Revision control
Copy as Markdown
Other Tools
use crate::attr::Attribute;
use crate::expr::Expr;
use crate::generics::{BoundLifetimes, TypeParamBound};
use crate::ident::Ident;
use crate::lifetime::Lifetime;
use crate::lit::LitStr;
use crate::mac::Macro;
use crate::path::{Path, QSelf};
use crate::punctuated::Punctuated;
use crate::token;
use proc_macro2::TokenStream;
ast_enum_of_structs! {
/// The possible types that a Rust value could have.
///
/// # Syntax tree enum
///
/// This type is a [syntax tree enum].
///
/// [syntax tree enum]: crate::expr::Expr#syntax-tree-enums
#[cfg_attr(docsrs, doc(cfg(any(feature = "full", feature = "derive"))))]
#[non_exhaustive]
pub enum Type {
/// A fixed size array type: `[T; n]`.
Array(TypeArray),
/// A bare function type: `fn(usize) -> bool`.
BareFn(TypeBareFn),
/// A type contained within invisible delimiters.
Group(TypeGroup),
/// An `impl Bound1 + Bound2 + Bound3` type where `Bound` is a trait or
/// a lifetime.
ImplTrait(TypeImplTrait),
/// Indication that a type should be inferred by the compiler: `_`.
Infer(TypeInfer),
/// A macro in the type position.
Macro(TypeMacro),
/// The never type: `!`.
Never(TypeNever),
/// A parenthesized type equivalent to the inner type.
Paren(TypeParen),
/// A path like `std::slice::Iter`, optionally qualified with a
/// self-type as in `<Vec<T> as SomeTrait>::Associated`.
Path(TypePath),
/// A raw pointer type: `*const T` or `*mut T`.
Ptr(TypePtr),
/// A reference type: `&'a T` or `&'a mut T`.
Reference(TypeReference),
/// A dynamically sized slice type: `[T]`.
Slice(TypeSlice),
/// A trait object type `dyn Bound1 + Bound2 + Bound3` where `Bound` is a
/// trait or a lifetime.
TraitObject(TypeTraitObject),
/// A tuple type: `(A, B, C, String)`.
Tuple(TypeTuple),
/// Tokens in type position not interpreted by Syn.
Verbatim(TokenStream),
// For testing exhaustiveness in downstream code, use the following idiom:
//
// match ty {
// #![cfg_attr(test, deny(non_exhaustive_omitted_patterns))]
//
// Type::Array(ty) => {...}
// Type::BareFn(ty) => {...}
// ...
// Type::Verbatim(ty) => {...}
//
// _ => { /* some sane fallback */ }
// }
//
// This way we fail your tests but don't break your library when adding
// a variant. You will be notified by a test failure when a variant is
// added, so that you can add code to handle it, but your library will
// continue to compile and work for downstream users in the interim.
}
}
ast_struct! {
/// A fixed size array type: `[T; n]`.
#[cfg_attr(docsrs, doc(cfg(any(feature = "full", feature = "derive"))))]
pub struct TypeArray {
pub bracket_token: token::Bracket,
pub elem: Box<Type>,
pub semi_token: Token![;],
pub len: Expr,
}
}
ast_struct! {
/// A bare function type: `fn(usize) -> bool`.
#[cfg_attr(docsrs, doc(cfg(any(feature = "full", feature = "derive"))))]
pub struct TypeBareFn {
pub lifetimes: Option<BoundLifetimes>,
pub unsafety: Option<Token![unsafe]>,
pub abi: Option<Abi>,
pub fn_token: Token![fn],
pub paren_token: token::Paren,
pub inputs: Punctuated<BareFnArg, Token![,]>,
pub variadic: Option<BareVariadic>,
pub output: ReturnType,
}
}
ast_struct! {
/// A type contained within invisible delimiters.
#[cfg_attr(docsrs, doc(cfg(any(feature = "full", feature = "derive"))))]
pub struct TypeGroup {
pub group_token: token::Group,
pub elem: Box<Type>,
}
}
ast_struct! {
/// An `impl Bound1 + Bound2 + Bound3` type where `Bound` is a trait or
/// a lifetime.
#[cfg_attr(docsrs, doc(cfg(any(feature = "full", feature = "derive"))))]
pub struct TypeImplTrait {
pub impl_token: Token![impl],
pub bounds: Punctuated<TypeParamBound, Token![+]>,
}
}
ast_struct! {
/// Indication that a type should be inferred by the compiler: `_`.
#[cfg_attr(docsrs, doc(cfg(any(feature = "full", feature = "derive"))))]
pub struct TypeInfer {
pub underscore_token: Token![_],
}
}
ast_struct! {
/// A macro in the type position.
#[cfg_attr(docsrs, doc(cfg(any(feature = "full", feature = "derive"))))]
pub struct TypeMacro {
pub mac: Macro,
}
}
ast_struct! {
/// The never type: `!`.
