1 files changed, 30 insertions, 12 deletions
diff --git a/src/ruuter/core.cljc b/src/ruuter/core.cljc
index c1c5644..c2e05a1 100644
--- a/src/ruuter/core.cljc
+++ b/src/ruuter/core.cljc
@@ -62,6 +62,18 @@
    :wildcard nil ;; {:param-name kw, :leaves [...]} or nil
    :leaves []}) ;; routes that terminate here [{:method :get :response fn :path str}]
 
+(defn- throw-conflict
+  "Throws an exception when two routes define different parameter names at the
+  same trie position."
+  [slot-type existing-name new-name path]
+  (let [msg (str "ruuter: conflicting " slot-type " parameter names at same position — :"
+                 (name existing-name) " and :" (name new-name)
+                 ". Route: " path)]
+    (throw (ex-info msg {:slot-type slot-type
+                         :existing-name existing-name
+                         :new-name new-name
+                         :path path}))))
+
 (defn- insert-route
   "Inserts a single route into the trie, returning the updated trie."
   [trie segments leaf]
@@ -76,22 +88,28 @@
           (assoc-in trie [:children value] child'))
 
         :param
-        (let [existing (:param trie)
-              child (if existing (:node existing) (empty-node))
-              child' (insert-route child remaining leaf)]
-          (assoc trie :param {:param-name value :node child'}))
+        (let [existing (:param trie)]
+          (when (and existing (not= (:param-name existing) value))
+            (throw-conflict "param" (:param-name existing) value (:path leaf)))
+          (let [child (if existing (:node existing) (empty-node))
+                child' (insert-route child remaining leaf)]
+            (assoc trie :param {:param-name value :node child'})))
 
         :optional
-        (let [existing (:optional trie)
-              child (if existing (:node existing) (empty-node))
-              child' (insert-route child remaining leaf)]
-          (assoc trie :optional {:param-name value :node child'}))
+        (let [existing (:optional trie)]
+          (when (and existing (not= (:param-name existing) value))
+            (throw-conflict "optional" (:param-name existing) value (:path leaf)))
+          (let [child (if existing (:node existing) (empty-node))
+                child' (insert-route child remaining leaf)]
+            (assoc trie :optional {:param-name value :node child'})))
 
         :wildcard
-        (let [existing (:wildcard trie)
-              leaves (if existing (:leaves existing) [])
-              leaves' (conj leaves leaf)]
-          (assoc trie :wildcard {:param-name value :leaves leaves'}))))))
+        (let [existing (:wildcard trie)]
+          (when (and existing (not= (:param-name existing) value))
+            (throw-conflict "wildcard" (:param-name existing) value (:path leaf)))
+          (let [leaves (if existing (:leaves existing) [])
+                leaves' (conj leaves leaf)]
+            (assoc trie :wildcard {:param-name value :leaves leaves'})))))))
 
 (defn compile-routes
   "Compiles a vector of route maps into a trie structure for efficient