enum_to_types/lib.rs
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//! Macro for generating pseudo-enums for type-level programming.
//! This is somewhat like https://github.com/fmease/tylift but implemented with `macro_rules!` syntax
//! ```
//! # use enum_to_types::enum_to_types;
//! # use std::marker::PhantomData;
//! enum_to_types!(AccessLevel; User, Admin);
//!
//! struct DataStorage<T: AccessLevel::AccessLevel>(i32, PhantomData<T>);
//!
//! impl<T: AccessLevel::AccessLevel> DataStorage<T> {
//! fn new(i: i32) -> Self {
//! Self(i, PhantomData)
//! }
//! }
//!
//! trait ReadStorage<T: AccessLevel::AccessLevel> {
//! fn read(&self) -> i32;
//! }
//!
//! impl ReadStorage<AccessLevel::Admin> for DataStorage<AccessLevel::User> {
//! fn read(&self) -> i32 {
//! self.0
//! }
//! }
//!
//! impl ReadStorage<AccessLevel::User> for DataStorage<AccessLevel::User> {
//! fn read(&self) -> i32 {
//! self.0
//! }
//! }
//!
//! impl ReadStorage<AccessLevel::Admin> for DataStorage<AccessLevel::Admin> {
//! fn read(&self) -> i32 {
//! self.0
//! }
//! }
//!
//! impl ReadStorage<AccessLevel::User> for DataStorage<AccessLevel::Admin> {
//! fn read(&self) -> i32 {
//! panic!("You have no rights to read this");
//! }
//! }
//!
//! fn main() {
//! let storage = DataStorage::<AccessLevel::Admin>::new(1);
//! assert_eq!(<DataStorage::<AccessLevel::Admin> as ReadStorage<AccessLevel::Admin>>::read(&storage), 1);
//! let storage = DataStorage::<AccessLevel::User>::new(5);
//! assert_eq!(<DataStorage::<AccessLevel::User> as ReadStorage<AccessLevel::User>>::read(&storage), 5);
//! // reading storage with `AccessLevel::Admin` by user will cause panic
//! }
//! ```
//! This may look very verbose but it gives a lot of flexibility.
//! Also, other examples can look less verbose.
/// Macro for generating pseudo-enums for type-level programming.
/// This is somewhat like https://github.com/fmease/tylift but implemented with `macro_rules!` syntax
/// ```
/// # use enum_to_types::enum_to_types;
/// # use std::marker::PhantomData;
/// enum_to_types!(AccessLevel; User, Admin);
///
/// struct DataStorage<T: AccessLevel::AccessLevel>(i32, PhantomData<T>);
///
/// impl<T: AccessLevel::AccessLevel> DataStorage<T> {
/// fn new(i: i32) -> Self {
/// Self(i, PhantomData)
/// }
/// }
///
/// trait ReadStorage<T: AccessLevel::AccessLevel> {
/// fn read(&self) -> i32;
/// }
///
/// impl ReadStorage<AccessLevel::Admin> for DataStorage<AccessLevel::User> {
/// fn read(&self) -> i32 {
/// self.0
/// }
/// }
///
/// impl ReadStorage<AccessLevel::User> for DataStorage<AccessLevel::User> {
/// fn read(&self) -> i32 {
/// self.0
/// }
/// }
///
/// impl ReadStorage<AccessLevel::Admin> for DataStorage<AccessLevel::Admin> {
/// fn read(&self) -> i32 {
/// self.0
/// }
/// }
///
/// impl ReadStorage<AccessLevel::User> for DataStorage<AccessLevel::Admin> {
/// fn read(&self) -> i32 {
/// panic!("You have no rights to read this");
/// }
/// }
///
/// fn main() {
/// let storage = DataStorage::<AccessLevel::Admin>::new(1);
/// assert_eq!(<DataStorage::<AccessLevel::Admin> as ReadStorage<AccessLevel::Admin>>::read(&storage), 1);
/// let storage = DataStorage::<AccessLevel::User>::new(5);
/// assert_eq!(<DataStorage::<AccessLevel::User> as ReadStorage<AccessLevel::User>>::read(&storage), 5);
/// // reading storage with `AccessLevel::Admin` by user will cause panic
/// }
/// ```
/// This may look very verbose but it gives a lot of flexibility.
/// Also, other examples can look less verbose.
#[macro_export]
macro_rules! enum_to_types {
($name:ident; $($variant:ident),+) => {
pub mod $name {
pub trait $name {}
$(
#[derive(Debug, Ord, Hash, Eq, PartialOrd, PartialEq)]
pub struct $variant;
impl $name for $variant {}
)+
}
};
}