From b0603395732d9142c390ebf33709d6a1f8c5acc5 Mon Sep 17 00:00:00 2001
From: Nathan Marz <nathan@nathanmarz.com>
Date: Thu, 23 Jun 2016 12:35:47 -0400
Subject: [PATCH] major optimization to multi-path by removing sequence
 operations at runtime

---
 src/clj/com/rpl/specter.cljx        | 44 ++++++++++++++++-------------
 test/com/rpl/specter/core_test.cljx | 14 +++++++++
 2 files changed, 38 insertions(+), 20 deletions(-)

diff --git a/src/clj/com/rpl/specter.cljx b/src/clj/com/rpl/specter.cljx
index 541c5a7..7471290 100644
--- a/src/clj/com/rpl/specter.cljx
+++ b/src/clj/com/rpl/specter.cljx
@@ -706,26 +706,30 @@
 (defpathedfn multi-path
   "A path that branches on multiple paths. For updates,
    applies updates to the paths in order."
-  [& paths]
-  (let [paths-comp (mapv i/comp-paths* (vec paths))
-        all-needed (mapv i/num-needed-params paths-comp)
-        idx-deltas (vec (cons 0 (reductions + all-needed)))
-        extracted (mapv i/extract-rich-tfns paths-comp)
-        sel-info (mapv vector (mapv first extracted) idx-deltas)
-        tran-info (mapv vector (mapv second extracted) idx-deltas)]
-    (richnav (reduce + 0 all-needed)
-      (select* [params params-idx vals structure next-fn]
-        (doseqres NONE [[s delta] sel-info]
-          (s params (+ params-idx delta) vals structure next-fn)
-          ))
-      (transform* [params params-idx vals structure next-fn]
-        (reduce
-          (fn [structure [t delta]]
-            (t params (+ params-idx delta) vals structure next-fn)
-            )
-          structure
-          tran-info
-          )))))
+  ([] STAY)
+  ([path] (i/comp-paths* path))
+  ([path1 path2]
+    (let [comp1 (i/comp-paths* path1)
+          comp2 (i/comp-paths* path2)
+          comp1-needed (i/num-needed-params comp1)
+          [s1 t1] (i/extract-rich-tfns comp1)
+          [s2 t2] (i/extract-rich-tfns comp2)
+          ]
+      (richnav (+ comp1-needed (i/num-needed-params comp2))
+        (select* [params params-idx vals structure next-fn]
+          (let [res1 (s1 params params-idx vals structure next-fn)
+                res2 (s2 params (+ params-idx comp1-needed) vals structure next-fn)]
+            (if (identical? NONE res2)
+              res1
+              res2
+              )))
+        (transform* [params params-idx vals structure next-fn]
+          (let [s1 (t1 params params-idx vals structure next-fn)]
+            (t2 params (+ params-idx comp1-needed) vals s1 next-fn)
+            )))))
+  ([path1 path2 & paths]
+    (reduce multi-path (multi-path path1 path2) paths)
+    ))
 
 (defpathedfn stay-then-continue
   "Navigates to the current element and then navigates via the provided path.
diff --git a/test/com/rpl/specter/core_test.cljx b/test/com/rpl/specter/core_test.cljx
index a1f088b..b81cd81 100644
--- a/test/com/rpl/specter/core_test.cljx
+++ b/test/com/rpl/specter/core_test.cljx
@@ -1327,3 +1327,17 @@
   (is (= 3 (multi-transform (s/terminal-val 3) 2)))
   (is (= 3 (multi-transform [s/VAL (s/terminal-val 3)] 2)))
   )
+
+
+(deftest multi-path-order-test
+  (is (= 102
+         (multi-transform
+           (s/multi-path
+            [odd? (s/terminal #(* 2 %))]
+            [even? (s/terminal-val 100)]
+            [#(= 100 %) (s/terminal inc)]
+            [#(= 101 %) (s/terminal inc)]
+
+            )
+           1
+           ))))