Macro chain_cmp::chmp

chmp!() { /* proc-macro */ }

Use the chmp macro to chain comparison operators.

You can use all of these operators: <, <=, >, >=, ==, !=.

Examples

Basic usage

use chain_cmp::chmp;

let (a, b, c) = (1, 2, 3);

let verbose = a < b && b <= c;
let concise = chmp!(a < b <= c);
assert_eq!(concise, verbose);

// You can use equality operators as well:
assert!(chmp!(a != b != c));

// And you can even chain more than three operators:
assert!(chmp!(a != b != c != a)); // making sure these values are pairwise distinct

// And of course mix and match operators:
assert!(chmp!(a < b <= c != a == a));

Short-circuiting

chmp will short-circuit to evaluate the fewest expressions possible.

fn panics() -> i32 {
    panic!();
}

assert!(!chmp!(i32::MAX < i32::MIN < panics())); // this **won't** panic

Comparing arbitrary expressions

As long as the comparison operators have the lowest precedence, chmp will evaluate any expression, like variables, blocks, function calls, etc.

const ANSWER: u32 = 42;

assert!(chmp!({
    println!("Life, the Universe, and Everything");
    ANSWER
} != 6 * 9 == 54));