[add] Added VarStoreScheduledController.

sjplayer/src/sjplayer/AbstractScheduledController.d

@@ -74,8 +74,7 @@ abstract class AbstractScheduledController : ScheduledControllerInterface {
     }
     auto temp = varstore_[name];
     if (!temp.isNull) return temp;
-    // TODO: std constants
-    return Nullable!float.init;
+    return StandardVarStore.GetByName(name);
   }
   void SetParameter(ref in Parameter param, ref in VarStore vars) {
     if (param.name.length < 2 || param.name[0..2] != "__") {

sjplayer/src/sjplayer/Context.d

@@ -21,7 +21,8 @@ import sjplayer.Actor,
        sjplayer.PostEffectControllerInterface,
        sjplayer.ProgramSet,
        sjplayer.ScheduledControllerInterface,
-       sjplayer.VarStore;
+       sjplayer.VarStore,
+       sjplayer.VarStoreScheduledController;
 
 ///
 class Context {
@@ -55,6 +56,10 @@ class Context {
           "circle",
           CircleElementScheduledControllerFactory(programs, varstore),
         ),
+        tuple(
+          "variable",
+          VarStoreScheduledControllerFactory(varstore),
+        ),
       );
     foreach (ref factory; factories) {
       factory[1].

sjplayer/src/sjplayer/VarStore.d

@@ -21,10 +21,19 @@ class VarStore : VarStoreInterface {
       case "actor_x": return Nullable!float(actor_.pos.x);
       case "actor_y": return Nullable!float(actor_.pos.y);
 
-      default: return Nullable!float.init;
+      default:
     }
+    return name in user_vars_?
+      Nullable!float(user_vars_[name]): Nullable!float.init;
+  }
+
+  ///
+  void opIndexAssign(float value, string name) {
+    user_vars_[name] = value;
   }
 
  private:
   const Actor actor_;
+
+  float[string] user_vars_;
 }

sjplayer/src/sjplayer/VarStoreScheduledController.d

@@ -0,0 +1,56 @@
+/// License: MIT
+module sjplayer.VarStoreScheduledController;
+
+import std.range.primitives;
+
+import sjscript;
+
+import sjplayer.AbstractScheduledController,
+       sjplayer.ContextBuilderInterface,
+       sjplayer.VarStore,
+       sjplayer.util.Parameter;
+
+///
+class VarStoreScheduledController : AbstractScheduledController {
+ public:
+  ///
+  alias VarStore = sjplayer.VarStore.VarStore;
+
+  ///
+  this(VarStore varstore, in ParametersBlock[] operations) {
+    super(varstore, operations);
+    varstore_ = varstore;
+  }
+
+  override void SetParameter(
+      ref in Parameter param,
+      ref in AbstractScheduledController.VarStore vars) {
+    const x_nullable = varstore_[param.name];
+    auto  x          = x_nullable.isNull? 0f: x_nullable.get;
+    param.CalculateParameter(x, vars);
+    varstore_[param.name] = x;
+  }
+
+ private:
+  VarStore varstore_;
+}
+
+///
+struct VarStoreScheduledControllerFactory {
+ public:
+  ///
+  this(VarStore varstore) {
+    varstore_ = varstore;
+  }
+
+  ///
+  void Create(R)(R params, ContextBuilderInterface builder)
+      if (isInputRange!R && is(ElementType!R == ParametersBlock)) {
+    auto product = new VarStoreScheduledController(
+        varstore_, SortParametersBlock(params));
+    builder.AddScheduledController(product);
+  }
+
+ private:
+  VarStore varstore_;
+}