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use crate::internals::symbol::*;
use crate::internals::{ungroup, Ctxt};
use proc_macro2::{Spacing, Span, TokenStream, TokenTree};
use quote::ToTokens;
use std::borrow::Cow;
use std::collections::BTreeSet;
use std::iter::FromIterator;
use syn::meta::ParseNestedMeta;
use syn::parse::ParseStream;
use syn::punctuated::Punctuated;
use syn::{parse_quote, token, Ident, Lifetime, Token};
// This module handles parsing of `#[serde(...)]` attributes. The entrypoints
// are `attr::Container::from_ast`, `attr::Variant::from_ast`, and
// `attr::Field::from_ast`. Each returns an instance of the corresponding
// struct. Note that none of them return a Result. Unrecognized, malformed, or
// duplicated attributes result in a span_err but otherwise are ignored. The
// user will see errors simultaneously for all bad attributes in the crate
// rather than just the first.
pub use crate::internals::case::RenameRule;
struct Attr<'c, T> {
cx: &'c Ctxt,
name: Symbol,
tokens: TokenStream,
value: Option<T>,
}
impl<'c, T> Attr<'c, T> {
fn none(cx: &'c Ctxt, name: Symbol) -> Self {
Attr {
cx,
name,
tokens: TokenStream::new(),
value: None,
}
}
fn set<A: ToTokens>(&mut self, obj: A, value: T) {
let tokens = obj.into_token_stream();
if self.value.is_some() {
let msg = format!("duplicate serde attribute `{}`", self.name);
self.cx.error_spanned_by(tokens, msg);
} else {
self.tokens = tokens;
self.value = Some(value);
}
}
fn set_opt<A: ToTokens>(&mut self, obj: A, value: Option<T>) {
if let Some(value) = value {
self.set(obj, value);
}
}
fn set_if_none(&mut self, value: T) {
if self.value.is_none() {
self.value = Some(value);
}
}
fn get(self) -> Option<T> {
self.value
}
fn get_with_tokens(self) -> Option<(TokenStream, T)> {
match self.value {
Some(v) => Some((self.tokens, v)),
None => None,
}
}
}
struct BoolAttr<'c>(Attr<'c, ()>);
impl<'c> BoolAttr<'c> {
fn none(cx: &'c Ctxt, name: Symbol) -> Self {
BoolAttr(Attr::none(cx, name))
}
fn set_true<A: ToTokens>(&mut self, obj: A) {
self.0.set(obj, ());
}
fn get(&self) -> bool {
self.0.value.is_some()
}
}
struct VecAttr<'c, T> {
cx: &'c Ctxt,
name: Symbol,
first_dup_tokens: TokenStream,
values: Vec<T>,
}
impl<'c, T> VecAttr<'c, T> {
fn none(cx: &'c Ctxt, name: Symbol) -> Self {
VecAttr {
cx,
name,
first_dup_tokens: TokenStream::new(),
values: Vec::new(),
}
}
fn insert<A: ToTokens>(&mut self, obj: A, value: T) {
if self.values.len() == 1 {
self.first_dup_tokens = obj.into_token_stream();
}
self.values.push(value);
}
fn at_most_one(mut self) -> Option<T> {
if self.values.len() > 1 {
let dup_token = self.first_dup_tokens;
let msg = format!("duplicate serde attribute `{}`", self.name);
self.cx.error_spanned_by(dup_token, msg);
None
} else {
self.values.pop()
}
}
fn get(self) -> Vec<T> {
self.values
}
}
pub struct Name {
serialize: String,
serialize_renamed: bool,
deserialize: String,
deserialize_renamed: bool,
deserialize_aliases: BTreeSet<String>,
}
fn unraw(ident: &Ident) -> String {
ident.to_string().trim_start_matches("r#").to_owned()
}
impl Name {
fn from_attrs(
source_name: String,
ser_name: Attr<String>,
de_name: Attr<String>,
de_aliases: Option<VecAttr<String>>,
) -> Name {
let mut alias_set = BTreeSet::new();
if let Some(de_aliases) = de_aliases {
for alias_name in de_aliases.get() {
alias_set.insert(alias_name);
}
}
let ser_name = ser_name.get();
let ser_renamed = ser_name.is_some();
let de_name = de_name.get();
let de_renamed = de_name.is_some();
Name {
serialize: ser_name.unwrap_or_else(|| source_name.clone()),
serialize_renamed: ser_renamed,
deserialize: de_name.unwrap_or(source_name),
deserialize_renamed: de_renamed,
deserialize_aliases: alias_set,
}
}
/// Return the container name for the container when serializing.
pub fn serialize_name(&self) -> &str {
&self.serialize
}
/// Return the container name for the container when deserializing.
pub fn deserialize_name(&self) -> &str {
&self.deserialize
}
fn deserialize_aliases(&self) -> &BTreeSet<String> {
&self.deserialize_aliases
}
}
#[derive(Copy, Clone)]
pub struct RenameAllRules {
serialize: RenameRule,
deserialize: RenameRule,
}
impl RenameAllRules {
/// Returns a new `RenameAllRules` with the individual rules of `self` and
/// `other_rules` joined by `RenameRules::or`.
pub fn or(self, other_rules: Self) -> Self {
Self {
serialize: self.serialize.or(other_rules.serialize),
deserialize: self.deserialize.or(other_rules.deserialize),
}
}
}
/// Represents struct or enum attribute information.
pub struct Container {
name: Name,
transparent: bool,
deny_unknown_fields: bool,
default: Default,
rename_all_rules: RenameAllRules,
rename_all_fields_rules: RenameAllRules,
ser_bound: Option<Vec<syn::WherePredicate>>,
de_bound: Option<Vec<syn::WherePredicate>>,
tag: TagType,
type_from: Option<syn::Type>,
type_try_from: Option<syn::Type>,
type_into: Option<syn::Type>,
remote: Option<syn::Path>,
identifier: Identifier,
has_flatten: bool,
serde_path: Option<syn::Path>,
is_packed: bool,
/// Error message generated when type can't be deserialized
expecting: Option<String>,
non_exhaustive: bool,
}
/// Styles of representing an enum.
pub enum TagType {
/// The default.
///
/// ```json
/// {"variant1": {"key1": "value1", "key2": "value2"}}
/// ```
External,
/// `#[serde(tag = "type")]`
///
/// ```json
/// {"type": "variant1", "key1": "value1", "key2": "value2"}
/// ```
Internal { tag: String },
/// `#[serde(tag = "t", content = "c")]`
///
/// ```json
/// {"t": "variant1", "c": {"key1": "value1", "key2": "value2"}}
/// ```
Adjacent { tag: String, content: String },
/// `#[serde(untagged)]`
///
/// ```json
/// {"key1": "value1", "key2": "value2"}
/// ```
None,
}
/// Whether this enum represents the fields of a struct or the variants of an
/// enum.
#[derive(Copy, Clone)]
pub enum Identifier {
/// It does not.
No,
/// This enum represents the fields of a struct. All of the variants must be
/// unit variants, except possibly one which is annotated with
/// `#[serde(other)]` and is a newtype variant.
Field,
/// This enum represents the variants of an enum. All of the variants must
/// be unit variants.
