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Diffstat (limited to 'syn/src/generics.rs')
| -rw-r--r-- | syn/src/generics.rs | 1152 |
1 files changed, 1152 insertions, 0 deletions
diff --git a/syn/src/generics.rs b/syn/src/generics.rs new file mode 100644 index 0000000..9feeab9 --- /dev/null +++ b/syn/src/generics.rs @@ -0,0 +1,1152 @@ +use super::*; +use crate::punctuated::{Iter, IterMut, Punctuated}; + +ast_struct! { + /// Lifetimes and type parameters attached to a declaration of a function, + /// enum, trait, etc. + /// + /// *This type is available if Syn is built with the `"derive"` or `"full"` + /// feature.* + #[derive(Default)] + pub struct Generics { + pub lt_token: Option<Token![<]>, + pub params: Punctuated<GenericParam, Token![,]>, + pub gt_token: Option<Token![>]>, + pub where_clause: Option<WhereClause>, + } +} + +ast_enum_of_structs! { + /// A generic type parameter, lifetime, or const generic: `T: Into<String>`, + /// `'a: 'b`, `const LEN: usize`. + /// + /// *This type is available if Syn is built with the `"derive"` or `"full"` + /// feature.* + /// + /// # Syntax tree enum + /// + /// This type is a [syntax tree enum]. + /// + /// [syntax tree enum]: enum.Expr.html#syntax-tree-enums + pub enum GenericParam { + /// A generic type parameter: `T: Into<String>`. + Type(TypeParam), + + /// A lifetime definition: `'a: 'b + 'c + 'd`. + Lifetime(LifetimeDef), + + /// A const generic parameter: `const LENGTH: usize`. + Const(ConstParam), + } +} + +ast_struct! { + /// A generic type parameter: `T: Into<String>`. + /// + /// *This type is available if Syn is built with the `"derive"` or + /// `"full"` feature.* + pub struct TypeParam { + pub attrs: Vec<Attribute>, + pub ident: Ident, + pub colon_token: Option<Token![:]>, + pub bounds: Punctuated<TypeParamBound, Token![+]>, + pub eq_token: Option<Token![=]>, + pub default: Option<Type>, + } +} + +ast_struct! { + /// A lifetime definition: `'a: 'b + 'c + 'd`. + /// + /// *This type is available if Syn is built with the `"derive"` or + /// `"full"` feature.* + pub struct LifetimeDef { + pub attrs: Vec<Attribute>, + pub lifetime: Lifetime, + pub colon_token: Option<Token![:]>, + pub bounds: Punctuated<Lifetime, Token![+]>, + } +} + +ast_struct! { + /// A const generic parameter: `const LENGTH: usize`. + /// + /// *This type is available if Syn is built with the `"derive"` or + /// `"full"` feature.* + pub struct ConstParam { + pub attrs: Vec<Attribute>, + pub const_token: Token![const], + pub ident: Ident, + pub colon_token: Token![:], + pub ty: Type, + pub eq_token: Option<Token![=]>, + pub default: Option<Expr>, + } +} + +impl Generics { + /// Returns an + /// <code + /// style="padding-right:0;">Iterator<Item = &</code><a + /// href="struct.TypeParam.html"><code + /// style="padding-left:0;padding-right:0;">TypeParam</code></a><code + /// style="padding-left:0;">></code> + /// over the type parameters in `self.params`. + pub fn type_params(&self) -> TypeParams { + TypeParams(self.params.iter()) + } + + /// Returns an + /// <code + /// style="padding-right:0;">Iterator<Item = &mut </code><a + /// href="struct.TypeParam.html"><code + /// style="padding-left:0;padding-right:0;">TypeParam</code></a><code + /// style="padding-left:0;">></code> + /// over the type parameters in `self.params`. + pub fn type_params_mut(&mut self) -> TypeParamsMut { + TypeParamsMut(self.params.iter_mut()) + } + + /// Returns an + /// <code + /// style="padding-right:0;">Iterator<Item = &</code><a + /// href="struct.LifetimeDef.html"><code + /// style="padding-left:0;padding-right:0;">LifetimeDef</code></a><code + /// style="padding-left:0;">></code> + /// over the lifetime parameters in `self.params`. + pub fn lifetimes(&self) -> Lifetimes { + Lifetimes(self.params.iter()) + } + + /// Returns an + /// <code + /// style="padding-right:0;">Iterator<Item = &mut </code><a + /// href="struct.LifetimeDef.html"><code + /// style="padding-left:0;padding-right:0;">LifetimeDef</code></a><code + /// style="padding-left:0;">></code> + /// over the lifetime parameters in `self.params`. + pub fn lifetimes_mut(&mut self) -> LifetimesMut { + LifetimesMut(self.params.iter_mut()) + } + + /// Returns an + /// <code + /// style="padding-right:0;">Iterator<Item = &</code><a + /// href="struct.ConstParam.html"><code + /// style="padding-left:0;padding-right:0;">ConstParam</code></a><code + /// style="padding-left:0;">></code> + /// over the constant parameters in `self.params`. + pub fn const_params(&self) -> ConstParams { + ConstParams(self.params.iter()) + } + + /// Returns an + /// <code + /// style="padding-right:0;">Iterator<Item = &mut </code><a + /// href="struct.ConstParam.html"><code + /// style="padding-left:0;padding-right:0;">ConstParam</code></a><code + /// style="padding-left:0;">></code> + /// over the constant parameters in `self.params`. + pub fn const_params_mut(&mut self) -> ConstParamsMut { + ConstParamsMut(self.params.iter_mut()) + } + + /// Initializes an empty `where`-clause if there is not one present already. + pub fn make_where_clause(&mut self) -> &mut WhereClause { + // This is Option::get_or_insert_with in Rust 1.20. + if self.where_clause.is_none() { + self.where_clause = Some(WhereClause { + where_token: <Token![where]>::default(), + predicates: Punctuated::new(), + }); + } + match &mut self.where_clause { + Some(where_clause) => where_clause, + None => unreachable!(), + } + } +} + +pub struct TypeParams<'a>(Iter<'a, GenericParam>); + +impl<'a> Iterator for TypeParams<'a> { + type Item = &'a TypeParam; + + fn next(&mut self) -> Option<Self::Item> { + let next = match self.0.next() { + Some(item) => item, + None => return None, + }; + if let GenericParam::Type(type_param) = next { + Some(type_param) + } else { + self.next() + } + } +} + +pub struct TypeParamsMut<'a>(IterMut<'a, GenericParam>); + +impl<'a> Iterator for TypeParamsMut<'a> { + type Item = &'a mut TypeParam; + + fn next(&mut self) -> Option<Self::Item> { + let next = match self.0.next() { + Some(item) => item, + None => return None, + }; + if let GenericParam::Type(type_param) = next { + Some(type_param) + } else { + self.next() + } + } +} + +pub struct Lifetimes<'a>(Iter<'a, GenericParam>); + +impl<'a> Iterator for Lifetimes<'a> { + type Item = &'a LifetimeDef; + + fn next(&mut self) -> Option<Self::Item> { + let next = match self.0.next() { + Some(item) => item, + None => return None, + }; + if let GenericParam::Lifetime(lifetime) = next { + Some(lifetime) + } else { + self.next() + } + } +} + +pub struct LifetimesMut<'a>(IterMut<'a, GenericParam>); + +impl<'a> Iterator for LifetimesMut<'a> { + type Item = &'a mut LifetimeDef; + + fn next(&mut self) -> Option<Self::Item> { + let next = match self.0.next() { + Some(item) => item, + None => return None, + }; + if let GenericParam::Lifetime(lifetime) = next { + Some(lifetime) + } else { + self.next() + } + } +} + +pub struct ConstParams<'a>(Iter<'a, GenericParam>); + +impl<'a> Iterator for ConstParams<'a> { + type Item = &'a ConstParam; + + fn next(&mut self) -> Option<Self::Item> { + let next = match self.0.next() { + Some(item) => item, + None => return None, + }; + if let GenericParam::Const(const_param) = next { + Some(const_param) + } else { + self.next() + } + } +} + +pub struct ConstParamsMut<'a>(IterMut<'a, GenericParam>); + +impl<'a> Iterator for ConstParamsMut<'a> { + type Item = &'a mut ConstParam; + + fn next(&mut self) -> Option<Self::Item> { + let next = match self.0.next() { + Some(item) => item, + None => return None, + }; + if let GenericParam::Const(const_param) = next { + Some(const_param) + } else { + self.next() + } + } +} + +/// Returned by `Generics::split_for_impl`. +/// +/// *This type is available if Syn is built with the `"derive"` or `"full"` +/// feature and the `"printing"` feature.* +#[cfg(feature = "printing")] +#[cfg_attr(feature = "extra-traits", derive(Debug, Eq, PartialEq, Hash))] +#[cfg_attr(feature = "clone-impls", derive(Clone))] +pub struct ImplGenerics<'a>(&'a Generics); + +/// Returned by `Generics::split_for_impl`. +/// +/// *This type is available if Syn is built with the `"derive"` or `"full"` +/// feature and the `"printing"` feature.* +#[cfg(feature = "printing")] +#[cfg_attr(feature = "extra-traits", derive(Debug, Eq, PartialEq, Hash))] +#[cfg_attr(feature = "clone-impls", derive(Clone))] +pub struct TypeGenerics<'a>(&'a Generics); + +/// Returned by `TypeGenerics::as_turbofish`. +/// +/// *This type is available if Syn is built with the `"derive"` or `"full"` +/// feature and the `"printing"` feature.* +#[cfg(feature = "printing")] +#[cfg_attr(feature = "extra-traits", derive(Debug, Eq, PartialEq, Hash))] +#[cfg_attr(feature = "clone-impls", derive(Clone))] +pub struct Turbofish<'a>(&'a Generics); + +#[cfg(feature = "printing")] +impl Generics { + /// Split a type's generics into the pieces required for impl'ing a trait + /// for that type. + /// + /// ``` + /// # use proc_macro2::{Span, Ident}; + /// # use quote::quote; + /// # + /// # let generics: syn::Generics = Default::default(); + /// # let name = Ident::new("MyType", Span::call_site()); + /// # + /// let (impl_generics, ty_generics, where_clause) = generics.split_for_impl(); + /// quote! { + /// impl #impl_generics MyTrait for #name #ty_generics #where_clause { + /// // ... + /// } + /// } + /// # ; + /// ``` + /// + /// *This method is available if Syn is built with the `"derive"` or + /// `"full"` feature and the `"printing"` feature.* + pub fn split_for_impl(&self) -> (ImplGenerics, TypeGenerics, Option<&WhereClause>) { + ( + ImplGenerics(self), + TypeGenerics(self), + self.where_clause.as_ref(), + ) + } +} + +#[cfg(feature = "printing")] +impl<'a> TypeGenerics<'a> { + /// Turn a type's generics like `<X, Y>` into a turbofish like `::<X, Y>`. + /// + /// *This method is available if Syn is built with the `"derive"` or + /// `"full"` feature and the `"printing"` feature.* + pub fn as_turbofish(&self) -> Turbofish { + Turbofish(self.0) + } +} + +ast_struct! { + /// A set of bound lifetimes: `for<'a, 'b, 'c>`. + /// + /// *This type is available if Syn is built with the `"derive"` or `"full"` + /// feature.* + #[derive(Default)] + pub struct BoundLifetimes { + pub for_token: Token![for], + pub lt_token: Token![<], + pub lifetimes: Punctuated<LifetimeDef, Token![,]>, + pub gt_token: Token![>], + } +} + +impl LifetimeDef { + pub fn new(lifetime: Lifetime) -> Self { + LifetimeDef { + attrs: Vec::new(), + lifetime, + colon_token: None, + bounds: Punctuated::new(), + } + } +} + +impl From<Ident> for TypeParam { + fn from(ident: Ident) -> Self { + TypeParam { + attrs: vec![], + ident, + colon_token: None, + bounds: Punctuated::new(), + eq_token: None, + default: None, + } + } +} + +ast_enum_of_structs! { + /// A trait or lifetime used as a bound on a type parameter. + /// + /// *This type is available if Syn is built with the `"derive"` or `"full"` + /// feature.