#[cfg_attr(docsrs, doc(cfg(any(feature = "full", feature = "derive"))))]
pub struct TypeNever {
pub bang_token: Token![!],
}
}
ast_struct! {
/// A parenthesized type equivalent to the inner type.
#[cfg_attr(docsrs, doc(cfg(any(feature = "full", feature = "derive"))))]
pub struct TypeParen {
pub paren_token: token::Paren,
pub elem: Box<Type>,
}
}
ast_struct! {
/// A path like `std::slice::Iter`, optionally qualified with a
/// self-type as in `<Vec<T> as SomeTrait>::Associated`.
#[cfg_attr(docsrs, doc(cfg(any(feature = "full", feature = "derive"))))]
pub struct TypePath {
pub qself: Option<QSelf>,
pub path: Path,
}
}
ast_struct! {
/// A raw pointer type: `*const T` or `*mut T`.
#[cfg_attr(docsrs, doc(cfg(any(feature = "full", feature = "derive"))))]
pub struct TypePtr {
pub star_token: Token![*],
pub const_token: Option<Token![const]>,
pub mutability: Option<Token![mut]>,
pub elem: Box<Type>,
}
}
ast_struct! {
/// A reference type: `&'a T` or `&'a mut T`.
#[cfg_attr(docsrs, doc(cfg(any(feature = "full", feature = "derive"))))]
pub struct TypeReference {
pub and_token: Token![&],
pub lifetime: Option<Lifetime>,
pub mutability: Option<Token![mut]>,
pub elem: Box<Type>,
}
}
ast_struct! {
/// A dynamically sized slice type: `[T]`.
#[cfg_attr(docsrs, doc(cfg(any(feature = "full", feature = "derive"))))]
pub struct TypeSlice {
pub bracket_token: token::Bracket,
pub elem: Box<Type>,
}
}
ast_struct! {
/// A trait object type `dyn Bound1 + Bound2 + Bound3` where `Bound` is a
/// trait or a lifetime.
#[cfg_attr(docsrs, doc(cfg(any(feature = "full", feature = "derive"))))]
pub struct TypeTraitObject {
pub dyn_token: Option<Token![dyn]>,
pub bounds: Punctuated<TypeParamBound, Token![+]>,
}
}
ast_struct! {
/// A tuple type: `(A, B, C, String)`.
#[cfg_attr(docsrs, doc(cfg(any(feature = "full", feature = "derive"))))]
pub struct TypeTuple {
pub paren_token: token::Paren,
pub elems: Punctuated<Type, Token![,]>,
}
}
ast_struct! {
/// The binary interface of a function: `extern "C"`.
#[cfg_attr(docsrs, doc(cfg(any(feature = "full", feature = "derive"))))]
pub struct Abi {
pub extern_token: Token![extern],
pub name: Option<LitStr>,
}
}
ast_struct! {
/// An argument in a function type: the `usize` in `fn(usize) -> bool`.
#[cfg_attr(docsrs, doc(cfg(any(feature = "full", feature = "derive"))))]
pub struct BareFnArg {
pub attrs: Vec<Attribute>,
pub name: Option<(Ident, Token![:])>,
pub ty: Type,
}
}
ast_struct! {
/// The variadic argument of a function pointer like `fn(usize, ...)`.
#[cfg_attr(docsrs, doc(cfg(any(feature = "full", feature = "derive"))))]
pub struct BareVariadic {
pub attrs: Vec<Attribute>,
pub name: Option<(Ident, Token![:])>,
pub dots: Token![...],
pub comma: Option<Token![,]>,
}
}
ast_enum! {
/// Return type of a function signature.
#[cfg_attr(docsrs, doc(cfg(any(feature = "full", feature = "derive"))))]
pub enum ReturnType {
/// Return type is not specified.
///
/// Functions default to `()` and closures default to type inference.
Default,
/// A particular type is returned.
Type(Token![->], Box<Type>),
}
}
#[cfg(feature = "parsing")]
pub(crate) mod parsing {
use crate::attr::Attribute;
use crate::error::{self, Result};
use crate::ext::IdentExt as _;
use crate::generics::{BoundLifetimes, TraitBound, TraitBoundModifier, TypeParamBound};
use crate::ident::Ident;
use crate::lifetime::Lifetime;
use crate::mac::{self, Macro};
use crate::parse::{Parse, ParseStream};
use crate::path;
use crate::path::{Path, PathArguments, QSelf};
use crate::punctuated::Punctuated;
use crate::token;
use crate::ty::{
Abi, BareFnArg, BareVariadic, ReturnType, Type, TypeArray, TypeBareFn, TypeGroup,
TypeImplTrait, TypeInfer, TypeMacro, TypeNever, TypeParen, TypePath, TypePtr,
TypeReference, TypeSlice, TypeTraitObject, TypeTuple,
};
use crate::verbatim;
use proc_macro2::Span;
#[cfg_attr(docsrs, doc(cfg(feature = "parsing")))]
impl Parse for Type {
fn parse(input: ParseStream) -> Result<Self> {
let allow_plus = true;
let allow_group_generic = true;
ambig_ty(input, allow_plus, allow_group_generic)
}
}
impl Type {
/// In some positions, types may not contain the `+` character, to
/// disambiguate them. For example in the expression `1 as T`, T may not
/// contain a `+` character.
