path: root/rust/syn/ty.rs

// SPDX-License-Identifier: Apache-2.0 OR MIT

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]>,