanned!(span=> _serde::__private::de::missing_field);
quote! {
#func(#content).map(#this_value::#variant_ident)
}
}
_ => {
missing_content_fallthrough = quote!(_ => #missing_content);
return None;
}
};
Some(quote! {
__Field::#variant_index => #arm,
})
})
.collect::<Vec<_>>();
if !missing_content_arms.is_empty() {
missing_content = quote! {
match __field {
#(#missing_content_arms)*
#missing_content_fallthrough
}
};
}
// Advance the map by one key, returning early in case of error.
let next_key = quote! {
_serde::de::MapAccess::next_key_seed(&mut __map, #tag_or_content)?
};
let variant_from_map = quote! {
_serde::de::MapAccess::next_value_seed(&mut __map, #variant_seed)?
};
// When allowing unknown fields, we want to transparently step through keys
// we don't care about until we find `tag`, `content`, or run out of keys.
let next_relevant_key = if deny_unknown_fields {
next_key
} else {
quote!({
let mut __rk : _serde::__private::Option<_serde::__private::de::TagOrContentField> = _serde::__private::None;
while let _serde::__private::Some(__k) = #next_key {
match __k {
_serde::__private::de::TagContentOtherField::Other => {
let _ = _serde::de::MapAccess::next_value::<_serde::de::IgnoredAny>(&mut __map)?;
continue;
},
_serde::__private::de::TagContentOtherField::Tag => {
__rk = _serde::__private::Some(_serde::__private::de::TagOrContentField::Tag);
break;
}
_serde::__private::de::TagContentOtherField::Content => {
__rk = _serde::__private::Some(_serde::__private::de::TagOrContentField::Content);
break;
}
}
}
__rk
})
};
// Step through remaining keys, looking for duplicates of previously-seen
// keys. When unknown fields are denied, any key that isn't a duplicate will
// at this point immediately produce an error.
let visit_remaining_keys = quote! {
match #next_relevant_key {
_serde::__private::Some(_serde::__private::de::TagOrContentField::Tag) => {
_serde::__private::Err(<__A::Error as _serde::de::Error>::duplicate_field(#tag))
}
_serde::__private::Some(_serde::__private::de::TagOrContentField::Content) => {
_serde::__private::Err(<__A::Error as _serde::de::Error>::duplicate_field(#content))
}
_serde::__private::None => _serde::__private::Ok(__ret),
}
};
let finish_content_then_tag = if variant_arms.is_empty() {
quote! {
match #variant_from_map {}
}
} else {
quote! {
let __ret = match #variant_from_map {
// Deserialize the buffered content now that we know the variant.
#(#variant_arms)*
}?;
// Visit remaining keys, looking for duplicates.
#visit_remaining_keys
}
};
quote_block! {
#variant_visitor
#variants_stmt
#[doc(hidden)]
struct __Seed #de_impl_generics #where_clause {
field: __Field,
marker: _serde::__private::PhantomData<#this_type #ty_generics>,
lifetime: _serde::__private::PhantomData<&#delife ()>,
}
impl #de_impl_generics _serde::de::DeserializeSeed<#delife> for __Seed #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>,
{
match self.field {
#(#variant_arms)*
}
}
}
#[doc(hidden)]
struct __Visitor #de_impl_generics #where_clause {
marker: _serde::__private::PhantomData<#this_type #ty_generics>,
lifetime: _serde::__private::PhantomData<&#delife ()>,
}
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)
}
fn visit_map<__A>(self, mut __map: __A) -> _serde::__private::Result<Self::Value, __A::Error>
where
__A: _serde::de::MapAccess<#delife>,
{
// Visit the first relevant key.
match #next_relevant_key {
// First key is the tag.
_serde::__private::Some(_serde::__private::de::TagOrContentField::Tag) => {
// Parse the tag.
let __field = #variant_from_map;
// Visit the second key.
match #next_relevant_key {
// Second key is a duplicate of the tag.
_serde::__private::Some(_serde::__private::de::TagOrContentField::Tag) => {
_serde::__private::Err(<__A::Error as _serde::de::Error>::duplicate_field(#tag))
}
// Second key is the content.
_serde::__private::Some(_serde::__private::de::TagOrContentField::Content) => {
let __ret = _serde::de::MapAccess::next_value_seed(&mut __map,
__Seed {
field: __field,
marker: _serde::__private::PhantomData,
lifetime: _serde::__private::PhantomData,
})?;
// Visit remaining keys, looking for duplicates.
#visit_remaining_keys
}
// There is no second key; might be okay if the we have a unit variant.
_serde::__private::None => #missing_content
}
}
// First key is the content.
_serde::__private::Some(_serde::__private::de::TagOrContentField::Content) => {
// Buffer up the content.
let __content = _serde::de::MapAccess::next_value::<_serde::__private::de::Content>(&mut __map)?;
// Visit the second key.
match #next_relevant_key {
// Second key is the tag.