* + pub enum TypeParamBound { + Trait(TraitBound), + Lifetime(Lifetime), + } +} + +ast_struct! { + /// A trait used as a bound on a type parameter. + /// + /// *This type is available if Syn is built with the `"derive"` or `"full"` + /// feature.* + pub struct TraitBound { + pub paren_token: Option<token::Paren>, + pub modifier: TraitBoundModifier, + /// The `for<'a>` in `for<'a> Foo<&'a T>` + pub lifetimes: Option<BoundLifetimes>, + /// The `Foo<&'a T>` in `for<'a> Foo<&'a T>` + pub path: Path, + } +} + +ast_enum! { + /// A modifier on a trait bound, currently only used for the `?` in + /// `?Sized`. + /// + /// *This type is available if Syn is built with the `"derive"` or `"full"` + /// feature.* + #[cfg_attr(feature = "clone-impls", derive(Copy))] + pub enum TraitBoundModifier { + None, + Maybe(Token![?]), + } +} + +ast_struct! { + /// A `where` clause in a definition: `where T: Deserialize<'de>, D: + /// 'static`. + /// + /// *This type is available if Syn is built with the `"derive"` or `"full"` + /// feature.* + pub struct WhereClause { + pub where_token: Token![where], + pub predicates: Punctuated<WherePredicate, Token![,]>, + } +} + +ast_enum_of_structs! { + /// A single predicate in a `where` clause: `T: Deserialize<'de>`. + /// + /// *This type is available if Syn is built with the `"derive"` or `"full"` + /// feature.* + /// + /// # Syntax tree enum + /// + /// This type is a [syntax tree enum]. + /// + /// [syntax tree enum]: enum.Expr.html#syntax-tree-enums + pub enum WherePredicate { + /// A type predicate in a `where` clause: `for<'c> Foo<'c>: Trait<'c>`. + Type(PredicateType), + + /// A lifetime predicate in a `where` clause: `'a: 'b + 'c`. + Lifetime(PredicateLifetime), + + /// An equality predicate in a `where` clause (unsupported). + Eq(PredicateEq), + } +} + +ast_struct! { + /// A type predicate in a `where` clause: `for<'c> Foo<'c>: Trait<'c>`. + /// + /// *This type is available if Syn is built with the `"derive"` or + /// `"full"` feature.* + pub struct PredicateType { + /// Any lifetimes from a `for` binding + pub lifetimes: Option<BoundLifetimes>, + /// The type being bounded + pub bounded_ty: Type, + pub colon_token: Token![:], + /// Trait and lifetime bounds (`Clone+Send+'static`) + pub bounds: Punctuated<TypeParamBound, Token![+]>, + } +} + +ast_struct! { + /// A lifetime predicate in a `where` clause: `'a: 'b + 'c`. + /// + /// *This type is available if Syn is built with the `"derive"` or + /// `"full"` feature.* + pub struct PredicateLifetime { + pub lifetime: Lifetime, + pub colon_token: Token![:], + pub bounds: Punctuated<Lifetime, Token![+]>, + } +} + +ast_struct! { + /// An equality predicate in a `where` clause (unsupported). + /// + /// *This type is available if Syn is built with the `"derive"` or + /// `"full"` feature.* + pub struct PredicateEq { + pub lhs_ty: Type, + pub eq_token: Token![=], + pub rhs_ty: Type, + } +} + +#[cfg(feature = "parsing")] +pub mod parsing { + use super::*; + + use crate::parse::{Parse, ParseStream, Result}; + + impl Parse for Generics { + fn parse(input: ParseStream) -> Result<Self> { + if !input.peek(Token![<]) { + return Ok(Generics::default()); + } + + let lt_token: Token![<] = input.parse()?; + + let mut params = Punctuated::new(); + let mut allow_lifetime_param = true; + let mut allow_type_param = true; + loop { + if input.peek(Token![>]) { + break; + } + + let attrs = input.call(Attribute::parse_outer)?; + let lookahead = input.lookahead1(); + if allow_lifetime_param && lookahead.peek(Lifetime) { + params.push_value(GenericParam::Lifetime(LifetimeDef { + attrs, + ..input.parse()? + })); + } else if allow_type_param && lookahead.peek(Ident) { + allow_lifetime_param = false; + params.push_value(GenericParam::Type(TypeParam { + attrs, + ..input.parse()? + })); + } else if lookahead.peek(Token![const]) { + allow_lifetime_param = false; + allow_type_param = false; + params.push_value(GenericParam::Const(ConstParam { + attrs, + ..input.parse()? + })); + } else { + return Err(lookahead.error()); + } + + if input.peek(Token![>]) { + break; + } + let punct = input.parse()?; + params.push_punct(punct); + } + + let gt_token: Token![>] = input.parse()?; + + Ok(Generics { + lt_token: Some(lt_token), + params, + gt_token: Some(gt_token), + where_clause: None, + }) + } + } + + impl Parse for GenericParam { + fn parse(input: ParseStream) -> Result<Self> { + let attrs = input.call(Attribute::parse_outer)?; + + let lookahead = input.lookahead1(); + if lookahead.peek(Ident) { + Ok(GenericParam::Type(TypeParam { + attrs, + ..input.parse()? + })) + } else if lookahead.peek(Lifetime) { + Ok(GenericParam::Lifetime(LifetimeDef { + attrs, + ..input.parse()? + })) + } else if lookahead.peek(Token![const]) { + Ok(GenericParam::Const(ConstParam { + attrs, + ..input.parse()? + })) + } else { + Err(lookahead.error()) + } + } + } + + impl Parse for LifetimeDef { + fn parse(input: ParseStream) -> Result<Self> { + let has_colon; + Ok(LifetimeDef { + attrs: input.call(Attribute::parse_outer)?, + lifetime: input.parse()?, + colon_token: { + if input.peek(Token![:]) { + has_colon = true; + Some(input.parse()?) + } else { + has_colon = false; + None + } + }, + bounds: { + let mut bounds = Punctuated::new(); + if has_colon { + loop { + if input.peek(Token![,]) || input.peek(Token![>]) { + break; + } + let value = input.parse()?; + bounds.push_value(value); + if !input.peek(Token![+]) { + break; + } + let punct = input.parse()?; + bounds.push_punct(punct); + } + } + bounds + }, + }) + } + } + + impl Parse for BoundLifetimes { + fn parse(input: ParseStream) -> Result<Self> { + Ok(BoundLifetimes { + for_token: input.parse()?, + lt_token: input.parse()?, + lifetimes: { + let mut lifetimes = Punctuated::new(); + while !input.peek(Token![>]) { + lifetimes.push_value(input.parse()?); + if input.peek(Token![>]) { + break; + } + lifetimes.push_punct(input.parse()?); + } + lifetimes + }, + gt_token: input.parse()?, + }) + } + } + + impl Parse for Option<BoundLifetimes> { + fn parse(input: ParseStream) -> Result<Self> { + if input.peek(Token![for]) { + input.parse().map(Some) + } else { + Ok(None) + } + } + } + + impl Parse for TypeParam { + fn parse(input: ParseStream) -> Result<Self> { + let has_colon; + let has_default; + Ok(TypeParam { + attrs: input.call(Attribute::parse_outer)?, + ident: input.parse()?, + colon_token: { + if input.peek(Token![:]) { + has_colon = true; + Some(input.parse()?) + } else { + has_colon = false; + None + } + }, + bounds: { + let mut bounds = Punctuated::new(); + if has_colon { + loop { + if input.peek(Token![,]) + || input.peek(Token![>]) + || input.peek(Token![=]) + { + break; + } + let value = input.parse()?; + bounds.push_value(value); + if !input.peek(Token![+]) { + break; + } + let punct = input.parse()?; + bounds.push_punct(punct); + } + } + bounds + }, + eq_token: { + if input.peek(Token![=]) { + has_default = true; + Some(input.parse()?) + } else { + has_default = false; + None + } + }, + default: { + if has_default { + Some(input.parse()?) + } else { + None + } + }, + }) + } + } + + impl Parse for TypeParamBound { + fn parse(input: ParseStream) -> Result<Self> { + if input.peek(Lifetime) { + return input.parse().map(TypeParamBound::Lifetime); + } + + if input.peek(token::Paren) { + let content; + let paren_token = parenthesized!