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//! Type names for rkyv_dyn. //! //! The goal of `TypeName` is to avoid allocations if //! possible. If all you need is the hash of a type name, //! then there's no reason to allocate a string to do it. //! //! rkyv_typename provides a derive macro to easily implement //! [`TypeName`], and has options to easily customize your //! type's name. //! //! ## Examples //! //! ``` //! use rkyv_typename::TypeName; //! #[derive(TypeName)] //! #[typename = "CoolType"] //! struct Example<T>(T); //! //! fn main() { //! let mut type_name = String::new(); //! Example::<i32>::build_type_name(|piece| type_name += piece); //! assert_eq!(type_name, "CoolType<i32>"); //! } //! ``` //! //! ## Features //! //! - `const_generics`: Uses the incomplete `const_generics` //! feature to implement array type names. //! - `std`: Implements [`TypeName`] for standard library //! types. //! //! By default, the `std` feature is enabled. #![cfg_attr(feature = "const_generics", allow(incomplete_features))] #![cfg_attr(feature = "const_generics", feature(const_generics))] mod core_impl; #[cfg(feature = "std")] mod std_impl; pub use rkyv_typename_derive::TypeName; /// Builds a name for a type. /// /// An implementation can be derived automatically with /// `#[derive(TypeName)]`. See [TypeName](macro@TypeName) /// for more details. /// /// Names cannot be guaranteed to be unique and although /// they are usually suitable to use as keys, precautions /// should be taken to ensure that if name collisions /// happen that they are detected and fixable. /// /// ## Examples /// /// Most of the time, `#[derive(TypeName)]` will suit your /// needs. However, if you need more control, you can always /// implement it manually: /// /// ``` /// use rkyv_typename::TypeName; /// /// struct Example; /// /// impl TypeName for Example { /// fn build_type_name<F: FnMut(&str)>(mut f: F) { /// f("CoolStruct"); /// } /// } /// /// struct GenericExample<T, U, V>(T, U, V); /// /// impl<T: TypeName, U: TypeName, V: TypeName> TypeName for GenericExample<T, U, V> { /// fn build_type_name<F: FnMut(&str)>(mut f: F) { /// f("CoolGeneric<"); /// T::build_type_name(&mut f); /// f(", "); /// U::build_type_name(&mut f); /// f(", "); /// V::build_type_name(&mut f); /// f(">"); /// } /// } /// /// fn type_name<T: TypeName>() -> String { /// let mut result = String::new(); /// T::build_type_name(|piece| result += piece); /// result /// } /// /// fn main() { /// assert_eq!(type_name::<Example>(), "CoolStruct"); /// assert_eq!(type_name::<GenericExample<i32, Option<String>, Example>>(), "CoolGeneric<i32, Option<String>, CoolStruct>"); /// } /// ``` pub trait TypeName { /// Submits the pieces of the type name to the given function. fn build_type_name<F: FnMut(&str)>(f: F); } #[cfg(test)] mod tests { use crate as rkyv_typename; use crate::TypeName; fn type_name_string<T: TypeName>() -> String { let mut result = String::new(); T::build_type_name(|piece| result += piece); result } #[test] fn builtin_types() { assert_eq!(type_name_string::<i32>(), "i32"); assert_eq!(type_name_string::<(i32,)>(), "(i32,)"); assert_eq!(type_name_string::<(i32, i32)>(), "(i32, i32)"); assert_eq!(type_name_string::<[[u8; 4]; 8]>(), "[[u8; 4]; 8]"); assert_eq!(type_name_string::<Option<[String; 1]>>(), "Option<[String; 1]>"); assert_eq!(type_name_string::<Option<[Option<u8>; 4]>>(), "Option<[Option<u8>; 4]>"); } #[test] fn derive() { #[derive(TypeName)] struct Test; assert_eq!(type_name_string::<Test>(), "Test"); } #[test] fn derive_generic() { #[derive(TypeName)] struct Test<T, U, V>(T, U, V); assert_eq!(type_name_string::<Test<u8, [i32; 4], Option<String>>>(), "Test<u8, [i32; 4], Option<String>>"); } #[test] fn derive_custom_typename() { #[derive(TypeName)] #[typename = "Custom"] struct Test; assert_eq!(type_name_string::<Test>(), "Custom"); #[derive(TypeName)] #[typename = "GenericCustom"] struct GenericTest<T>(T); assert_eq!(type_name_string::<GenericTest<i32>>(), "GenericCustom<i32>"); assert_eq!(type_name_string::<GenericTest<Test>>(), "GenericCustom<Custom>"); } }