_serde::__private::Some(_serde::__private::de::TagOrContentField::Tag) => {
let __deserializer = _serde::__private::de::ContentDeserializer::<__A::Error>::new(__content);
#finish_content_then_tag
}
// Second key is a duplicate of the content.
_serde::__private::Some(_serde::__private::de::TagOrContentField::Content) => {
_serde::__private::Err(<__A::Error as _serde::de::Error>::duplicate_field(#content))
}
// There is no second key.
_serde::__private::None => {
_serde::__private::Err(<__A::Error as _serde::de::Error>::missing_field(#tag))
}
}
}
// There is no first key.
_serde::__private::None => {
_serde::__private::Err(<__A::Error as _serde::de::Error>::missing_field(#tag))
}
}
}
fn visit_seq<__A>(self, mut __seq: __A) -> _serde::__private::Result<Self::Value, __A::Error>
where
__A: _serde::de::SeqAccess<#delife>,
{
// Visit the first element - the tag.
match _serde::de::SeqAccess::next_element(&mut __seq)? {
_serde::__private::Some(__field) => {
// Visit the second element - the content.
match _serde::de::SeqAccess::next_element_seed(
&mut __seq,
__Seed {
field: __field,
marker: _serde::__private::PhantomData,
lifetime: _serde::__private::PhantomData,
},
)? {
_serde::__private::Some(__ret) => _serde::__private::Ok(__ret),
// There is no second element.
_serde::__private::None => {
_serde::__private::Err(_serde::de::Error::invalid_length(1, &self))
}
}
}
// There is no first element.
_serde::__private::None => {
_serde::__private::Err(_serde::de::Error::invalid_length(0, &self))
}
}
}
}
#[doc(hidden)]
const FIELDS: &'static [&'static str] = &[#tag, #content];
_serde::Deserializer::deserialize_struct(
__deserializer,
#type_name,
FIELDS,
__Visitor {
marker: _serde::__private::PhantomData::<#this_type #ty_generics>,
lifetime: _serde::__private::PhantomData,
},
)
}
}
fn deserialize_untagged_enum(
params: &Parameters,
variants: &[Variant],
cattrs: &attr::Container,
) -> Fragment {
let first_attempt = None;
deserialize_untagged_enum_after(params, variants, cattrs, first_attempt)
}
fn deserialize_untagged_enum_after(
params: &Parameters,
variants: &[Variant],
cattrs: &attr::Container,
first_attempt: Option<Expr>,
) -> Fragment {
let attempts = variants
.iter()
.filter(|variant| !variant.attrs.skip_deserializing())
.map(|variant| {
Expr(deserialize_untagged_variant(
params,
variant,
cattrs,
quote!(__deserializer),
))
});
// TODO this message could be better by saving the errors from the failed
// attempts. The heuristic used by TOML was to count the number of fields
// processed before an error, and use the error that happened after the
// largest number of fields. I'm not sure I like that. Maybe it would be
// better to save all the errors and combine them into one message that
// explains why none of the variants matched.
let fallthrough_msg = format!(
"data did not match any variant of untagged enum {}",
params.type_name()
);
let fallthrough_msg = cattrs.expecting().unwrap_or(&fallthrough_msg);
// Ignore any error associated with non-untagged deserialization so that we
// can fall through to the untagged variants. This may be infallible so we
// need to provide the error type.
let first_attempt = first_attempt.map(|expr| {
quote! {
if let _serde::__private::Result::<_, __D::Error>::Ok(__ok) = (|| #expr)() {
return _serde::__private::Ok(__ok);
}
}
});
quote_block! {
let __content = <_serde::__private::de::Content as _serde::Deserialize>::deserialize(__deserializer)?;
let __deserializer = _serde::__private::de::ContentRefDeserializer::<__D::Error>::new(&__content);
#first_attempt
#(
if let _serde::__private::Ok(__ok) = #attempts {
return _serde::__private::Ok(__ok);
}
)*
_serde::__private::Err(_serde::de::Error::custom(#fallthrough_msg))
}
}
fn deserialize_externally_tagged_variant(
params: &Parameters,
variant: &Variant,
cattrs: &attr::Container,
) -> Fragment {
if let Some(path) = variant.attrs.deserialize_with() {
let (wrapper, wrapper_ty, unwrap_fn) = wrap_deserialize_variant_with(params, variant, path);
return quote_block! {
#wrapper
_serde::__private::Result::map(
_serde::de::VariantAccess::newtype_variant::<#wrapper_ty>(__variant), #unwrap_fn)
};
}
let variant_ident = &variant.ident;
match variant.style {
Style::Unit => {
let this_value = &params.this_value;
quote_block! {
_serde::de::VariantAccess::unit_variant(__variant)?;
_serde::__private::Ok(#this_value::#variant_ident)
}
}
Style::Newtype => deserialize_externally_tagged_newtype_variant(
variant_ident,
params,
&variant.fields[0],
cattrs,
),
Style::Tuple => deserialize_tuple(
params,
&variant.fields,
cattrs,
TupleForm::ExternallyTagged(variant_ident),
),
Style::Struct => deserialize_struct(
params,
&variant.fields,
cattrs,
StructForm::ExternallyTagged(variant_ident),
),
}
}
// Generates significant part of the visit_seq and visit_map bodies of visitors
// for the variants of internally tagged enum.