///
/// This parser does not allow a `+`, while the default parser does.
#[cfg_attr(docsrs, doc(cfg(feature = "parsing")))]
pub fn without_plus(input: ParseStream) -> Result<Self> {
let allow_plus = false;
let allow_group_generic = true;
ambig_ty(input, allow_plus, allow_group_generic)
}
}
pub(crate) fn ambig_ty(
input: ParseStream,
allow_plus: bool,
allow_group_generic: bool,
) -> Result<Type> {
let begin = input.fork();
if input.peek(token::Group) {
let mut group: TypeGroup = input.parse()?;
if input.peek(Token![::]) && input.peek3(Ident::peek_any) {
if let Type::Path(mut ty) = *group.elem {
Path::parse_rest(input, &mut ty.path, false)?;
return Ok(Type::Path(ty));
} else {
return Ok(Type::Path(TypePath {
qself: Some(QSelf {
lt_token: Token,
position: 0,
as_token: None,
gt_token: Token,
ty: group.elem,
}),
path: Path::parse_helper(input, false)?,
}));
}
} else if input.peek(Token![<]) && allow_group_generic
|| input.peek(Token![::]) && input.peek3(Token![<])
{
if let Type::Path(mut ty) = *group.elem {
let arguments = &mut ty.path.segments.last_mut().unwrap().arguments;
if arguments.is_none() {
*arguments = PathArguments::AngleBracketed(input.parse()?);
Path::parse_rest(input, &mut ty.path, false)?;
return Ok(Type::Path(ty));
} else {
group.elem = Box::new(Type::Path(ty));
}
}
}
return Ok(Type::Group(group));
}
let mut lifetimes = None::<BoundLifetimes>;
let mut lookahead = input.lookahead1();
if lookahead.peek(Token![for]) {
lifetimes = input.parse()?;
lookahead = input.lookahead1();
if !lookahead.peek(Ident)
&& !lookahead.peek(Token![fn])
&& !lookahead.peek(Token![unsafe])
&& !lookahead.peek(Token![extern])
&& !lookahead.peek(Token![super])
&& !lookahead.peek(Token![self])
&& !lookahead.peek(Token![Self])
&& !lookahead.peek(Token![crate])
|| input.peek(Token![dyn])
{
return Err(lookahead.error());
}
}
if lookahead.peek(token::Paren) {
let content;
let paren_token = parenthesized!(content in input);
if content.is_empty() {
return Ok(Type::Tuple(TypeTuple {
paren_token,
elems: Punctuated::new(),
}));
}
if content.peek(Lifetime) {
return Ok(Type::Paren(TypeParen {
paren_token,
elem: Box::new(Type::TraitObject(content.parse()?)),
}));
}
if content.peek(Token![?]) {
return Ok(Type::TraitObject(TypeTraitObject {
dyn_token: None,
bounds: {
let mut bounds = Punctuated::new();
bounds.push_value(TypeParamBound::Trait(TraitBound {
paren_token: Some(paren_token),
..content.parse()?
}));
while let Some(plus) = input.parse()? {
bounds.push_punct(plus);
bounds.push_value({
let allow_precise_capture = false;
let allow_tilde_const = false;
TypeParamBound::parse_single(
input,
allow_precise_capture,
allow_tilde_const,
)?
});
}
bounds
},
}));
}
let mut first: Type = content.parse()?;
if content.peek(Token![,]) {
return Ok(Type::Tuple(TypeTuple {
paren_token,
elems: {
let mut elems = Punctuated::new();
elems.push_value(first);
elems.push_punct(content.parse()?);
while !content.is_empty() {
elems.push_value(content.parse()?);
if content.is_empty() {
break;
}
elems.push_punct(content.parse()?);
}
elems
},
}));
}
if allow_plus && input.peek(Token![+]) {
loop {
let first = match first {
Type::Path(TypePath { qself: None, path }) => {
TypeParamBound::Trait(TraitBound {
paren_token: Some(paren_token),
modifier: TraitBoundModifier::None,
lifetimes: None,
path,
})
}
Type::TraitObject(TypeTraitObject {
dyn_token: None,
bounds,
}) => {
if bounds.len() > 1 || bounds.trailing_punct() {
first = Type::TraitObject(TypeTraitObject {
dyn_token: None,
bounds,
});
break;
}
match bounds.into_iter().next().unwrap() {
TypeParamBound::Trait(trait_bound) => {
TypeParamBound::Trait(TraitBound {
paren_token: Some(paren_token),
..trait_bound
})
}
other @ (TypeParamBound::Lifetime(_)
| TypeParamBound::PreciseCapture(_)
| TypeParamBound::Verbatim(_)) => other,
}
}
_ => break,
};
return Ok(Type::TraitObject(TypeTraitObject {
dyn_token: None,
bounds: {
let mut bounds = Punctuated::new();
bounds.push_value(first);
while let Some(plus) = input.parse()? {
bounds.push_punct(plus);
bounds.push_value({
let allow_precise_capture = false;
let allow_tilde_const = false;
TypeParamBound::parse_single(
input,
allow_precise_capture,
allow_tilde_const,
)?
