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// Invariants:
// - 'orig' is a valid path, and in particular, the '/'-split components are non-empty;
// - 'comps' describes a non-empty prefix of 'orig'.
#[derive(Debug)]
pub struct Path<'a> {
orig: &'a str,
comps: Vec<(usize, &'a str)>, // (offset, component)
}
impl<'a> Path<'a> {
/// Returns the split path if the path is valid. A valid path has the following requirements:
/// * It does not contain unicode control characters;
/// * When split on '/', the resulting components are all non-empty and neither start nor end
/// with unicode whitespace characters.
pub fn split(s: &str) -> Option<Path> {
let mut comps = Vec::new();
let mut start = 0; // of current component
for (i, c) in s.char_indices() {
match c {
'/' if i == start => return None, // empty component
'/' => {
let comp = &s[start..i];
if comp.starts_with(|c2: char| c2.is_whitespace()) ||
comp.ends_with(|c2: char| c2.is_whitespace()) {
return None;
}
comps.push((start, comp));
start = i + 1;
},
_ if c.is_control() => return None,
_ => {}, // include in current component
}
}
// check and add the last component
if start == s.len() {
return None; // slash at end of input
}
comps.push((start, &s[start..s.len()]));
Some(Path { orig: s, comps })
}
pub fn without_last(&self) -> Option<(Path, &str)> {
let n = self.comps.len();
if n > 1 {
Some((Path { orig: self.orig, comps: self.comps[0 .. n - 1].into() }, self.comps[n - 1].1))
} else {
None
}
}
pub fn join(&self) -> &str {
if self.comps.len() == 0 {
""
} else {
let (lastoff, lastcomp) = self.comps[self.comps.len() - 1];
&self.orig[0 .. lastoff + lastcomp.len()]
}
}
}
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