fn deserialize_internally_tagged_variant(
params: &Parameters,
variant: &Variant,
cattrs: &attr::Container,
deserializer: TokenStream,
) -> Fragment {
if variant.attrs.deserialize_with().is_some() {
return deserialize_untagged_variant(params, variant, cattrs, deserializer);
}
let variant_ident = &variant.ident;
match effective_style(variant) {
Style::Unit => {
let this_value = &params.this_value;
let type_name = params.type_name();
let variant_name = variant.ident.to_string();
let default = variant.fields.get(0).map(|field| {
let default = Expr(expr_is_missing(field, cattrs));
quote!((#default))
});
quote_block! {
_serde::Deserializer::deserialize_any(#deserializer, _serde::__private::de::InternallyTaggedUnitVisitor::new(#type_name, #variant_name))?;
_serde::__private::Ok(#this_value::#variant_ident #default)
}
}
Style::Newtype => deserialize_untagged_newtype_variant(
variant_ident,
params,
&variant.fields[0],
&deserializer,
),
Style::Struct => deserialize_struct(
params,
&variant.fields,
cattrs,
StructForm::InternallyTagged(variant_ident, deserializer),
),
Style::Tuple => unreachable!("checked in serde_derive_internals"),
}
}
fn deserialize_untagged_variant(
params: &Parameters,
variant: &Variant,
cattrs: &attr::Container,
deserializer: TokenStream,
) -> Fragment {
if let Some(path) = variant.attrs.deserialize_with() {
let unwrap_fn = unwrap_to_variant_closure(params, variant, false);
return quote_block! {
_serde::__private::Result::map(#path(#deserializer), #unwrap_fn)
};
}
let variant_ident = &variant.ident;
match effective_style(variant) {
Style::Unit => {
let this_value = &params.this_value;
let type_name = params.type_name();
let variant_name = variant.ident.to_string();
let default = variant.fields.get(0).map(|field| {
let default = Expr(expr_is_missing(field, cattrs));
quote!((#default))
});
quote_expr! {
match _serde::Deserializer::deserialize_any(
#deserializer,
_serde::__private::de::UntaggedUnitVisitor::new(#type_name, #variant_name)
) {
_serde::__private::Ok(()) => _serde::__private::Ok(#this_value::#variant_ident #default),
_serde::__private::Err(__err) => _serde::__private::Err(__err),
}
}
}
Style::Newtype => deserialize_untagged_newtype_variant(
variant_ident,
params,
&variant.fields[0],
&deserializer,
),
Style::Tuple => deserialize_tuple(
params,
&variant.fields,
cattrs,
TupleForm::Untagged(variant_ident, deserializer),
),
Style::Struct => deserialize_struct(
params,
&variant.fields,
cattrs,
StructForm::Untagged(variant_ident, deserializer),
),
}
}
fn deserialize_externally_tagged_newtype_variant(
variant_ident: &syn::Ident,
params: &Parameters,
field: &Field,
cattrs: &attr::Container,
) -> Fragment {
let this_value = &params.this_value;
if field.attrs.skip_deserializing() {
let default = Expr(expr_is_missing(field, cattrs));
return quote_block! {
_serde::de::VariantAccess::unit_variant(__variant)?;
_serde::__private::Ok(#this_value::#variant_ident(#default))
};
}
match field.attrs.deserialize_with() {
None => {
let field_ty = field.ty;
let span = field.original.span();
let func =
quote_spanned!(span=> _serde::de::VariantAccess::newtype_variant::<#field_ty>);
quote_expr! {
_serde::__private::Result::map(#func(__variant), #this_value::#variant_ident)
}
}
Some(path) => {
let (wrapper, wrapper_ty) = wrap_deserialize_field_with(params, field.ty, path);
quote_block! {
#wrapper
_serde::__private::Result::map(
_serde::de::VariantAccess::newtype_variant::<#wrapper_ty>(__variant),
|__wrapper| #this_value::#variant_ident(__wrapper.value))
}
}
}
}
fn deserialize_untagged_newtype_variant(
variant_ident: &syn::Ident,
params: &Parameters,
field: &Field,
deserializer: &TokenStream,
) -> Fragment {
let this_value = &params.this_value;
let field_ty = field.ty;
match field.attrs.deserialize_with() {
None => {
let span = field.original.span();
let func = quote_spanned!(span=> <#field_ty as _serde::Deserialize>::deserialize);
quote_expr! {
_serde::__private::Result::map(#func(#deserializer), #this_value::#variant_ident)
}
}
Some(path) => {
quote_block! {
let __value: _serde::__private::Result<#field_ty, _> = #path(#deserializer);
_serde::__private::Result::map(__value, #this_value::#variant_ident)
}
}
}
}
