implement cd

1 files changed, 44 insertions, 0 deletions

diff --git a/src/builtins.rs b/src/builtins.rs
new file mode 100644
index 0000000..225ef5b
--- /dev/null
+++ b/src/builtins.rs
@@ -0,0 +1,44 @@
+pub fn is(exe: &str) -> bool {
+    matches!(exe, "cd")
+}
+
+pub fn run(exe: &str, args: &[String]) -> u8 {
+    match exe {
+        "cd" => {
+            impls::cd(args.iter().map(|s| s.as_ref()).next().unwrap_or(""))
+        }
+        _ => unreachable!(),
+    }
+}
+
+mod impls {
+    pub fn cd(dir: &str) -> u8 {
+        let dir = if dir.is_empty() {
+            home()
+        } else if dir.starts_with('~') {
+            let path: std::path::PathBuf = dir.into();
+            if let std::path::Component::Normal(prefix) =
+                path.components().next().unwrap()
+            {
+                if prefix.to_str() == Some("~") {
+                    home().join(path.strip_prefix(prefix).unwrap())
+                } else {
+                    // TODO
+                    return 1;
+                }
+            } else {
+                unreachable!()
+            }
+        } else {
+            dir.into()
+        };
+        match std::env::set_current_dir(dir) {
+            Ok(()) => 0,
+            Err(_) => 1,
+        }
+    }
+
+    fn home() -> std::path::PathBuf {
+        std::env::var_os("HOME").unwrap().into()
+    }
+}