Variant,
}
impl Identifier {
#[cfg(feature = "deserialize_in_place")]
pub fn is_some(self) -> bool {
match self {
Identifier::No => false,
Identifier::Field | Identifier::Variant => true,
}
}
}
impl Container {
/// Extract out the `#[serde(...)]` attributes from an item.
pub fn from_ast(cx: &Ctxt, item: &syn::DeriveInput) -> Self {
let mut ser_name = Attr::none(cx, RENAME);
let mut de_name = Attr::none(cx, RENAME);
let mut transparent = BoolAttr::none(cx, TRANSPARENT);
let mut deny_unknown_fields = BoolAttr::none(cx, DENY_UNKNOWN_FIELDS);
let mut default = Attr::none(cx, DEFAULT);
let mut rename_all_ser_rule = Attr::none(cx, RENAME_ALL);
let mut rename_all_de_rule = Attr::none(cx, RENAME_ALL);
let mut rename_all_fields_ser_rule = Attr::none(cx, RENAME_ALL_FIELDS);
let mut rename_all_fields_de_rule = Attr::none(cx, RENAME_ALL_FIELDS);
let mut ser_bound = Attr::none(cx, BOUND);
let mut de_bound = Attr::none(cx, BOUND);
let mut untagged = BoolAttr::none(cx, UNTAGGED);
let mut internal_tag = Attr::none(cx, TAG);
let mut content = Attr::none(cx, CONTENT);
let mut type_from = Attr::none(cx, FROM);
let mut type_try_from = Attr::none(cx, TRY_FROM);
let mut type_into = Attr::none(cx, INTO);
let mut remote = Attr::none(cx, REMOTE);
let mut field_identifier = BoolAttr::none(cx, FIELD_IDENTIFIER);
let mut variant_identifier = BoolAttr::none(cx, VARIANT_IDENTIFIER);
let mut serde_path = Attr::none(cx, CRATE);
let mut expecting = Attr::none(cx, EXPECTING);
let mut non_exhaustive = false;
for attr in &item.attrs {
if attr.path() != SERDE {
non_exhaustive |=
matches!(&attr.meta, syn::Meta::Path(path) if path == NON_EXHAUSTIVE);
continue;
}
if let syn::Meta::List(meta) = &attr.meta {
if meta.tokens.is_empty() {
continue;
}
}
if let Err(err) = attr.parse_nested_meta(|meta| {
if meta.path == RENAME {
// #[serde(rename = "foo")]
// #[serde(rename(serialize = "foo", deserialize = "bar"))]
let (ser, de) = get_renames(cx, RENAME, &meta)?;
ser_name.set_opt(&meta.path, ser.as_ref().map(syn::LitStr::value));
de_name.set_opt(&meta.path, de.as_ref().map(syn::LitStr::value));
} else if meta.path == RENAME_ALL {
// #[serde(rename_all = "foo")]
// #[serde(rename_all(serialize = "foo", deserialize = "bar"))]
let one_name = meta.input.peek(Token![=]);
let (ser, de) = get_renames(cx, RENAME_ALL, &meta)?;
if let Some(ser) = ser {
match RenameRule::from_str(&ser.value()) {
Ok(rename_rule) => rename_all_ser_rule.set(&meta.path, rename_rule),
Err(err) => cx.error_spanned_by(ser, err),
}
}
if let Some(de) = de {
match RenameRule::from_str(&de.value()) {
Ok(rename_rule) => rename_all_de_rule.set(&meta.path, rename_rule),
Err(err) => {
if !one_name {
cx.error_spanned_by(de, err);
}
}
}
}
} else if meta.path == RENAME_ALL_FIELDS {
// #[serde(rename_all_fields = "foo")]
// #[serde(rename_all_fields(serialize = "foo", deserialize = "bar"))]
let one_name = meta.input.peek(Token![=]);
let (ser, de) = get_renames(cx, RENAME_ALL_FIELDS, &meta)?;
match item.data {
syn::Data::Enum(_) => {
if let Some(ser) = ser {
match RenameRule::from_str(&ser.value()) {
Ok(rename_rule) => {
rename_all_fields_ser_rule.set(&meta.path, rename_rule);
}
Err(err) => cx.error_spanned_by(ser, err),
}
}
if let Some(de) = de {
match RenameRule::from_str(&de.value()) {
Ok(rename_rule) => {
rename_all_fields_de_rule.set(&meta.path, rename_rule);
}
Err(err) => {
if !one_name {
cx.error_spanned_by(de, err);
}
}
}
}
}
syn::Data::Struct(_) => {
let msg = "#[serde(rename_all_fields)] can only be used on enums";
cx.syn_error(meta.error(msg));
}
syn::Data::Union(_) => {
let msg = "#[serde(rename_all_fields)] can only be used on enums";
cx.syn_error(meta.error(msg));
}
}
} else if meta.path == TRANSPARENT {
// #[serde(transparent)]
transparent.set_true(meta.path);
} else if meta.path == DENY_UNKNOWN_FIELDS {
// #[serde(deny_unknown_fields)]
deny_unknown_fields.set_true(meta.path);
} else if meta.path == DEFAULT {
if meta.input.peek(Token![=]) {
// #[serde(default = "...")]
if let Some(path) = parse_lit_into_expr_path(cx, DEFAULT, &meta)? {
match &item.data {
syn::Data::Struct(syn::DataStruct { fields, .. }) => match fields {
syn::Fields::Named(_) | syn::Fields::Unnamed(_) => {
default.set(&meta.path, Default::Path(path));
}
syn::Fields::Unit => {
let msg = "#[serde(default = \"...\")] can only be used on structs that have fields";
cx.syn_error(meta.error(msg));
}
},
syn::Data::Enum(_) => {
let msg = "#[serde(default = \"...\")] can only be used on structs";
cx.syn_error(meta.error(msg));
}
syn::Data::Union(_) => {
let msg = "#[serde(default = \"...\")] can only be used on structs";
cx.syn_error(meta.error(msg));
}
}
}
} else {
// #[serde(default)]
match &item.data {
syn::Data::Struct(syn::DataStruct { fields, .. }) => match fields {
syn::Fields::Named(_) | syn::Fields::Unnamed(_) => {
default.set(meta.path, Default::Default);
}
syn::Fields::Unit => {
let msg = "#[serde(default)] can only be used on structs that have fields";
cx.error_spanned_by(fields, msg);
}
},
syn::Data::Enum(_) => {
let msg = "#[serde(default)] can only be used on structs";
cx.syn_error(meta.error(msg));
}
syn::Data::Union(_) => {
let msg = "#[serde(default)] can only be used on structs";
cx.syn_error(meta.error(msg));
}
}
}
} else if meta.path == BOUND {
// #[serde(bound = "T: SomeBound")]
// #[serde(bound(serialize = "...", deserialize = "..."))]