fn deserialize_generated_identifier(
fields: &[(&str, Ident, &BTreeSet<String>)],
cattrs: &attr::Container,
is_variant: bool,
ignore_variant: Option<TokenStream>,
fallthrough: Option<TokenStream>,
) -> Fragment {
let this_value = quote!(__Field);
let field_idents: &Vec<_> = &fields.iter().map(|(_, ident, _)| ident).collect();
let visitor_impl = Stmts(deserialize_identifier(
&this_value,
fields,
is_variant,
fallthrough,
None,
!is_variant && cattrs.has_flatten(),
None,
));
let lifetime = if !is_variant && cattrs.has_flatten() {
Some(quote!(<'de>))
} else {
None
};
quote_block! {
#[allow(non_camel_case_types)]
#[doc(hidden)]
enum __Field #lifetime {
#(#field_idents,)*
#ignore_variant
}
#[doc(hidden)]
struct __FieldVisitor;
impl<'de> _serde::de::Visitor<'de> for __FieldVisitor {
type Value = __Field #lifetime;
#visitor_impl
}
impl<'de> _serde::Deserialize<'de> for __Field #lifetime {
#[inline]
fn deserialize<__D>(__deserializer: __D) -> _serde::__private::Result<Self, __D::Error>
where
__D: _serde::Deserializer<'de>,
{
_serde::Deserializer::deserialize_identifier(__deserializer, __FieldVisitor)
}
}
}
}
/// Generates enum and its `Deserialize` implementation that represents each
/// non-skipped field of the struct
fn deserialize_field_identifier(
fields: &[(&str, Ident, &BTreeSet<String>)],
cattrs: &attr::Container,
) -> Stmts {
let (ignore_variant, fallthrough) = if cattrs.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(
fields,
cattrs,
false,
ignore_variant,
fallthrough,
))
}
// Generates `Deserialize::deserialize` body for an enum with
// `serde(field_identifier)` or `serde(variant_identifier)` attribute.
fn deserialize_custom_identifier(
params: &Parameters,
variants: &[Variant],
cattrs: &attr::Container,
) -> Fragment {
let is_variant = match cattrs.identifier() {
attr::Identifier::Variant => true,
attr::Identifier::Field => false,
attr::Identifier::No => unreachable!(),
};
let this_type = params.this_type.to_token_stream();
let this_value = params.this_value.to_token_stream();
let (ordinary, fallthrough, fallthrough_borrowed) = if let Some(last) = variants.last() {
let last_ident = &last.ident;
if last.attrs.other() {
// Process `serde(other)` attribute. It would always be found on the
// last variant (checked in `check_identifier`), so all preceding
// are ordinary variants.
let ordinary = &variants[..variants.len() - 1];
let fallthrough = quote!(_serde::__private::Ok(#this_value::#last_ident));
(ordinary, Some(fallthrough), None)
} else if let Style::Newtype = last.style {
let ordinary = &variants[..variants.len() - 1];
let fallthrough = |value| {
quote! {
_serde::__private::Result::map(
_serde::Deserialize::deserialize(
_serde::__private::de::IdentifierDeserializer::from(#value)
),
#this_value::#last_ident)
}
};
(
ordinary,
Some(fallthrough(quote!(__value))),
Some(fallthrough(quote!(_serde::__private::de::Borrowed(
__value
)))),
)
} else {
(variants, None, None)
}
} else {
(variants, None, None)
};
let names_idents: Vec<_> = ordinary
.iter()
.map(|variant| {
(
variant.attrs.name().deserialize_name(),
variant.ident.clone(),
variant.attrs.aliases(),
)
})
.collect();
let names = names_idents.iter().flat_map(|&(_, _, aliases)| aliases);
let names_const = if fallthrough.is_some() {
None
} else if is_variant {
let variants = quote! {
#[doc(hidden)]
const VARIANTS: &'static [&'static str] = &[ #(#names),* ];
};
Some(variants)
} else {
let fields = quote! {
#[doc(hidden)]
const FIELDS: &'static [&'static str] = &[ #(#names),* ];
};
Some(fields)
};
let (de_impl_generics, de_ty_generics, ty_generics, where_clause) =
split_with_de_lifetime(params);
let delife = params.borrowed.de_lifetime();
let visitor_impl = Stmts(deserialize_identifier(
&this_value,
&names_idents,
is_variant,
fallthrough,
fallthrough_borrowed,
false,
cattrs.expecting(),
));
quote_block! {
#names_const
#[doc(hidden)]
struct __FieldVisitor #de_impl_generics #where_clause {
marker: _serde::__private::PhantomData<#this_type #ty_generics>,
lifetime: _serde::__private::PhantomData<&#delife ()>,
}
impl #de_impl_generics _serde::de::Visitor<#delife> for __FieldVisitor #de_ty_generics #where_clause {
type Value = #this_type #ty_generics;
#visitor_impl
}
