Warrior_EA/System/NewBar.mqh

//+------------------------------------------------------------------+
//|                                                       NewBar.mqh |
//|                                                     AnimateDread |
//|                                             https://www.mql5.com |
//+------------------------------------------------------------------+
#property copyright "AnimateDread"
#property link      "https://www.mql5.com"
#ifndef WARRIOR_SYSTEM_NEWBAR_MQH
#define WARRIOR_SYSTEM_NEWBAR_MQH
//+------------------------------------------------------------------+
//| "HAS A NEW BAR OPENED SINCE I LAST ASKED?"                        |
//|                                                                   |
//| A CLASS, not the free function this file used to hold, and the    |
//| reason is the one piece of state involved: the last bar time. A   |
//| free function has to keep that in a `static`, which makes it ONE  |
//| watermark shared by every caller - so the first caller each tick  |
//| consumes the transition and every other caller is told "no new    |
//| bar" for a bar that just opened. That is silent and direction-    |
//| dependent, which is the worst shape a bug can have. One instance  |
//| per consumer, each with its own watermark, and the question is    |
//| answerable by as many callers as want to ask it.                  |
//|                                                                   |
//| FIRST CALL COUNTS AS NEW. A gate built on this runs the moment    |
//| the EA attaches rather than sitting idle until the next bar       |
//| closes - on H4 that would be up to four hours of a live EA        |
//| deliberately doing nothing.                                       |
//+------------------------------------------------------------------+
class CNewBar
  {
private:
   datetime          m_lastTime;
   bool              m_seen;         // false until the first successful read

public:
                     CNewBar(void) : m_lastTime(0), m_seen(false) {}
   //--- Reset the watermark, so the next call reports a new bar again.
   void              Reset(void) { m_lastTime = 0; m_seen = false; }
   //--- The bar time this instance last accepted (0 = never read one).
   datetime          LastBarTime(void) const { return m_lastTime; }
   //--- True exactly once per opened bar of `symbol`/`period` (defaults: the chart's own).
   bool              IsNewBar(const string symbol = NULL, const ENUM_TIMEFRAMES period = PERIOD_CURRENT)
     {
      string sym = (symbol == NULL || symbol == "") ? _Symbol : symbol;
      datetime cTime[];
      ArraySetAsSeries(cTime, true);
      //--- CopyTime can fail or come back empty (history not yet synced right after attach, or a gap
      //--- on an illiquid symbol). Indexing cTime[0] unguarded would raise "array out of range" and
      //--- abort the whole tick. Answering "not a new bar" is the safe direction to fail: the caller
      //--- skips this tick's bar-boundary work and asks again on the next one.
      if(CopyTime(sym, period, 0, 1, cTime) <= 0 || ArraySize(cTime) == 0)
         return false;
      if(!m_seen)
        {
         m_seen = true;
         m_lastTime = cTime[0];
         return true;               // first observation - see the header note
        }
      if(cTime[0] <= m_lastTime)
         return false;
      m_lastTime = cTime[0];
      return true;
     }
  };
#endif // WARRIOR_SYSTEM_NEWBAR_MQH