Path Dedot

This is a library for extending Path and PathBuf in order to parse the path which contains dots.

Please read the following examples to know the parsing rules.

Examples

If a path starts with a single dot, the dot means your program's current working directory (CWD).

use std::path::Path;
use std::env;

use path_dedot::*;

let p = Path::new("./path/to/123/456");

assert_eq!(Path::join(env::current_dir().unwrap().as_path(), Path::new("path/to/123/456")).to_str().unwrap(), p.parse_dot().unwrap().to_str().unwrap());

If a path starts with a pair of dots, the dots means the parent of the CWD. If the CWD is root, the parent is still root.

use std::path::Path;
use std::env;

use path_dedot::*;

let p = Path::new("../path/to/123/456");

let cwd = env::current_dir().unwrap();

let cwd_parent = cwd.parent();

match cwd_parent {
   Some(cwd_parent) => {
      assert_eq!(Path::join(&cwd_parent, Path::new("path/to/123/456")).to_str().unwrap(), p.parse_dot().unwrap().to_str().unwrap());
   }
   None => {
      assert_eq!(Path::join(Path::new("/"), Path::new("path/to/123/456")).to_str().unwrap(), p.parse_dot().unwrap().to_str().unwrap());
   }
}

In addition to starting with, the Single Dot and Double Dots can also be placed to other positions. Single Dot means noting and will be ignored. Double Dots means the parent.

use std::path::Path;

use path_dedot::*;

let p = Path::new("/path/to/../123/456/./777");

assert_eq!("/path/123/456/777", p.parse_dot().unwrap().to_str().unwrap());

use std::path::Path;

use path_dedot::*;

let p = Path::new("/path/to/../123/456/./777/..");

assert_eq!("/path/123/456", p.parse_dot().unwrap().to_str().unwrap());

You should notice that parse_dot method does not aim to get an absolute path. A path which does not start with a MAIN_SEPARATOR, Single Dot and Double Dots, will not have each of them after the parse_dot method is used.

use std::path::Path;

use path_dedot::*;

let p = Path::new("path/to/../123/456/./777/..");

assert_eq!("path/123/456", p.parse_dot().unwrap().to_str().unwrap());

Double Dots which is not placed at the start cannot get the parent beyond the original path. Why not? With this constraint, you can insert an absolute path to the start as a virtual root in order to protect your file system from being exposed.

use std::path::Path;

use path_dedot::*;

let p = Path::new("path/to/../../../../123/456/./777/..");

assert_eq!("123/456", p.parse_dot().unwrap().to_str().unwrap());

use std::path::Path;

use path_dedot::*;

let p = Path::new("/path/to/../../../../123/456/./777/..");

assert_eq!("/123/456", p.parse_dot().unwrap().to_str().unwrap());

If a path is entirely consumed by its Double Dots, an empty path will be returned.

use std::path::Path;

use path_dedot::*;

let p = Path::new("path/to/../../..");

assert_eq!("", p.parse_dot().unwrap().to_str().unwrap());

Starting from a given current working directory

With the parse_dot_from function, you can provide the current working directory that the relative paths should be resolved from.

use std::env;
use std::path::Path;

use path_dedot::*;

let p = Path::new("../path/to/123/456");
let cwd = env::current_dir().unwrap();

println!("{}", p.parse_dot_from(cwd).unwrap().to_str().unwrap());

Caching

The parse_dot method requires the CWD only when the input path starts with a Single Dot or Double Dots, and by default, it creates a new PathBuf instance of the CWD every time in its operation. The overhead is obvious. Although it allows us to safely change the CWD at runtime by the program itself (e.g. using the std::env::set_current_dir function) or outside controls (e.g. using gdb to call chdir), we don't need that in most cases.

In order to parse paths with better performance, the fixed_workdir feature can be enabled.

[dependencies.path-dedot]
version = "*"
features = ["fixed_workdir"]

Benchmark

No-cache

cargo bench

fixed_workdir

cargo bench --features fixed_workdir

Crates.io

https://crates.io/crates/path-dedot

Documentation

https://docs.rs/path-dedot

License

MIT