Sindbad~EG File Manager
use internals::respan::respan;
use internals::symbol::*;
use internals::{ungroup, Ctxt};
use proc_macro2::{Spacing, Span, TokenStream, TokenTree};
use quote::ToTokens;
use std::borrow::Cow;
use std::collections::BTreeSet;
use syn;
use syn::parse::{self, Parse, ParseStream};
use syn::punctuated::Punctuated;
use syn::Ident;
use syn::Meta::{List, NameValue, Path};
use syn::NestedMeta::{Lit, Meta};
// 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 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() {
self.cx
.error_spanned_by(tokens, format!("duplicate serde attribute `{}`", self.name));
} 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) -> Result<Option<T>, ()> {
if self.values.len() > 1 {
let dup_token = self.first_dup_tokens;
self.cx.error_spanned_by(
dup_token,
format!("duplicate serde attribute `{}`", self.name),
);
Err(())
} else {
Ok(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: Vec<String>,
}
#[allow(deprecated)]
fn unraw(ident: &Ident) -> String {
// str::trim_start_matches was added in 1.30, trim_left_matches deprecated
// in 1.33. We currently support rustc back to 1.15 so we need to continue
// to use the deprecated one.
ident.to_string().trim_left_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 deserialize_aliases = match de_aliases {
Some(de_aliases) => {
let mut alias_list = BTreeSet::new();
for alias_name in de_aliases.get() {
alias_list.insert(alias_name);
}
alias_list.into_iter().collect()
}
None => Vec::new(),
};
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,
}
}
/// Return the container name for the container when serializing.
pub fn serialize_name(&self) -> String {
self.serialize.clone()
}
/// Return the container name for the container when deserializing.
pub fn deserialize_name(&self) -> String {
self.deserialize.clone()
}
fn deserialize_aliases(&self) -> Vec<String> {
let mut aliases = self.deserialize_aliases.clone();
let main_name = self.deserialize_name();
if !aliases.contains(&main_name) {
aliases.push(main_name);
}
aliases
}
}
pub struct RenameAllRules {
serialize: RenameRule,
deserialize: RenameRule,
}
/// Represents struct or enum attribute information.
pub struct Container {
name: Name,
transparent: bool,
deny_unknown_fields: bool,
default: Default,
rename_all_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>,
}
/// 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 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);
for meta_item in item
.attrs
.iter()
.flat_map(|attr| get_serde_meta_items(cx, attr))
.flatten()
{
match &meta_item {
// Parse `#[serde(rename = "foo")]`
Meta(NameValue(m)) if m.path == RENAME => {
if let Ok(s) = get_lit_str(cx, RENAME, &m.lit) {
ser_name.set(&m.path, s.value());
de_name.set(&m.path, s.value());
}
}
// Parse `#[serde(rename(serialize = "foo", deserialize = "bar"))]`
Meta(List(m)) if m.path == RENAME => {
if let Ok((ser, de)) = get_renames(cx, &m.nested) {
ser_name.set_opt(&m.path, ser.map(syn::LitStr::value));
de_name.set_opt(&m.path, de.map(syn::LitStr::value));
}
}
// Parse `#[serde(rename_all = "foo")]`
Meta(NameValue(m)) if m.path == RENAME_ALL => {
if let Ok(s) = get_lit_str(cx, RENAME_ALL, &m.lit) {
match RenameRule::from_str(&s.value()) {
Ok(rename_rule) => {
rename_all_ser_rule.set(&m.path, rename_rule);