let __visitor = __FieldVisitor {
marker: _serde::__private::PhantomData::<#this_type #ty_generics>,
lifetime: _serde::__private::PhantomData,
};
_serde::Deserializer::deserialize_identifier(__deserializer, __visitor)
}
}
fn deserialize_identifier(
this_value: &TokenStream,
fields: &[(&str, Ident, &BTreeSet<String>)],
is_variant: bool,
fallthrough: Option<TokenStream>,
fallthrough_borrowed: Option<TokenStream>,
collect_other_fields: bool,
expecting: Option<&str>,
) -> Fragment {
let str_mapping = fields.iter().map(|(_, ident, aliases)| {
// `aliases` also contains a main name
quote!(#(#aliases)|* => _serde::__private::Ok(#this_value::#ident))
});
let bytes_mapping = fields.iter().map(|(_, ident, aliases)| {
// `aliases` also contains a main name
let aliases = aliases
.iter()
.map(|alias| Literal::byte_string(alias.as_bytes()));
quote!(#(#aliases)|* => _serde::__private::Ok(#this_value::#ident))
});
let expecting = expecting.unwrap_or(if is_variant {
"variant identifier"
} else {
"field identifier"
});
let bytes_to_str = if fallthrough.is_some() || collect_other_fields {
None
} else {
Some(quote! {
let __value = &_serde::__private::from_utf8_lossy(__value);
})
};
let (
value_as_str_content,
value_as_borrowed_str_content,
value_as_bytes_content,
value_as_borrowed_bytes_content,
) = if collect_other_fields {
(
Some(quote! {
let __value = _serde::__private::de::Content::String(_serde::__private::ToString::to_string(__value));
}),
Some(quote! {
let __value = _serde::__private::de::Content::Str(__value);
}),
Some(quote! {
let __value = _serde::__private::de::Content::ByteBuf(__value.to_vec());
}),
Some(quote! {
let __value = _serde::__private::de::Content::Bytes(__value);
}),
)
} else {
(None, None, None, None)
};
let fallthrough_arm_tokens;
let fallthrough_arm = if let Some(fallthrough) = &fallthrough {
fallthrough
} else if is_variant {
fallthrough_arm_tokens = quote! {
_serde::__private::Err(_serde::de::Error::unknown_variant(__value, VARIANTS))
};
&fallthrough_arm_tokens
} else {
fallthrough_arm_tokens = quote! {
_serde::__private::Err(_serde::de::Error::unknown_field(__value, FIELDS))
};
&fallthrough_arm_tokens
};
let visit_other = if collect_other_fields {
quote! {
fn visit_bool<__E>(self, __value: bool) -> _serde::__private::Result<Self::Value, __E>
where
__E: _serde::de::Error,
{
_serde::__private::Ok(__Field::__other(_serde::__private::de::Content::Bool(__value)))
}
fn visit_i8<__E>(self, __value: i8) -> _serde::__private::Result<Self::Value, __E>
where
__E: _serde::de::Error,
{
_serde::__private::Ok(__Field::__other(_serde::__private::de::Content::I8(__value)))
}
fn visit_i16<__E>(self, __value: i16) -> _serde::__private::Result<Self::Value, __E>
where
__E: _serde::de::Error,
{
_serde::__private::Ok(__Field::__other(_serde::__private::de::Content::I16(__value)))
}
fn visit_i32<__E>(self, __value: i32) -> _serde::__private::Result<Self::Value, __E>
where
__E: _serde::de::Error,
{
_serde::__private::Ok(__Field::__other(_serde::__private::de::Content::I32(__value)))
}
fn visit_i64<__E>(self, __value: i64) -> _serde::__private::Result<Self::Value, __E>
where
__E: _serde::de::Error,
{
_serde::__private::Ok(__Field::__other(_serde::__private::de::Content::I64(__value)))
}
fn visit_u8<__E>(self, __value: u8) -> _serde::__private::Result<Self::Value, __E>
where
__E: _serde::de::Error,
{
_serde::__private::Ok(__Field::__other(_serde::__private::de::Content::U8(__value)))
}
fn visit_u16<__E>(self, __value: u16) -> _serde::__private::Result<Self::Value, __E>
where
__E: _serde::de::Error,
{
_serde::__private::Ok(__Field::__other(_serde::__private::de::Content::U16(__value)))
}
fn visit_u32<__E>(self, __value: u32) -> _serde::__private::Result<Self::Value, __E>
where
__E: _serde::de::Error,
{
_serde::__private::Ok(__Field::__other(_serde::__private::de::Content::U32(__value)))
}
fn visit_u64<__E>(self, __value: u64) -> _serde::__private::Result<Self::Value, __E>
where
__E: _serde::de::Error,
{
_serde::__private::Ok(__Field::__other(_serde::__private::de::Content::U64(__value)))
}
fn visit_f32<__E>(self, __value: f32) -> _serde::__private::Result<Self::Value, __E>
where
__E: _serde::de::Error,
{
