use_similarity/
lib.rs

1#![forbid(unsafe_code)]
2#![doc = include_str!("../README.md")]
3
4/// A positive finite scale ratio used for geometric similarity.
5#[derive(Debug, Clone, Copy, PartialEq)]
6pub struct SimilarityRatio {
7    scale: f64,
8}
9
10impl SimilarityRatio {
11    /// Creates a positive finite similarity ratio.
12    #[must_use]
13    pub const fn new(scale: f64) -> Option<Self> {
14        if scale.is_finite() && scale > 0.0 {
15            Some(Self { scale })
16        } else {
17            None
18        }
19    }
20
21    /// Returns the scale factor.
22    #[must_use]
23    pub const fn scale(self) -> f64 {
24        self.scale
25    }
26
27    /// Applies the ratio to a length.
28    #[must_use]
29    pub fn apply_length(self, length: f64) -> f64 {
30        length * self.scale
31    }
32}
33
34#[cfg(test)]
35mod tests {
36    use super::SimilarityRatio;
37
38    #[test]
39    fn scales_lengths() {
40        let ratio = SimilarityRatio::new(2.0).expect("valid ratio");
41
42        assert_eq!(ratio.scale(), 2.0);
43        assert_eq!(ratio.apply_length(3.0), 6.0);
44        assert_eq!(SimilarityRatio::new(0.0), None);
45    }
46}
use_similarity/lib.rs

use_similarity/
lib.rs