rename_all_de_rule.set(&m.path, rename_rule);
}
Err(err) => cx.error_spanned_by(s, err),
}
}
}
// Parse `#[serde(rename_all(serialize = "foo", deserialize = "bar"))]`
Meta(List(m)) if m.path == RENAME_ALL => {
if let Ok((ser, de)) = get_renames(cx, &m.nested) {
if let Some(ser) = ser {
match RenameRule::from_str(&ser.value()) {
Ok(rename_rule) => rename_all_ser_rule.set(&m.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(&m.path, rename_rule),
Err(err) => cx.error_spanned_by(de, err),
}
}
}
}
// Parse `#[serde(transparent)]`
Meta(Path(word)) if word == TRANSPARENT => {
transparent.set_true(word);
}
// Parse `#[serde(deny_unknown_fields)]`
Meta(Path(word)) if word == DENY_UNKNOWN_FIELDS => {
deny_unknown_fields.set_true(word);
}
// Parse `#[serde(default)]`
Meta(Path(word)) if word == DEFAULT => match &item.data {
syn::Data::Struct(syn::DataStruct { fields, .. }) => match fields {
syn::Fields::Named(_) => {
default.set(word, Default::Default);
}
syn::Fields::Unnamed(_) | syn::Fields::Unit => cx.error_spanned_by(
fields,
"#[serde(default)] can only be used on structs with named fields",
),
},
syn::Data::Enum(syn::DataEnum { enum_token, .. }) => cx.error_spanned_by(
enum_token,
"#[serde(default)] can only be used on structs with named fields",
),
syn::Data::Union(syn::DataUnion { union_token, .. }) => cx.error_spanned_by(
union_token,
"#[serde(default)] can only be used on structs with named fields",
),
},
// Parse `#[serde(default = "...")]`
Meta(NameValue(m)) if m.path == DEFAULT => {
if let Ok(path) = parse_lit_into_expr_path(cx, DEFAULT, &m.lit) {
match &item.data {
syn::Data::Struct(syn::DataStruct { fields, .. }) => {
match fields {
syn::Fields::Named(_) => {
default.set(&m.path, Default::Path(path));
}
syn::Fields::Unnamed(_) | syn::Fields::Unit => cx
.error_spanned_by(
fields,
"#[serde(default = \"...\")] can only be used on structs with named fields",
),
}
}
syn::Data::Enum(syn::DataEnum { enum_token, .. }) => cx
.error_spanned_by(
enum_token,
"#[serde(default = \"...\")] can only be used on structs with named fields",
),
syn::Data::Union(syn::DataUnion {
union_token, ..
}) => cx.error_spanned_by(
union_token,
"#[serde(default = \"...\")] can only be used on structs with named fields",
),
}
}
}
// Parse `#[serde(bound = "T: SomeBound")]`
Meta(NameValue(m)) if m.path == BOUND => {
if let Ok(where_predicates) = parse_lit_into_where(cx, BOUND, BOUND, &m.lit) {
ser_bound.set(&m.path, where_predicates.clone());
de_bound.set(&m.path, where_predicates);
}
}
// Parse `#[serde(bound(serialize = "...", deserialize = "..."))]`
Meta(List(m)) if m.path == BOUND => {
if let Ok((ser, de)) = get_where_predicates(cx, &m.nested) {
ser_bound.set_opt(&m.path, ser);
de_bound.set_opt(&m.path, de);
}
}
// Parse `#[serde(untagged)]`
Meta(Path(word)) if word == UNTAGGED => match item.data {
syn::Data::Enum(_) => {
untagged.set_true(word);
}
syn::Data::Struct(syn::DataStruct { struct_token, .. }) => {
cx.error_spanned_by(
struct_token,
"#[serde(untagged)] can only be used on enums",
);
}
syn::Data::Union(syn::DataUnion { union_token, .. }) => {
cx.error_spanned_by(
union_token,
"#[serde(untagged)] can only be used on enums",
);
}
},
// Parse `#[serde(tag = "type")]`
Meta(NameValue(m)) if m.path == TAG => {
if let Ok(s) = get_lit_str(cx, TAG, &m.lit) {
