| /*! |
| This module defines "naive" implementations of substring search. |
| |
| These are sometimes useful to compare with "real" substring implementations. |
| The idea is that they are so simple that they are unlikely to be incorrect. |
| */ |
| |
| /// Naively search forwards for the given needle in the given haystack. |
| pub(crate) fn find(haystack: &[u8], needle: &[u8]) -> Option<usize> { |
| let end = haystack.len().checked_sub(needle.len()).map_or(0, |i| i + 1); |
| for i in 0..end { |
| if needle == &haystack[i..i + needle.len()] { |
| return Some(i); |
| } |
| } |
| None |
| } |
| |
| /// Naively search in reverse for the given needle in the given haystack. |
| pub(crate) fn rfind(haystack: &[u8], needle: &[u8]) -> Option<usize> { |
| let end = haystack.len().checked_sub(needle.len()).map_or(0, |i| i + 1); |
| for i in (0..end).rev() { |
| if needle == &haystack[i..i + needle.len()] { |
| return Some(i); |
| } |
| } |
| None |
| } |
| |
| #[cfg(test)] |
| mod tests { |
| use crate::tests::substring; |
| |
| use super::*; |
| |
| #[test] |
| fn forward() { |
| substring::Runner::new().fwd(|h, n| Some(find(h, n))).run() |
| } |
| |
| #[test] |
| fn reverse() { |
| substring::Runner::new().rev(|h, n| Some(rfind(h, n))).run() |
| } |
| } |