let (ser, de) = get_where_predicates(cx, &meta)?;
ser_bound.set_opt(&meta.path, ser);
de_bound.set_opt(&meta.path, de);
} else if meta.path == UNTAGGED {
// #[serde(untagged)]
match item.data {
syn::Data::Enum(_) => {
untagged.set_true(&meta.path);
}
syn::Data::Struct(_) => {
let msg = "#[serde(untagged)] can only be used on enums";
cx.syn_error(meta.error(msg));
}
syn::Data::Union(_) => {
let msg = "#[serde(untagged)] can only be used on enums";
cx.syn_error(meta.error(msg));
}
}
} else if meta.path == TAG {
// #[serde(tag = "type")]
if let Some(s) = get_lit_str(cx, TAG, &meta)? {
match &item.data {
syn::Data::Enum(_) => {
internal_tag.set(&meta.path, s.value());
}
syn::Data::Struct(syn::DataStruct { fields, .. }) => match fields {
syn::Fields::Named(_) => {
internal_tag.set(&meta.path, s.value());
}
syn::Fields::Unnamed(_) | syn::Fields::Unit => {
let msg = "#[serde(tag = \"...\")] can only be used on enums and structs with named fields";
cx.syn_error(meta.error(msg));
}
},
syn::Data::Union(_) => {
let msg = "#[serde(tag = \"...\")] can only be used on enums and structs with named fields";
cx.syn_error(meta.error(msg));
}
}
}
} else if meta.path == CONTENT {
// #[serde(content = "c")]
if let Some(s) = get_lit_str(cx, CONTENT, &meta)? {
match &item.data {
syn::Data::Enum(_) => {
content.set(&meta.path, s.value());
}
syn::Data::Struct(_) => {
let msg = "#[serde(content = \"...\")] can only be used on enums";
cx.syn_error(meta.error(msg));
}
syn::Data::Union(_) => {
let msg = "#[serde(content = \"...\")] can only be used on enums";
cx.syn_error(meta.error(msg));
}
}
}
} else if meta.path == FROM {
// #[serde(from = "Type")]
if let Some(from_ty) = parse_lit_into_ty(cx, FROM, &meta)? {
type_from.set_opt(&meta.path, Some(from_ty));
}
} else if meta.path == TRY_FROM {
// #[serde(try_from = "Type")]
if let Some(try_from_ty) = parse_lit_into_ty(cx, TRY_FROM, &meta)? {
type_try_from.set_opt(&meta.path, Some(try_from_ty));
}
} else if meta.path == INTO {
// #[serde(into = "Type")]
if let Some(into_ty) = parse_lit_into_ty(cx, INTO, &meta)? {
type_into.set_opt(&meta.path, Some(into_ty));
}
} else if meta.path == REMOTE {
// #[serde(remote = "...")]
if let Some(path) = parse_lit_into_path(cx, REMOTE, &meta)? {
if is_primitive_path(&path, "Self") {
remote.set(&meta.path, item.ident.clone().into());
} else {
remote.set(&meta.path, path);
}
}
} else if meta.path == FIELD_IDENTIFIER {
// #[serde(field_identifier)]
field_identifier.set_true(&meta.path);
} else if meta.path == VARIANT_IDENTIFIER {
// #[serde(variant_identifier)]
variant_identifier.set_true(&meta.path);
} else if meta.path == CRATE {
// #[serde(crate = "foo")]
if let Some(path) = parse_lit_into_path(cx, CRATE, &meta)? {
serde_path.set(&meta.path, path);
}
} else if meta.path == EXPECTING {
// #[serde(expecting = "a message")]
if let Some(s) = get_lit_str(cx, EXPECTING, &meta)? {
expecting.set(&meta.path, s.value());
}
} else {
let path = meta.path.to_token_stream().to_string().replace(' ', "");
return Err(
meta.error(format_args!("unknown serde container attribute `{}`", path))
);
}
Ok(())
}) {
cx.syn_error(err);
}
}
let mut is_packed = false;
for attr in &item.attrs {
if attr.path() == REPR {
let _ = attr.parse_args_with(|input: ParseStream| {
while let Some(token) = input.parse()? {
if let TokenTree::Ident(ident) = token {
is_packed |= ident == "packed";
}
}
Ok(())
});
}
}
Container {
name: Name::from_attrs(unraw(&item.ident), ser_name, de_name, None),
transparent: transparent.get(),
deny_unknown_fields: deny_unknown_fields.get(),
default: default.get().unwrap_or(Default::None),
rename_all_rules: RenameAllRules {
serialize: rename_all_ser_rule.get().unwrap_or(RenameRule::None),
deserialize: rename_all_de_rule.get().unwrap_or(RenameRule::None),
},
rename_all_fields_rules: RenameAllRules {
serialize: rename_all_fields_ser_rule.get().unwrap_or(RenameRule::None),
deserialize: rename_all_fields_de_rule.get().unwrap_or(RenameRule::None),
},
ser_bound: ser_bound.get(),
de_bound: de_bound.get(),
tag: decide_tag(cx, item, untagged, internal_tag, content),
type_from: type_from.get(),
type_try_from: type_try_from.get(),
type_into: type_into.get(),
remote: remote.get(),
identifier: decide_identifier(cx, item, field_identifier, variant_identifier),
has_flatten: false,
serde_path: serde_path.get(),
is_packed,
expecting: expecting.get(),
non_exhaustive,
}
}
pub fn name(&self) -> &Name {
&self.name
}
pub fn rename_all_rules(&self) -> RenameAllRules {
self.rename_all_rules
}
pub fn rename_all_fields_rules(&self) -> RenameAllRules {
self.rename_all_fields_rules
}
pub fn transparent(&self) -> bool {
self.transparent
}
pub fn deny_unknown_fields(&self) -> bool {
self.deny_unknown_fields
}
pub fn default(&self) -> &Default {
&self.default
}
pub fn ser_bound(&self) -> Option<&[syn::WherePredicate]> {
self.ser_bound.as_ref().map(|vec| &vec[..])
}
pub fn de_bound(&self) -> Option<&[syn::WherePredicate]> {
self.de_bound.as_ref().map(|vec| &vec[..])
}
pub fn tag(&self) -> &TagType {
&self.tag
}
pub fn type_from(&self) -> Option<&syn::Type> {
self.type_from.as_ref()
}
pub fn type_try_from(&self) -> Option<&syn::Type> {
self.type_try_from.as_ref()
}
pub fn type_into(&self) -> Option<&syn::Type> {
self.type_into.as_ref()
}
pub fn remote(&self) -> Option<&syn::Path> {
self.remote.as_ref()
}
pub fn is_packed(&self) -> bool {
self.is_packed
}
pub fn identifier(&self) -> Identifier {
self.identifier
}
pub fn has_flatten(&self) -> bool {
self.has_flatten
}
pub fn mark_has_flatten(&mut self) {
self.has_flatten = true;
}
pub fn custom_serde_path(&self) -> Option<&syn::Path> {
self.serde_path.as_ref()
}
pub fn serde_path(&self) -> Cow<syn::Path> {
self.custom_serde_path()
.map_or_else(|| Cow::Owned(parse_quote!(_serde)), Cow::Borrowed)
}
/// Error message generated when type can't be deserialized.
/// If `None`, default message will be used
pub fn expecting(&self) -> Option<&str> {
self.expecting.as_ref().map(String::as_ref)
}
pub fn non_exhaustive(&self) -> bool {
self.non_exhaustive
}
}
fn decide_tag(
cx: &Ctxt,
item: &syn::DeriveInput,
untagged: BoolAttr,
internal_tag: Attr<String>,
content: Attr<String>,
) -> TagType {
match (
untagged.0.get_with_tokens(),
internal_tag.get_with_tokens(),
content.get_with_tokens(),
) {
(None, None, None) => TagType::External,
(Some(_), None, None) => TagType::None,
(None, Some((_, tag)), None) => {
// Check that there are no tuple variants.