});
}
bounds
},
}));
}
}
Ok(Type::Paren(TypeParen {
paren_token,
elem: Box::new(first),
}))
} else if lookahead.peek(Token![fn])
|| lookahead.peek(Token![unsafe])
|| lookahead.peek(Token![extern])
{
let mut bare_fn: TypeBareFn = input.parse()?;
bare_fn.lifetimes = lifetimes;
Ok(Type::BareFn(bare_fn))
} else if lookahead.peek(Ident)
|| input.peek(Token![super])
|| input.peek(Token![self])
|| input.peek(Token![Self])
|| input.peek(Token![crate])
|| lookahead.peek(Token![::])
|| lookahead.peek(Token![<])
{
let ty: TypePath = input.parse()?;
if ty.qself.is_some() {
return Ok(Type::Path(ty));
}
if input.peek(Token![!]) && !input.peek(Token![!=]) && ty.path.is_mod_style() {
let bang_token: Token![!] = input.parse()?;
let (delimiter, tokens) = mac::parse_delimiter(input)?;
return Ok(Type::Macro(TypeMacro {
mac: Macro {
path: ty.path,
bang_token,
delimiter,
tokens,
},
}));
}
if lifetimes.is_some() || allow_plus && input.peek(Token![+]) {
let mut bounds = Punctuated::new();
bounds.push_value(TypeParamBound::Trait(TraitBound {
paren_token: None,
modifier: TraitBoundModifier::None,
lifetimes,
path: ty.path,
}));
if allow_plus {
while input.peek(Token![+]) {
bounds.push_punct(input.parse()?);
if !(input.peek(Ident::peek_any)
|| input.peek(Token![::])
|| input.peek(Token![?])
|| input.peek(Lifetime)
|| input.peek(token::Paren))
{
break;
}
bounds.push_value({
let allow_precise_capture = false;
let allow_tilde_const = false;
TypeParamBound::parse_single(
input,
allow_precise_capture,
allow_tilde_const,
)?
});
}
}
return Ok(Type::TraitObject(TypeTraitObject {
dyn_token: None,
bounds,
}));
}
Ok(Type::Path(ty))
} else if lookahead.peek(Token![dyn]) {
let dyn_token: Token![dyn] = input.parse()?;
let dyn_span = dyn_token.span;
let star_token: Option<Token![*]> = input.parse()?;
let bounds = TypeTraitObject::parse_bounds(dyn_span, input, allow_plus)?;
return Ok(if star_token.is_some() {
Type::Verbatim(verbatim::between(&begin, input))
} else {
Type::TraitObject(TypeTraitObject {
dyn_token: Some(dyn_token),
bounds,
})
});
} else if lookahead.peek(token::Bracket) {
let content;
let bracket_token = bracketed!(content in input);
let elem: Type = content.parse()?;
if content.peek(Token![;]) {
Ok(Type::Array(TypeArray {
bracket_token,
elem: Box::new(elem),
semi_token: content.parse()?,
len: content.parse()?,
}))
} else {
Ok(Type::Slice(TypeSlice {
bracket_token,
elem: Box::new(elem),
}))
}
} else if lookahead.peek(Token![*]) {
input.parse().map(Type::Ptr)
} else if lookahead.peek(Token![&]) {
input.parse().map(Type::Reference)
} else if lookahead.peek(Token![!]) && !input.peek(Token![=]) {
input.parse().map(Type::Never)
} else if lookahead.peek(Token![impl]) {
TypeImplTrait::parse(input, allow_plus).map(Type::ImplTrait)
} else if lookahead.peek(Token![_]) {
input.parse().map(Type::Infer)
} else if lookahead.peek(Lifetime) {
input.parse().map(Type::TraitObject)
} else {
Err(lookahead.error())
}
}
#[cfg_attr(docsrs, doc(cfg(feature = "parsing")))]
impl Parse for TypeSlice {
fn parse(input: ParseStream) -> Result<Self> {
let content;
Ok(TypeSlice {
bracket_token: bracketed!(content in input),
elem: content.parse()?,
})
}
}
#[cfg_attr(docsrs, doc(cfg(feature = "parsing")))]
impl Parse for TypeArray {
fn parse(input: ParseStream) -> Result<Self> {
let content;
Ok(TypeArray {
bracket_token: bracketed!(content in input),
elem: content.parse()?,
semi_token: content.parse()?,
len: content.parse()?,
})
}
}
#[cfg_attr(docsrs, doc(cfg(feature = "parsing")))]
impl Parse for TypePtr {
fn parse(input: ParseStream) -> Result<Self> {
let star_token: Token![*] = input.parse()?;
let lookahead = input.lookahead1();
let (const_token, mutability) = if lookahead.peek(Token![const]) {
(Some(input.parse()?), None)
} else if lookahead.peek(Token![mut]) {
(None, Some(input.parse()?))
