brustfuck

Brainfuck in Rust. The "I regret nothing" Project.

An entirely declarative brainfuck macro.

The brainfuck generates a function that takes two parameters. A std::io::Read and a std::io::Write.

use std::io::Write;
use brustfuck::brainfuck;

fn main() {
	let function = brainfuck! {
//		[ This program prints "Hello World!" and a newline to the screen, its
//		  length is 106 active command characters. [It is not the shortest.]
//
//		  This loop is an "initial comment loop", a simple way of adding a comment
//		  to a BF program such that you don't have to worry about any command
//		  characters. Any ".", ",", "+", "-", "<" and ">" characters are simply
//		  ignored, the "[" and "]" characters just have to be balanced. This
//		  loop and the commands it contains are ignored because the current cell
//		  defaults to a value of 0; the 0 value causes this loop to be skipped.
//		]
		++++++++                // Set Cell #0 to 8
		[
			>++++               // Add 4 to Cell #1; this will always set Cell #1 to 4
			[                   // as the cell will be cleared by the loop
				>++             // Add 2 to Cell #2
				>+++            // Add 3 to Cell #3
				>+++            // Add 3 to Cell #4
				>+              // Add 1 to Cell #5
				<<<<-           // Decrement the loop counter in Cell #1
			]                   // Loop till Cell #1 is zero; number of iterations is 4
			>+                  // Add 1 to Cell #2
			>+                  // Add 1 to Cell #3
			>-                  // Subtract 1 from Cell #4
			>>+                 // Add 1 to Cell #6
			[<]                 // Move back to the first zero cell you find; this will
								// be Cell #1 which was cleared by the previous loop
			<-                  // Decrement the loop Counter in Cell #0
		]                       // Loop till Cell #0 is zero; number of iterations is 8

		// The result of this is:
		// Cell No :   0   1   2   3   4   5   6
		// Contents:   0   0  72 104  88  32   8
		// Pointer :   ^

		>>.                     // Cell #2 has value 72 which is 'H'
		>---.                   // Subtract 3 from Cell #3 to get 101 which is 'e'
		+++++++..+++.           // Likewise for 'llo' from Cell #3
		>>.                     // Cell #5 is 32 for the space
		<-.                     // Subtract 1 from Cell #4 for 87 to give a 'W'
		<.                      // Cell #3 was set to 'o' from the end of 'Hello'
		+++.------.--------.    // Cell #3 for 'rl' and 'd'
		>>+.                    // Add 1 to Cell #5 gives us an exclamation point
		>++.                    // And finally a newline from Cell #6
	};

	let mut output = vec![];

	function(&mut std::io::stdin().lock(), &mut output).unwrap();
	println!("Output:");
	std::io::stdout().write_all(&output).unwrap();
}

Output: Hello World!