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#[cfg(feature = "parsing")]
use crate::error::Result;
use crate::expr::Expr;
use crate::generics::TypeParamBound;
use crate::ident::Ident;
use crate::lifetime::Lifetime;
use crate::punctuated::Punctuated;
use crate::token;
use crate::ty::{ReturnType, Type};
ast_struct! {
/// A path at which a named item is exported (e.g. `std::collections::HashMap`).
#[cfg_attr(docsrs, doc(cfg(any(feature = "full", feature = "derive"))))]
pub struct Path {
pub leading_colon: Option<Token![::]>,
pub segments: Punctuated<PathSegment, Token![::]>,
}
}
impl<T> From<T> for Path
where
T: Into<PathSegment>,
{
fn from(segment: T) -> Self {
let mut path = Path {
leading_colon: None,
segments: Punctuated::new(),
};
path.segments.push_value(segment.into());
path
}
}
impl Path {
/// Determines whether this is a path of length 1 equal to the given
/// ident.
///
/// For them to compare equal, it must be the case that:
///
/// - the path has no leading colon,
/// - the number of path segments is 1,
/// - the first path segment has no angle bracketed or parenthesized
/// path arguments, and
/// - the ident of the first path segment is equal to the given one.
///
/// # Example
///
/// ```
/// use proc_macro2::TokenStream;
/// use syn::{Attribute, Error, Meta, Result};
///
/// fn get_serde_meta_item(attr: &Attribute) -> Result<Option<&TokenStream>> {
/// if attr.path().is_ident("serde") {
/// match &attr.meta {
/// Meta::List(meta) => Ok(Some(&meta.tokens)),
/// bad => Err(Error::new_spanned(bad, "unrecognized attribute")),
/// }
/// } else {
/// Ok(None)
/// }
/// }
/// ```
pub fn is_ident<I>(&self, ident: &I) -> bool
where
I: ?Sized,
Ident: PartialEq<I>,
{
match self.get_ident() {
Some(id) => id == ident,
None => false,
}
}
/// If this path consists of a single ident, returns the ident.
///
/// A path is considered an ident if:
///
/// - the path has no leading colon,
/// - the number of path segments is 1, and
/// - the first path segment has no angle bracketed or parenthesized
/// path arguments.
pub fn get_ident(&self) -> Option<&Ident> {
if self.leading_colon.is_none()
&& self.segments.len() == 1
&& self.segments[0].arguments.is_none()
{
Some(&self.segments[0].ident)
} else {
None
}
}
/// An error if this path is not a single ident, as defined in `get_ident`.
#[cfg(feature = "parsing")]
#[cfg_attr(docsrs, doc(cfg(feature = "parsing")))]
pub fn require_ident(&self) -> Result<&Ident> {
self.get_ident().ok_or_else(|| {
crate::error::new2(
self.segments.first().unwrap().ident.span(),
self.segments.last().unwrap().ident.span(),
"expected this path to be an identifier",
)
})
}
}
ast_struct! {
/// A segment of a path together with any path arguments on that segment.
#[cfg_attr(docsrs, doc(cfg(any(feature = "full", feature = "derive"))))]
pub struct PathSegment {
pub ident: Ident,
pub arguments: PathArguments,
}
}
impl<T> From<T> for PathSegment
where
T: Into<Ident>,
{
fn from(ident: T) -> Self {
PathSegment {
ident: ident.into(),
arguments: PathArguments::None,
}
}
}
ast_enum! {
/// Angle bracketed or parenthesized arguments of a path segment.
///
/// ## Angle bracketed
///
/// The `<'a, T>` in `std::slice::iter<'a, T>`.
///
/// ## Parenthesized
///
/// The `(A, B) -> C` in `Fn(A, B) -> C`.
#[cfg_attr(docsrs, doc(cfg(any(feature = "full", feature = "derive"))))]
pub enum PathArguments {
None,
/// The `<'a, T>` in `std::slice::iter<'a, T>`.
AngleBracketed(AngleBracketedGenericArguments),
/// The `(A, B) -> C` in `Fn(A, B) -> C`.
