Add count() mothod to OrderPoolMatcher; update README example to us…

…e foreachorder

README.md

@@ -543,16 +543,12 @@ Here is a simple example:
 // for simplicity, I will not use the Lang/Script class
 void OnStart()
   {
-   TradingPool pool;
    LinkedList<Order*> list;
-   int total= pool.total();
-   for(int i=0; i<total; i++)
+   TradingPool pool;
+   foreachorder(pool)
      {
-      if(Order::Select(i))
-        {
          OrderPrint(); // to compare with Order.toString
          list.push(new Order());
-        }
      }
 
    PrintFormat("There are %d orders. ",list.size());
@@ -574,7 +570,6 @@ void OnStart()
    //--- foreachv macro: declare element varaible o in the second parameter
    foreachv(Order*,o,list)
      Print(o.toString());
-
   }
 //+------------------------------------------------------------------+
 ```

Trade/OrderPool.mqh

@@ -44,6 +44,21 @@ private:
 public:
                      OrderPoolMatcher(const OrderMatcher *m):m_om(m){}
    virtual bool      matches() const {return m_om?m_om.matches():true;}
+
+   //--- count the number of orders that satisfies the matcher condition
+   //--- generally you don't want to use this method unless all you want is the number of satisfying orders
+   //--- use foreachorder for iteration. The select(int) method does not work with count()
+   int               count() const
+     {
+      int total=total();
+      int c=0;
+      for(int i=0; i<total; i++)
+        {
+         // we use matches here instead of m_om.matches because the matches method may be overidden by child classes
+         if(select(i) && matches()) c++;
+        }
+      return c;
+     }
   };
 //+------------------------------------------------------------------+
 //| The pool of orders from the Terminal order history tab           |