} else {
return Err(lookahead.error());
};
Ok(TypePtr {
star_token,
const_token,
mutability,
elem: Box::new(input.call(Type::without_plus)?),
})
}
}
#[cfg_attr(docsrs, doc(cfg(feature = "parsing")))]
impl Parse for TypeReference {
fn parse(input: ParseStream) -> Result<Self> {
Ok(TypeReference {
and_token: input.parse()?,
lifetime: input.parse()?,
mutability: input.parse()?,
// & binds tighter than +, so we don't allow + here.
elem: Box::new(input.call(Type::without_plus)?),
})
}
}
#[cfg_attr(docsrs, doc(cfg(feature = "parsing")))]
impl Parse for TypeBareFn {
fn parse(input: ParseStream) -> Result<Self> {
let args;
let mut variadic = None;
Ok(TypeBareFn {
lifetimes: input.parse()?,
unsafety: input.parse()?,
abi: input.parse()?,
fn_token: input.parse()?,
paren_token: parenthesized!(args in input),
inputs: {
let mut inputs = Punctuated::new();
while !args.is_empty() {
let attrs = args.call(Attribute::parse_outer)?;
if inputs.empty_or_trailing()
&& (args.peek(Token![...])
|| (args.peek(Ident) || args.peek(Token![_]))
&& args.peek2(Token![:])
&& args.peek3(Token![...]))
{
variadic = Some(parse_bare_variadic(&args, attrs)?);
break;
}
let allow_self = inputs.is_empty();
let arg = parse_bare_fn_arg(&args, allow_self)?;
inputs.push_value(BareFnArg { attrs, ..arg });
if args.is_empty() {
break;
}
let comma = args.parse()?;
inputs.push_punct(comma);
}
inputs
},
variadic,
output: input.call(ReturnType::without_plus)?,
})
}
}
#[cfg_attr(docsrs, doc(cfg(feature = "parsing")))]
impl Parse for TypeNever {
fn parse(input: ParseStream) -> Result<Self> {
Ok(TypeNever {
bang_token: input.parse()?,
})
}
}
#[cfg_attr(docsrs, doc(cfg(feature = "parsing")))]
impl Parse for TypeInfer {
fn parse(input: ParseStream) -> Result<Self> {
Ok(TypeInfer {
underscore_token: input.parse()?,
})
}
}
#[cfg_attr(docsrs, doc(cfg(feature = "parsing")))]
impl Parse for TypeTuple {
fn parse(input: ParseStream) -> Result<Self> {
let content;
let paren_token = parenthesized!(content in input);
if content.is_empty() {
return Ok(TypeTuple {
paren_token,
elems: Punctuated::new(),
});
}
let first: Type = content.parse()?;
Ok(TypeTuple {
paren_token,
elems: {
let mut elems = Punctuated::new();
elems.push_value(first);
elems.push_punct(content.parse()?);
while !content.is_empty() {
elems.push_value(content.parse()?);
if content.is_empty() {
break;
}
elems.push_punct(content.parse()?);
}
elems
},
})
}
}
#[cfg_attr(docsrs, doc(cfg(feature = "parsing")))]
impl Parse for TypeMacro {
fn parse(input: ParseStream) -> Result<Self> {
Ok(TypeMacro {
mac: input.parse()?,
})
}
}
#[cfg_attr(docsrs, doc(cfg(feature = "parsing")))]
impl Parse for TypePath {
fn parse(input: ParseStream) -> Result<Self> {
let expr_style = false;
let (qself, path) = path::parsing::qpath(input, expr_style)?;
Ok(TypePath { qself, path })
}
}
impl ReturnType {
#[cfg_attr(docsrs, doc(cfg(feature = "parsing")))]
pub fn without_plus(input: ParseStream) -> Result<Self> {
let allow_plus = false;
Self::parse(input, allow_plus)
}
pub(crate) fn parse(input: ParseStream, allow_plus: bool) -> Result<Self> {
if input.peek(Token![->]) {
let arrow = input.parse()?;
let allow_group_generic = true;
let ty = ambig_ty(input, allow_plus, allow_group_generic)?;
Ok(ReturnType::Type(arrow, Box::new(ty)))
} else {
Ok(ReturnType::Default)
}
}
}
#[cfg_attr(docsrs, doc(cfg(feature = "parsing")))]
impl Parse for ReturnType {
fn parse(input: ParseStream) -> Result<Self> {
let allow_plus = true;
Self::parse(input, allow_plus)
}
}
#[cfg_attr(docsrs, doc(cfg(feature = "parsing")))]
impl Parse for TypeTraitObject {
fn parse(input: ParseStream) -> Result<Self> {
let allow_plus = true;
Self::parse(input, allow_plus)
}
}
impl TypeTraitObject {
#[cfg_attr(docsrs, doc(cfg(feature = "parsing")))]
pub fn without_plus(input: ParseStream) -> Result<Self> {
let allow_plus = false;
Self::parse(input, allow_plus)
}
// Only allow multiple trait references if allow_plus is true.
