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use std::cmp::Ordering;
fn version_non_digit_cmp(a: &str, b: &str) -> Ordering {
let mut a_chars = a.chars();
let mut b_chars = b.chars();
loop {
match (a_chars.next(), b_chars.next()) {
(Some(c1), Some(c2)) if c1 == c2 => {}
(None, None) => return Ordering::Equal,
(_, Some('~')) => return Ordering::Greater,
(Some('~'), _) => return Ordering::Less,
(None, Some(_)) => return Ordering::Less,
(Some(_), None) => return Ordering::Greater,
(Some(c1), Some(c2)) if c1.is_ascii_alphabetic() && !c2.is_ascii_alphabetic() => {
return Ordering::Less
}
(Some(c1), Some(c2)) if !c1.is_ascii_alphabetic() && c2.is_ascii_alphabetic() => {
return Ordering::Greater
}
(Some(c1), Some(c2)) => return c1.cmp(&c2),
}
}
}
fn remove_file_ending(a: &str) -> &str {
let mut ending_start = None;
let mut prev_was_dot = false;
for (idx, char) in a.char_indices() {
if char == '.' {
if ending_start.is_none() || prev_was_dot {
ending_start = Some(idx);
}
prev_was_dot = true;
} else if prev_was_dot {
prev_was_dot = false;
if !char.is_ascii_alphabetic() && char != '~' {
ending_start = None;
}
} else if !char.is_ascii_alphanumeric() && char != '~' {
ending_start = None;
}
}
if prev_was_dot {
ending_start = None;
}
if let Some(ending_start) = ending_start {
&a[..ending_start]
} else {
a
}
}
pub fn version_cmp(mut a: &str, mut b: &str) -> Ordering {
let str_cmp = a.cmp(b);
if str_cmp == Ordering::Equal {
return str_cmp;
}
match (a.is_empty(), b.is_empty()) {
(true, false) => return Ordering::Less,
(false, true) => return Ordering::Greater,
(true, true) => unreachable!(),
(false, false) => {}
}
match (a == ".", b == ".") {
(true, false) => return Ordering::Less,
(false, true) => return Ordering::Greater,
(true, true) => unreachable!(),
(false, false) => {}
}
match (a == "..", b == "..") {
(true, false) => return Ordering::Less,
(false, true) => return Ordering::Greater,
(true, true) => unreachable!(),
(false, false) => {}
}
match (a.starts_with('.'), b.starts_with('.')) {
(true, false) => return Ordering::Less,
(false, true) => return Ordering::Greater,
(true, true) => {
a = &a[1..];
b = &b[1..];
}
_ => {}
}
let (mut a, mut b) = match (remove_file_ending(a), remove_file_ending(b)) {
(a_stripped, b_stripped) if a_stripped == b_stripped => {
(a, b)
}
stripped => stripped,
};
loop {
let a_numerical_start = a.find(|c: char| c.is_ascii_digit()).unwrap_or(a.len());
let b_numerical_start = b.find(|c: char| c.is_ascii_digit()).unwrap_or(b.len());
let a_str = &a[..a_numerical_start];
let b_str = &b[..b_numerical_start];
match version_non_digit_cmp(a_str, b_str) {
Ordering::Equal => {}
ord => return ord,
}
a = &a[a_numerical_start..];
b = &b[a_numerical_start..];
let a_numerical_end = a.find(|c: char| !c.is_ascii_digit()).unwrap_or(a.len());
let b_numerical_end = b.find(|c: char| !c.is_ascii_digit()).unwrap_or(b.len());
let a_str = a[..a_numerical_end].trim_start_matches('0');
let b_str = b[..b_numerical_end].trim_start_matches('0');
match a_str.len().cmp(&b_str.len()) {
Ordering::Equal => {}
ord => return ord,
}
match a_str.cmp(b_str) {
Ordering::Equal => {}
ord => return ord,
}
a = &a[a_numerical_end..];
b = &b[b_numerical_end..];
if a.is_empty() && b.is_empty() {
return str_cmp;
}
}
}
#[cfg(test)]
mod tests {
use crate::version_cmp::version_cmp;
use std::cmp::Ordering;
#[test]
fn test_version_cmp() {
assert_eq!(version_cmp("hello", "hello"), Ordering::Equal);
assert_eq!(version_cmp("file12", "file12"), Ordering::Equal);
assert_eq!(
version_cmp("file12-suffix", "file12-suffix"),
Ordering::Equal
);
assert_eq!(
version_cmp("file12-suffix24", "file12-suffix24"),
Ordering::Equal
);
assert_eq!(version_cmp("world", "wo"), Ordering::Greater,);
