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Merge pull request #2987 from Mingun/split-de-generator

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Refactor: split de generator over multiple files
This commit is contained in:
David Tolnay 2025-09-25 09:41:29 -07:00 committed by GitHub
commit 502a065a4c
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10 changed files with 2416 additions and 2324 deletions
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2368
serde_derive/src/de.rs
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96
serde_derive/src/de/enum_.rs Normal file
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use crate::de::enum_adjacently;
use crate::de::enum_externally;
use crate::de::enum_internally;
use crate::de::enum_untagged;
use crate::de::identifier;
use crate::de::{field_i, FieldWithAliases, Parameters};
use crate::fragment::{Expr, Fragment, Stmts};
use crate::internals::ast::Variant;
use crate::internals::attr;
use crate::private;
use proc_macro2::TokenStream;
use quote::quote;
/// Generates `Deserialize::deserialize` body for an `enum Enum {...}`
pub(super) fn generate_body(
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));
// 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 tagged_frag = quote! {
if let _serde::#private::Result::<_, __D::Error>::Ok(__ok) = (|| #tagged_frag)() {
return _serde::#private::Ok(__ok);
}
};
enum_untagged::generate_body(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 => enum_externally::generate_body(params, variants, cattrs),
attr::TagType::Internal { tag } => {
enum_internally::generate_body(params, variants, cattrs, tag)
}
attr::TagType::Adjacent { tag, content } => {
enum_adjacently::generate_body(params, variants, cattrs, tag, content)
}
attr::TagType::None => enum_untagged::generate_body(params, variants, cattrs, None),
}
}
pub fn prepare_enum_variant_enum(variants: &[Variant]) -> (TokenStream, Stmts) {
let deserialized_variants = variants
.iter()
.enumerate()
.filter(|&(_i, variant)| !variant.attrs.skip_deserializing());
let fallthrough = deserialized_variants
.clone()
.find(|(_i, variant)| variant.attrs.other())
.map(|(i, _variant)| {
let ignore_variant = field_i(i);
quote!(_serde::#private::Ok(__Field::#ignore_variant))
});
let variants_stmt = {
let variant_names = deserialized_variants
.clone()
.flat_map(|(_i, variant)| variant.attrs.aliases());
quote! {
#[doc(hidden)]
const VARIANTS: &'static [&'static str] = &[ #(#variant_names),* ];
}
};
let deserialized_variants: Vec<_> = deserialized_variants
.map(|(i, variant)| FieldWithAliases {
ident: field_i(i),
aliases: variant.attrs.aliases(),
})
.collect();
let variant_visitor = Stmts(identifier::generate_identifier(
&deserialized_variants,
false, // variant identifiers do not depend on the presence of flatten fields
true,
None,
fallthrough,
));
(variants_stmt, variant_visitor)
}