if let syn::Data::Enum(data) = &item.data {
for variant in &data.variants {
match &variant.fields {
syn::Fields::Named(_) | syn::Fields::Unit => {}
syn::Fields::Unnamed(fields) => {
if fields.unnamed.len() != 1 {
let msg =
"#[serde(tag = \"...\")] cannot be used with tuple variants";
cx.error_spanned_by(variant, msg);
break;
}
}
}
}
}
TagType::Internal { tag }
}
(Some((untagged_tokens, ())), Some((tag_tokens, _)), None) => {
let msg = "enum cannot be both untagged and internally tagged";
cx.error_spanned_by(untagged_tokens, msg);
cx.error_spanned_by(tag_tokens, msg);
TagType::External // doesn't matter, will error
}
(None, None, Some((content_tokens, _))) => {
let msg = "#[serde(tag = \"...\", content = \"...\")] must be used together";
cx.error_spanned_by(content_tokens, msg);
TagType::External
}
(Some((untagged_tokens, ())), None, Some((content_tokens, _))) => {
let msg = "untagged enum cannot have #[serde(content = \"...\")]";
cx.error_spanned_by(untagged_tokens, msg);
cx.error_spanned_by(content_tokens, msg);
TagType::External
}
(None, Some((_, tag)), Some((_, content))) => TagType::Adjacent { tag, content },
(Some((untagged_tokens, ())), Some((tag_tokens, _)), Some((content_tokens, _))) => {
let msg = "untagged enum cannot have #[serde(tag = \"...\", content = \"...\")]";
cx.error_spanned_by(untagged_tokens, msg);
cx.error_spanned_by(tag_tokens, msg);
cx.error_spanned_by(content_tokens, msg);
TagType::External
}
}
}
fn decide_identifier(
cx: &Ctxt,
item: &syn::DeriveInput,
field_identifier: BoolAttr,
variant_identifier: BoolAttr,
) -> Identifier {
match (
&item.data,
field_identifier.0.get_with_tokens(),
variant_identifier.0.get_with_tokens(),
) {
(_, None, None) => Identifier::No,
(_, Some((field_identifier_tokens, ())), Some((variant_identifier_tokens, ()))) => {
let msg =
"#[serde(field_identifier)] and #[serde(variant_identifier)] cannot both be set";
cx.error_spanned_by(field_identifier_tokens, msg);
cx.error_spanned_by(variant_identifier_tokens, msg);
Identifier::No
}
(syn::Data::Enum(_), Some(_), None) => Identifier::Field,
(syn::Data::Enum(_), None, Some(_)) => Identifier::Variant,
(syn::Data::Struct(syn::DataStruct { struct_token, .. }), Some(_), None) => {
let msg = "#[serde(field_identifier)] can only be used on an enum";
cx.error_spanned_by(struct_token, msg);
Identifier::No
}
(syn::Data::Union(syn::DataUnion { union_token, .. }), Some(_), None) => {
let msg = "#[serde(field_identifier)] can only be used on an enum";
cx.error_spanned_by(union_token, msg);
Identifier::No
}
(syn::Data::Struct(syn::DataStruct { struct_token, .. }), None, Some(_)) => {
let msg = "#[serde(variant_identifier)] can only be used on an enum";
cx.error_spanned_by(struct_token, msg);
Identifier::No
}
(syn::Data::Union(syn::DataUnion { union_token, .. }), None, Some(_)) => {
let msg = "#[serde(variant_identifier)] can only be used on an enum";
cx.error_spanned_by(union_token, msg);
Identifier::No
}
}
}
/// Represents variant attribute information
pub struct Variant {
name: Name,
rename_all_rules: RenameAllRules,
ser_bound: Option<Vec<syn::WherePredicate>>,
de_bound: Option<Vec<syn::WherePredicate>>,
skip_deserializing: bool,
skip_serializing: bool,
other: bool,
serialize_with: Option<syn::ExprPath>,
deserialize_with: Option<syn::ExprPath>,
borrow: Option<BorrowAttribute>,
untagged: bool,
}
struct BorrowAttribute {
path: syn::Path,
lifetimes: Option<BTreeSet<syn::Lifetime>>,
}
impl Variant {
pub fn from_ast(cx: &Ctxt, variant: &syn::Variant) -> Self {
let mut ser_name = Attr::none(cx, RENAME);
let mut de_name = Attr::none(cx, RENAME);
let mut de_aliases = VecAttr::none(cx, RENAME);
let mut skip_deserializing = BoolAttr::none(cx, SKIP_DESERIALIZING);
let mut skip_serializing = BoolAttr::none(cx, SKIP_SERIALIZING);
let mut rename_all_ser_rule = Attr::none(cx, RENAME_ALL);
let mut rename_all_de_rule = Attr::none(cx, RENAME_ALL);
let mut ser_bound = Attr::none(cx, BOUND);
let mut de_bound = Attr::none(cx, BOUND);
let mut other = BoolAttr::none(cx, OTHER);
let mut serialize_with = Attr::none(cx, SERIALIZE_WITH);
let mut deserialize_with = Attr::none(cx, DESERIALIZE_WITH);
let mut borrow = Attr::none(cx, BORROW);
let mut untagged = BoolAttr::none(cx, UNTAGGED);
for attr in &variant.attrs {
if attr.path() != SERDE {
continue;
}
if let syn::Meta::List(meta) = &attr.meta {
if meta.tokens.is_empty() {
continue;
}
}
if let Err(err) = attr.parse_nested_meta(|meta| {
if meta.path == RENAME {
// #[serde(rename = "foo")]
// #[serde(rename(serialize = "foo", deserialize = "bar"))]
let (ser, de) = get_multiple_renames(cx, &meta)?;
ser_name.set_opt(&meta.path, ser.as_ref().map(syn::LitStr::value));
for de_value in de {
de_name.set_if_none(de_value.value());
de_aliases.insert(&meta.path, de_value.value());
}
} else if meta.path == ALIAS {
// #[serde(alias = "foo")]
if let Some(s) = get_lit_str(cx, ALIAS, &meta)? {
de_aliases.insert(&meta.path, s.value());
}
} else if meta.path == RENAME_ALL {
// #[serde(rename_all = "foo")]
// #[serde(rename_all(serialize = "foo", deserialize = "bar"))]
let one_name = meta.input.peek(Token![=]);
let (ser, de) = get_renames(cx, RENAME_ALL, &meta)?;
if let Some(ser) = ser {
match RenameRule::from_str(&ser.value()) {
Ok(rename_rule) => rename_all_ser_rule.set(&meta.path, rename_rule),
Err(err) => cx.error_spanned_by(ser, err),
}
}
if let Some(de) = de {
match RenameRule::from_str(&de.value()) {
Ok(rename_rule) => rename_all_de_rule.set(&meta.path, rename_rule),
Err(err) => {
if !one_name {
cx.error_spanned_by(de, err);
}
}
}
}
} else if meta.path == SKIP {
// #[serde(skip)]
skip_serializing.set_true(&meta.path);
skip_deserializing.set_true(&meta.path);
} else if meta.path == SKIP_DESERIALIZING {
// #[serde(skip_deserializing)]
skip_deserializing.set_true(&meta.path);
} else if meta.path == SKIP_SERIALIZING {
// #[serde(skip_serializing)]
skip_serializing.set_true(&meta.path);
} else if meta.path == OTHER {
// #[serde(other)]
other.set_true(&meta.path);
} else if meta.path == BOUND {
// #[serde(bound = "T: SomeBound")]
// #[serde(bound(serialize = "...", deserialize = "..."))]
let (ser, de) = get_where_predicates(cx, &meta)?;
ser_bound.set_opt(&meta.path, ser);
de_bound.set_opt(&meta.path, de);
} else if meta.path == WITH {
// #[serde(with = "...")]
if let Some(path) = parse_lit_into_expr_path(cx, WITH, &meta)? {
let mut ser_path = path.clone();
ser_path
.path
.segments
.push(Ident::new("serialize", Span::call_site()).into());
serialize_with.set(&meta.path, ser_path);
let mut de_path = path;
de_path
.path
.segments
.push(Ident::new("deserialize", Span::call_site()).into());
deserialize_with.set(&meta.path, de_path);
}
} else if meta.path == SERIALIZE_WITH {
// #[serde(serialize_with = "...")]
