Add simple undo demo

demo/reagentdemo/intro.cljs

@@ -100,7 +100,7 @@
       [slider {:value bmi :min 10 :max 50 :param :bmi}]]]))
 
 (def funmap (-> "reagentdemo/intro.cljs" get-source common/fun-map))
-(defn src-for [defs] (common/src-for funmap defs))
+(def src-for (partial common/src-for funmap))
 
 (defn intro []
   (let [github {:href "https://github.com/holmsand/reagent"}

demo/reagentdemo/news.cljs

@@ -1,6 +1,49 @@
 (ns reagentdemo.news
-  (:require [reagent.core :as reagent :refer [atom]]))
+  (:require [reagent.core :as reagent :refer [atom]]
+            [reagent.debug :refer-macros [dbg println]]
+            [reagentdemo.syntax :refer-macros [get-source]]
+            [reagentdemo.common :as common :refer [demo-component]]
+            [todomvc :as todomvc]))
+
+(def funmap (-> "reagentdemo/news.cljs" get-source common/fun-map))
+(def src-for (partial common/src-for funmap))
+
+(def state todomvc/todos)
+
+(def undo-list (atom nil))
+
+(defn undo []
+  (let [undos @undo-list]
+    (when-let [old (first undos)]
+      (reset! state old)
+      (reset! undo-list (rest undos)))))
+
+(defn undo-button []
+  (let [n (count @undo-list)]
+    [:input {:type "button" :on-click undo
+             :disabled (zero? n)
+             :value (str "Undo (" n ")")}]))
+
+(defn todomvc-with-undo []
+  (add-watch state ::undo-watcher
+             (fn [_ _ old-state _]
+               (swap! undo-list conj old-state)))
+  [:div
+   [undo-button]
+   [todomvc/todo-app]])
+
+(defn undo-demo []
+  [demo-component {:comp todomvc-with-undo
+                   :src (src-for [:state :undo-list :undo :save-state
+                                  :undo-button :todomvc-with-undo])}])
+
+(def undo-demo-cleanup
+  (with-meta undo-demo {:component-will-unmount
+                        (fn []
+                          (reset! undo-list nil)
+                          (remove-watch state ::undo-watcher))}))
 
 (defn main []
-  [:div
-   [:h2 "This should become news"]])
+  [:div.reagent-demo
+   [:h1 "This should become news"]
+   [undo-demo-cleanup]])

demo/reagentdemo/syntax.cljs

@@ -8,7 +8,8 @@
                "empty" "into" "assoc-in" "dissoc" "get-in" "when-not"
                "filter" "vals" "count" "complement" "identity" "dotimes"
                "update-in" "sorted-map" "inc" "dec" "false" "true" "not"
-               "="})
+               "=" "partial" "first" "second" "rest" "list" "conj"
+               "drop" "when-let" "if-let" "add-watch"})
 
 (def styles {:comment  {:style {:color "gray"
                                 :font-style "italic"}}