Re-render components in mount order instead of tree depth

This should be more robust, and allows us to stop passing tree
levels along to every component.

src/reagent/impl/batching.cljs

@@ -8,6 +8,11 @@
 
 ;;; Update batching
 
+(defonce mount-count #js {:count 0})
+
+(defn next-mount-count []
+  (.! mount-count :count (inc (.' mount-count :count))))
+
 (defn fake-raf [f]
   (js/setTimeout f 16))
 
@@ -21,14 +26,14 @@
           (.' w :msRequestAnimationFrame)
           fake-raf))))
 
-(defn compare-levels [c1 c2]
-  (- (.' c1 :props.level)
-     (.' c2 :props.level)))
+(defn compare-mount-order [c1 c2]
+  (- (.' c2 :cljsMountOrder)
+     (.' c1 :cljsMountOrder)))
 
 (defn run-queue [a]
-  ;; sort components by level, to make sure parents
+  ;; sort components by mount order, to make sure parents
   ;; are rendered before children
-  (.sort a compare-levels)
+  (.sort a compare-mount-order)
   (dotimes [i (alength a)]
     (let [c (aget a i)]
       (when (.' c :cljsIsDirty)

src/reagent/impl/component.cljs

@@ -49,7 +49,7 @@
                     5 (f (nth argv 1) (nth argv 2) (nth argv 3) (nth argv 4))
                     (apply f (subvec argv 1)))))]
       (if (vector? res)
-        (.' c asComponent res (.' p :level))
+        (.' c asComponent res)
         (if (ifn? res)
           (do
             (.! c :cljsRender res)
@@ -96,6 +96,13 @@
       (this-as c
                (f c (.' oldprops :argv))))
 
+    :componentDidMount
+    (fn []
+      (this-as c
+               (.! c :cljsMountOrder (batch/next-mount-count))
+               (when-not (nil? f)
+                 (f c))))
+
     :componentWillUnmount
     (fn []
       (this-as c
@@ -129,6 +136,7 @@
       (or wrap (default-wrapper f)))))
 
 (def obligatory {:shouldComponentUpdate nil
+                 :componentDidMount nil
                  :componentWillUnmount nil})
 
 (def dash-to-camel (util/memoize-1 util/dash-to-camel))

src/reagent/impl/template.cljs

@@ -143,8 +143,7 @@
     (when-not (nil? input-setup)
       (input-setup this jsprops))
     (make-element argv comp jsprops
-                  (if hasprops 2 1)
-                  (inc (.' inprops :level)))))
+                  (if hasprops 2 1))))
 
 (defn wrapped-should-update [c nextprops nextstate]
   (or util/*always-update*
@@ -209,13 +208,12 @@
 (defn get-key [x]
   (when (map? x) (get x :key)))
 
-(defn vec-to-comp [v level]
+(defn vec-to-comp [v]
   (assert (pos? (count v)) "Hiccup form should not be empty")
   (assert (valid-tag? (nth v 0))
           (str "Invalid Hiccup form: " (pr-str v)))
   (let [c (as-class (nth v 0))
-        jsprops #js{:argv v
-                    :level level}]
+        jsprops #js{:argv v}]
     (let [k (-> v meta get-key)
           k' (if (nil? k)
                (-> v (nth 1 nil) get-key)
@@ -235,40 +233,38 @@
 (declare expand-seq)
 
 (defn as-component
-  ([x] (as-component x 0))
-  ([x level]
+  [x]
   (cond (string? x) x
-           (vector? x) (vec-to-comp x level)
+        (vector? x) (vec-to-comp x)
         (seq? x) (if (dev?)
                    (if (nil? ratom/*ratom-context*)
-                        (expand-seq x level)
+                     (expand-seq x)
                      (let [s (ratom/capture-derefed
-                                 #(expand-seq x level)
+                              #(expand-seq x)
                               seq-ctx)]
                        (when (ratom/captured seq-ctx)
                          (warn-on-deref x))
                        s))
-                      (expand-seq x level))
-           true x)))
+                   (expand-seq x))
+        true x))
 
 (defn create-class [spec]
   (comp/create-class spec as-component))
 
-(defn expand-seq [s level]
-  (let [a (into-array s)
-        level' (inc level)]
+(defn expand-seq [s]
+  (let [a (into-array s)]
     (dotimes [i (alength a)]
-      (aset a i (as-component (aget a i) level')))
+      (aset a i (as-component (aget a i))))
     a))
 
-(defn make-element [argv comp jsprops first-child level]
+(defn make-element [argv comp jsprops first-child]
   (if (== (count argv) (inc first-child))
     ;; Optimize common case of one child
     (.' js/React createElement comp jsprops
-        (as-component (nth argv first-child) level))
+        (as-component (nth argv first-child)))
     (.apply (.' js/React :createElement) nil
             (reduce-kv (fn [a k v]
                          (when (>= k first-child)
-                           (.push a (as-component v level)))
+                           (.push a (as-component v)))
                          a)
                        #js[comp jsprops] argv))))