pub(crate) fn parse(input: ParseStream, allow_plus: bool) -> Result<Self> {
let dyn_token: Option<Token![dyn]> = input.parse()?;
let dyn_span = match &dyn_token {
Some(token) => token.span,
None => input.span(),
};
let bounds = Self::parse_bounds(dyn_span, input, allow_plus)?;
Ok(TypeTraitObject { dyn_token, bounds })
}
fn parse_bounds(
dyn_span: Span,
input: ParseStream,
allow_plus: bool,
) -> Result<Punctuated<TypeParamBound, Token![+]>> {
let allow_precise_capture = false;
let allow_tilde_const = false;
let bounds = TypeParamBound::parse_multiple(
input,
allow_plus,
allow_precise_capture,
allow_tilde_const,
)?;
let mut last_lifetime_span = None;
let mut at_least_one_trait = false;
for bound in &bounds {
match bound {
TypeParamBound::Trait(_) => {
at_least_one_trait = true;
break;
}
TypeParamBound::Lifetime(lifetime) => {
last_lifetime_span = Some(lifetime.ident.span());
}
TypeParamBound::PreciseCapture(_) | TypeParamBound::Verbatim(_) => {
unreachable!()
}
}
}
// Just lifetimes like `'a + 'b` is not a TraitObject.
if !at_least_one_trait {
let msg = "at least one trait is required for an object type";
return Err(error::new2(dyn_span, last_lifetime_span.unwrap(), msg));
}
Ok(bounds)
}
}
#[cfg_attr(docsrs, doc(cfg(feature = "parsing")))]
impl Parse for TypeImplTrait {
fn parse(input: ParseStream) -> Result<Self> {
let allow_plus = true;
Self::parse(input, allow_plus)
}
}
impl TypeImplTrait {
#[cfg_attr(docsrs, doc(cfg(feature = "parsing")))]
pub fn without_plus(input: ParseStream) -> Result<Self> {
let allow_plus = false;
Self::parse(input, allow_plus)
}
pub(crate) fn parse(input: ParseStream, allow_plus: bool) -> Result<Self> {
let impl_token: Token![impl] = input.parse()?;
let allow_precise_capture = true;
let allow_tilde_const = false;
let bounds = TypeParamBound::parse_multiple(
input,
allow_plus,
allow_precise_capture,
allow_tilde_const,
)?;
let mut last_nontrait_span = None;
let mut at_least_one_trait = false;
for bound in &bounds {
match bound {
TypeParamBound::Trait(_) => {
at_least_one_trait = true;
break;
}
TypeParamBound::Lifetime(lifetime) => {
last_nontrait_span = Some(lifetime.ident.span());
}
TypeParamBound::PreciseCapture(precise_capture) => {
#[cfg(feature = "full")]
{
last_nontrait_span = Some(precise_capture.gt_token.span);
}
#[cfg(not(feature = "full"))]
{
_ = precise_capture;
unreachable!();
}
}
TypeParamBound::Verbatim(_) => {
// ~const Trait
at_least_one_trait = true;
break;
}
}
}
if !at_least_one_trait {
let msg = "at least one trait must be specified";
return Err(error::new2(
impl_token.span,
last_nontrait_span.unwrap(),
msg,
));
}
Ok(TypeImplTrait { impl_token, bounds })
}
}
#[cfg_attr(docsrs, doc(cfg(feature = "parsing")))]
impl Parse for TypeGroup {
fn parse(input: ParseStream) -> Result<Self> {
let group = crate::group::parse_group(input)?;
Ok(TypeGroup {
group_token: group.token,
elem: group.content.parse()?,
})
}
}
#[cfg_attr(docsrs, doc(cfg(feature = "parsing")))]
impl Parse for TypeParen {
fn parse(input: ParseStream) -> Result<Self> {
let allow_plus = false;
Self::parse(input, allow_plus)
}
}
impl TypeParen {
fn parse(input: ParseStream, allow_plus: bool) -> Result<Self> {
let content;
Ok(TypeParen {
paren_token: parenthesized!(content in input),
elem: Box::new({
let allow_group_generic = true;
ambig_ty(&content, allow_plus, allow_group_generic)?