_serde::__private::Ok(__Field::__other(_serde::__private::de::Content::F32(__value)))
}
fn visit_f64<__E>(self, __value: f64) -> _serde::__private::Result<Self::Value, __E>
where
__E: _serde::de::Error,
{
_serde::__private::Ok(__Field::__other(_serde::__private::de::Content::F64(__value)))
}
fn visit_char<__E>(self, __value: char) -> _serde::__private::Result<Self::Value, __E>
where
__E: _serde::de::Error,
{
_serde::__private::Ok(__Field::__other(_serde::__private::de::Content::Char(__value)))
}
fn visit_unit<__E>(self) -> _serde::__private::Result<Self::Value, __E>
where
__E: _serde::de::Error,
{
_serde::__private::Ok(__Field::__other(_serde::__private::de::Content::Unit))
}
}
} else {
let u64_mapping = fields.iter().enumerate().map(|(i, (_, ident, _))| {
let i = i as u64;
quote!(#i => _serde::__private::Ok(#this_value::#ident))
});
let u64_fallthrough_arm_tokens;
let u64_fallthrough_arm = if let Some(fallthrough) = &fallthrough {
fallthrough
} else {
let index_expecting = if is_variant { "variant" } else { "field" };
let fallthrough_msg = format!("{} index 0 <= i < {}", index_expecting, fields.len());
u64_fallthrough_arm_tokens = quote! {
_serde::__private::Err(_serde::de::Error::invalid_value(
_serde::de::Unexpected::Unsigned(__value),
&#fallthrough_msg,
))
};
&u64_fallthrough_arm_tokens
};
quote! {
fn visit_u64<__E>(self, __value: u64) -> _serde::__private::Result<Self::Value, __E>
where
__E: _serde::de::Error,
{
match __value {
#(#u64_mapping,)*
_ => #u64_fallthrough_arm,
}
}
}
};
let visit_borrowed = if fallthrough_borrowed.is_some() || collect_other_fields {
let str_mapping = str_mapping.clone();
let bytes_mapping = bytes_mapping.clone();
let fallthrough_borrowed_arm = fallthrough_borrowed.as_ref().unwrap_or(fallthrough_arm);
Some(quote! {
fn visit_borrowed_str<__E>(self, __value: &'de str) -> _serde::__private::Result<Self::Value, __E>
where
__E: _serde::de::Error,
{
match __value {
#(#str_mapping,)*
_ => {
#value_as_borrowed_str_content
#fallthrough_borrowed_arm
}
}
}
fn visit_borrowed_bytes<__E>(self, __value: &'de [u8]) -> _serde::__private::Result<Self::Value, __E>
where
__E: _serde::de::Error,
{
match __value {
#(#bytes_mapping,)*
_ => {
#bytes_to_str
#value_as_borrowed_bytes_content
#fallthrough_borrowed_arm
}
}
}
})
} else {
None
};
quote_block! {
fn expecting(&self, __formatter: &mut _serde::__private::Formatter) -> _serde::__private::fmt::Result {
_serde::__private::Formatter::write_str(__formatter, #expecting)
}
#visit_other
fn visit_str<__E>(self, __value: &str) -> _serde::__private::Result<Self::Value, __E>
where
__E: _serde::de::Error,
{
match __value {
#(#str_mapping,)*
_ => {
#value_as_str_content
#fallthrough_arm
}
}
}
fn visit_bytes<__E>(self, __value: &[u8]) -> _serde::__private::Result<Self::Value, __E>
where
__E: _serde::de::Error,
{
match __value {
#(#bytes_mapping,)*
_ => {
#bytes_to_str
#value_as_bytes_content
#fallthrough_arm
}
}
}
#visit_borrowed
}
}
fn deserialize_map(
struct_path: &TokenStream,
params: &Parameters,
fields: &[Field],
cattrs: &attr::Container,
) -> 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 cattrs.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 cattrs.has_flatten() {
Some(quote! {
__Field::__other(__name) => {
__collect.push(_serde::__private::Some((
__name,
_serde::de::MapAccess::next_value(&mut __map)?)));
}
})
} 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 cattrs.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) = __key.as_str() {
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();
)),
attr::Default::Path(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
}
};
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!(!cattrs.has_flatten());
// 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, _) = split_with_de_lifetime(params);
let let_default = match cattrs.default() {
attr::Default::Default => Some(quote!(
let __default: #this_type #ty_generics = _serde::__private::Default::default();
)),
attr::Default::Path(path) => Some(quote!(
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())
}
/// This function wraps the expression in `#[serde(deserialize_with = "...")]`
/// in a trait to prevent it from accessing the internal `Deserialize` state.