(content in input); + let mut bound: TraitBound = content.parse()?; + bound.paren_token = Some(paren_token); + return Ok(TypeParamBound::Trait(bound)); + } + + input.parse().map(TypeParamBound::Trait) + } + } + + impl Parse for TraitBound { + fn parse(input: ParseStream) -> Result<Self> { + let modifier: TraitBoundModifier = input.parse()?; + let lifetimes: Option<BoundLifetimes> = input.parse()?; + + let mut path: Path = input.parse()?; + if path.segments.last().unwrap().arguments.is_empty() && input.peek(token::Paren) { + let parenthesized = PathArguments::Parenthesized(input.parse()?); + path.segments.last_mut().unwrap().arguments = parenthesized; + } + + Ok(TraitBound { + paren_token: None, + modifier, + lifetimes, + path, + }) + } + } + + impl Parse for TraitBoundModifier { + fn parse(input: ParseStream) -> Result<Self> { + if input.peek(Token![?]) { + input.parse().map(TraitBoundModifier::Maybe) + } else { + Ok(TraitBoundModifier::None) + } + } + } + + impl Parse for ConstParam { + fn parse(input: ParseStream) -> Result<Self> { + let mut default = None; + Ok(ConstParam { + attrs: input.call(Attribute::parse_outer)?, + const_token: input.parse()?, + ident: input.parse()?, + colon_token: input.parse()?, + ty: input.parse()?, + eq_token: { + if input.peek(Token![=]) { + let eq_token = input.parse()?; + default = Some(input.parse::<Expr>()?); + Some(eq_token) + } else { + None + } + }, + default, + }) + } + } + + impl Parse for WhereClause { + fn parse(input: ParseStream) -> Result<Self> { + Ok(WhereClause { + where_token: input.parse()?, + predicates: { + let mut predicates = Punctuated::new(); + loop { + if input.is_empty() + || input.peek(token::Brace) + || input.peek(Token![,]) + || input.peek(Token![;]) + || input.peek(Token![:]) && !input.peek(Token![::]) + || input.peek(Token![=]) + { + break; + } + let value = input.parse()?; + predicates.push_value(value); + if !input.peek(Token![,]) { + break; + } + let punct = input.parse()?; + predicates.push_punct(punct); + } + predicates + }, + }) + } + } + + impl Parse for Option<WhereClause> { + fn parse(input: ParseStream) -> Result<Self> { + if input.peek(Token![where]) { + input.parse().map(Some) + } else { + Ok(None) + } + } + } + + impl Parse for WherePredicate { + fn parse(input: ParseStream) -> Result<Self> { + if input.peek(Lifetime) && input.peek2(Token![:]) { + Ok(WherePredicate::Lifetime(PredicateLifetime { + lifetime: input.parse()?, + colon_token: input.parse()?, + bounds: { + let mut bounds = Punctuated::new(); + loop { + if input.is_empty() + || input.peek(token::Brace) + || input.peek(Token![,]) + || input.peek(Token![;]) + || input.peek(Token![:]) + || input.peek(Token![=]) + { + break; + } + let value = input.parse()?; + bounds.push_value(value); + if !input.peek(Token![+]) { + break; + } + let punct = input.parse()?; + bounds.push_punct(punct); + } + bounds + }, + })) + } else { + Ok(WherePredicate::Type(PredicateType { + lifetimes: input.parse()?, + bounded_ty: input.parse()?, + colon_token: input.parse()?, + bounds: { + let mut bounds = Punctuated::new(); + loop { + if input.is_empty() + || input.peek(token::Brace) + || input.peek(Token![,]) + || input.peek(Token![;]) + || input.peek(Token![:]) && !input.peek(Token![::]) + || input.peek(Token![=]) + { + break; + } + let value = input.parse()?; + bounds.push_value(value); + if !input.peek(Token![+]) { + break; + } + let punct = input.parse()?; + bounds.push_punct(punct); + } + bounds + }, + })) + } + } + } +} + +#[cfg(feature = "printing")] +mod printing { + use super::*; + + use proc_macro2::TokenStream; + use quote::{ToTokens, TokenStreamExt}; + + use crate::attr::FilterAttrs; + use crate::print::TokensOrDefault; + + impl ToTokens for Generics { + fn to_tokens(&self, tokens: &mut TokenStream) { + if self.params.is_empty() { + return; + } + + TokensOrDefault(&self.lt_token).to_tokens(tokens); + + // Print lifetimes before types and consts, regardless of their + // order in self.params. + // + // TODO: ordering rules for const parameters vs type parameters have + // not been settled yet. https://github.com/rust-lang/rust/issues/44580 + let mut trailing_or_empty = true; + for param in self.params.pairs() { + if let GenericParam::Lifetime(_) = **param.value() { + param.to_tokens(tokens); + trailing_or_empty = param.punct().is_some(); + } + } + for param in self.params.pairs() { + match **param.value() { + GenericParam::Type(_) | GenericParam::Const(_) => { + if !trailing_or_empty { + <Token![,]>::default().to_tokens(tokens); + trailing_or_empty = true; + } + param.to_tokens(tokens); + } + GenericParam::Lifetime(_) => {} + } + } + + TokensOrDefault(&self.gt_token).to_tokens(tokens); + } + } + + impl<'a> ToTokens for ImplGenerics<'a> { + fn to_tokens(&self, tokens: &mut TokenStream) { + if self.0.params.is_empty() { + return; + } + + TokensOrDefault(&self.0.lt_token).to_tokens(tokens); + + // Print lifetimes before types and consts, regardless of their + // order in self.params. + // + // TODO: ordering rules for const parameters vs type parameters have + // not been settled yet. https://github.com/rust-lang/rust/issues/44580 + let mut trailing_or_empty = true; + for param in self.0.params.pairs() { + if let GenericParam::Lifetime(_) = **param.value() { + param.to_tokens(tokens); + trailing_or_empty = param.punct().is_some(); + } + } + for param in self.0.params.pairs() { + if let GenericParam::Lifetime(_) = **param.value() { + continue; + } + if !trailing_or_empty { + <Token![,]>::default().to_tokens(tokens); + trailing_or_empty = true; + } + match *param.value() { + GenericParam::Lifetime(_) => unreachable!(), + GenericParam::Type(param) => { + // Leave off the type parameter defaults + tokens.append_all(param.attrs.outer()); + param.ident.to_tokens(tokens); + if !param.bounds.is_empty() { + TokensOrDefault(¶m.colon_token).to_tokens(tokens); + param.bounds.to_tokens(tokens); + } + } + GenericParam::Const(param) => { + // Leave off the const parameter defaults + tokens.append_all(param.attrs.outer()); + param.const_token.to_tokens(tokens); + param.ident.to_tokens(tokens); + param.colon_token.to_tokens(tokens); + param.ty.to_tokens(tokens); + } + } + param.punct().to_tokens(tokens); + } + + TokensOrDefault(&self.0.gt_token).to_tokens(tokens); + } + } + + impl<'a> ToTokens for TypeGenerics<'a> { + fn to_tokens(&self, tokens: &mut TokenStream) { + if self.0.params.is_empty() { + return; + } + + TokensOrDefault(&self.0.lt_token).to_tokens(tokens); + + // Print lifetimes before types and consts, regardless of their + // order in self.params. + // + // TODO: ordering rules for const parameters vs type parameters have + // not been settled yet. https://github.com/rust-lang/rust/issues/44580 + let mut trailing_or_empty = true; + for param in self.0.params.pairs() { + if let GenericParam::Lifetime(def) = *param.value() { + // Leave off the lifetime bounds and attributes + def.lifetime.to_tokens(tokens); + param.punct().to_tokens(tokens); + trailing_or_empty = param.punct().is_some(); + } + } + for param in self.0.params.pairs() { + if let GenericParam::Lifetime(_) = **param.value() { + continue; + } + if !trailing_or_empty { + <Token![,]>::default().to_tokens(tokens); + trailing_or_empty = true; + } + match *param.value() { + GenericParam::Lifetime(_) => unreachable!