Parenthesized(ParenthesizedGenericArguments),
}
}
impl Default for PathArguments {
fn default() -> Self {
PathArguments::None
}
}
impl PathArguments {
pub fn is_empty(&self) -> bool {
match self {
PathArguments::None => true,
PathArguments::AngleBracketed(bracketed) => bracketed.args.is_empty(),
PathArguments::Parenthesized(_) => false,
}
}
pub fn is_none(&self) -> bool {
match self {
PathArguments::None => true,
PathArguments::AngleBracketed(_) | PathArguments::Parenthesized(_) => false,
}
}
}
ast_enum! {
/// An individual generic argument, like `'a`, `T`, or `Item = T`.
#[cfg_attr(docsrs, doc(cfg(any(feature = "full", feature = "derive"))))]
#[non_exhaustive]
pub enum GenericArgument {
/// A lifetime argument.
Lifetime(Lifetime),
/// A type argument.
Type(Type),
/// A const expression. Must be inside of a block.
///
/// NOTE: Identity expressions are represented as Type arguments, as
/// they are indistinguishable syntactically.
Const(Expr),
/// A binding (equality constraint) on an associated type: the `Item =
/// u8` in `Iterator<Item = u8>`.
AssocType(AssocType),
/// An equality constraint on an associated constant: the `PANIC =
/// false` in `Trait<PANIC = false>`.
AssocConst(AssocConst),
/// An associated type bound: `Iterator<Item: Display>`.
Constraint(Constraint),
}
}
ast_struct! {
/// Angle bracketed arguments of a path segment: the `<K, V>` in `HashMap<K,
/// V>`.
#[cfg_attr(docsrs, doc(cfg(any(feature = "full", feature = "derive"))))]
pub struct AngleBracketedGenericArguments {
pub colon2_token: Option<Token![::]>,
pub lt_token: Token![<],
pub args: Punctuated<GenericArgument, Token![,]>,
pub gt_token: Token![>],
}
}
ast_struct! {
/// A binding (equality constraint) on an associated type: the `Item = u8`
/// in `Iterator<Item = u8>`.
#[cfg_attr(docsrs, doc(cfg(any(feature = "full", feature = "derive"))))]
pub struct AssocType {
pub ident: Ident,
pub generics: Option<AngleBracketedGenericArguments>,
pub eq_token: Token![=],
pub ty: Type,
}
}
ast_struct! {
/// An equality constraint on an associated constant: the `PANIC = false` in
/// `Trait<PANIC = false>`.
#[cfg_attr(docsrs, doc(cfg(any(feature = "full", feature = "derive"))))]
pub struct AssocConst {
pub ident: Ident,
pub generics: Option<AngleBracketedGenericArguments>,
pub eq_token: Token![=],
pub value: Expr,
}
}
ast_struct! {
/// An associated type bound: `Iterator<Item: Display>`.
#[cfg_attr(docsrs, doc(cfg(any(feature = "full", feature = "derive"))))]
pub struct Constraint {
pub ident: Ident,
pub generics: Option<AngleBracketedGenericArguments>,
pub colon_token: Token![:],
pub bounds: Punctuated<TypeParamBound, Token![+]>,
}
}
ast_struct! {
/// Arguments of a function path segment: the `(A, B) -> C` in `Fn(A,B) ->
/// C`.
#[cfg_attr(docsrs, doc(cfg(any(feature = "full", feature = "derive"))))]
pub struct ParenthesizedGenericArguments {
pub paren_token: token::Paren,
/// `(A, B)`
pub inputs: Punctuated<Type, Token![,]>,
/// `C`
pub output: ReturnType,
}
}
ast_struct! {
/// The explicit Self type in a qualified path: the `T` in `<T as
/// Display>::fmt`.
///
/// The actual path, including the trait and the associated item, is stored
/// separately. The `position` field represents the index of the associated
/// item qualified with this Self type.
