add specialized MAP-VALS navigator to circumvent the unavoidable overhead of [ALL LAST]

scripts/benchmarks.clj

@@ -106,6 +106,7 @@
     (reduce-kv (fn [m k v] (assoc m k (inc v))) {} data)
     (manual-similar-reduce-kv data)
     (transform [ALL LAST] inc data)
+    (transform MAP-VALS inc data)
     ))
 
 (let [data (->> (for [i (range 1000)] [i i]) (into {}))]
@@ -114,6 +115,7 @@
     (reduce-kv (fn [m k v] (assoc m k (inc v))) {} data)
     (manual-similar-reduce-kv data)
     (transform [ALL LAST] inc data)
+    (transform MAP-VALS inc data)
     ))
 
 

src/clj/com/rpl/specter.cljx

@@ -163,6 +163,14 @@
   ALL
   (comp-paths (i/->AllNavigator)))
 
+(defnav MAP-VALS []
+  (select* [this structure next-fn]
+    (doall (mapcat next-fn (vals structure))))
+  (transform* [this structure next-fn]
+    (i/map-vals-transform structure next-fn)
+    ))
+
+
 (def VAL (i/->ValCollect))
 
 (def

src/clj/com/rpl/specter/impl.cljx

@@ -702,6 +702,49 @@
   (transform* [this structure next-fn]
     (all-transform structure next-fn)))
 
+(defprotocol MapValsTransformProtocol
+  (map-vals-transform [structure next-fn]))
+
+(defn map-vals-non-transient-transform [structure empty-map next-fn]
+  (reduce-kv
+    (fn [m k v]
+      (assoc m k (next-fn v)))
+    empty-map
+    structure))
+
+(extend-protocol MapValsTransformProtocol
+  #+clj clojure.lang.PersistentArrayMap #+cljs cljs.core/PersistentArrayMap
+  (map-vals-transform [structure next-fn]
+    (map-vals-non-transient-transform structure {} next-fn)
+    )
+
+  #+clj clojure.lang.PersistentTreeMap #+cljs cljs.core/PersistentTreeMap
+  (map-vals-transform [structure next-fn]
+    (map-vals-non-transient-transform structure (sorted-map) next-fn)
+    )
+
+  #+clj clojure.lang.PersistentHashMap #+cljs cljs.core/PersistentHashMap
+  (map-vals-transform [structure next-fn]
+    (persistent!
+      (reduce-kv
+        (fn [m k v]
+          (assoc! m k (next-fn v)))
+        (transient
+          #+clj clojure.lang.PersistentHashMap/EMPTY #+cljs cljs.core.PersistentHashMap.EMPTY
+          )
+        structure
+        )))
+
+  #+clj Object #+cljs default
+  (map-vals-transform [structure next-fn]
+    (reduce-kv
+      (fn [m k v]
+        (assoc m k (next-fn v)))
+      (empty structure)
+      structure))
+  )
+
+
 (deftype ValCollect [])
 
 (extend-protocol p/Collector

test/com/rpl/specter/core_test.cljx

@@ -64,8 +64,9 @@
 
 (defspec select-all-on-map
   (for-all+
-    [m (limit-size 5 (gen/map gen/keyword gen/int))]
-    (= (select [s/ALL s/LAST] m)
+    [m (limit-size 5 (gen/map gen/keyword gen/int))
+     p (gen/elements [s/MAP-VALS [s/ALL s/LAST]])]
+    (= (select p m)
        (for [[k v] m] v))
     ))
 
@@ -81,8 +82,9 @@
 
 (defspec transform-all-on-map
   (for-all+
-    [m (limit-size 5 (gen/map gen/keyword gen/int))]
-    (= (transform [s/ALL s/LAST] inc m)
+    [m (limit-size 5 (gen/map gen/keyword gen/int))
+     p (gen/elements [s/MAP-VALS [s/ALL s/LAST]])]
+    (= (transform p inc m)
        (into {} (for [[k v] m] [k (inc v)]))
        )))