src/extname.rs in faster_path-0.2.6 vs src/extname.rs in faster_path-0.3.1

@@ -1,13 +1,63 @@
-use path_parsing::extract_last_path_segment;
+use path_parsing::SEP;
+use std::str;
 
+struct ExtnameCoords {
+  word: bool,
+  pred: bool,
+  dot: bool,
+  start: usize,
+  end: usize,
+}
+
+impl ExtnameCoords {
+  pub fn dec(&mut self) {
+    self.start -= 1;
+    if !self.word {
+      self.end -= 1;
+    }
+  }
+}
+
 pub fn extname(pth: &str) -> &str {
-  let name = extract_last_path_segment(pth);
+  let path = pth.as_bytes();
+  let mut extname = ExtnameCoords {
+    word: false,
+    pred: false,
+    dot: false,
+    start: path.len(),
+    end: path.len(),
+  };
 
-  if let Some(dot_i) = name.rfind('.') {
-    if dot_i > 0 && dot_i < name.len() - 1 && name[..dot_i].chars().rev().next().unwrap() != '.' {
-      return &name[dot_i..]
+  for &item in path.iter().rev() {
+    if (item == b'.' && !extname.dot) || item == SEP {
+      if item == SEP && extname.word {
+        return ""
+      }
+
+      if !extname.pred {
+        extname.dec();
+      }
+
+      if extname.word {
+        extname.dot = true;
+      }
+    } else {
+      if extname.dot {
+        extname.pred = true;
+        break;
+      } else {
+        extname.word = true;
+      }
+
+      if !extname.pred {
+        extname.dec()
+      }
     }
   }
 
-  ""
+  if !extname.pred {
+    return "";
+  }
+
+  str::from_utf8(&path[extname.start..extname.end]).unwrap_or("")
 }