///
/// ```text
/// <Vec<T> as a::b::Trait>::AssociatedItem
/// ^~~~~~ ~~~~~~~~~~~~~~^
/// ty position = 3
///
/// <Vec<T>>::AssociatedItem
/// ^~~~~~ ^
/// ty position = 0
/// ```
#[cfg_attr(docsrs, doc(cfg(any(feature = "full", feature = "derive"))))]
pub struct QSelf {
pub lt_token: Token![<],
pub ty: Box<Type>,
pub position: usize,
pub as_token: Option<Token![as]>,
pub gt_token: Token![>],
}
}
#[cfg(feature = "parsing")]
pub(crate) mod parsing {
use crate::error::Result;
#[cfg(feature = "full")]
use crate::expr::ExprBlock;
use crate::expr::{Expr, ExprPath};
use crate::ext::IdentExt as _;
#[cfg(feature = "full")]
use crate::generics::TypeParamBound;
use crate::ident::Ident;
use crate::lifetime::Lifetime;
use crate::lit::Lit;
use crate::parse::{Parse, ParseStream};
#[cfg(feature = "full")]
use crate::path::Constraint;
use crate::path::{
AngleBracketedGenericArguments, AssocConst, AssocType, GenericArgument,
ParenthesizedGenericArguments, Path, PathArguments, PathSegment, QSelf,
};
use crate::punctuated::Punctuated;
use crate::token;
use crate::ty::{ReturnType, Type};
#[cfg(not(feature = "full"))]
use crate::verbatim;
#[cfg_attr(docsrs, doc(cfg(feature = "parsing")))]
impl Parse for Path {
fn parse(input: ParseStream) -> Result<Self> {
Self::parse_helper(input, false)
}
}
#[cfg_attr(docsrs, doc(cfg(feature = "parsing")))]
impl Parse for GenericArgument {
fn parse(input: ParseStream) -> Result<Self> {
if input.peek(Lifetime) && !input.peek2(Token![+]) {
return Ok(GenericArgument::Lifetime(input.parse()?));
}
if input.peek(Lit) || input.peek(token::Brace) {
return const_argument(input).map(GenericArgument::Const);
}
let mut argument: Type = input.parse()?;
match argument {
Type::Path(mut ty)
if ty.qself.is_none()
&& ty.path.leading_colon.is_none()
&& ty.path.segments.len() == 1
&& match &ty.path.segments[0].arguments {
PathArguments::None | PathArguments::AngleBracketed(_) => true,
PathArguments::Parenthesized(_) => false,
} =>
{
if let Some(eq_token) = input.parse::<Option<Token![=]>>()? {
let segment = ty.path.segments.pop().unwrap().into_value();
let ident = segment.ident;
let generics = match segment.arguments {
PathArguments::None => None,
PathArguments::AngleBracketed(arguments) => Some(arguments),
PathArguments::Parenthesized(_) => unreachable!(),
};
return if input.peek(Lit) || input.peek(token::Brace) {
Ok(GenericArgument::AssocConst(AssocConst {
ident,
generics,
eq_token,
value: const_argument(input)?,
}))
} else {
Ok(GenericArgument::AssocType(AssocType {
ident,
generics,
eq_token,
ty: input.parse()?,
}))
};
}
#[cfg(feature = "full")]
if let Some(colon_token) = input.parse::<Option<Token![:]>>()? {
let segment = ty.path.segments.pop().unwrap().into_value();
return Ok(GenericArgument::Constraint(Constraint {
ident: segment.ident,
generics: match segment.arguments {
PathArguments::None => None,
PathArguments::AngleBracketed(arguments) => Some(arguments),
PathArguments::Parenthesized(_) => unreachable!(),
},
colon_token,
bounds: {
let mut bounds = Punctuated::new();
loop {
if input.peek(Token![,]) || input.peek(Token![>]) {
break;
}
bounds.push_value({
let allow_precise_capture = false;
let allow_tilde_const = true;
TypeParamBound::parse_single(
input,
allow_precise_capture,
allow_tilde_const,
)?