match &item.data {
syn::Data::Enum(_) => {
internal_tag.set(&m.path, s.value());
}
syn::Data::Struct(syn::DataStruct { fields, .. }) => match fields {
syn::Fields::Named(_) => {
internal_tag.set(&m.path, s.value());
}
syn::Fields::Unnamed(_) | syn::Fields::Unit => {
cx.error_spanned_by(
fields,
"#[serde(tag = \"...\")] can only be used on enums and structs with named fields",
);
}
},
syn::Data::Union(syn::DataUnion { union_token, .. }) => {
cx.error_spanned_by(
union_token,
"#[serde(tag = \"...\")] can only be used on enums and structs with named fields",
);
}
}
}
}
// Parse `#[serde(content = "c")]`
Meta(NameValue(m)) if m.path == CONTENT => {
if let Ok(s) = get_lit_str(cx, CONTENT, &m.lit) {
match &item.data {
syn::Data::Enum(_) => {
content.set(&m.path, s.value());
}
syn::Data::Struct(syn::DataStruct { struct_token, .. }) => {
cx.error_spanned_by(
struct_token,
"#[serde(content = \"...\")] can only be used on enums",
);
}
syn::Data::Union(syn::DataUnion { union_token, .. }) => {
cx.error_spanned_by(
union_token,
"#[serde(content = \"...\")] can only be used on enums",
);
}
}
}
}
// Parse `#[serde(from = "Type")]
Meta(NameValue(m)) if m.path == FROM => {
if let Ok(from_ty) = parse_lit_into_ty(cx, FROM, &m.lit) {
type_from.set_opt(&m.path, Some(from_ty));
}
}
// Parse `#[serde(try_from = "Type")]
Meta(NameValue(m)) if m.path == TRY_FROM => {
if let Ok(try_from_ty) = parse_lit_into_ty(cx, TRY_FROM, &m.lit) {
type_try_from.set_opt(&m.path, Some(try_from_ty));
}
}
// Parse `#[serde(into = "Type")]
Meta(NameValue(m)) if m.path == INTO => {
if let Ok(into_ty) = parse_lit_into_ty(cx, INTO, &m.lit) {
type_into.set_opt(&m.path, Some(into_ty));
}
}
// Parse `#[serde(remote = "...")]`
Meta(NameValue(m)) if m.path == REMOTE => {
if let Ok(path) = parse_lit_into_path(cx, REMOTE, &m.lit) {
if is_primitive_path(&path, "Self") {
remote.set(&m.path, item.ident.clone().into());
} else {
remote.set(&m.path, path);
}
}
}
// Parse `#[serde(field_identifier)]`
Meta(Path(word)) if word == FIELD_IDENTIFIER => {
field_identifier.set_true(word);
}
// Parse `#[serde(variant_identifier)]`
Meta(Path(word)) if word == VARIANT_IDENTIFIER => {
variant_identifier.set_true(word);
}
// Parse `#[serde(crate = "foo")]`
Meta(NameValue(m)) if m.path == CRATE => {
if let Ok(path) = parse_lit_into_path(cx, CRATE, &m.lit) {
serde_path.set(&m.path, path);
}
}
// Parse `#[serde(expecting = "a message")]`
Meta(NameValue(m)) if m.path == EXPECTING => {
if let Ok(s) = get_lit_str(cx, EXPECTING, &m.lit) {
expecting.set(&m.path, s.value());
}
}
Meta(meta_item) => {
let path = meta_item
.path()
.into_token_stream()
.to_string()
.replace(' ', "");
cx.error_spanned_by(
meta_item.path(),
format!("unknown serde container attribute `{}`", path),
);
}
Lit(lit) => {
cx.error_spanned_by(lit, "unexpected literal in serde container attribute");
}
}
}
let mut is_packed = false;
for attr in &item.attrs {
if attr.path.is_ident("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),
},
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(),
}
}
pub fn name(&self) -> &Name {
&self.name
}
pub fn rename_all_rules(&self) -> &RenameAllRules {
&self.rename_all_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)
}
}
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 {
cx.error_spanned_by(
