1use std::{
  2    borrow::Cow,
  3    ffi::OsStr,
  4    path::{Display, Path, PathBuf},
  5    sync::Arc,
  6};
  7
  8#[repr(transparent)]
  9#[derive(PartialEq, Eq, PartialOrd, Ord, Hash)]
 10pub struct RelPath([u8]);
 11
 12impl RelPath {
 13    pub fn new<S: AsRef<[u8]> + ?Sized>(s: &S) -> &Self {
 14        unsafe { &*(s.as_ref() as *const [u8] as *const Self) }
 15    }
 16
 17    pub fn components(&self) -> RelPathComponents {
 18        RelPathComponents(&self.0)
 19    }
 20
 21    pub fn file_name(&self) -> Option<&[u8]> {
 22        self.components().next_back()
 23    }
 24
 25    pub fn parent(&self) -> Option<&Self> {
 26        let mut components = self.components();
 27        components.next_back()?;
 28        Some(Self::new(components.0))
 29    }
 30
 31    pub fn starts_with(&self, other: &Self) -> bool {
 32        let mut components = self.components();
 33        other.components().all(|other_component| {
 34            components
 35                .next()
 36                .map_or(false, |component| component == other_component)
 37        })
 38    }
 39
 40    pub fn strip_prefix(&self, other: &Self) -> Result<&Self, ()> {
 41        let mut components = self.components();
 42        other
 43            .components()
 44            .all(|other_component| {
 45                components
 46                    .next()
 47                    .map_or(false, |component| component == other_component)
 48            })
 49            .then(|| Self::new(components.0))
 50            .ok_or_else(|| ())
 51    }
 52
 53    pub fn append_to_abs_path(&self, abs_path: &Path) -> PathBuf {
 54        // TODO: implement this differently
 55        let mut result = abs_path.to_path_buf();
 56        for component in self.components() {
 57            result.push(String::from_utf8_lossy(component).as_ref());
 58        }
 59        result
 60    }
 61
 62    pub fn to_proto(&self) -> String {
 63        String::from_utf8_lossy(&self.0).to_string()
 64    }
 65
 66    pub fn as_bytes(&self) -> &[u8] {
 67        &self.0
 68    }
 69
 70    pub fn as_os_str(&self) -> Cow<'_, OsStr> {
 71        #[cfg(target_os = "windows")]
 72        {
 73            use std::ffi::OsString;
 74            let path = String::from_utf8_lossy(&self.0);
 75            match path {
 76                Cow::Borrowed(s) => Cow::Borrowed(OsStr::new(s)),
 77                Cow::Owned(s) => Cow::Owned(OsString::from(s)),
 78            }
 79        }
 80        #[cfg(not(target_os = "windows"))]
 81        {
 82            Cow::Borrowed(self.0.as_os_str())
 83        }
 84    }
 85}
 86
 87impl From<&RelPath> for Arc<RelPath> {
 88    fn from(rel_path: &RelPath) -> Self {
 89        let bytes: Arc<[u8]> = Arc::from(&rel_path.0);
 90        unsafe { Arc::from_raw(Arc::into_raw(bytes) as *const RelPath) }
 91    }
 92}
 93
 94impl AsRef<RelPath> for &str {
 95    fn as_ref(&self) -> &RelPath {
 96        RelPath::new(self)
 97    }
 98}
 99
100impl std::fmt::Debug for RelPath {
101    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
102        if let Ok(str) = std::str::from_utf8(&self.0) {
103            write!(f, "RelPath({})", str)
104        } else {
105            write!(f, "RelPath({:?})", &self.0)
106        }
107    }
108}
109
110pub struct RelPathComponents<'a>(&'a [u8]);
111
112const SEPARATOR: u8 = b'/';
113
114impl<'a> Iterator for RelPathComponents<'a> {
115    type Item = &'a [u8];
116
117    fn next(&mut self) -> Option<Self::Item> {
118        if let Some(sep_ix) = self.0.iter().position(|&byte| byte == SEPARATOR) {
119            let (head, tail) = self.0.split_at(sep_ix);
120            self.0 = &tail[1..];
121            Some(head)
122        } else if self.0.is_empty() {
123            None
124        } else {
125            let result = self.0;
126            self.0 = &[];
127            Some(result)
128        }
129    }
130}
131
132impl<'a> DoubleEndedIterator for RelPathComponents<'a> {
133    fn next_back(&mut self) -> Option<Self::Item> {
134        if let Some(sep_ix) = self.0.iter().rposition(|&byte| byte == SEPARATOR) {
135            let (head, tail) = self.0.split_at(sep_ix);
136            self.0 = head;
137            Some(&tail[1..])
138        } else if self.0.is_empty() {
139            None
140        } else {
141            let result = self.0;
142            self.0 = &[];
143            Some(result)
144        }
145    }
146}
147
148#[cfg(test)]
149mod tests {
150    use super::*;
151
152    #[test]
153    fn test_rel_path_components() {
154        let path = RelPath::new("foo/bar/baz");
155        let mut components = path.components();
156        assert_eq!(components.next(), Some("foo".as_bytes()));
157        assert_eq!(components.next(), Some("bar".as_bytes()));
158        assert_eq!(components.next(), Some("baz".as_bytes()));
159        assert_eq!(components.next(), None);
160    }
161
162    #[test]
163    fn test_rel_path_parent() {
164        assert_eq!(
165            RelPath::new("foo/bar/baz").parent().unwrap(),
166            RelPath::new("foo/bar")
167        );
168        assert_eq!(RelPath::new("foo").parent().unwrap(), RelPath::new(""));
169        assert_eq!(RelPath::new("").parent(), None);
170    }
171}