fn wrap_deserialize_with(
params: &Parameters,
value_ty: &TokenStream,
deserialize_with: &syn::ExprPath,
) -> (TokenStream, TokenStream) {
let this_type = &params.this_type;
let (de_impl_generics, de_ty_generics, ty_generics, where_clause) =
split_with_de_lifetime(params);
let delife = params.borrowed.de_lifetime();
let wrapper = quote! {
#[doc(hidden)]
struct __DeserializeWith #de_impl_generics #where_clause {
value: #value_ty,
phantom: _serde::__private::PhantomData<#this_type #ty_generics>,
lifetime: _serde::__private::PhantomData<&#delife ()>,
}
impl #de_impl_generics _serde::Deserialize<#delife> for __DeserializeWith #de_ty_generics #where_clause {
fn deserialize<__D>(__deserializer: __D) -> _serde::__private::Result<Self, __D::Error>
where
__D: _serde::Deserializer<#delife>,
{
_serde::__private::Ok(__DeserializeWith {
value: #deserialize_with(__deserializer)?,
phantom: _serde::__private::PhantomData,
lifetime: _serde::__private::PhantomData,
})
}
}
};
let wrapper_ty = quote!(__DeserializeWith #de_ty_generics);
(wrapper, wrapper_ty)
}
fn wrap_deserialize_field_with(
params: &Parameters,
field_ty: &syn::Type,
deserialize_with: &syn::ExprPath,
) -> (TokenStream, TokenStream) {
wrap_deserialize_with(params, &quote!(#field_ty), deserialize_with)
}
fn wrap_deserialize_variant_with(
params: &Parameters,
variant: &Variant,
deserialize_with: &syn::ExprPath,
) -> (TokenStream, TokenStream, TokenStream) {
let field_tys = variant.fields.iter().map(|field| field.ty);
let (wrapper, wrapper_ty) =
wrap_deserialize_with(params, &quote!((#(#field_tys),*)), deserialize_with);
let unwrap_fn = unwrap_to_variant_closure(params, variant, true);
(wrapper, wrapper_ty, unwrap_fn)
}
// Generates closure that converts single input parameter to the final value.
fn unwrap_to_variant_closure(
params: &Parameters,
variant: &Variant,
with_wrapper: bool,
) -> TokenStream {
let this_value = &params.this_value;
let variant_ident = &variant.ident;
let (arg, wrapper) = if with_wrapper {
(quote! { __wrap }, quote! { __wrap.value })
} else {
let field_tys = variant.fields.iter().map(|field| field.ty);
(quote! { __wrap: (#(#field_tys),*) }, quote! { __wrap })
};
let field_access = (0..variant.fields.len()).map(|n| {
Member::Unnamed(Index {
index: n as u32,
span: Span::call_site(),
})
});
match variant.style {
Style::Struct if variant.fields.len() == 1 => {
let member = &variant.fields[0].member;
quote! {
|#arg| #this_value::#variant_ident { #member: #wrapper }
}
}
Style::Struct => {
let members = variant.fields.iter().map(|field| &field.member);
quote! {
|#arg| #this_value::#variant_ident { #(#members: #wrapper.#field_access),* }
}
}
Style::Tuple => quote! {
|#arg| #this_value::#variant_ident(#(#wrapper.#field_access),*)
},
Style::Newtype => quote! {
|#arg| #this_value::#variant_ident(#wrapper)
},
Style::Unit => quote! {
|#arg| #this_value::#variant_ident
},
}
}
fn expr_is_missing(field: &Field, cattrs: &attr::Container) -> Fragment {
match field.attrs.default() {
attr::Default::Default => {
let span = field.original.span();
let func = quote_spanned!(span=> _serde::__private::Default::default);
return quote_expr!(#func());
}
attr::Default::Path(path) => {
return quote_expr!(#path());
}
attr::Default::None => { /* below */ }
}
match *cattrs.default() {
attr::Default::Default | attr::Default::Path(_) => {
let member = &field.member;
return quote_expr!(__default.#member);
}
attr::Default::None => { /* below */ }
}
let name = field.attrs.name().deserialize_name();
match field.attrs.deserialize_with() {
None => {
let span = field.original.span();
let func = quote_spanned!(span=> _serde::__private::de::missing_field);
quote_expr! {
#func(#name)?