variant,
"#[serde(tag = \"...\")] cannot be used with tuple variants",
);
break;
}
}
}
}
}
TagType::Internal { tag }
}
(Some((untagged_tokens, _)), Some((tag_tokens, _)), None) => {
cx.error_spanned_by(
untagged_tokens,
"enum cannot be both untagged and internally tagged",
);
cx.error_spanned_by(
tag_tokens,
"enum cannot be both untagged and internally tagged",
);
TagType::External // doesn't matter, will error
}
(None, None, Some((content_tokens, _))) => {
cx.error_spanned_by(
content_tokens,
"#[serde(tag = \"...\", content = \"...\")] must be used together",
);
TagType::External
}
(Some((untagged_tokens, _)), None, Some((content_tokens, _))) => {
cx.error_spanned_by(
untagged_tokens,
"untagged enum cannot have #[serde(content = \"...\")]",
);
cx.error_spanned_by(
content_tokens,
"untagged enum cannot have #[serde(content = \"...\")]",
);
TagType::External
}
(None, Some((_, tag)), Some((_, content))) => TagType::Adjacent { tag, content },
(Some((untagged_tokens, _)), Some((tag_tokens, _)), Some((content_tokens, _))) => {
cx.error_spanned_by(
untagged_tokens,
"untagged enum cannot have #[serde(tag = \"...\", content = \"...\")]",
);
cx.error_spanned_by(
tag_tokens,
"untagged enum cannot have #[serde(tag = \"...\", content = \"...\")]",
);
cx.error_spanned_by(
content_tokens,
"untagged enum cannot have #[serde(tag = \"...\", content = \"...\")]",
);
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, _))) => {
cx.error_spanned_by(
field_identifier_tokens,
"#[serde(field_identifier)] and #[serde(variant_identifier)] cannot both be set",
);
cx.error_spanned_by(
variant_identifier_tokens,
"#[serde(field_identifier)] and #[serde(variant_identifier)] cannot both be set",
);
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) => {
cx.error_spanned_by(
struct_token,
"#[serde(field_identifier)] can only be used on an enum",
);
Identifier::No
}
(syn::Data::Union(syn::DataUnion { union_token, .. }), Some(_), None) => {
cx.error_spanned_by(
union_token,
"#[serde(field_identifier)] can only be used on an enum",
);
Identifier::No
}
(syn::Data::Struct(syn::DataStruct { struct_token, .. }), None, Some(_)) => {
cx.error_spanned_by(
struct_token,
"#[serde(variant_identifier)] can only be used on an enum",
);
Identifier::No
}
(syn::Data::Union(syn::DataUnion { union_token, .. }), None, Some(_)) => {
cx.error_spanned_by(
union_token,
"#[serde(variant_identifier)] can only be used on an enum",
);
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<syn::Meta>,
}
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);
for meta_item in variant
.attrs
.iter()
.flat_map(|attr| get_serde_meta_items(cx, attr))
.flatten()
{
match &meta_item {
// Parse `#[serde(rename = "foo")]`
Meta(NameValue(m)) if m.path == RENAME => {
if let Ok(s) = get_lit_str(cx, RENAME, &m.lit) {
ser_name.set(&m.path, s.value());
de_name.set_if_none(s.value());
de_aliases.insert(&m.path, s.value());
}
}
// Parse `#[serde(rename(serialize = "foo", deserialize = "bar"))]`
Meta(List(m)) if m.path == RENAME => {
if let Ok((ser, de)) = get_multiple_renames(cx, &m.nested) {
ser_name.set_opt(&m.path, ser.map(syn::LitStr::value));
for de_value in de {
de_name.set_if_none(de_value.value());
de_aliases.insert(&m.path, de_value.value());
}
}
}
// Parse `#[serde(alias = "foo")]`