if let Some(path) = parse_lit_into_expr_path(cx, SERIALIZE_WITH, &meta)? {
serialize_with.set(&meta.path, path);
}
} else if meta.path == DESERIALIZE_WITH {
// #[serde(deserialize_with = "...")]
if let Some(path) = parse_lit_into_expr_path(cx, DESERIALIZE_WITH, &meta)? {
deserialize_with.set(&meta.path, path);
}
} else if meta.path == BORROW {
let borrow_attribute = if meta.input.peek(Token![=]) {
// #[serde(borrow = "'a + 'b")]
let lifetimes = parse_lit_into_lifetimes(cx, &meta)?;
BorrowAttribute {
path: meta.path.clone(),
lifetimes: Some(lifetimes),
}
} else {
// #[serde(borrow)]
BorrowAttribute {
path: meta.path.clone(),
lifetimes: None,
}
};
match &variant.fields {
syn::Fields::Unnamed(fields) if fields.unnamed.len() == 1 => {
borrow.set(&meta.path, borrow_attribute);
}
_ => {
let msg = "#[serde(borrow)] may only be used on newtype variants";
cx.error_spanned_by(variant, msg);
}
}
} else if meta.path == UNTAGGED {
untagged.set_true(&meta.path);
} else {
let path = meta.path.to_token_stream().to_string().replace(' ', "");
return Err(
meta.error(format_args!("unknown serde variant attribute `{}`", path))
);
}
Ok(())
}) {
cx.syn_error(err);
}
}
Variant {
name: Name::from_attrs(unraw(&variant.ident), ser_name, de_name, Some(de_aliases)),
rename_all_rules: RenameAllRules {
serialize: rename_all_ser_rule.get().unwrap_or(RenameRule::None),
deserialize: rename_all_de_rule.get().unwrap_or(RenameRule::None),
},
ser_bound: ser_bound.get(),
de_bound: de_bound.get(),
skip_deserializing: skip_deserializing.get(),
skip_serializing: skip_serializing.get(),
other: other.get(),
serialize_with: serialize_with.get(),
deserialize_with: deserialize_with.get(),
borrow: borrow.get(),
untagged: untagged.get(),
}
}
pub fn name(&self) -> &Name {
&self.name
}
pub fn aliases(&self) -> &BTreeSet<String> {
self.name.deserialize_aliases()
}
pub fn rename_by_rules(&mut self, rules: RenameAllRules) {
if !self.name.serialize_renamed {
self.name.serialize = rules.serialize.apply_to_variant(&self.name.serialize);
}
if !self.name.deserialize_renamed {
self.name.deserialize = rules.deserialize.apply_to_variant(&self.name.deserialize);
}
self.name
.deserialize_aliases
.insert(self.name.deserialize.clone());
}
pub fn rename_all_rules(&self) -> RenameAllRules {
self.rename_all_rules
}
pub fn ser_bound(&self) -> Option<&[syn::WherePredicate]> {
self.ser_bound.as_ref().map(|vec| &vec[..])
}
pub fn de_bound(&self) -> Option<&[syn::WherePredicate]> {
self.de_bound.as_ref().map(|vec| &vec[..])
}
pub fn skip_deserializing(&self) -> bool {
self.skip_deserializing
}
pub fn skip_serializing(&self) -> bool {
self.skip_serializing
}
pub fn other(&self) -> bool {
self.other
}
pub fn serialize_with(&self) -> Option<&syn::ExprPath> {
self.serialize_with.as_ref()
}
pub fn deserialize_with(&self) -> Option<&syn::ExprPath> {
self.deserialize_with.as_ref()
}
pub fn untagged(&self) -> bool {
self.untagged
}
}
/// Represents field attribute information
pub struct Field {
name: Name,
skip_serializing: bool,
skip_deserializing: bool,
skip_serializing_if: Option<syn::ExprPath>,
default: Default,
serialize_with: Option<syn::ExprPath>,
deserialize_with: Option<syn::ExprPath>,
ser_bound: Option<Vec<syn::WherePredicate>>,
de_bound: Option<Vec<syn::WherePredicate>>,
borrowed_lifetimes: BTreeSet<syn::Lifetime>,
getter: Option<syn::ExprPath>,
flatten: bool,
transparent: bool,
}
/// Represents the default to use for a field when deserializing.
pub enum Default {
/// Field must always be specified because it does not have a default.
None,
/// The default is given by `std::default::Default::default()`.
Default,
/// The default is given by this function.
Path(syn::ExprPath),
}
impl Default {
pub fn is_none(&self) -> bool {
match self {
Default::None => true,
Default::Default | Default::Path(_) => false,
}
}
}
impl Field {
/// Extract out the `#[serde(...)]` attributes from a struct field.
pub fn from_ast(
cx: &Ctxt,
index: usize,
field: &syn::Field,
attrs: Option<&Variant>,
container_default: &Default,
) -> Self {
let mut ser_name = Attr::none(cx, RENAME);
let mut de_name = Attr::none(cx, RENAME);
let mut de_aliases = VecAttr::none(cx, RENAME);
let mut skip_serializing = BoolAttr::none(cx, SKIP_SERIALIZING);
let mut skip_deserializing = BoolAttr::none(cx, SKIP_DESERIALIZING);
let mut skip_serializing_if = Attr::none(cx, SKIP_SERIALIZING_IF);
let mut default = Attr::none(cx, DEFAULT);
let mut serialize_with = Attr::none(cx, SERIALIZE_WITH);
let mut deserialize_with = Attr::none(cx, DESERIALIZE_WITH);
let mut ser_bound = Attr::none(cx, BOUND);
let mut de_bound = Attr::none(cx, BOUND);
let mut borrowed_lifetimes = Attr::none(cx, BORROW);
let mut getter = Attr::none(cx, GETTER);
let mut flatten = BoolAttr::none(cx, FLATTEN);
let ident = match &field.ident {
Some(ident) => unraw(ident),
None => index.to_string(),
};
if let Some(borrow_attribute) = attrs.and_then(|variant| variant.borrow.as_ref()) {
if let Ok(borrowable) = borrowable_lifetimes(cx, &ident, field) {
if let Some(lifetimes) = &borrow_attribute.lifetimes {
for lifetime in lifetimes {
if !borrowable.contains(lifetime) {
let msg =
format!("field `{}` does not have lifetime {}", ident, lifetime);
cx.error_spanned_by(field, msg);
}
}
borrowed_lifetimes.set(&borrow_attribute.path, lifetimes.clone());
} else {
borrowed_lifetimes.set(&borrow_attribute.path, borrowable);
}
}
}
for attr in &field.attrs {
if attr.path() != SERDE {
continue;
}
if let syn::Meta::List(meta) = &attr.meta {
if meta.tokens.is_empty() {
continue;
}
}
if let Err(err) = attr.parse_nested_meta(|meta| {
if meta.path == RENAME {
// #[serde(rename = "foo")]
// #[serde(rename(serialize = "foo", deserialize = "bar"))]
let (ser, de) = get_multiple_renames(cx, &meta)?;
ser_name.set_opt(&meta.path, ser.as_ref().map(syn::LitStr::value));
for de_value in de {
de_name.set_if_none(de_value.value());
de_aliases.insert(&meta.path, de_value.value());
}
} else if meta.path == ALIAS {
// #[serde(alias = "foo")]
if let Some(s) = get_lit_str(cx, ALIAS, &meta)? {
de_aliases.insert(&meta.path, s.value());
}
} else if meta.path == DEFAULT {
if meta.input.peek(Token![=]) {
// #[serde(default = "...")]
