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Cycle_match

Convenient macros for combining cycles (for, while, loop) with a match.

Build Status Mit/Apache licensed crates.io Documentation

Purpose: To read lines from a file ignoring comments and special characters using macros (for_match, while_match).

#[macro_use]
extern crate cycle_match;

use std::io::Read;

fn main() -> Result<(), std:: io::Error> {
	let mut read_buffer = [0u8; 128];
	let mut buffer = Vec::with_capacity(130);
	let mut file = std::fs::File::open("./read.txt")?;
	
	while_match!((file.read(&mut read_buffer)) -> || {
		Ok(0) => break,
		Ok(len) => {
			let real_array = &read_buffer[..len];
			
			for_match!(@'read (real_array.into_iter()) -> |iter| {
				Some(13u8) => continue,
				Some(b'\n') => {
					if buffer.len() > 0 {
						println!("#line: {}", unsafe { std::str::from_utf8_unchecked(&buffer) });
						buffer.clear();
					}
				},
				Some(b'#') => while_match!((iter) -> || {
					Some(b'\n') => continue 'read,
					Some(_a) => {},
					_ => break 'read,
				}),
				Some(a) => buffer.push(*a),
				_ => break,
			});
		},
		
		Err(e) => return Err(e),
	});
	if buffer.len() > 0 {
		println!("#line: {}", unsafe { std::str::from_utf8_unchecked(&buffer) });
	}
	
	Ok(())
}

Use 1 (while_match)

Purpose: Convert characters to a digital sequence using a macro while_math.

#[macro_use]
extern crate cycle_match;

fn main() {
	let data = b"123456789";
	
	let mut num = 0usize;
	
	let mut iter = data.iter();
	while_match!((iter) -> || {
		Some(b'0') => {},
		Some(a @ b'1' ..= b'9') => {
			num *= 10;
			num += (a - b'0') as usize;
		},
		Some(a) => panic!("Unk byte: {:?}", a),
		_ => break
	});
	
	assert_eq!(num, 123456789);
}

Use 2 (for_match)

Purpose: Convert characters to a digital sequence using a macro for_match.

#[macro_use]
extern crate cycle_match;

fn main() {
	let data = "123456789";
	
	let mut num = 0;	
	for_match!((data.as_bytes().into_iter()) -> || {
		Some(b'0') => {},
		Some(a @ b'1' ..= b'9') => {
			num *= 10;
			num += (a - b'0') as usize;
		},
		Some(a) => panic!("Unk byte: {:?}", a),
		_ => break num,
	});
	
	println!("{}", num);
}

// See the "for_match" example for a more beautiful version.

Use 3 (loop_match)

Purpose: Count the sum of all bytes of a string using the loop_match macro.

#[macro_use]
extern crate cycle_match;

fn main() {
	let data = "1234567890";
	
	let mut data_n_index = 0usize;
	let mut iter = data.as_bytes().into_iter();
	loop_match!((iter.next()) -> || {
		Some(a) => data_n_index += *a as usize,
		_ => break,
	});
	
	assert_eq!(data_n_index, 525);
}

Description of input data record

  1. loop_match
loop_match!(@'begin (num, 0 ...) -> |num_add ...| {...} )
Record form: (A_Variable, ...) -> || ...
			
1. (A_Variable, Required): The name of the variable or executable expression to compare.
2. (..._variable, Optional): Description of internal variables.


Possible record (1): (a) -> || ...
// loop { match a {...} }

Possible record (2): (a.next(), ...) -> |...| ...
// let mut $(...) = $(...)
// loop { match a.next() {...} }

Possible record (3): (a.next(), 1024, ...) -> |my_usize, ...| -> ...
// let mut my_usize = 1024;
// let mut $(...) = $(...)
// loop { match a.next() {...} }
  1. while_match
while_match!(@'begin (data.iter(), let mut a, 1024usize) -> |my_usize| {...} )
Record form: (Iterator, A_Variable, ...) -> |...| ...
			
1. (Iterator, Required): The name of the iterator we are working with.
2. (A_Variable, Optional): The name of the rewritable variable (you can omit and write _ or declare a new variable with the desired name using `let mut MyVar`)
3. (..._variable, Optional): Description of internal variables.