Meta(NameValue(m)) if m.path == ALIAS => {
if let Ok(s) = get_lit_str(cx, ALIAS, &m.lit) {
de_aliases.insert(&m.path, s.value());
}
}
// Parse `#[serde(rename_all = "foo")]`
Meta(NameValue(m)) if m.path == RENAME_ALL => {
if let Ok(s) = get_lit_str(cx, RENAME_ALL, &m.lit) {
match RenameRule::from_str(&s.value()) {
Ok(rename_rule) => {
rename_all_ser_rule.set(&m.path, rename_rule);
rename_all_de_rule.set(&m.path, rename_rule);
}
Err(err) => cx.error_spanned_by(s, err),
}
}
}
// Parse `#[serde(rename_all(serialize = "foo", deserialize = "bar"))]`
Meta(List(m)) if m.path == RENAME_ALL => {
if let Ok((ser, de)) = get_renames(cx, &m.nested) {
if let Some(ser) = ser {
match RenameRule::from_str(&ser.value()) {
Ok(rename_rule) => rename_all_ser_rule.set(&m.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(&m.path, rename_rule),
Err(err) => cx.error_spanned_by(de, err),
}
}
}
}
// Parse `#[serde(skip)]`
Meta(Path(word)) if word == SKIP => {
skip_serializing.set_true(word);
skip_deserializing.set_true(word);
}
// Parse `#[serde(skip_deserializing)]`
Meta(Path(word)) if word == SKIP_DESERIALIZING => {
skip_deserializing.set_true(word);
}
// Parse `#[serde(skip_serializing)]`
Meta(Path(word)) if word == SKIP_SERIALIZING => {
skip_serializing.set_true(word);
}
// Parse `#[serde(other)]`
Meta(Path(word)) if word == OTHER => {
other.set_true(word);
}
// Parse `#[serde(bound = "T: SomeBound")]`
Meta(NameValue(m)) if m.path == BOUND => {
if let Ok(where_predicates) = parse_lit_into_where(cx, BOUND, BOUND, &m.lit) {
ser_bound.set(&m.path, where_predicates.clone());
de_bound.set(&m.path, where_predicates);
}
}
// Parse `#[serde(bound(serialize = "...", deserialize = "..."))]`
Meta(List(m)) if m.path == BOUND => {
if let Ok((ser, de)) = get_where_predicates(cx, &m.nested) {
ser_bound.set_opt(&m.path, ser);
de_bound.set_opt(&m.path, de);
}
}
// Parse `#[serde(with = "...")]`
Meta(NameValue(m)) if m.path == WITH => {
if let Ok(path) = parse_lit_into_expr_path(cx, WITH, &m.lit) {
let mut ser_path = path.clone();
ser_path
.path
.segments
.push(Ident::new("serialize", Span::call_site()).into());
serialize_with.set(&m.path, ser_path);
let mut de_path = path;
de_path
.path
.segments
.push(Ident::new("deserialize", Span::call_site()).into());
deserialize_with.set(&m.path, de_path);
}
}
// Parse `#[serde(serialize_with = "...")]`
Meta(NameValue(m)) if m.path == SERIALIZE_WITH => {
if let Ok(path) = parse_lit_into_expr_path(cx, SERIALIZE_WITH, &m.lit) {
serialize_with.set(&m.path, path);
}
}
// Parse `#[serde(deserialize_with = "...")]`
Meta(NameValue(m)) if m.path == DESERIALIZE_WITH => {
if let Ok(path) = parse_lit_into_expr_path(cx, DESERIALIZE_WITH, &m.lit) {
deserialize_with.set(&m.path, path);
}
}
// Defer `#[serde(borrow)]` and `#[serde(borrow = "'a + 'b")]`
Meta(m) if m.path() == BORROW => match &variant.fields {
syn::Fields::Unnamed(fields) if fields.unnamed.len() == 1 => {
borrow.set(m.path(), m.clone());
}
_ => {
cx.error_spanned_by(
variant,
"#[serde(borrow)] may only be used on newtype variants",
);
}
},
Meta(meta_item) => {
let path = meta_item
.path()
.into_token_stream()
.to_string()
.replace(' ', "");
cx.error_spanned_by(
meta_item.path(),
format!("unknown serde variant attribute `{}`", path),
);
}
Lit(lit) => {
cx.error_spanned_by(lit, "unexpected literal in serde variant attribute");