});
if !input.peek(Token![+]) {
break;
}
let punct: Token![+] = input.parse()?;
bounds.push_punct(punct);
}
bounds
},
}));
}
argument = Type::Path(ty);
}
_ => {}
}
Ok(GenericArgument::Type(argument))
}
}
pub(crate) fn const_argument(input: ParseStream) -> Result<Expr> {
let lookahead = input.lookahead1();
if input.peek(Lit) {
let lit = input.parse()?;
return Ok(Expr::Lit(lit));
}
if input.peek(Ident) {
let ident: Ident = input.parse()?;
return Ok(Expr::Path(ExprPath {
attrs: Vec::new(),
qself: None,
path: Path::from(ident),
}));
}
if input.peek(token::Brace) {
#[cfg(feature = "full")]
{
let block: ExprBlock = input.parse()?;
return Ok(Expr::Block(block));
}
#[cfg(not(feature = "full"))]
{
let begin = input.fork();
let content;
braced!(content in input);
content.parse::<Expr>()?;
let verbatim = verbatim::between(&begin, input);
return Ok(Expr::Verbatim(verbatim));
}
}
Err(lookahead.error())
}
impl AngleBracketedGenericArguments {
/// Parse `::<…>` with mandatory leading `::`.
///
/// The ordinary [`Parse`] impl for `AngleBracketedGenericArguments`
/// parses optional leading `::`.
#[cfg(feature = "full")]
#[cfg_attr(docsrs, doc(cfg(all(feature = "parsing", feature = "full"))))]
pub fn parse_turbofish(input: ParseStream) -> Result<Self> {
let colon2_token: Token![::] = input.parse()?;
Self::do_parse(Some(colon2_token), input)
}
pub(crate) fn do_parse(
colon2_token: Option<Token![::]>,
input: ParseStream,
) -> Result<Self> {
Ok(AngleBracketedGenericArguments {
colon2_token,
lt_token: input.parse()?,
args: {
let mut args = Punctuated::new();
loop {
if input.peek(Token![>]) {
break;
}
let value: GenericArgument = input.parse()?;
args.push_value(value);
if input.peek(Token![>]) {
break;
}
let punct: Token![,] = input.parse()?;
args.push_punct(punct);
}
args
},
gt_token: input.parse()?,
})
}
}
#[cfg_attr(docsrs, doc(cfg(feature = "parsing")))]
impl Parse for AngleBracketedGenericArguments {
fn parse(input: ParseStream) -> Result<Self> {
let colon2_token: Option<Token![::]> = input.parse()?;
Self::do_parse(colon2_token, input)
}
}
#[cfg_attr(docsrs, doc(cfg(feature = "parsing")))]
impl Parse for ParenthesizedGenericArguments {
fn parse(input: ParseStream) -> Result<Self> {
let content;
Ok(ParenthesizedGenericArguments {
paren_token: parenthesized!(content in input),
inputs: content.parse_terminated(Type::parse, Token![,])?,
output: input.call(ReturnType::without_plus)?,
})
}
}
#[cfg_attr(docsrs, doc(cfg(feature = "parsing")))]
impl Parse for PathSegment {
fn parse(input: ParseStream) -> Result<Self> {
Self::parse_helper(input, false)
}
}
impl PathSegment {
fn parse_helper(input: ParseStream, expr_style: bool) -> Result<Self> {
if input.peek(Token![super])
|| input.peek(Token![self])
|| input.peek(Token![crate])
|| cfg!(feature = "full") && input.peek(Token![try])
{
let ident = input.call(Ident::parse_any)?;
return Ok(PathSegment::from(ident));
}
let ident = if input.peek(Token![Self]) {
input.call(Ident::parse_any)?
} else {
input.parse()?
};
if !expr_style && input.peek(Token![<]) && !input.peek(Token![<=])
|| input.peek(Token![::]) && input.peek3(Token![<])
{
Ok(PathSegment {
ident,
arguments: PathArguments::AngleBracketed(input.parse()?),
})
} else {
Ok(PathSegment::from(ident))
}
}
}
impl Path {
/// Parse a `Path` containing no path arguments on any of its segments.
///
/// # Example
///
/// ```
/// use syn::{Path, Result, Token};
/// use syn::parse::{Parse, ParseStream};
///
/// // A simplified single `use` statement like:
/// //
/// // use std::collections::HashMap;
/// //
/// // Note that generic parameters are not allowed in a `use` statement
/// // so the following must not be accepted.