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serde_derive/src/de/enum_adjacently.rs Normal file
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//! Generator of the deserialization code for the adjacently tagged enums:
//!
//! ```ignore
//! #[serde(tag = "...", content = "...")]
//! enum Enum {}
//! ```
use crate::de::enum_;
use crate::de::enum_untagged;
use crate::de::{field_i, Parameters};
use crate::fragment::{Fragment, Match};
use crate::internals::ast::{Style, Variant};
use crate::internals::attr;
use crate::private;
use quote::{quote, quote_spanned};
use syn::spanned::Spanned;
/// Generates `Deserialize::deserialize` body for an `enum Enum {...}` with `#[serde(tag, content)]` attributes
pub(super) fn generate_body(
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) = params.generics();
let delife = params.borrowed.de_lifetime();
let (variants_stmt, variant_visitor) = enum_::prepare_enum_variant_enum(variants);
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(enum_untagged::generate_variant(params, variant, cattrs));
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 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, #field_visitor_ty {
tag: #tag,
content: #content,
})?
};
let variant_from_map = quote! {
_serde::de::MapAccess::next_value_seed(&mut __map, _serde::#private::de::AdjacentlyTaggedEnumVariantSeed::<__Field> {
enum_name: #rust_name,
variants: VARIANTS,
fields_enum: _serde::#private::PhantomData
})?
};
// 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 __seed = __Seed {
variant: #variant_from_map,
marker: _serde::#private::PhantomData,
lifetime: _serde::#private::PhantomData,
};
let __deserializer = _serde::#private::de::ContentDeserializer::<__A::Error>::new(__content);
let __ret = _serde::de::DeserializeSeed::deserialize(__seed, __deserializer)?;
// Visit remaining keys, looking for duplicates.
#visit_remaining_keys
}
};
quote_block! {
#variant_visitor
#variants_stmt
#[doc(hidden)]
struct __Seed #de_impl_generics #where_clause {
variant: __Field,
marker: _serde::#private::PhantomData<#this_type #ty_generics>,
lifetime: _serde::#private::PhantomData<&#delife ()>,
}
#[automatically_derived]
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.variant {
#(#variant_arms)*
}
}
}
#[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)
}
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 {
variant: __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_seed(&mut __map, _serde::#private::de::ContentVisitor::new())?;
// Visit the second key.
match #next_relevant_key {
// Second key is the tag.
_serde::#private::Some(_serde::#private::de::TagOrContentField::Tag) => {
#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(__variant) => {
// Visit the second element - the content.
match _serde::de::SeqAccess::next_element_seed(
&mut __seq,
__Seed {
variant: __variant,
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,
},
)
}
}

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serde_derive/src/de/enum_externally.rs Normal file
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//! Generator of the deserialization code for the externally tagged enums:
//!
//! ```ignore
//! enum Enum {}
//! ```
use crate::de::enum_;
use crate::de::struct_;
use crate::de::tuple;
use crate::de::{
expr_is_missing, field_i, unwrap_to_variant_closure, wrap_deserialize_field_with,
wrap_deserialize_with, Parameters, StructForm, TupleForm,
};
use crate::fragment::{Expr, Fragment, Match};
use crate::internals::ast::{Field, Style, Variant};
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 an `enum Enum {...}` without additional attributes
pub(super) fn generate_body(
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) = params.generics();
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) = enum_::prepare_enum_variant_enum(variants);
// 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 ()>,
}
#[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)
}
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_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 => tuple::generate_body(
params,
&variant.fields,
cattrs,
TupleForm::ExternallyTagged(variant_ident),
),
Style::Struct => struct_::generate_body(
params,
&variant.fields,
cattrs,
StructForm::ExternallyTagged(variant_ident),
),
}
}
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)
}
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))
}
}
}
}

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//! Generator of the deserialization code for the internally tagged enums:
//!
//! ```ignore
//! #[serde(tag = "...")]
//! enum Enum {}
//! ```
use crate::de::enum_;
use crate::de::enum_untagged;
use crate::de::struct_;
use crate::de::{
effective_style, expr_is_missing, field_i, unwrap_to_variant_closure, Parameters, StructForm,
};
use crate::fragment::{Expr, Fragment, Match};
use crate::internals::ast::{Style, Variant};
use crate::internals::attr;
use crate::private;
use quote::quote;
/// Generates `Deserialize::deserialize` body for an `enum Enum {...}` with `#[serde(tag)]` attribute
pub(super) fn generate_body(
params: &Parameters,
variants: &[Variant],
cattrs: &attr::Container,
tag: &str,
) -> Fragment {
let (variants_stmt, variant_visitor) = enum_::prepare_enum_variant_enum(variants);
// 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! {
__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)*
}
}
}
// 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,
) -> 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.first().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 => {
enum_untagged::generate_newtype_variant(variant_ident, params, &variant.fields[0])
}
Style::Struct => struct_::generate_body(
params,
&variant.fields,
cattrs,
StructForm::InternallyTagged(variant_ident),
),
Style::Tuple => unreachable!("checked in serde_derive_internals"),
}
}