}
}
}
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(),
}
}
pub fn name(&self) -> &Name {
&self.name
}
pub fn aliases(&self) -> Vec<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);
}
}
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()
}
}
/// 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(),
};
let variant_borrow = attrs
.and_then(|variant| variant.borrow.as_ref())
.map(|borrow| Meta(borrow.clone()));
for meta_item in field
.attrs
.iter()
.flat_map(|attr| get_serde_meta_items(cx, attr))
.flatten()
.chain(variant_borrow)
{
match &meta_item {
// Parse `#[serde(rename = "foo")]`
Meta(NameValue(m)) if m.path == RENAME => {
if let Ok(s) = get_lit_str(cx, RENAME, &m.lit) {
ser_name.set(&m.path, s.value());
de_name.set_if_none(s.value());
de_aliases.insert(&m.path, s.value());
}
}
// Parse `#[serde(rename(serialize = "foo", deserialize = "bar"))]`
Meta(List(m)) if m.path == RENAME => {
if let Ok((ser, de)) = get_multiple_renames(cx, &m.nested) {
ser_name.set_opt(&m.path, ser.map(syn::LitStr::value));
for de_value in de {
de_name.set_if_none(de_value.value());
de_aliases.insert(&m.path, de_value.value());
}
}
}
// Parse `#[serde(alias = "foo")]`
Meta(NameValue(m)) if m.path == ALIAS => {
if let Ok(s) = get_lit_str(cx, ALIAS, &m.lit) {
de_aliases.insert(&m.path, s.value());
}
}
// Parse `#[serde(default)]`
Meta(Path(word)) if word == DEFAULT => {
default.set(word, Default::Default);
}
// Parse `#[serde(default = "...")]`
Meta(NameValue(m)) if m.path == DEFAULT => {
if let Ok(path) = parse_lit_into_expr_path(cx, DEFAULT, &m.lit) {
default.set(&m.path, Default::Path(path));
}
}
// Parse `#[serde(skip_serializing)]`
Meta(Path(word)) if word == SKIP_SERIALIZING => {
skip_serializing.set_true(word);
}
// Parse `#[serde(skip_deserializing)]`
Meta(Path(word)) if word == SKIP_DESERIALIZING => {
skip_deserializing.set_true(word);
}
// Parse `#[serde(skip)]`
Meta(Path(word)) if word == SKIP => {
skip_serializing.set_true(word);
skip_deserializing.set_true(word);
}
// Parse `#[serde(skip_serializing_if = "...")]`
Meta(NameValue(m)) if m.path == SKIP_SERIALIZING_IF => {
if let Ok(path) = parse_lit_into_expr_path(cx, SKIP_SERIALIZING_IF, &m.lit) {
skip_serializing_if.set(&m.path, path);
}
}
// Parse `#[serde(serialize_with = "...")]`
Meta(NameValue(m)) if m.path == SERIALIZE_WITH => {
if let Ok(path) = parse_lit_into_expr_path(cx, SERIALIZE_WITH, &m.lit) {
serialize_with.set(&m.path, path);
}
}
// Parse `#[serde(deserialize_with = "...")]`
Meta(NameValue(m)) if m.path == DESERIALIZE_WITH => {
if let Ok(path) = parse_lit_into_expr_path(cx, DESERIALIZE_WITH, &m.lit) {
deserialize_with.set(&m.path, path);
}
}
// Parse `#[serde(with = "...")]`
Meta(NameValue(m)) if m.path == WITH => {
if let Ok(path) = parse_lit_into_expr_path(cx, WITH, &m.lit) {
let mut ser_path = path.clone();
ser_path
.path
.segments
.push(Ident::new("serialize", Span::call_site()).into());
serialize_with.set(&m.path, ser_path);
let mut de_path = path;
de_path
.path
.segments
.push(Ident::new("deserialize", Span::call_site()).into());
deserialize_with.set(&m.path, de_path);
}
}
// Parse `#[serde(bound = "T: SomeBound")]`
Meta(NameValue(m)) if m.path == BOUND => {
if let Ok(where_predicates) = parse_lit_into_where(cx, BOUND, BOUND, &m.lit) {