if let Some(path) = parse_lit_into_expr_path(cx, DEFAULT, &meta)? {
default.set(&meta.path, Default::Path(path));
}
} else {
// #[serde(default)]
default.set(&meta.path, Default::Default);
}
} else if meta.path == SKIP_SERIALIZING {
// #[serde(skip_serializing)]
skip_serializing.set_true(&meta.path);
} else if meta.path == SKIP_DESERIALIZING {
// #[serde(skip_deserializing)]
skip_deserializing.set_true(&meta.path);
} else if meta.path == SKIP {
// #[serde(skip)]
skip_serializing.set_true(&meta.path);
skip_deserializing.set_true(&meta.path);
} else if meta.path == SKIP_SERIALIZING_IF {
// #[serde(skip_serializing_if = "...")]
if let Some(path) = parse_lit_into_expr_path(cx, SKIP_SERIALIZING_IF, &meta)? {
skip_serializing_if.set(&meta.path, path);
}
} else if meta.path == SERIALIZE_WITH {
// #[serde(serialize_with = "...")]
if let Some(path) = parse_lit_into_expr_path(cx, SERIALIZE_WITH, &meta)? {
serialize_with.set(&meta.path, path);
}
} else if meta.path == DESERIALIZE_WITH {
// #[serde(deserialize_with = "...")]
if let Some(path) = parse_lit_into_expr_path(cx, DESERIALIZE_WITH, &meta)? {
deserialize_with.set(&meta.path, path);
}
} else if meta.path == WITH {
// #[serde(with = "...")]
if let Some(path) = parse_lit_into_expr_path(cx, WITH, &meta)? {
let mut ser_path = path.clone();
ser_path
.path
.segments
.push(Ident::new("serialize", Span::call_site()).into());
serialize_with.set(&meta.path, ser_path);
let mut de_path = path;
de_path
.path
.segments
.push(Ident::new("deserialize", Span::call_site()).into());
deserialize_with.set(&meta.path, de_path);
}
} else if meta.path == BOUND {
// #[serde(bound = "T: SomeBound")]
// #[serde(bound(serialize = "...", deserialize = "..."))]
let (ser, de) = get_where_predicates(cx, &meta)?;
ser_bound.set_opt(&meta.path, ser);
de_bound.set_opt(&meta.path, de);
} else if meta.path == BORROW {
if meta.input.peek(Token![=]) {
// #[serde(borrow = "'a + 'b")]
let lifetimes = parse_lit_into_lifetimes(cx, &meta)?;
if let Ok(borrowable) = borrowable_lifetimes(cx, &ident, field) {
for lifetime in &lifetimes {
if !borrowable.contains(lifetime) {
let msg = format!(
"field `{}` does not have lifetime {}",
ident, lifetime,
);
cx.error_spanned_by(field, msg);
}
}
borrowed_lifetimes.set(&meta.path, lifetimes);
}
} else {
// #[serde(borrow)]
if let Ok(borrowable) = borrowable_lifetimes(cx, &ident, field) {
borrowed_lifetimes.set(&meta.path, borrowable);
}
}
} else if meta.path == GETTER {
// #[serde(getter = "...")]
if let Some(path) = parse_lit_into_expr_path(cx, GETTER, &meta)? {
getter.set(&meta.path, path);
}
} else if meta.path == FLATTEN {
// #[serde(flatten)]
flatten.set_true(&meta.path);
} else {
let path = meta.path.to_token_stream().to_string().replace(' ', "");
return Err(
meta.error(format_args!("unknown serde field attribute `{}`", path))
);
}
Ok(())
}) {
cx.syn_error(err);
}
}
// Is skip_deserializing, initialize the field to Default::default() unless a
// different default is specified by `#[serde(default = "...")]` on
// ourselves or our container (e.g. the struct we are in).
if let Default::None = *container_default {
if skip_deserializing.0.value.is_some() {
default.set_if_none(Default::Default);
}
}
let mut borrowed_lifetimes = borrowed_lifetimes.get().unwrap_or_default();
if !borrowed_lifetimes.is_empty() {
// Cow<str> and Cow<[u8]> never borrow by default:
//
// impl<'de, 'a, T: ?Sized> Deserialize<'de> for Cow<'a, T>
//
// A #[serde(borrow)] attribute enables borrowing that corresponds
// roughly to these impls:
//
// impl<'de: 'a, 'a> Deserialize<'de> for Cow<'a, str>
// impl<'de: 'a, 'a> Deserialize<'de> for Cow<'a, [u8]>
if is_cow(&field.ty, is_str) {
let mut path = syn::Path {
leading_colon: None,
segments: Punctuated::new(),
};
let span = Span::call_site();
path.segments.push(Ident::new("_serde", span).into());
path.segments.push(Ident::new("__private", span).into());
path.segments.push(Ident::new("de", span).into());
path.segments
.push(Ident::new("borrow_cow_str", span).into());
let expr = syn::ExprPath {
attrs: Vec::new(),
qself: None,
path,
};
deserialize_with.set_if_none(expr);
} else if is_cow(&field.ty, is_slice_u8) {
let mut path = syn::Path {
leading_colon: None,
segments: Punctuated::new(),
};
let span = Span::call_site();
path.segments.push(Ident::new("_serde", span).into());
path.segments.push(Ident::new("__private", span).into());
path.segments.push(Ident::new("de", span).into());
path.segments
.push(Ident::new("borrow_cow_bytes", span).into());
let expr = syn::ExprPath {
attrs: Vec::new(),
qself: None,
path,
};
deserialize_with.set_if_none(expr);
}
} else if is_implicitly_borrowed(&field.ty) {
// Types &str and &[u8] are always implicitly borrowed. No need for
// a #[serde(borrow)].
collect_lifetimes(&field.ty, &mut borrowed_lifetimes);
}
Field {
name: Name::from_attrs(ident, ser_name, de_name, Some(de_aliases)),
skip_serializing: skip_serializing.get(),
skip_deserializing: skip_deserializing.get(),
skip_serializing_if: skip_serializing_if.get(),
default: default.get().unwrap_or(Default::None),
serialize_with: serialize_with.get(),
deserialize_with: deserialize_with.get(),
ser_bound: ser_bound.get(),
de_bound: de_bound.get(),
borrowed_lifetimes,
getter: getter.get(),
flatten: flatten.get(),
transparent: false,
}
}
pub fn name(&self) -> &Name {
&self.name
}
pub fn aliases(&self) -> &BTreeSet<String> {
self.name.deserialize_aliases()
}
pub fn rename_by_rules(&mut self, rules: RenameAllRules) {
if !self.name.serialize_renamed {
self.name.serialize = rules.serialize.apply_to_field(&self.name.serialize);
}
if !self.name.deserialize_renamed {
self.name.deserialize = rules.deserialize.apply_to_field(&self.name.deserialize);
}
self.name
.deserialize_aliases
.insert(self.name.deserialize.clone());
}
pub fn skip_serializing(&self) -> bool {
self.skip_serializing
}
pub fn skip_deserializing(&self) -> bool {
self.skip_deserializing
}
pub fn skip_serializing_if(&self) -> Option<&syn::ExprPath> {
self.skip_serializing_if.as_ref()
}
pub fn default(&self) -> &Default {
&self.default
}
pub fn serialize_with(&self) -> Option<&syn::ExprPath> {
self.serialize_with.as_ref()
}
pub fn deserialize_with(&self) -> Option<&syn::ExprPath> {
self.deserialize_with.as_ref()
}
pub fn ser_bound(&self) -> Option<&[syn::WherePredicate]> {
self.ser_bound.as_ref().map(|vec| &vec[..])