Possible record (1): (slice) -> ...
// let mut __hidden_a;
// loop { __hidden_a = slice.next(); ... }

Possible record (2): (slice.my_next()) -> ...
// let mut __hidden_a;
// loop { __hidden_a = slice.my_next(); ... }

Possible record (3): (slice, _, ...) -> ...
// let mut __hidden_a;
// let mut $(...) = $(...)
// loop { __hidden_a = slice.next() }

Possible record (4): (iter, a, ...) -> ...
// let mut a;
// let mut $(...) = $(...)
// loop { a = iter.next() ... }

Possible record (4): (iter, let mut a, ...) -> ...
// let mut a;
// let mut $(...) = $(...)
// loop { a = iter.next() }

Possible record (5): (iter, _ 1024, ...) -> |my_usize, ...| ...
// let mut __hidden_a;
// let mut my_usize = 1024;
// let mut $(...) = $(...)
// loop { __hidden_a = iter.next() }
  1. for_match
for_match!(@'begin (data, _, 0usize) -> |_, num| {...} );
Record form: (Iterator, A_Variable, ...) -> |Iterator, ...| ...

1. (Iterator, Required): The name of the iterator we are working with.
2. (A_Variable, Optional): The name of the rewritable variable (you can omit and write _ or declare a new variable with the desired name using `let mut MyVar`)
3. (..._variable, Optional): Description of internal variables.


Possible record (1): (slice) -> || ...
// let mut __hidden_iter = slice.iter();
// let mut __hidden_a;
// loop { __hidden_a = __hidden_iter.next(); ... }

Possible record (2): (slice) -> |iter| ...  
// let mut iter = slice.iter();
// let mut __hidden_a;
// loop { __hidden_a = iter.next(); ... }

Possible record  (3): (slice.into_iter(), let mut a) -> || ...
// let mut __hidden_iter = slice.into_iter();
// let mut a;
// loop { a = iter.next(); ... }

Possible record (4): (slice.into_iter(), let mut a, 1024usize, ...) -> |iter, my_usize, ...| ...
// let mut iter = slice.into_iter();
// let mut my_usize = 1024usize;
// let mut a;
// let ... = ...
// loop { a = iter.next(); ... }

Possible record (5): (slice.into_iter(), a, 1024usize, ...) -> |iter, my_usize, ...| ...
// let mut iter = slice.into_iter();
// let mut my_usize = 1024usize;
// let ... = ...
// loop { a = iter.next(); ... }

Possible record (6): (slice.into_iter(), _, ...) -> |_, ...| ...
// let mut __hidden_iter = slice.into_iter();
// let mut __hidden_a;  // _ -> __hidden
// let ... = ...
// loop { __hidden_a = __hidden_iter.next(); ... }

Possible record (7): (a.into_iter(), let mut a, 1024, ...) -> |iter, my_usize, ...| -> ...
// let mut iter = a.into_iter();
// let mut a;
// let mut my_usize = 1024;
// let ... = ...
// loop { a = iter.next(); ... }

What can be written in the body of macros?

  1. The same thing that you write in the body of the match language construct.
#[macro_use]
extern crate cycle_match;

fn main() {
	let data = b"123456789";
	
	let mut num = 0usize;
	
	let mut iter = data.iter();
	while_match!((iter) -> || {
		Some(b'0') => {},
		Some(a @ b'1' ..= b'9') => {
			num *= 10;
			num += (a - b'0') as usize;
		},
		Some(a) => panic!("Unk byte: {:?}", a),
		_ => break
	});
	
	assert_eq!(num, 123456789);
}
  1. Combined language construct match with remote blocks of executable code.

/// !Use only for needs that you especially need, as the macro value is lost.

The standard macro body usually consists only of the internal parts of the match language construct, but it is possible to add code that executes before and after match. To do this, you need to move the executable code and the match code to the necessary blocks.

#[macro_use]
extern crate cycle_match;

fn main() {
	let mut num = 1;
	loop_match!(@'begin (num, 0) -> |num_add| {
		#[insert] { // Possible executable code before the `match` language construct
			// Any possible executable code
		},
		#[begin] { // The body of the language construct `match`
			0 ..= 255	=> num_add += 2,
			255 ..= 655 => num_add += 3,
			655 ..= 955 => num_add += 4,
			
			_		=> break,
		},
		#[insert] { // Possible executable code after the `match` language construct
			num *= num_add;
			// Any possible executable code
		}
	});
	assert_eq!(num, 4224);
}