fix(directory): improve truncation detection (#3266)

src/modules/conda.rs

@@ -21,7 +21,7 @@ pub fn module<'a>(context: &'a Context) -> Option<Module<'a>> {
         return None;
     }
 
-    let conda_env = truncate(conda_env, config.truncation_length);
+    let conda_env = truncate(&conda_env, config.truncation_length).unwrap_or(conda_env);
 
     let parsed = StringFormatter::new(config.format).and_then(|formatter| {
         formatter

src/modules/directory.rs

@@ -60,6 +60,8 @@ pub fn module<'a>(context: &'a Context) -> Option<Module<'a>> {
         None
     };
 
+    let mut is_truncated = dir_string.is_some();
+
     // the home directory if required.
     let dir_string =
         dir_string.unwrap_or_else(|| contract_path(display_dir, &home_dir, &home_symbol));
@@ -71,9 +73,15 @@ pub fn module<'a>(context: &'a Context) -> Option<Module<'a>> {
     let dir_string = substitute_path(dir_string, &config.substitutions);
 
     // Truncate the dir string to the maximum number of path components
-    let dir_string = truncate(dir_string, config.truncation_length as usize);
+    let dir_string =
+        if let Some(truncated) = truncate(&dir_string, config.truncation_length as usize) {
+            is_truncated = true;
+            truncated
+        } else {
+            dir_string
+        };
 
-    let prefix = if is_truncated(&dir_string, &home_symbol) {
+    let prefix = if is_truncated {
         // Substitutions could have changed the prefix, so don't allow them and
         // fish-style path contraction together
         if config.fish_style_pwd_dir_length > 0 && config.substitutions.is_empty() {
@@ -170,12 +178,6 @@ fn remove_extended_path_prefix(path: String) -> String {
     path
 }
 
-fn is_truncated(path: &str, home_symbol: &str) -> bool {
-    !(path.starts_with(&home_symbol)
-        || PathBuf::from(path).has_root()
-        || (cfg!(target_os = "windows") && PathBuf::from(String::from(path) + r"\").has_root()))
-}
-
 fn is_readonly_dir(path: &Path) -> bool {
     match directory_utils::is_write_allowed(path) {
         Ok(res) => !res,
@@ -755,11 +757,12 @@ mod tests {
             })
             .path(&dir)
             .collect();
+        let dir_str = dir.to_slash_lossy();
         let expected = Some(format!(
             "{} ",
             Color::Cyan
                 .bold()
-                .paint(truncate(dir.to_slash_lossy(), 100))
+                .paint(truncate(&dir_str, 100).unwrap_or(dir_str))
         ));
 
         assert_eq!(expected, actual);

src/modules/utils/directory.rs

@@ -2,9 +2,10 @@
 ///
 /// Will truncate a path to only show the last `length` components in a path.
 /// If a length of `0` is provided, the path will not be truncated.
-pub fn truncate(dir_string: String, length: usize) -> String {
+/// A value will only be returned if the path has been truncated.
+pub fn truncate(dir_string: &str, length: usize) -> Option<String> {
     if length == 0 {
-        return dir_string;
+        return None;
     }
 
     let mut components = dir_string.split('/').collect::<Vec<&str>>();
@@ -15,11 +16,11 @@ pub fn truncate(dir_string: String, length: usize) -> String {
     }
 
     if components.len() <= length {
-        return dir_string;
+        return None;
     }
 
     let truncated_components = &components[components.len() - length..];
-    truncated_components.join("/")
+    Some(truncated_components.join("/"))
 }
 
 #[cfg(test)]
@@ -29,42 +30,42 @@ mod tests {
     #[test]
     fn truncate_smaller_path_than_provided_length() {
         let path = "~/starship";
-        let output = truncate(path.to_string(), 3);
-        assert_eq!(output, "~/starship")
+        let output = truncate(path, 3);
+        assert_eq!(output, None)
     }
 
     #[test]
     fn truncate_same_path_as_provided_length() {
         let path = "~/starship/engines";
-        let output = truncate(path.to_string(), 3);
-        assert_eq!(output, "~/starship/engines")
+        let output = truncate(path, 3);
+        assert_eq!(output, None)
     }
 
     #[test]
     fn truncate_slightly_larger_path_than_provided_length() {
         let path = "~/starship/engines/booster";
-        let output = truncate(path.to_string(), 3);
-        assert_eq!(output, "starship/engines/booster")
+        let output = truncate(path, 3);
+        assert_eq!(output.as_deref(), Some("starship/engines/booster"))
     }
 
     #[test]
     fn truncate_larger_path_than_provided_length() {
         let path = "~/starship/engines/booster/rocket";
-        let output = truncate(path.to_string(), 3);
-        assert_eq!(output, "engines/booster/rocket")
+        let output = truncate(path, 3);
+        assert_eq!(output.as_deref(), Some("engines/booster/rocket"));
     }
 
     #[test]
     fn truncate_same_path_as_provided_length_from_root() {
         let path = "/starship/engines/booster";
-        let output = truncate(path.to_string(), 3);
-        assert_eq!(output, "/starship/engines/booster");
+        let output = truncate(path, 3);
+        assert_eq!(output, None);
     }
 
     #[test]
     fn truncate_larger_path_than_provided_length_from_root() {
         let path = "/starship/engines/booster/rocket";
-        let output = truncate(path.to_string(), 3);
-        assert_eq!(output, "engines/booster/rocket");
+        let output = truncate(path, 3);
+        assert_eq!(output.as_deref(), Some("engines/booster/rocket"));
     }
 }