}
pub fn de_bound(&self) -> Option<&[syn::WherePredicate]> {
self.de_bound.as_ref().map(|vec| &vec[..])
}
pub fn borrowed_lifetimes(&self) -> &BTreeSet<syn::Lifetime> {
&self.borrowed_lifetimes
}
pub fn getter(&self) -> Option<&syn::ExprPath> {
self.getter.as_ref()
}
pub fn flatten(&self) -> bool {
self.flatten
}
pub fn transparent(&self) -> bool {
self.transparent
}
pub fn mark_transparent(&mut self) {
self.transparent = true;
}
}
type SerAndDe<T> = (Option<T>, Option<T>);
fn get_ser_and_de<'c, T, F, R>(
cx: &'c Ctxt,
attr_name: Symbol,
meta: &ParseNestedMeta,
f: F,
) -> syn::Result<(VecAttr<'c, T>, VecAttr<'c, T>)>
where
T: Clone,
F: Fn(&Ctxt, Symbol, Symbol, &ParseNestedMeta) -> syn::Result<R>,
R: Into<Option<T>>,
{
let mut ser_meta = VecAttr::none(cx, attr_name);
let mut de_meta = VecAttr::none(cx, attr_name);
let lookahead = meta.input.lookahead1();
if lookahead.peek(Token![=]) {
if let Some(both) = f(cx, attr_name, attr_name, meta)?.into() {
ser_meta.insert(&meta.path, both.clone());
de_meta.insert(&meta.path, both);
}
} else if lookahead.peek(token::Paren) {
meta.parse_nested_meta(|meta| {
if meta.path == SERIALIZE {
if let Some(v) = f(cx, attr_name, SERIALIZE, &meta)?.into() {
ser_meta.insert(&meta.path, v);
}
} else if meta.path == DESERIALIZE {
if let Some(v) = f(cx, attr_name, DESERIALIZE, &meta)?.into() {
de_meta.insert(&meta.path, v);
}
} else {
return Err(meta.error(format_args!(
"malformed {0} attribute, expected `{0}(serialize = ..., deserialize = ...)`",
attr_name,
)));
}
Ok(())
})?;
} else {
return Err(lookahead.error());
}
Ok((ser_meta, de_meta))
}
fn get_renames(
cx: &Ctxt,
attr_name: Symbol,
meta: &ParseNestedMeta,
) -> syn::Result<SerAndDe<syn::LitStr>> {
let (ser, de) = get_ser_and_de(cx, attr_name, meta, get_lit_str2)?;
Ok((ser.at_most_one(), de.at_most_one()))
}
fn get_multiple_renames(
cx: &Ctxt,
meta: &ParseNestedMeta,
) -> syn::Result<(Option<syn::LitStr>, Vec<syn::LitStr>)> {
let (ser, de) = get_ser_and_de(cx, RENAME, meta, get_lit_str2)?;
Ok((ser.at_most_one(), de.get()))
}
fn get_where_predicates(
cx: &Ctxt,
meta: &ParseNestedMeta,
) -> syn::Result<SerAndDe<Vec<syn::WherePredicate>>> {
let (ser, de) = get_ser_and_de(cx, BOUND, meta, parse_lit_into_where)?;
Ok((ser.at_most_one(), de.at_most_one()))
}
fn get_lit_str(
cx: &Ctxt,
attr_name: Symbol,
meta: &ParseNestedMeta,
) -> syn::Result<Option<syn::LitStr>> {
get_lit_str2(cx, attr_name, attr_name, meta)
}
fn get_lit_str2(
cx: &Ctxt,
attr_name: Symbol,
meta_item_name: Symbol,
meta: &ParseNestedMeta,
) -> syn::Result<Option<syn::LitStr>> {
let expr: syn::Expr = meta.value()?.parse()?;
let mut value = &expr;
while let syn::Expr::Group(e) = value {
value = &e.expr;
}
if let syn::Expr::Lit(syn::ExprLit {
lit: syn::Lit::Str(lit),
..
}) = value
{
let suffix = lit.suffix();
if !suffix.is_empty() {
cx.error_spanned_by(
lit,
format!("unexpected suffix `{}` on string literal", suffix),
);
}
Ok(Some(lit.clone()))
} else {
cx.error_spanned_by(
expr,
format!(
"expected serde {} attribute to be a string: `{} = \"...\"`",
attr_name, meta_item_name
),
);
Ok(None)
}
}
fn parse_lit_into_path(
cx: &Ctxt,
attr_name: Symbol,
meta: &ParseNestedMeta,
) -> syn::Result<Option<syn::Path>> {
let string = match get_lit_str(cx, attr_name, meta)? {
Some(string) => string,
None => return Ok(None),
};
Ok(match string.parse() {
Ok(path) => Some(path),
Err(_) => {
cx.error_spanned_by(
&string,
format!("failed to parse path: {:?}", string.value()),
);
None
}
})
}
fn parse_lit_into_expr_path(
cx: &Ctxt,
attr_name: Symbol,
meta: &ParseNestedMeta,
) -> syn::Result<Option<syn::ExprPath>> {
let string = match get_lit_str(cx, attr_name, meta)? {
Some(string) => string,
None => return Ok(None),
};
Ok(match string.parse() {
Ok(expr) => Some(expr),
Err(_) => {
cx.error_spanned_by(
&string,
format!("failed to parse path: {:?}", string.value()),
);
None
}
})
}
fn parse_lit_into_where(
cx: &Ctxt,
attr_name: Symbol,
meta_item_name: Symbol,
meta: &ParseNestedMeta,
) -> syn::Result<Vec<syn::WherePredicate>> {
let string = match get_lit_str2(cx, attr_name, meta_item_name, meta)? {
Some(string) => string,
None => return Ok(Vec::new()),
};
Ok(
match string.parse_with(Punctuated::<syn::WherePredicate, Token![,]>::parse_terminated) {
Ok(predicates) => Vec::from_iter(predicates),
Err(err) => {
cx.error_spanned_by(string, err);
Vec::new()
}
},
)
}
fn parse_lit_into_ty(
cx: &Ctxt,
attr_name: Symbol,
meta: &ParseNestedMeta,
) -> syn::Result<Option<syn::Type>> {
let string = match get_lit_str(cx, attr_name, meta)? {
Some(string) => string,
None => return Ok(None),
};
Ok(match string.parse() {
Ok(ty) => Some(ty),
Err(_) => {
cx.error_spanned_by(
&string,
format!("failed to parse type: {} = {:?}", attr_name, string.value()),
);
None
}
})
}
// Parses a string literal like "'a + 'b + 'c" containing a nonempty list of
// lifetimes separated by `+`.
fn parse_lit_into_lifetimes(
cx: &Ctxt,
meta: &ParseNestedMeta,
) -> syn::Result<BTreeSet<syn::Lifetime>> {
let string = match get_lit_str(cx, BORROW, meta)? {
Some(string) => string,
None => return Ok(BTreeSet::new()),
};
if let Ok(lifetimes) = string.parse_with(|input: ParseStream| {
let mut set = BTreeSet::new();
while !input.is_empty() {
let lifetime: Lifetime = input.parse()?;
if !set.insert(lifetime.clone()) {
cx.error_spanned_by(
&string,
format!("duplicate borrowed lifetime `{}`", lifetime),
);
}
if input.is_empty() {
break;
}
input.parse::<Token![+]>()?;
}
Ok(set)
}) {
if lifetimes.is_empty() {
cx.error_spanned_by(string, "at least one lifetime must be borrowed");
}
return Ok(lifetimes);
}
cx.error_spanned_by(
&string,
format!("failed to parse borrowed lifetimes: {:?}", string.value()),
);
Ok(BTreeSet::new())
}
fn is_implicitly_borrowed(ty: &syn::Type) -> bool {
is_implicitly_borrowed_reference(ty) || is_option(ty, is_implicitly_borrowed_reference)
}
fn is_implicitly_borrowed_reference(ty: &syn::Type) -> bool {
is_reference(ty, is_str) || is_reference(ty, is_slice_u8)
}
// Whether the type looks like it might be `std::borrow::Cow<T>` where elem="T".
