use_range/
lib.rs

1#![forbid(unsafe_code)]
2#![doc = include_str!("../README.md")]
3
4//! Comparable range validation helpers.
5
6use core::{cmp::Ordering, fmt};
7use use_bound::{LowerBound, UpperBound};
8
9pub mod prelude;
10
11#[derive(Debug, Clone, PartialEq, Eq)]
12pub enum RangeError {
13    InvertedBounds,
14}
15
16impl fmt::Display for RangeError {
17    fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
18        match self {
19            Self::InvertedBounds => formatter.write_str("lower bound cannot exceed upper bound"),
20        }
21    }
22}
23
24impl std::error::Error for RangeError {}
25
26#[derive(Debug, Clone, PartialEq, Eq)]
27pub struct RangeConstraint<T> {
28    lower: Option<LowerBound<T>>,
29    upper: Option<UpperBound<T>>,
30}
31
32impl<T: PartialOrd> RangeConstraint<T> {
33    /// Creates a reusable range from optional lower and upper bounds.
34    ///
35    /// # Errors
36    ///
37    /// Returns [`RangeError::InvertedBounds`] when the provided bounds describe an empty or
38    /// inverted range.
39    pub fn new(
40        lower: Option<LowerBound<T>>,
41        upper: Option<UpperBound<T>>,
42    ) -> Result<Self, RangeError> {
43        if let (Some(lower_bound), Some(upper_bound)) = (&lower, &upper) {
44            match lower_bound.value().partial_cmp(upper_bound.value()) {
45                Some(Ordering::Greater) | None => return Err(RangeError::InvertedBounds),
46                Some(Ordering::Equal)
47                    if matches!(lower_bound, LowerBound::Exclusive(_))
48                        || matches!(upper_bound, UpperBound::Exclusive(_)) =>
49                {
50                    return Err(RangeError::InvertedBounds);
51                },
52                Some(Ordering::Less | Ordering::Equal) => {},
53            }
54        }
55
56        Ok(Self { lower, upper })
57    }
58
59    #[must_use]
60    pub fn contains(&self, value: &T) -> bool {
61        self.lower
62            .as_ref()
63            .is_none_or(|lower_bound| lower_bound.allows(value))
64            && self
65                .upper
66                .as_ref()
67                .is_none_or(|upper_bound| upper_bound.allows(value))
68    }
69}
70
71#[cfg(test)]
72mod tests {
73    use super::{RangeConstraint, RangeError};
74    use use_bound::{exclusive_maximum, exclusive_minimum, maximum, minimum};
75
76    #[test]
77    fn range_contains_values_inside_the_bounds() -> Result<(), RangeError> {
78        let range = RangeConstraint::new(Some(minimum(1)), Some(maximum(10)))?;
79        assert!(range.contains(&5));
80        assert!(!range.contains(&11));
81        Ok(())
82    }
83
84    #[test]
85    fn range_rejects_empty_exclusive_intervals() {
86        assert_eq!(
87            RangeConstraint::new(Some(exclusive_minimum(1)), Some(exclusive_maximum(1))),
88            Err(RangeError::InvertedBounds)
89        );
90    }
91}
use_range/lib.rs

use_range/
lib.rs
