rust-range-check

This is a little library that helps with range and bounds checking. It works with Rust’s standard Range, RangeFrom, and RangeTo types.

View the Rustdoc

Installation

This crate works with Cargo. Add the following to your Cargo.toml dependencies section:

[dependencies]
range_check = "0.1"

Checking whether a range contains a value

The trait Contains is implemented on the range types. As long as the data type in question is PartialOrd, it can be used to check whether a value of that type is contained within a range:

use range_check::Contains;

let range = 3000..5000;
assert!(range.contains(4123));

let range = 10..;
assert!(range.contains(23));

There’s also the Within trait, which does the same check, only with the range as the argument:

use range_check::Within;

assert!(4123.is_within(3000..5000));
assert!(23.is_within(10..));

Failing early if a value is outside a range

It can sometimes be more helpful to automatically return a failure case, such as with the try! macro, than just check whether a value is inside a range. The Check trait returns Results that contain debugging information for when a value doesn’t lie within a range:

use range_check::Check;

struct Clock {
    hour: i8,
    minute: i8,
}

impl Clock {
    fn new(hour: i8, minute: i8) -> range_check::Result<Clock, i8> {
        Ok(Clock {
            hour:   try!(hour.check_range(0..24)),
            minute: try!(minute.check_range(0..60)),
        })
    }
}

assert!(Clock::new(23, 59).is_ok());
assert!(Clock::new(24, 00).is_err());

Displaying the Error that gets returned in the error case shows you exactly which range failed to be satisfied:

use std::string::ToString;
use range_check::Check;

let failure = 13.check_range(0..10).unwrap_err();
assert_eq!(failure.to_string(), "value (13) outside of range (0 .. 10)");