}),
})
}
}
#[cfg_attr(docsrs, doc(cfg(feature = "parsing")))]
impl Parse for BareFnArg {
fn parse(input: ParseStream) -> Result<Self> {
let allow_self = false;
parse_bare_fn_arg(input, allow_self)
}
}
fn parse_bare_fn_arg(input: ParseStream, allow_self: bool) -> Result<BareFnArg> {
let attrs = input.call(Attribute::parse_outer)?;
let begin = input.fork();
let has_mut_self = allow_self && input.peek(Token![mut]) && input.peek2(Token![self]);
if has_mut_self {
input.parse::<Token![mut]>()?;
}
let mut has_self = false;
let mut name = if (input.peek(Ident) || input.peek(Token![_]) || {
has_self = allow_self && input.peek(Token![self]);
has_self
}) && input.peek2(Token![:])
&& !input.peek2(Token![::])
{
let name = input.call(Ident::parse_any)?;
let colon: Token![:] = input.parse()?;
Some((name, colon))
} else {
has_self = false;
None
};
let ty = if allow_self && !has_self && input.peek(Token![mut]) && input.peek2(Token![self])
{
input.parse::<Token![mut]>()?;
input.parse::<Token![self]>()?;
None
} else if has_mut_self && name.is_none() {
input.parse::<Token![self]>()?;
None
} else {
Some(input.parse()?)
};
let ty = match ty {
Some(ty) if !has_mut_self => ty,
_ => {
name = None;
Type::Verbatim(verbatim::between(&begin, input))
}
};
Ok(BareFnArg { attrs, name, ty })
}
fn parse_bare_variadic(input: ParseStream, attrs: Vec<Attribute>) -> Result<BareVariadic> {
Ok(BareVariadic {
attrs,
name: if input.peek(Ident) || input.peek(Token![_]) {
let name = input.call(Ident::parse_any)?;
let colon: Token![:] = input.parse()?;
Some((name, colon))
} else {
None
},
dots: input.parse()?,
comma: input.parse()?,
})
}
#[cfg_attr(docsrs, doc(cfg(feature = "parsing")))]
impl Parse for Abi {
fn parse(input: ParseStream) -> Result<Self> {
Ok(Abi {
extern_token: input.parse()?,
name: input.parse()?,
})
}
}
#[cfg_attr(docsrs, doc(cfg(feature = "parsing")))]
impl Parse for Option<Abi> {
fn parse(input: ParseStream) -> Result<Self> {
if input.peek(Token![extern]) {
input.parse().map(Some)
} else {
Ok(None)
}
}
}
}
#[cfg(feature = "printing")]
mod printing {
use crate::attr::FilterAttrs;
use crate::path;
use crate::path::printing::PathStyle;
use crate::print::TokensOrDefault;
use crate::ty::{
Abi, BareFnArg, BareVariadic, ReturnType, TypeArray, TypeBareFn, TypeGroup, TypeImplTrait,
TypeInfer, TypeMacro, TypeNever, TypeParen, TypePath, TypePtr, TypeReference, TypeSlice,
TypeTraitObject, TypeTuple,
};
use proc_macro2::TokenStream;
use quote::{ToTokens, TokenStreamExt};
#[cfg_attr(docsrs, doc(cfg(feature = "printing")))]
impl ToTokens for TypeSlice {
fn to_tokens(&self, tokens: &mut TokenStream) {
self.bracket_token.surround(tokens, |tokens| {
self.elem.to_tokens(tokens);
});
}
}
#[cfg_attr(docsrs, doc(cfg(feature = "printing")))]
impl ToTokens for TypeArray {
fn to_tokens(&self, tokens: &mut TokenStream) {
self.bracket_token.surround(tokens, |tokens| {
self.elem.to_tokens(tokens);
self.semi_token.to_tokens(tokens);
self.len.to_tokens(tokens);
});
}
}
#[cfg_attr(docsrs, doc(cfg(feature = "printing")))]
impl ToTokens for TypePtr {
fn to_tokens(&self, tokens: &mut TokenStream) {
self.star_token.to_tokens(tokens);
match &self.mutability {
Some(tok) => tok.to_tokens(tokens),
None => {
TokensOrDefault(&self.const_token).to_tokens(tokens);
}
}
self.elem.to_tokens(tokens);
}
}
#[cfg_attr(docsrs, doc(cfg(feature = "printing")))]
impl ToTokens for TypeReference {
fn to_tokens(&self, tokens: &mut TokenStream) {
self.and_token.to_tokens(tokens);
self.lifetime.to_tokens(tokens);
self.mutability.to_tokens(tokens);
self.elem.to_tokens(tokens);
}
}
#[cfg_attr(docsrs, doc(cfg(feature = "printing")))]
impl ToTokens for TypeBareFn {
fn to_tokens(&self, tokens: &mut TokenStream) {
self.lifetimes.to_tokens(tokens);
self.unsafety.to_tokens(tokens);
self.abi.to_tokens(tokens);
self.fn_token.to_tokens(tokens);
self.paren_token.surround(tokens, |tokens| {
self.inputs.to_tokens(tokens);
if let Some(variadic) = &self.variadic {
if !self.inputs.empty_or_trailing() {
let span = variadic.dots.spans[0];
Token.to_tokens(tokens);
}
variadic.to_tokens(tokens);
}
});
self.output.to_tokens(tokens);
}
}
#[cfg_attr(docsrs, doc(cfg(feature = "printing")))]
impl ToTokens for TypeNever {
fn to_tokens(&self, tokens: &mut TokenStream) {
self.bang_token.to_tokens(tokens);
}
}
#[cfg_attr(docsrs, doc(cfg(feature = "printing")))]
impl ToTokens for TypeTuple {
fn to_tokens(&self, tokens: &mut TokenStream) {
self.paren_token.surround(tokens, |tokens| {
self.elems.to_tokens(tokens);
// If we only have one argument, we need a trailing comma to
// distinguish TypeTuple from TypeParen.
