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use std::{
path::{Path, PathBuf},
ops::{Deref, DerefMut},
env, io
};
use serde::{
ser::{Serialize, Serializer},
de::{Deserialize, Deserializer}
};
#[derive(Debug, Clone, PartialEq, Eq, Hash, PartialOrd, Ord)]
pub struct CwdBaseDir(PathBuf);
impl CwdBaseDir {
/// Creates a new `CwdBaseDir` instance containing exactly the given path.
pub fn new_unchanged(path: PathBuf) -> Self {
CwdBaseDir(path)
}
/// Creates a `CwdBaseDir` from a path by prefixing the path with the
/// current working dir if it's relative.
///
/// If the path is not relative it's directly used.
///
/// # Os state side effects
///
/// As this function accesses the current working directory (CWD) it's
/// not pure as the CWD can be changed (e.g. by `std::env::set_current_dir`).
///
/// # Error
///
/// As getting the CWD can fail this function can fail with a I/O Error, too.
pub fn from_path<P>(path: P) -> Result<Self, io::Error>
where P: AsRef<Path> + Into<PathBuf>
{
let path =
if path.as_ref().is_absolute() {
path.into()
} else {
let mut cwd = env::current_dir()?;
cwd.push(path.as_ref());
cwd
};
Ok(CwdBaseDir(path))
}
/// Turns this path into a `PathBuf` by stripping the current working dir
/// if it starts with it.
///
/// If this path does not start with the CWD it's returned directly.
///
/// # Os state side effects
///
/// As this function used the current working dir (CWD) it is affected
/// by any function changing the CWD as a side effect.
///
/// # Error
///
/// Accessing the current working dir can fail, as such this function
/// can fail.
pub fn to_base_path(&self) -> Result<&Path, io::Error> {
let cwd = env::current_dir()?;
self.strip_prefix(&cwd)
.or_else(|_err_does_not_has_that_prefix| {
Ok(&self)
})
}
/// Turns this instance into the `PathBuf` it dereferences to.
pub fn into_inner_with_prefix(self) -> PathBuf {
let CwdBaseDir(path) = self;
path
}
}
impl Deref for CwdBaseDir {
type Target = PathBuf;
fn deref(&self) -> &Self::Target {
&self.0
}
}
impl DerefMut for CwdBaseDir {
fn deref_mut(&mut self) -> &mut Self::Target {
&mut self.0
}
}
impl AsRef<Path> for CwdBaseDir {
fn as_ref(&self) -> &Path {
&self.0
}
}
impl<'de> Deserialize<'de> for CwdBaseDir {
fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
where D: Deserializer<'de>
{
use serde::de::Error;
let path_buf = PathBuf::deserialize(deserializer)?;
Self::from_path(path_buf)
.map_err(|err| D::Error::custom(err))
}
}
impl Serialize for CwdBaseDir {
fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
where S: Serializer,
{
use serde::ser::Error;
let path = self.to_base_path()
.map_err(|err| S::Error::custom(err))?;
path.serialize(serializer)
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn from_path_does_not_affect_absolute_paths() {
let path = Path::new("/the/dog");
let base_dir = CwdBaseDir::from_path(path).unwrap();
assert_eq!(&*base_dir, Path::new("/the/dog"))
}
#[test]
fn from_path_prefixes_with_cwd() {
let cwd = env::current_dir().unwrap();
let expected = cwd.join("./the/dog");
let base_dir = CwdBaseDir::from_path("./the/dog").unwrap();
assert_eq!(&*base_dir, &expected);
}
#[test]
fn to_base_path_removes_cwd_prefix() {
let cwd = env::current_dir().unwrap();
let dir = cwd.join("hy/there");
let base_dir = CwdBaseDir::new_unchanged(dir);
let path = base_dir.to_base_path().unwrap();
assert_eq!(path, Path::new("hy/there"));
}
}
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