/// //
/// // use a::<b>::c;
/// struct SingleUse {
/// use_token: Token![use],
/// path: Path,
/// }
///
/// impl Parse for SingleUse {
/// fn parse(input: ParseStream) -> Result<Self> {
/// Ok(SingleUse {
/// use_token: input.parse()?,
/// path: input.call(Path::parse_mod_style)?,
/// })
/// }
/// }
/// ```
#[cfg_attr(docsrs, doc(cfg(feature = "parsing")))]
pub fn parse_mod_style(input: ParseStream) -> Result<Self> {
Ok(Path {
leading_colon: input.parse()?,
segments: {
let mut segments = Punctuated::new();
loop {
if !input.peek(Ident)
&& !input.peek(Token![super])
&& !input.peek(Token![self])
&& !input.peek(Token![Self])
&& !input.peek(Token![crate])
{
break;
}
let ident = Ident::parse_any(input)?;
segments.push_value(PathSegment::from(ident));
if !input.peek(Token![::]) {
break;
}
let punct = input.parse()?;
segments.push_punct(punct);
}
if segments.is_empty() {
return Err(input.parse::<Ident>().unwrap_err());
} else if segments.trailing_punct() {
return Err(input.error("expected path segment after `::`"));
}
segments
},
})
}
pub(crate) fn parse_helper(input: ParseStream, expr_style: bool) -> Result<Self> {
let mut path = Path {
leading_colon: input.parse()?,
segments: {
let mut segments = Punctuated::new();
let value = PathSegment::parse_helper(input, expr_style)?;
segments.push_value(value);
segments
},
};
Path::parse_rest(input, &mut path, expr_style)?;
Ok(path)
}
pub(crate) fn parse_rest(
input: ParseStream,
path: &mut Self,
expr_style: bool,
) -> Result<()> {
while input.peek(Token![::]) && !input.peek3(token::Paren) {
let punct: Token![::] = input.parse()?;
path.segments.push_punct(punct);
let value = PathSegment::parse_helper(input, expr_style)?;
path.segments.push_value(value);
}
Ok(())
}
pub(crate) fn is_mod_style(&self) -> bool {
self.segments
.iter()
.all(|segment| segment.arguments.is_none())
}
}
pub(crate) fn qpath(input: ParseStream, expr_style: bool) -> Result<(Option<QSelf>, Path)> {
if input.peek(Token![<]) {
let lt_token: Token![<] = input.parse()?;
let this: Type = input.parse()?;
let path = if input.peek(Token![as]) {
let as_token: Token![as] = input.parse()?;
let path: Path = input.parse()?;
Some((as_token, path))
} else {
None
};
let gt_token: Token![>] = input.parse()?;
let colon2_token: Token![::] = input.parse()?;
let mut rest = Punctuated::new();
loop {
let path = PathSegment::parse_helper(input, expr_style)?;
rest.push_value(path);
if !input.peek(Token![::]) {
break;
}
let punct: Token![::] = input.parse()?;
rest.push_punct(punct);
}
let (position, as_token, path) = match path {
Some((as_token, mut path)) => {
let pos = path.segments.len();
path.segments.push_punct(colon2_token);
path.segments.extend(rest.into_pairs());
(pos, Some(as_token), path)
}
None => {
let path = Path {
leading_colon: Some(colon2_token),
segments: rest,
};
(0, None, path)
}
};
let qself = QSelf {
lt_token,
ty: Box::new(this),
position,
as_token,
gt_token,
};
Ok((Some(qself), path))
} else {
let path = Path::parse_helper(input, expr_style)?;
Ok((None, path))
}
}
}
#[cfg(feature = "printing")]
pub(crate) mod printing {
use crate::generics;