ser_bound.set(&m.path, where_predicates.clone());
de_bound.set(&m.path, where_predicates);
}
}
// Parse `#[serde(bound(serialize = "...", deserialize = "..."))]`
Meta(List(m)) if m.path == BOUND => {
if let Ok((ser, de)) = get_where_predicates(cx, &m.nested) {
ser_bound.set_opt(&m.path, ser);
de_bound.set_opt(&m.path, de);
}
}
// Parse `#[serde(borrow)]`
Meta(Path(word)) if word == BORROW => {
if let Ok(borrowable) = borrowable_lifetimes(cx, &ident, field) {
borrowed_lifetimes.set(word, borrowable);
}
}
// Parse `#[serde(borrow = "'a + 'b")]`
Meta(NameValue(m)) if m.path == BORROW => {
if let Ok(lifetimes) = parse_lit_into_lifetimes(cx, BORROW, &m.lit) {
if let Ok(borrowable) = borrowable_lifetimes(cx, &ident, field) {
for lifetime in &lifetimes {
if !borrowable.contains(lifetime) {
cx.error_spanned_by(
field,
format!(
"field `{}` does not have lifetime {}",
ident, lifetime
),
);
}
}
borrowed_lifetimes.set(&m.path, lifetimes);
}
}
}
// Parse `#[serde(getter = "...")]`
Meta(NameValue(m)) if m.path == GETTER => {
if let Ok(path) = parse_lit_into_expr_path(cx, GETTER, &m.lit) {
getter.set(&m.path, path);
}
}
// Parse `#[serde(flatten)]`
Meta(Path(word)) if word == FLATTEN => {
flatten.set_true(word);
}
Meta(meta_item) => {
let path = meta_item
.path()
.into_token_stream()
.to_string()
.replace(' ', "");
cx.error_spanned_by(
meta_item.path(),
format!("unknown serde field attribute `{}`", path),
);
}
Lit(lit) => {
cx.error_spanned_by(lit, "unexpected literal in serde field attribute");
}
}
}
// 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) -> Vec<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);
}
}
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<'a, 'b, T, F>(
cx: &'b Ctxt,
attr_name: Symbol,
metas: &'a Punctuated<syn::NestedMeta, Token![,]>,
f: F,
) -> Result<(VecAttr<'b, T>, VecAttr<'b, T>), ()>
where
T: 'a,
F: Fn(&Ctxt, Symbol, Symbol, &'a syn::Lit) -> Result<T, ()>,
{
let mut ser_meta = VecAttr::none(cx, attr_name);
let mut de_meta = VecAttr::none(cx, attr_name);
for meta in metas {
match meta {
Meta(NameValue(meta)) if meta.path == SERIALIZE => {
if let Ok(v) = f(cx, attr_name, SERIALIZE, &meta.lit) {
ser_meta.insert(&meta.path, v);
}
}
Meta(NameValue(meta)) if meta.path == DESERIALIZE => {
if let Ok(v) = f(cx, attr_name, DESERIALIZE, &meta.lit) {
de_meta.insert(&meta.path, v);
}
}
_ => {
cx.error_spanned_by(
meta,
format!(
"malformed {0} attribute, expected `{0}(serialize = ..., deserialize = ...)`",
attr_name
),
);
return Err(());
}
}
}
Ok((ser_meta, de_meta))
}
fn get_renames<'a>(
cx: &Ctxt,
items: &'a Punctuated<syn::NestedMeta, Token![,]>,
) -> Result<SerAndDe<&'a syn::LitStr>, ()> {
let (ser, de) = get_ser_and_de(cx, RENAME, items, get_lit_str2)?;
Ok((ser.at_most_one()?, de.at_most_one()?))
}
fn get_multiple_renames<'a>(
cx: &Ctxt,
items: &'a Punctuated<syn::NestedMeta, Token![,]>,
) -> Result<(Option<&'a syn::LitStr>, Vec<&'a syn::LitStr>), ()> {
let (ser, de) = get_ser_and_de(cx, RENAME, items, get_lit_str2)?;
Ok((ser.at_most_one()?, de.get()))
}
fn get_where_predicates(
cx: &Ctxt,
items: &Punctuated<syn::NestedMeta, Token![,]>,
) -> Result<SerAndDe<Vec<syn::WherePredicate>>, ()> {
let (ser, de) = get_ser_and_de(cx, BOUND, items, parse_lit_into_where)?;
Ok((ser.at_most_one()?, de.at_most_one()?))