(), + GenericParam::Type(param) => { + // Leave off the type parameter defaults + param.ident.to_tokens(tokens); + } + GenericParam::Const(param) => { + // Leave off the const parameter defaults + param.ident.to_tokens(tokens); + } + } + param.punct().to_tokens(tokens); + } + + TokensOrDefault(&self.0.gt_token).to_tokens(tokens); + } + } + + impl<'a> ToTokens for Turbofish<'a> { + fn to_tokens(&self, tokens: &mut TokenStream) { + if !self.0.params.is_empty() { + <Token![::]>::default().to_tokens(tokens); + TypeGenerics(self.0).to_tokens(tokens); + } + } + } + + impl ToTokens for BoundLifetimes { + fn to_tokens(&self, tokens: &mut TokenStream) { + self.for_token.to_tokens(tokens); + self.lt_token.to_tokens(tokens); + self.lifetimes.to_tokens(tokens); + self.gt_token.to_tokens(tokens); + } + } + + impl ToTokens for LifetimeDef { + fn to_tokens(&self, tokens: &mut TokenStream) { + tokens.append_all(self.attrs.outer()); + self.lifetime.to_tokens(tokens); + if !self.bounds.is_empty() { + TokensOrDefault(&self.colon_token).to_tokens(tokens); + self.bounds.to_tokens(tokens); + } + } + } + + impl ToTokens for TypeParam { + fn to_tokens(&self, tokens: &mut TokenStream) { + tokens.append_all(self.attrs.outer()); + self.ident.to_tokens(tokens); + if !self.bounds.is_empty() { + TokensOrDefault(&self.colon_token).to_tokens(tokens); + self.bounds.to_tokens(tokens); + } + if self.default.is_some() { + TokensOrDefault(&self.eq_token).to_tokens(tokens); + self.default.to_tokens(tokens); + } + } + } + + impl ToTokens for TraitBound { + fn to_tokens(&self, tokens: &mut TokenStream) { + let to_tokens = |tokens: &mut TokenStream| { + self.modifier.to_tokens(tokens); + self.lifetimes.to_tokens(tokens); + self.path.to_tokens(tokens); + }; + match &self.paren_token { + Some(paren) => paren.surround(tokens, to_tokens), + None => to_tokens(tokens), + } + } + } + + impl ToTokens for TraitBoundModifier { + fn to_tokens(&self, tokens: &mut TokenStream) { + match self { + TraitBoundModifier::None => {} + TraitBoundModifier::Maybe(t) => t.to_tokens(tokens), + } + } + } + + impl ToTokens for ConstParam { + fn to_tokens(&self, tokens: &mut TokenStream) { + tokens.append_all(self.attrs.outer()); + self.const_token.to_tokens(tokens); + self.ident.to_tokens(tokens); + self.colon_token.to_tokens(tokens); + self.ty.to_tokens(tokens); + if self.default.is_some() { + TokensOrDefault(&self.eq_token).to_tokens(tokens); + self.default.to_tokens(tokens); + } + } + } + + impl ToTokens for WhereClause { + fn to_tokens(&self, tokens: &mut TokenStream) { + if !self.predicates.is_empty() { + self.where_token.to_tokens(tokens); + self.predicates.to_tokens(tokens); + } + } + } + + impl ToTokens for PredicateType { + fn to_tokens(&self, tokens: &mut TokenStream) { + self.lifetimes.to_tokens(tokens); + self.bounded_ty.to_tokens(tokens); + self.colon_token.to_tokens(tokens); + self.bounds.to_tokens(tokens); + } + } + + impl ToTokens for PredicateLifetime { + fn to_tokens(&self, tokens: &mut TokenStream) { + self.lifetime.to_tokens(tokens); + self.colon_token.to_tokens(tokens); + self.bounds.to_tokens(tokens); + } + } + + impl ToTokens for PredicateEq { + fn to_tokens(&self, tokens: &mut TokenStream) { + self.lhs_ty.to_tokens(tokens); + self.eq_token.to_tokens(tokens); + self.rhs_ty.to_tokens(tokens); + } + } +} |