use crate::path::{
AngleBracketedGenericArguments, AssocConst, AssocType, Constraint, GenericArgument,
ParenthesizedGenericArguments, Path, PathArguments, PathSegment, QSelf,
};
use crate::print::TokensOrDefault;
#[cfg(feature = "parsing")]
use crate::spanned::Spanned;
#[cfg(feature = "parsing")]
use proc_macro2::Span;
use proc_macro2::TokenStream;
use quote::ToTokens;
use std::cmp;
pub(crate) enum PathStyle {
Expr,
Mod,
AsWritten,
}
impl Copy for PathStyle {}
impl Clone for PathStyle {
fn clone(&self) -> Self {
*self
}
}
#[cfg_attr(docsrs, doc(cfg(feature = "printing")))]
impl ToTokens for Path {
fn to_tokens(&self, tokens: &mut TokenStream) {
print_path(tokens, self, PathStyle::AsWritten);
}
}
pub(crate) fn print_path(tokens: &mut TokenStream, path: &Path, style: PathStyle) {
path.leading_colon.to_tokens(tokens);
for segment in path.segments.pairs() {
print_path_segment(tokens, segment.value(), style);
segment.punct().to_tokens(tokens);
}
}
#[cfg_attr(docsrs, doc(cfg(feature = "printing")))]
impl ToTokens for PathSegment {
fn to_tokens(&self, tokens: &mut TokenStream) {
print_path_segment(tokens, self, PathStyle::AsWritten);
}
}
fn print_path_segment(tokens: &mut TokenStream, segment: &PathSegment, style: PathStyle) {
segment.ident.to_tokens(tokens);
print_path_arguments(tokens, &segment.arguments, style);
}
#[cfg_attr(docsrs, doc(cfg(feature = "printing")))]
impl ToTokens for PathArguments {
fn to_tokens(&self, tokens: &mut TokenStream) {
print_path_arguments(tokens, self, PathStyle::AsWritten);
}
}
fn print_path_arguments(tokens: &mut TokenStream, arguments: &PathArguments, style: PathStyle) {
match arguments {
PathArguments::None => {}
PathArguments::AngleBracketed(arguments) => {
print_angle_bracketed_generic_arguments(tokens, arguments, style);
}
PathArguments::Parenthesized(arguments) => {
print_parenthesized_generic_arguments(tokens, arguments, style);
}
}
}
#[cfg_attr(docsrs, doc(cfg(feature = "printing")))]
impl ToTokens for GenericArgument {
#[allow(clippy::match_same_arms)]
fn to_tokens(&self, tokens: &mut TokenStream) {
match self {
GenericArgument::Lifetime(lt) => lt.to_tokens(tokens),
GenericArgument::Type(ty) => ty.to_tokens(tokens),
GenericArgument::Const(expr) => {
generics::printing::print_const_argument(expr, tokens);
}
GenericArgument::AssocType(assoc) => assoc.to_tokens(tokens),
GenericArgument::AssocConst(assoc) => assoc.to_tokens(tokens),
GenericArgument::Constraint(constraint) => constraint.to_tokens(tokens),
}
}
}
#[cfg_attr(docsrs, doc(cfg(feature = "printing")))]
impl ToTokens for AngleBracketedGenericArguments {
fn to_tokens(&self, tokens: &mut TokenStream) {
print_angle_bracketed_generic_arguments(tokens, self, PathStyle::AsWritten);
}
}
pub(crate) fn print_angle_bracketed_generic_arguments(
tokens: &mut TokenStream,
arguments: &AngleBracketedGenericArguments,
style: PathStyle,
) {
if let PathStyle::Mod = style {
return;
}
conditionally_print_turbofish(tokens, &arguments.colon2_token, style);
arguments.lt_token.to_tokens(tokens);
// Print lifetimes before types/consts/bindings, regardless of their
// order in args.
