2 files changed, 93 insertions, 0 deletions
diff --git a/helix-core/src/lib.rs b/helix-core/src/lib.rs
index 2823959f..be01c302 100644
--- a/helix-core/src/lib.rs
+++ b/helix-core/src/lib.rs
@@ -11,6 +11,7 @@ pub mod macros;
 pub mod match_brackets;
 pub mod movement;
 pub mod object;
+pub mod path;
 mod position;
 pub mod register;
 pub mod search;
diff --git a/helix-core/src/path.rs b/helix-core/src/path.rs
new file mode 100644
index 00000000..6c37cfa1
--- /dev/null
+++ b/helix-core/src/path.rs
@@ -0,0 +1,92 @@
+use std::path::{Component, Path, PathBuf};
+
+/// Replaces users home directory from `path` with tilde `~` if the directory
+/// is available, otherwise returns the path unchanged.
+pub fn fold_home_dir(path: &Path) -> PathBuf {
+    if let Ok(home) = super::home_dir() {
+        if path.starts_with(&home) {
+            // it's ok to unwrap, the path starts with home dir
+            return PathBuf::from("~").join(path.strip_prefix(&home).unwrap());
+        }
+    }
+
+    path.to_path_buf()
+}
+
+/// Expands tilde `~` into users home directory if avilable, otherwise returns the path
+/// unchanged. The tilde will only be expanded when present as the first component of the path
+/// and only slash follows it.
+pub fn expand_tilde(path: &Path) -> PathBuf {
+    let mut components = path.components().peekable();
+    if let Some(Component::Normal(c)) = components.peek() {
+        if c == &"~" {
+            if let Ok(home) = super::home_dir() {
+                // it's ok to unwrap, the path starts with `~`
+                return home.join(path.strip_prefix("~").unwrap());
+            }
+        }
+    }
+
+    path.to_path_buf()
+}
+
+/// Normalize a path, removing things like `.` and `..`.
+///
+/// CAUTION: This does not resolve symlinks (unlike
+/// [`std::fs::canonicalize`]). This may cause incorrect or surprising
+/// behavior at times. This should be used carefully. Unfortunately,
+/// [`std::fs::canonicalize`] can be hard to use correctly, since it can often
+/// fail, or on Windows returns annoying device paths. This is a problem Cargo
+/// needs to improve on.
+/// Copied from cargo: <https://github.com/rust-lang/cargo/blob/070e459c2d8b79c5b2ac5218064e7603329c92ae/crates/cargo-util/src/paths.rs#L81>
+pub fn get_normalized_path(path: &Path) -> PathBuf {
+    let path = expand_tilde(path);
+    let mut components = path.components().peekable();
+    let mut ret = if let Some(c @ Component::Prefix(..)) = components.peek().cloned() {
+        components.next();
+        PathBuf::from(c.as_os_str())
+    } else {
+        PathBuf::new()
+    };
+
+    for component in components {
+        match component {
+            Component::Prefix(..) => unreachable!(),
+            Component::RootDir => {
+                ret.push(component.as_os_str());
+            }
+            Component::CurDir => {}
+            Component::ParentDir => {
+                ret.pop();
+            }
+            Component::Normal(c) => {
+                ret.push(c);
+            }
+        }
+    }
+    ret
+}
+
+/// Returns the canonical, absolute form of a path with all intermediate components normalized.
+///
+/// This function is used instead of `std::fs::canonicalize` because we don't want to verify
+/// here if the path exists, just normalize it's components.
+pub fn get_canonicalized_path(path: &Path) -> std::io::Result<PathBuf> {
+    let path = if path.is_relative() {
+        std::env::current_dir().map(|current_dir| current_dir.join(path))?
+    } else {
+        path.to_path_buf()
+    };
+
+    Ok(get_normalized_path(path.as_path()))
+}
+
+pub fn get_relative_path(path: &Path) -> PathBuf {
+    let path = if path.is_absolute() {
+        let cwdir = std::env::current_dir().expect("couldn't determine current directory");
+        path.strip_prefix(cwdir).unwrap_or(path)
+    } else {
+        path
+    };
+    fold_home_dir(path)
+}