}
}
Some(_) => {
quote_expr! {
return _serde::__private::Err(<__A::Error as _serde::de::Error>::missing_field(#name))
}
}
}
}
fn expr_is_missing_seq(
assign_to: Option<TokenStream>,
index: usize,
field: &Field,
cattrs: &attr::Container,
expecting: &str,
) -> TokenStream {
match field.attrs.default() {
attr::Default::Default => {
let span = field.original.span();
return quote_spanned!(span=> #assign_to _serde::__private::Default::default());
}
attr::Default::Path(path) => {
return quote_spanned!(path.span()=> #assign_to #path());
}
attr::Default::None => { /* below */ }
}
match *cattrs.default() {
attr::Default::Default | attr::Default::Path(_) => {
let member = &field.member;
quote!(#assign_to __default.#member)
}
attr::Default::None => quote!(
return _serde::__private::Err(_serde::de::Error::invalid_length(#index, &#expecting))
),
}
}
fn effective_style(variant: &Variant) -> Style {
match variant.style {
Style::Newtype if variant.fields[0].attrs.skip_deserializing() => Style::Unit,
other => other,
}
}
struct DeImplGenerics<'a>(&'a Parameters);
#[cfg(feature = "deserialize_in_place")]
struct InPlaceImplGenerics<'a>(&'a Parameters);
impl<'a> ToTokens for DeImplGenerics<'a> {
fn to_tokens(&self, tokens: &mut TokenStream) {
let mut generics = self.0.generics.clone();
if let Some(de_lifetime) = self.0.borrowed.de_lifetime_param() {
generics.params = Some(syn::GenericParam::Lifetime(de_lifetime))
.into_iter()
.chain(generics.params)
.collect();
}
let (impl_generics, _, _) = generics.split_for_impl();
impl_generics.to_tokens(tokens);
}
}
#[cfg(feature = "deserialize_in_place")]
impl<'a> ToTokens for InPlaceImplGenerics<'a> {
fn to_tokens(&self, tokens: &mut TokenStream) {
let place_lifetime = place_lifetime();
let mut generics = self.0.generics.clone();
// Add lifetime for `&'place mut Self, and `'a: 'place`
for param in &mut generics.params {
match param {
syn::GenericParam::Lifetime(param) => {
param.bounds.push(place_lifetime.lifetime.clone());
}
syn::GenericParam::Type(param) => {
param.bounds.push(syn::TypeParamBound::Lifetime(
place_lifetime.lifetime.clone(),
));
}
syn::GenericParam::Const(_) => {}
}
}
generics.params = Some(syn::GenericParam::Lifetime(place_lifetime))
.into_iter()
.chain(generics.params)
.collect();
if let Some(de_lifetime) = self.0.borrowed.de_lifetime_param() {
generics.params = Some(syn::GenericParam::Lifetime(de_lifetime))
.into_iter()
.chain(generics.params)
.collect();
}
let (impl_generics, _, _) = generics.split_for_impl();
impl_generics.to_tokens(tokens);
}
}
#[cfg(feature = "deserialize_in_place")]
impl<'a> DeImplGenerics<'a> {
fn in_place(self) -> InPlaceImplGenerics<'a> {
InPlaceImplGenerics(self.0)
}
}
struct DeTypeGenerics<'a>(&'a Parameters);
#[cfg(feature = "deserialize_in_place")]
struct InPlaceTypeGenerics<'a>(&'a Parameters);
fn de_type_generics_to_tokens(
mut generics: syn::Generics,
borrowed: &BorrowedLifetimes,
tokens: &mut TokenStream,
) {
if borrowed.de_lifetime_param().is_some() {
let def = syn::LifetimeParam {
attrs: Vec::new(),
lifetime: syn::Lifetime::new("'de", Span::call_site()),
colon_token: None,
bounds: Punctuated::new(),
};
// Prepend 'de lifetime to list of generics
generics.params = Some(syn::GenericParam::Lifetime(def))
.into_iter()
.chain(generics.params)
.collect();
}
let (_, ty_generics, _) = generics.split_for_impl();
ty_generics.to_tokens(tokens);
}
impl<'a> ToTokens for DeTypeGenerics<'a> {
fn to_tokens(&self, tokens: &mut TokenStream) {
de_type_generics_to_tokens(self.0.generics.clone(), &self.0.borrowed, tokens);
}
}
#[cfg(feature = "deserialize_in_place")]
impl<'a> ToTokens for InPlaceTypeGenerics<'a> {
fn to_tokens(&self, tokens: &mut TokenStream) {
let mut generics = self.0.generics.clone();
generics.params = Some(syn::GenericParam::Lifetime(place_lifetime()))
.into_iter()
.chain(generics.params)
.collect();
de_type_generics_to_tokens(generics, &self.0.borrowed, tokens);
}
}
#[cfg(feature = "deserialize_in_place")]
impl<'a> DeTypeGenerics<'a> {
fn in_place(self) -> InPlaceTypeGenerics<'a> {
InPlaceTypeGenerics(self.0)
}
}
#[cfg(feature = "deserialize_in_place")]
fn place_lifetime() -> syn::LifetimeParam {
syn::LifetimeParam {
attrs: Vec::new(),
lifetime: syn::Lifetime::new("'place", Span::call_site()),
colon_token: None,
bounds: Punctuated::new(),
}
}
fn split_with_de_lifetime(
params: &Parameters,
) -> (
DeImplGenerics,
DeTypeGenerics,
syn::TypeGenerics,
Option<&syn::WhereClause>,
) {
let de_impl_generics = DeImplGenerics(params);
let de_ty_generics = DeTypeGenerics(params);
let (_, ty_generics, where_clause) = params.generics.split_for_impl();
(de_impl_generics, de_ty_generics, ty_generics, where_clause)
}
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