copy_impl/

lib.rs

//Copyright (c) 2021-2024 #UlinProject (Denis Kotlyarov)


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/*!
Macro for effortlessly duplicating impl block code across various types in Rust.

## Example:

```rust
use std::{error::Error, fmt::Write};
use copy_impl::copy_impl;

struct CustomNum<T>(T);
struct UncheckedCustomNum<T>(T);

copy_impl! {
	impl (CustomNum<i8>),
	impl (CustomNum<i16>),
	impl (CustomNum<i32>),
	impl (UncheckedCustomNum<i8>),
	impl (UncheckedCustomNum<i16>) {
		pub fn write_to(&self, mut w: impl Write) -> Result<(), std::fmt::Error> {
			write!(w, "{}", self.0)
		}
	}
}

fn main() -> Result<(), Box<dyn Error>> {
	let mut tbuff = String::new();
	CustomNum(1i8).write_to(&mut tbuff)?;
	CustomNum(2i16).write_to(&mut tbuff)?;
	CustomNum(3i32).write_to(&mut tbuff)?;
	
	UncheckedCustomNum(4i8).write_to(&mut tbuff)?;
	UncheckedCustomNum(5i16).write_to(&mut tbuff)?;
	// UncheckedCustomNum(6i32).write_to(&mut tbuff)?;
	/*
		no method named `write_to` found for struct `UncheckedCustomNum<i32>` in the current scope
		the method was found for
		- `UncheckedCustomNum<i8>`
		- `UncheckedCustomNum<i16>`
	*/
	
	assert_eq!(tbuff, "12345");
	
	Ok(())
}
```

*/

#![no_std]

///
/// Macro for easily copying impl block code for different types.
/// ```rust
/// use std::{error::Error, fmt::Write};
/// use copy_impl::copy_impl;
/// 
/// struct CustomNum<T>(T);
/// struct UncheckedCustomNum<T>(T);
/// 
/// copy_impl! {
/// 	impl (CustomNum<i8>),
/// 	impl (CustomNum<i16>),
/// 	impl (CustomNum<i32>),
/// 	impl (UncheckedCustomNum<i8>),
/// 	impl (UncheckedCustomNum<i16>) {
/// 		pub fn write_to(&self, mut w: impl Write) -> Result<(), std::fmt::Error> {
/// 			write!(w, "{}", self.0)
/// 		}
/// 	}
/// }
/// ```
#[macro_export]
macro_rules! copy_impl {
	[ /* COLD_START */
		impl $(<$($p_impl:tt)*>)? ($($impl:tt)*) $(where ($($where:tt)*))?
		
		$($all:tt)*
	] => {
		$crate::copy_impl! {
			[ // the COLD_START!
				[
					/* COPY_IMPL_DATA */
					[ 
						[ $($($p_impl)*)? ] // <T>
						[ $($impl)* ] // impldata
						[ $($($where)*)? ]
					]
				]
			]
			
			$($all)*
		}
	};
	
	[ /* HOT_CONTINUE */
		[
			[
				/* COPY_IMPL_DATA */
				$($all_copy_impl_data:tt)+
			]
		]
		
		, impl $(<$($p_impl:tt)*>)? ($($impl:tt)*) $(where ($($where:tt)*))?
		
		$($all:tt)*
	] => {
		$crate::copy_impl! {
			[
				[
					/* COPY_IMPL_DATA */
					$($all_copy_impl_data)+
					
					[ 
						[ $($($p_impl)*)? ] // <T>
						[ $($impl)* ] // impldata
						[ $($($where)*)? ]
					]
					/* all */
				]
			]
			
			$($all)*
		}
	};
	
	[ /* skip (,) */
		[
			[
				/* COPY_IMPL_DATA */
				$($all_copy_impl_data:tt)*
			]
		]
		,
		
		$($all:tt)*
	] => {
		$crate::copy_impl! {
			[
				[
					/* COPY_IMPL_DATA */
					$($all_copy_impl_data)*
				]
			]
			
			$($all)*
		}
	};
	
	[ // END HEADERS(IMPL), the CODE!
		[
			[ /* COPY_IMPL_DATA */
				$([
					[ $($p_impl:tt)* ]
					[ $($impl:tt)* ]
					[ $($where:tt)* ]
				])+
			]
		]
		{ $($code:tt)* }
		
		$(
			; $($all:tt)*
		)?
	] => {
		$crate::__internal_make_copy_impl! {
			[]
			[$($code)*] ->
			
			$([
				[$($p_impl)*] // <T>
				[$($impl)*] // impldata
				[$($where)*]
			])+
		}
		
		$(
			$crate::copy_impl! {
				$($all)*
			}
		)?
	};
	
	[ $(;)? ] => {};
	
	[ /* UNK */ $($all:tt)+ ] => {
		compile_error!(stringify!(
			$($all)+
		));
	}
}

#[macro_export]
#[doc(hidden)]
macro_rules! __internal_make_copy_impl {
	[
		[
			/* RARRAY */
			$($rarray:tt)*
		]
		[$($code:tt)*] ->
		
		[ [$($p_impl:tt)*][$($impl:tt)*][$($where:tt)*] ]
		$($unk:tt)*
	] => {
		$crate::__internal_make_copy_impl! {
			[
				$($rarray)*
				[
					[$($p_impl)*]
					[$($impl)*]
					[$($where)*]
					[$($code)*]
				]
			]
			[$($code)*] ->
			
			$($unk)*
		}
	};
	[
		[
			$([
				[$($p_impl:tt)*]
				[$($impl:tt)*]
				[$($where:tt)*]
				[$($code:tt)*]
			])*
		]
		[$($_code:tt)*] ->
	] => {
		$(
			impl $(<$($p_impl)*>)? $($impl)* $(where $($where)*)? {
				$($code)*
			}
		)*
	}
}