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serde_derive/src/de/enum_untagged.rs Normal file
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//! Generator of the deserialization code for the untagged enums:
//!
//! ```ignore
//! #[serde(untagged)]
//! enum Enum {}
//! ```
use crate::de::struct_;
use crate::de::tuple;
use crate::de::{
effective_style, expr_is_missing, unwrap_to_variant_closure, Parameters, StructForm, TupleForm,
};
use crate::fragment::{Expr, Fragment};
use crate::internals::ast::{Field, Style, Variant};
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 an `enum Enum {...}` with `#[serde(untagged)]` attribute
pub(super) fn generate_body(
params: &Parameters,
variants: &[Variant],
cattrs: &attr::Container,
first_attempt: Option<TokenStream>,
) -> Fragment {
let attempts = variants
.iter()
.filter(|variant| !variant.attrs.skip_deserializing())
.map(|variant| Expr(generate_variant(params, variant, cattrs)));
// 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);
let private2 = private;
quote_block! {
let __content = _serde::de::DeserializeSeed::deserialize(_serde::#private::de::ContentVisitor::new(), __deserializer)?;
let __deserializer = _serde::#private::de::ContentRefDeserializer::<__D::Error>::new(&__content);
#first_attempt
#(
if let _serde::#private2::Ok(__ok) = #attempts {
return _serde::#private2::Ok(__ok);
}
)*
_serde::#private::Err(_serde::de::Error::custom(#fallthrough_msg))
}
}
// Also used by adjacently tagged enums
pub(super) fn generate_variant(
params: &Parameters,
variant: &Variant,
cattrs: &attr::Container,
) -> 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.first().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 => generate_newtype_variant(variant_ident, params, &variant.fields[0]),
Style::Tuple => tuple::generate_body(
params,
&variant.fields,
cattrs,
TupleForm::Untagged(variant_ident),
),
Style::Struct => struct_::generate_body(
params,
&variant.fields,
cattrs,
StructForm::Untagged(variant_ident),
),
}
}
// Also used by internally tagged enums
// Implicitly (via `generate_variant`) used by adjacently tagged enums
pub(super) fn generate_newtype_variant(
variant_ident: &syn::Ident,
params: &Parameters,
field: &Field,
) -> 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)
}
}
}
}

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//! Contains generators of enums that represents identifiers of fields in structs or variants in enums.
use crate::de::{FieldWithAliases, Parameters};
use crate::fragment::{Fragment, Stmts};
use crate::internals::ast::{Style, Variant};
use crate::internals::attr;
use crate::private;
use proc_macro2::{Literal, TokenStream};
use quote::{quote, ToTokens};
// Generates `Deserialize::deserialize` body for an enum with
// `serde(field_identifier)` or `serde(variant_identifier)` attribute.
pub(super) fn generate_body(
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 idents_aliases: Vec<_> = ordinary
.iter()
.map(|variant| FieldWithAliases {
ident: variant.ident.clone(),
aliases: variant.attrs.aliases(),
})
.collect();
let names = idents_aliases.iter().flat_map(|variant| variant.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) = params.generics();
let delife = params.borrowed.de_lifetime();
let visitor_impl = Stmts(deserialize_identifier(
&this_value,
&idents_aliases,
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 ()>,
}
#[automatically_derived]
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)
}
}
pub(super) fn generate_identifier(
deserialized_fields: &[FieldWithAliases],
has_flatten: bool,
is_variant: bool,
ignore_variant: Option<TokenStream>,
fallthrough: Option<TokenStream>,
) -> Fragment {
let this_value = quote!(__Field);
let field_idents: &Vec<_> = &deserialized_fields
.iter()
.map(|field| &field.ident)
.collect();
let visitor_impl = Stmts(deserialize_identifier(
&this_value,
deserialized_fields,
is_variant,
fallthrough,
None,
!is_variant && has_flatten,
None,
));
let lifetime = if !is_variant && 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;
#[automatically_derived]
impl<'de> _serde::de::Visitor<'de> for __FieldVisitor {
type Value = __Field #lifetime;
#visitor_impl
}
#[automatically_derived]
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)
}
}
}
}
fn deserialize_identifier(
this_value: &TokenStream,
deserialized_fields: &[FieldWithAliases],
is_variant: bool,
fallthrough: Option<TokenStream>,
fallthrough_borrowed: Option<TokenStream>,
collect_other_fields: bool,
expecting: Option<&str>,
) -> Fragment {
let str_mapping = deserialized_fields.iter().map(|field| {
let ident = &field.ident;
let aliases = field.aliases;
let private2 = private;
// `aliases` also contains a main name
quote! {
#(
#aliases => _serde::#private2::Ok(#this_value::#ident),
)*
}
});
let bytes_mapping = deserialized_fields.iter().map(|field| {
let ident = &field.ident;
// `aliases` also contains a main name
let aliases = field
.aliases
.iter()
.map(|alias| Literal::byte_string(alias.value.as_bytes()));
let private2 = private;
quote! {
#(
#aliases => _serde::#private2::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 = deserialized_fields.iter().enumerate().map(|(i, field)| {
let i = i as u64;
let ident = &field.ident;
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,
deserialized_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
}
}