}
pub fn get_serde_meta_items(cx: &Ctxt, attr: &syn::Attribute) -> Result<Vec<syn::NestedMeta>, ()> {
if attr.path != SERDE {
return Ok(Vec::new());
}
match attr.parse_meta() {
Ok(List(meta)) => Ok(meta.nested.into_iter().collect()),
Ok(other) => {
cx.error_spanned_by(other, "expected #[serde(...)]");
Err(())
}
Err(err) => {
cx.syn_error(err);
Err(())
}
}
}
fn get_lit_str<'a>(cx: &Ctxt, attr_name: Symbol, lit: &'a syn::Lit) -> Result<&'a syn::LitStr, ()> {
get_lit_str2(cx, attr_name, attr_name, lit)
}
fn get_lit_str2<'a>(
cx: &Ctxt,
attr_name: Symbol,
meta_item_name: Symbol,
lit: &'a syn::Lit,
) -> Result<&'a syn::LitStr, ()> {
if let syn::Lit::Str(lit) = lit {
Ok(lit)
} else {
cx.error_spanned_by(
lit,
format!(
"expected serde {} attribute to be a string: `{} = \"...\"`",
attr_name, meta_item_name
),
);
Err(())
}
}
fn parse_lit_into_path(cx: &Ctxt, attr_name: Symbol, lit: &syn::Lit) -> Result<syn::Path, ()> {
let string = get_lit_str(cx, attr_name, lit)?;
parse_lit_str(string).map_err(|_| {
cx.error_spanned_by(lit, format!("failed to parse path: {:?}", string.value()));
})
}
fn parse_lit_into_expr_path(
cx: &Ctxt,
attr_name: Symbol,
lit: &syn::Lit,
) -> Result<syn::ExprPath, ()> {
let string = get_lit_str(cx, attr_name, lit)?;
parse_lit_str(string).map_err(|_| {
cx.error_spanned_by(lit, format!("failed to parse path: {:?}", string.value()));
})
}
fn parse_lit_into_where(
cx: &Ctxt,
attr_name: Symbol,
meta_item_name: Symbol,
lit: &syn::Lit,
) -> Result<Vec<syn::WherePredicate>, ()> {
let string = get_lit_str2(cx, attr_name, meta_item_name, lit)?;
if string.value().is_empty() {
return Ok(Vec::new());
}
let where_string = syn::LitStr::new(&format!("where {}", string.value()), string.span());
parse_lit_str::<syn::WhereClause>(&where_string)
.map(|wh| wh.predicates.into_iter().collect())
.map_err(|err| cx.error_spanned_by(lit, err))
}
fn parse_lit_into_ty(cx: &Ctxt, attr_name: Symbol, lit: &syn::Lit) -> Result<syn::Type, ()> {
let string = get_lit_str(cx, attr_name, lit)?;
parse_lit_str(string).map_err(|_| {
cx.error_spanned_by(
lit,
format!("failed to parse type: {} = {:?}", attr_name, string.value()),
);
})
}
// Parses a string literal like "'a + 'b + 'c" containing a nonempty list of
// lifetimes separated by `+`.
fn parse_lit_into_lifetimes(
cx: &Ctxt,
attr_name: Symbol,
lit: &syn::Lit,
) -> Result<BTreeSet<syn::Lifetime>, ()> {
let string = get_lit_str(cx, attr_name, lit)?;
if string.value().is_empty() {
cx.error_spanned_by(lit, "at least one lifetime must be borrowed");
return Err(());
}
struct BorrowedLifetimes(Punctuated<syn::Lifetime, Token![+]>);
impl Parse for BorrowedLifetimes {
fn parse(input: ParseStream) -> parse::Result<Self> {
Punctuated::parse_separated_nonempty(input).map(BorrowedLifetimes)
}
}
if let Ok(BorrowedLifetimes(lifetimes)) = parse_lit_str(string) {
let mut set = BTreeSet::new();
for lifetime in lifetimes {
if !set.insert(lifetime.clone()) {
cx.error_spanned_by(lit, format!("duplicate borrowed lifetime `{}`", lifetime));
}
}
return Ok(set);
}
cx.error_spanned_by(
lit,
format!("failed to parse borrowed lifetimes: {:?}", string.value()),
);
Err(())
}
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() {
cx.error_spanned_by(
field,
format!("field `{}` has no lifetimes to borrow", name),
);
Err(())
} else {
Ok(lifetimes)
}
}
fn collect_lifetimes(ty: &syn::Type, out: &mut BTreeSet<syn::Lifetime>) {
match ty {
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::Binding(binding) => {
collect_lifetimes(&binding.ty, out);
}
syn::GenericArgument::Constraint(_)
| syn::GenericArgument::Const(_) => {}
}
}
}
}
}
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(_) => {}
#[cfg_attr(all(test, exhaustive), deny(non_exhaustive_omitted_patterns))]
_ => {}
}
}
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);
}
_ => {}
}
}
}
fn parse_lit_str<T>(s: &syn::LitStr) -> parse::Result<T>
where
T: Parse,
{
let tokens = spanned_tokens(s)?;
syn::parse2(tokens)
}
fn spanned_tokens(s: &syn::LitStr) -> parse::Result<TokenStream> {
let stream = syn::parse_str(&s.value())?;
Ok(respan(stream, s.span()))
}
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