// This can have false negatives and false positives.
//
// False negative:
//
// use std::borrow::Cow as Pig;
//
// #[derive(Deserialize)]
// struct S<'a> {
// #[serde(borrow)]
// pig: Pig<'a, str>,
// }
//
// False positive:
//
// type str = [i16];
//
// #[derive(Deserialize)]
// struct S<'a> {
// #[serde(borrow)]
// cow: Cow<'a, str>,
// }
fn is_cow(ty: &syn::Type, elem: fn(&syn::Type) -> bool) -> bool {
let path = match ungroup(ty) {
syn::Type::Path(ty) => &ty.path,
_ => {
return false;
}
};
let seg = match path.segments.last() {
Some(seg) => seg,
None => {
return false;
}
};
let args = match &seg.arguments {
syn::PathArguments::AngleBracketed(bracketed) => &bracketed.args,
_ => {
return false;
}
};
seg.ident == "Cow"
&& args.len() == 2
&& match (&args[0], &args[1]) {
(syn::GenericArgument::Lifetime(_), syn::GenericArgument::Type(arg)) => elem(arg),
_ => false,
}
}
fn is_option(ty: &syn::Type, elem: fn(&syn::Type) -> bool) -> bool {
let path = match ungroup(ty) {
syn::Type::Path(ty) => &ty.path,
_ => {
return false;
}
};
let seg = match path.segments.last() {
Some(seg) => seg,
None => {
return false;
}
};
let args = match &seg.arguments {
syn::PathArguments::AngleBracketed(bracketed) => &bracketed.args,
_ => {
return false;
}
};
seg.ident == "Option"
&& args.len() == 1
&& match &args[0] {
syn::GenericArgument::Type(arg) => elem(arg),
_ => false,
}
}
// Whether the type looks like it might be `&T` where elem="T". This can have
// false negatives and false positives.
//
// False negative:
//
// type Yarn = str;
//
// #[derive(Deserialize)]
// struct S<'a> {
// r: &'a Yarn,
// }
//
// False positive:
//
// type str = [i16];
//
// #[derive(Deserialize)]
// struct S<'a> {
// r: &'a str,
// }
fn is_reference(ty: &syn::Type, elem: fn(&syn::Type) -> bool) -> bool {
match ungroup(ty) {
syn::Type::Reference(ty) => ty.mutability.is_none() && elem(&ty.elem),
_ => false,
}
}
fn is_str(ty: &syn::Type) -> bool {
is_primitive_type(ty, "str")
}
fn is_slice_u8(ty: &syn::Type) -> bool {
match ungroup(ty) {
syn::Type::Slice(ty) => is_primitive_type(&ty.elem, "u8"),
_ => false,
}
}
fn is_primitive_type(ty: &syn::Type, primitive: &str) -> bool {
match ungroup(ty) {
syn::Type::Path(ty) => ty.qself.is_none() && is_primitive_path(&ty.path, primitive),
_ => false,
}
}
fn is_primitive_path(path: &syn::Path, primitive: &str) -> bool {
path.leading_colon.is_none()
&& path.segments.len() == 1
&& path.segments[0].ident == primitive
&& path.segments[0].arguments.is_empty()
}
// All lifetimes that this type could borrow from a Deserializer.
//
// For example a type `S<'a, 'b>` could borrow `'a` and `'b`. On the other hand
// a type `for<'a> fn(&'a str)` could not borrow `'a` from the Deserializer.
//
// This is used when there is an explicit or implicit `#[serde(borrow)]`
// attribute on the field so there must be at least one borrowable lifetime.
fn borrowable_lifetimes(
cx: &Ctxt,
name: &str,
field: &syn::Field,
) -> Result<BTreeSet<syn::Lifetime>, ()> {
let mut lifetimes = BTreeSet::new();
collect_lifetimes(&field.ty, &mut lifetimes);
if lifetimes.is_empty() {
let msg = format!("field `{}` has no lifetimes to borrow", name);
cx.error_spanned_by(field, msg);
Err(())
} else {
Ok(lifetimes)
}
}
fn collect_lifetimes(ty: &syn::Type, out: &mut BTreeSet<syn::Lifetime>) {
match ty {
#![cfg_attr(all(test, exhaustive), deny(non_exhaustive_omitted_patterns))]
syn::Type::Slice(ty) => {
collect_lifetimes(&ty.elem, out);
}
syn::Type::Array(ty) => {
collect_lifetimes(&ty.elem, out);
}
syn::Type::Ptr(ty) => {
collect_lifetimes(&ty.elem, out);
}
syn::Type::Reference(ty) => {
out.extend(ty.lifetime.iter().cloned());
collect_lifetimes(&ty.elem, out);
}
syn::Type::Tuple(ty) => {
for elem in &ty.elems {
collect_lifetimes(elem, out);
}
}
syn::Type::Path(ty) => {
if let Some(qself) = &ty.qself {
collect_lifetimes(&qself.ty, out);
}
for seg in &ty.path.segments {
if let syn::PathArguments::AngleBracketed(bracketed) = &seg.arguments {
for arg in &bracketed.args {
match arg {
syn::GenericArgument::Lifetime(lifetime) => {
out.insert(lifetime.clone());
}
syn::GenericArgument::Type(ty) => {
collect_lifetimes(ty, out);
}
syn::GenericArgument::AssocType(binding) => {
collect_lifetimes(&binding.ty, out);
}
syn::GenericArgument::Const(_)
| syn::GenericArgument::AssocConst(_)
| syn::GenericArgument::Constraint(_)
| _ => {}
}
}
}
}
}
syn::Type::Paren(ty) => {
collect_lifetimes(&ty.elem, out);
}
syn::Type::Group(ty) => {
collect_lifetimes(&ty.elem, out);
}
syn::Type::Macro(ty) => {
collect_lifetimes_from_tokens(ty.mac.tokens.clone(), out);
}
syn::Type::BareFn(_)
| syn::Type::Never(_)
| syn::Type::TraitObject(_)
| syn::Type::ImplTrait(_)
| syn::Type::Infer(_)
| syn::Type::Verbatim(_) => {}
_ => {}
}
}
fn collect_lifetimes_from_tokens(tokens: TokenStream, out: &mut BTreeSet<syn::Lifetime>) {
let mut iter = tokens.into_iter();
while let Some(tt) = iter.next() {
match &tt {
TokenTree::Punct(op) if op.as_char() == '\'' && op.spacing() == Spacing::Joint => {
if let Some(TokenTree::Ident(ident)) = iter.next() {
out.insert(syn::Lifetime {
apostrophe: op.span(),
ident,
});
}
}
TokenTree::Group(group) => {
let tokens = group.stream();
collect_lifetimes_from_tokens(tokens, out);
}
_ => {}
}
}
}