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netdoc: split off string utils

This commit is contained in:
Nick Mathewson 2020-10-31 13:31:32 -04:00
parent cb59ae3933
commit 8569af82dd
3 changed files with 4 additions and 57 deletions
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2
tor-netdoc/src/doc/microdesc.rs
View File

@ -223,7 +223,7 @@ impl Microdesc {
));
}
// Unwrap is safe here because we are parsing these strings from s
util::str_offset(s, first.kwd_str()).unwrap()
util::str::str_offset(s, first.kwd_str()).unwrap()
};
// Legacy (tap) onion key

2
tor-netdoc/src/parse/tokenize.rs
View File

@ -433,7 +433,7 @@ impl<'a, K: Keyword> Item<'a, K> {
///
/// Returns None if this item doesn't actually belong to the string.
pub fn offset_in(&self, s: &str) -> Option<usize> {
crate::util::str_offset(s, self.kwd_str)
crate::util::str::str_offset(s, self.kwd_str)
}
/// Return the position of the n'th argument of this item.
///

57
tor-netdoc/src/util.rs
View File

@ -1,5 +1,7 @@
//! Misc helper functions and types for use in parsing network documents
pub(crate) mod str;
use std::iter::Peekable;
/// An iterator adaptor that pauses when a given predicate is true.
@ -86,44 +88,6 @@ impl<'a, I: Iterator, F: FnMut(&I::Item) -> bool> Iterator for PauseAt<'a, I, F>
}
}
/// Return the position of one string slice within another.
///
/// If `needle` is indeed part of `haystack`, returns some offset
/// `off`, such that `needle` is the same as
/// `&haystack[off..needle.len()]`.
///
/// Returns None if `needle` is not a part of `haystack`.
///
/// Remember, offsets are in bytes, not in characters.
///
/// # Example
/// ```ignore
/// use tor_netdoc::util::str_offset;
/// let quote = "A rose is a rose is a rose."; // -- Gertrude Stein
/// assert_eq!(&quote[2..6], "rose");
/// assert_eq!(str_offset(quote, &quote[2..6]).unwrap(), 2);
/// assert_eq!(&quote[12..16], "rose");
/// assert_eq!(str_offset(quote, &quote[12..16]).unwrap(), 12);
/// assert_eq!(&quote[22..26], "rose");
/// assert_eq!(str_offset(quote, &quote[22..26]).unwrap(), 22);
///
/// assert_eq!(str_offset(quote, "rose"), None);
///
/// assert_eq!(str_offset(&quote[1..], &quote[2..6]), Some(1));
/// assert_eq!(str_offset(&quote[1..5], &quote[2..6]), None);
/// ```
pub fn str_offset(haystack: &str, needle: &str) -> Option<usize> {
let needle_start_u = needle.as_ptr() as usize;
let needle_end_u = needle_start_u + needle.len();
let haystack_start_u = haystack.as_ptr() as usize;
let haystack_end_u = haystack_start_u + haystack.len();
if haystack_start_u <= needle_start_u && needle_end_u <= haystack_end_u {
Some(needle_start_u - haystack_start_u)
} else {
None
}
}
#[cfg(test)]
mod tests {
@ -174,21 +138,4 @@ mod tests {
assert_eq!(iter.peek(), None);
assert_eq!(iter.next(), None);
}
#[test]
fn test_str_offset() {
use super::str_offset;
let quote = "A rose is a rose is a rose."; // -- Gertrude Stein
assert_eq!(&quote[2..6], "rose");
assert_eq!(str_offset(quote, &quote[2..6]).unwrap(), 2);
assert_eq!(&quote[12..16], "rose");
assert_eq!(str_offset(quote, &quote[12..16]).unwrap(), 12);
assert_eq!(&quote[22..26], "rose");
assert_eq!(str_offset(quote, &quote[22..26]).unwrap(), 22);
assert_eq!(str_offset(quote, "rose"), None);
assert_eq!(str_offset(&quote[1..], &quote[2..6]), Some(1));
assert_eq!(str_offset(&quote[1..5], &quote[2..6]), None);
}
}