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use crate::de::identifier;
use crate::de::{
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(super) fn generate_body(
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
}
}
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)
}
}
/// Generates `Deserialize::deserialize_in_place` body for a `struct Struct {...}`
#[cfg(feature = "deserialize_in_place")]
pub(super) fn generate_body_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,
})
})
}
#[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(())
}
}
/// 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(identifier::generate_identifier(
deserialized_fields,
has_flatten,
false,
ignore_variant,
fallthrough,
))
}

281
serde_derive/src/de/tuple.rs Normal file
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@ -0,0 +1,281 @@
use crate::de::{deserialize_seq, has_flatten, Parameters, TupleForm};
#[cfg(feature = "deserialize_in_place")]
use crate::de::{deserialize_seq_in_place, place_lifetime};
use crate::fragment::{Fragment, 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 Tuple(...);` including `struct Newtype(T);`
pub(super) fn generate_body(
params: &Parameters,
fields: &[Field],
cattrs: &attr::Container,
form: TupleForm,
) -> Fragment {
assert!(
!has_flatten(fields),
"tuples and tuple variants cannot have flatten fields"
);
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) = 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 {
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(_) => 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 ()>,
}
#[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_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_newtype_struct(
type_path: &TokenStream,
params: &Parameters,
field: &Field,
) -> TokenStream {
let delife = params.borrowed.de_lifetime();
let field_ty = field.ty;
let deserializer_var = quote!(__e);
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(#deserializer_var)?
}
}
Some(path) => {
// 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(with = "...")]
// ^^^^^
quote_spanned! {path.span()=>
#path(#deserializer_var)?
}
}
};
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, #deserializer_var: __E) -> _serde::#private::Result<Self::Value, __E::Error>
where
__E: _serde::Deserializer<#delife>,
{
let __field0: #field_ty = #value;
_serde::#private::Ok(#result)
}
}
}
/// Generates `Deserialize::deserialize_in_place` body for a `struct Tuple(...);` including `struct Newtype(T);`
#[cfg(feature = "deserialize_in_place")]
pub(super) fn generate_body_in_place(
params: &Parameters,
fields: &[Field],
cattrs: &attr::Container,
) -> Fragment {
assert!(
!has_flatten(fields),
"tuples and tuple variants cannot have flatten fields"
);
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) = params.generics();
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 ()>,
}
#[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)
}
#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
}
}

51
serde_derive/src/de/unit.rs Normal file
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@ -0,0 +1,51 @@
use crate::de::Parameters;
use crate::fragment::Fragment;
use crate::internals::attr;
use crate::private;
use quote::quote;
/// Generates `Deserialize::deserialize` body for a `struct Unit;`
pub(super) fn generate_body(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) = params.generics();
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 ()>,
}
#[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)
}
#[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,
},
)
}
}