assert_eq!(version_cmp("hello10wo", "hello10world"), Ordering::Less,);
assert_eq!(version_cmp("world", "hello"), Ordering::Greater,);
assert_eq!(version_cmp("hello", "world"), Ordering::Less);
assert_eq!(version_cmp("apple", "ant"), Ordering::Greater);
assert_eq!(version_cmp("ant", "apple"), Ordering::Less);
assert_eq!(
version_cmp("Beef", "apple"),
Ordering::Less,
"Uppercase letters are sorted before all lowercase letters"
);
assert_eq!(version_cmp("Apple", "apple"), Ordering::Less);
assert_eq!(version_cmp("apple", "aPple"), Ordering::Greater);
assert_eq!(
version_cmp("100", "20"),
Ordering::Greater,
"Greater numbers are greater even if they start with a smaller digit",
);
assert_eq!(
version_cmp("20", "20"),
Ordering::Equal,
"Equal numbers are equal"
);
assert_eq!(
version_cmp("15", "200"),
Ordering::Less,
"Small numbers are smaller"
);
assert_eq!(
version_cmp("1000", "apple"),
Ordering::Less,
"Numbers are sorted before other characters"
);
assert_eq!(
version_cmp("file1000", "fileapple"),
Ordering::Less,
"Numbers in the middle of the name are sorted before other characters"
);
assert_eq!(
version_cmp("012", "12"),
Ordering::Less,
"A single leading zero can make a difference"
);
assert_eq!(
version_cmp("000800", "0000800"),
Ordering::Greater,
"Leading number of zeroes is used even if both non-zero number of zeros"
);
assert_eq!(version_cmp("ab10", "aa11"), Ordering::Greater);
assert_eq!(
version_cmp("aa10", "aa11"),
Ordering::Less,
"Numbers after other characters are handled correctly."
);
assert_eq!(
version_cmp("aa2", "aa100"),
Ordering::Less,
"Numbers after alphabetical characters are handled correctly."
);
assert_eq!(
version_cmp("aa10bb", "aa11aa"),
Ordering::Less,
"Number is used even if alphabetical characters after it differ."
);
assert_eq!(
version_cmp("aa10aa0010", "aa11aa1"),
Ordering::Less,
"Second number is ignored if the first number differs."
);
assert_eq!(
version_cmp("aa10aa0010", "aa10aa1"),
Ordering::Greater,
"Second number is used if the rest is equal."
);
assert_eq!(
version_cmp("aa10aa0010", "aa00010aa1"),
Ordering::Greater,
"Second number is used if the rest is equal up to leading zeroes of the first number."
);
assert_eq!(
version_cmp("aa10aa0022", "aa010aa022"),
Ordering::Greater,
"The leading zeroes of the first number has priority."
);
assert_eq!(
version_cmp("aa10aa0022", "aa10aa022"),
Ordering::Less,
"The leading zeroes of other numbers than the first are used."
);
assert_eq!(
version_cmp("file-1.4", "file-1.13"),
Ordering::Less,
"Periods are handled as normal text, not as a decimal point."
);
assert_eq!(
version_cmp("aa2000000000000000000000bb", "aa002000000000000000000001bb"),
Ordering::Less,
"Numbers larger than u64::MAX are handled correctly without crashing"
);
assert_eq!(
version_cmp("aa2000000000000000000000bb", "aa002000000000000000000000bb"),
Ordering::Greater,
"Leading zeroes for numbers larger than u64::MAX are \
handled correctly without crashing"
);
assert_eq!(
version_cmp(" a", "a"),
Ordering::Greater,
"Whitespace is after letters because letters are before non-letters"
);
assert_eq!(
version_cmp("a~", "ab"),
Ordering::Less,
"A tilde is before other letters"
);
assert_eq!(
version_cmp("a~", "a"),
Ordering::Less,
"A tilde is before the line end"
);
assert_eq!(
version_cmp("~", ""),
Ordering::Greater,
"A tilde is after the empty string"
);
assert_eq!(
version_cmp(".f", ".1"),
Ordering::Greater,
"if both start with a dot it is ignored for the comparison"
);
assert_eq!(
version_cmp("a..a", "a.+"),
Ordering::Less,
".a is stripped before the comparison"
);
assert_eq!(
version_cmp("a.", "a+"),
Ordering::Greater,
". is not stripped before the comparison"
);
assert_eq!(
version_cmp("a\0a", "a"),
Ordering::Greater,
"NULL bytes are handled comparison"
);
}
}