if self.elems.len() == 1 && !self.elems.trailing_punct() {
<Token![,]>::default().to_tokens(tokens);
}
});
}
}
#[cfg_attr(docsrs, doc(cfg(feature = "printing")))]
impl ToTokens for TypePath {
fn to_tokens(&self, tokens: &mut TokenStream) {
path::printing::print_qpath(tokens, &self.qself, &self.path, PathStyle::AsWritten);
}
}
#[cfg_attr(docsrs, doc(cfg(feature = "printing")))]
impl ToTokens for TypeTraitObject {
fn to_tokens(&self, tokens: &mut TokenStream) {
self.dyn_token.to_tokens(tokens);
self.bounds.to_tokens(tokens);
}
}
#[cfg_attr(docsrs, doc(cfg(feature = "printing")))]
impl ToTokens for TypeImplTrait {
fn to_tokens(&self, tokens: &mut TokenStream) {
self.impl_token.to_tokens(tokens);
self.bounds.to_tokens(tokens);
}
}
#[cfg_attr(docsrs, doc(cfg(feature = "printing")))]
impl ToTokens for TypeGroup {
fn to_tokens(&self, tokens: &mut TokenStream) {
self.group_token.surround(tokens, |tokens| {
self.elem.to_tokens(tokens);
});
}
}
#[cfg_attr(docsrs, doc(cfg(feature = "printing")))]
impl ToTokens for TypeParen {
fn to_tokens(&self, tokens: &mut TokenStream) {
self.paren_token.surround(tokens, |tokens| {
self.elem.to_tokens(tokens);
});
}
}
#[cfg_attr(docsrs, doc(cfg(feature = "printing")))]
impl ToTokens for TypeInfer {
fn to_tokens(&self, tokens: &mut TokenStream) {
self.underscore_token.to_tokens(tokens);
}
}
#[cfg_attr(docsrs, doc(cfg(feature = "printing")))]
impl ToTokens for TypeMacro {
fn to_tokens(&self, tokens: &mut TokenStream) {
self.mac.to_tokens(tokens);
}
}
#[cfg_attr(docsrs, doc(cfg(feature = "printing")))]
impl ToTokens for ReturnType {
fn to_tokens(&self, tokens: &mut TokenStream) {
match self {
ReturnType::Default => {}
ReturnType::Type(arrow, ty) => {
arrow.to_tokens(tokens);
ty.to_tokens(tokens);
}
}
}
}
#[cfg_attr(docsrs, doc(cfg(feature = "printing")))]
impl ToTokens for BareFnArg {
fn to_tokens(&self, tokens: &mut TokenStream) {
tokens.append_all(self.attrs.outer());
if let Some((name, colon)) = &self.name {
name.to_tokens(tokens);
colon.to_tokens(tokens);
}
self.ty.to_tokens(tokens);
}
}
#[cfg_attr(docsrs, doc(cfg(feature = "printing")))]
impl ToTokens for BareVariadic {
fn to_tokens(&self, tokens: &mut TokenStream) {
tokens.append_all(self.attrs.outer());
if let Some((name, colon)) = &self.name {
name.to_tokens(tokens);
colon.to_tokens(tokens);
}
self.dots.to_tokens(tokens);
self.comma.to_tokens(tokens);
}
}
#[cfg_attr(docsrs, doc(cfg(feature = "printing")))]
impl ToTokens for Abi {
fn to_tokens(&self, tokens: &mut TokenStream) {
self.extern_token.to_tokens(tokens);
self.name.to_tokens(tokens);
}
}
}