feat(mingling): add directory environment resources and setup

Add four new resource types for common directory paths and a
convenience setup struct that registers all of them at once.

1 files changed, 81 insertions, 0 deletions

diff --git a/mingling/src/res/dirs/current_exe.rs b/mingling/src/res/dirs/current_exe.rs
new file mode 100644
index 0000000..051fcee
--- /dev/null
+++ b/mingling/src/res/dirs/current_exe.rs
@@ -0,0 +1,81 @@
+use std::{
+    env::current_exe,
+    path::{Path, PathBuf},
+};
+
+/// A global resource that provides the path of the current executable.
+///
+/// This struct wraps a `PathBuf` representing the full filesystem path of the
+/// currently running executable at the time of creation.
+///
+/// # Default behavior
+///
+/// The `Default` implementation calls `std::env::current_exe().unwrap()` internally,
+/// which will **panic** if the executable path cannot be determined (e.g., if the
+/// `/proc` filesystem is not available). If you want to handle this error gracefully,
+/// use [`ResCurrentExe::new`] instead, which returns a `Result`.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct ResCurrentExe {
+    exe: PathBuf,
+}
+
+impl ResCurrentExe {
+    /// Creates a new `ResCurrentExe` by querying the OS for the current executable path.
+    ///
+    /// Returns `Err` if the executable path cannot be determined (e.g., the `/proc`
+    /// filesystem is not available on Linux, or the process handle is invalid).
+    /// Unlike the `Default` implementation, this method does not panic on failure.
+    pub fn new() -> Result<Self, std::io::Error> {
+        Ok(Self { exe: current_exe()? })
+    }
+}
+
+impl Default for ResCurrentExe {
+    fn default() -> Self {
+        Self { exe: current_exe().unwrap() }
+    }
+}
+
+impl From<PathBuf> for ResCurrentExe {
+    fn from(path: PathBuf) -> Self {
+        Self { exe: path }
+    }
+}
+
+impl From<&Path> for ResCurrentExe {
+    fn from(path: &Path) -> Self {
+        Self { exe: path.to_path_buf() }
+    }
+}
+
+impl From<&PathBuf> for ResCurrentExe {
+    fn from(path: &PathBuf) -> Self {
+        Self { exe: path.clone() }
+    }
+}
+
+impl From<ResCurrentExe> for PathBuf {
+    fn from(res: ResCurrentExe) -> Self {
+        res.exe
+    }
+}
+
+impl AsRef<Path> for ResCurrentExe {
+    fn as_ref(&self) -> &Path {
+        self.exe.as_path()
+    }
+}
+
+impl std::ops::Deref for ResCurrentExe {
+    type Target = PathBuf;
+
+    fn deref(&self) -> &Self::Target {
+        &self.exe
+    }
+}
+
+impl std::ops::DerefMut for ResCurrentExe {
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        &mut self.exe
+    }
+}