let mut trailing_or_empty = true;
for param in arguments.args.pairs() {
match param.value() {
GenericArgument::Lifetime(_) => {
param.to_tokens(tokens);
trailing_or_empty = param.punct().is_some();
}
GenericArgument::Type(_)
| GenericArgument::Const(_)
| GenericArgument::AssocType(_)
| GenericArgument::AssocConst(_)
| GenericArgument::Constraint(_) => {}
}
}
for param in arguments.args.pairs() {
match param.value() {
GenericArgument::Type(_)
| GenericArgument::Const(_)
| GenericArgument::AssocType(_)
| GenericArgument::AssocConst(_)
| GenericArgument::Constraint(_) => {
if !trailing_or_empty {
<Token![,]>::default().to_tokens(tokens);
}
param.to_tokens(tokens);
trailing_or_empty = param.punct().is_some();
}
GenericArgument::Lifetime(_) => {}
}
}
arguments.gt_token.to_tokens(tokens);
}
#[cfg_attr(docsrs, doc(cfg(feature = "printing")))]
impl ToTokens for AssocType {
fn to_tokens(&self, tokens: &mut TokenStream) {
self.ident.to_tokens(tokens);
self.generics.to_tokens(tokens);
self.eq_token.to_tokens(tokens);
self.ty.to_tokens(tokens);
}
}
#[cfg_attr(docsrs, doc(cfg(feature = "printing")))]
impl ToTokens for AssocConst {
fn to_tokens(&self, tokens: &mut TokenStream) {
self.ident.to_tokens(tokens);
self.generics.to_tokens(tokens);
self.eq_token.to_tokens(tokens);
generics::printing::print_const_argument(&self.value, tokens);
}
}
#[cfg_attr(docsrs, doc(cfg(feature = "printing")))]
impl ToTokens for Constraint {
fn to_tokens(&self, tokens: &mut TokenStream) {
self.ident.to_tokens(tokens);
self.generics.to_tokens(tokens);
self.colon_token.to_tokens(tokens);
self.bounds.to_tokens(tokens);
}
}
#[cfg_attr(docsrs, doc(cfg(feature = "printing")))]
impl ToTokens for ParenthesizedGenericArguments {
fn to_tokens(&self, tokens: &mut TokenStream) {
print_parenthesized_generic_arguments(tokens, self, PathStyle::AsWritten);
}
}
fn print_parenthesized_generic_arguments(
tokens: &mut TokenStream,
arguments: &ParenthesizedGenericArguments,
style: PathStyle,
) {
if let PathStyle::Mod = style {
return;
}
conditionally_print_turbofish(tokens, &None, style);
arguments.paren_token.surround(tokens, |tokens| {
arguments.inputs.to_tokens(tokens);
});
arguments.output.to_tokens(tokens);
}
pub(crate) fn print_qpath(
tokens: &mut TokenStream,
qself: &Option<QSelf>,
path: &Path,
style: PathStyle,
) {
let qself = match qself {
Some(qself) => qself,
None => {
print_path(tokens, path, style);
return;
}
};
qself.lt_token.to_tokens(tokens);
qself.ty.to_tokens(tokens);
let pos = cmp::min(qself.position, path.segments.len());
let mut segments = path.segments.pairs();
if pos > 0 {
TokensOrDefault(&qself.as_token).to_tokens(tokens);
path.leading_colon.to_tokens(tokens);
for (i, segment) in segments.by_ref().take(pos).enumerate() {
print_path_segment(tokens, segment.value(), PathStyle::AsWritten);
if i + 1 == pos {
qself.gt_token.to_tokens(tokens);
}
segment.punct().to_tokens(tokens);
}
} else {
qself.gt_token.to_tokens(tokens);
path.leading_colon.to_tokens(tokens);
}
for segment in segments {
print_path_segment(tokens, segment.value(), style);
segment.punct().to_tokens(tokens);
}
}
fn conditionally_print_turbofish(
tokens: &mut TokenStream,
colon2_token: &Option<Token![::]>,
style: PathStyle,
) {
match style {
PathStyle::Expr => TokensOrDefault(colon2_token).to_tokens(tokens),
PathStyle::Mod => unreachable!(),
PathStyle::AsWritten => colon2_token.to_tokens(tokens),
}
}
#[cfg(feature = "parsing")]
#[cfg_attr(docsrs, doc(cfg(all(feature = "parsing", feature = "printing"))))]
impl Spanned for QSelf {
fn span(&self) -> Span {
struct QSelfDelimiters<'a>(&'a QSelf);
impl<'a> ToTokens for QSelfDelimiters<'a> {
fn to_tokens(&self, tokens: &mut TokenStream) {
self.0.lt_token.to_tokens(tokens);
self.0.gt_token.to_tokens(tokens);
}
}
QSelfDelimiters(self).span()
}
}
}