diff --git a/Indicators/Tick/Indi_TickMt.h b/Indicators/Tick/Indi_TickMt.h
index c2dcf44c8..89269bc5a 100644
--- a/Indicators/Tick/Indi_TickMt.h
+++ b/Indicators/Tick/Indi_TickMt.h
@@ -165,6 +165,7 @@ class Indi_TickMt : public IndicatorTick<Indi_TickMtParams, double, ItemsHistory
 
 #endif
 
+#ifdef __MQL4__
     // In MQL4 or MQL5 (if there's no history returned by CopyTicksRange) we
     // try to create and return OHLC ticks by calling iOpen/iHigh/iLow/iClose
     // for each bar in history. Candle indicator will form candles from those
@@ -201,6 +202,11 @@ class Indi_TickMt : public IndicatorTick<Indi_TickMtParams, double, ItemsHistory
       _out_ticks[_tick_idx++] = _tick_c;
     }
 
+#endif
+
+#ifndef __MQL__
+    // @fixit In C++ we currently don't have a system to retrieve historic OHLCs from MT servers.
+#endif
     return ArraySize(_out_ticks) != 0;
   }
 
@@ -265,6 +271,6 @@ class Indi_TickMt : public IndicatorTick<Indi_TickMtParams, double, ItemsHistory
     // Appending tick into the history.
     AppendEntry(_entry);
 
-    return _ask != WRONG_VALUE && _bid != WRONG_VALUE;
+    return _ask != (double)WRONG_VALUE && _bid != (double)WRONG_VALUE;
   }
 };
diff --git a/Makefile b/Makefile
index c432baf65..906819ed0 100644
--- a/Makefile
+++ b/Makefile
@@ -1,6 +1,6 @@
 CFLAGS := -Wall -Wextra -std=c++17 -w # Compiler flags
 EMCC_CFLAGS := $(CFLAGS) --bind -s ASSERTIONS=1 -s ERROR_ON_UNDEFINED_SYMBOLS=0 -s EXIT_RUNTIME=0 -s EXPORTED_FUNCTIONS="[]" -s WASM=1 -s MODULARIZE=1 -s NO_EXIT_RUNTIME=1
-MAKEFILES := $(wildcard **/tests/Makefile) # $(wildcard **/**/tests/Makefile)
+MAKEFILES := $(wildcard **/tests/Makefile) $(wildcard **/**/tests/Makefile)
 
 # Check if the system is Linux
 UNAME_S := $(shell uname -s)
diff --git a/Platform/Chart3D/Chart3D.h b/Platform/Chart3D/Chart3D.h
index 165ca88ec..9148a3987 100644
--- a/Platform/Chart3D/Chart3D.h
+++ b/Platform/Chart3D/Chart3D.h
@@ -30,24 +30,27 @@
   #pragma once
 #endif
 
-#include "../Chart/Bar.struct.h"
-#include "../../Indicator/IndicatorData.h"
-#include "../../Indicators/Price/Indi_MA.h"
-#include "../../Storage/Instances.h"
-#include "../../Refs.mqh"
-#include "../../Serializer/SerializerConverter.h"
-#include "../../Serializer/SerializerJson.h"
-#include "Chart3DCandles.h"
-#include "Chart3DType.h"
-#include "Cube.h"
-#include "Device.h"
-#include "Interface.h"
-
-#ifdef __MQL5__
-  // Resource variables.
-  #resource "Shaders/chart3d_vs.hlsl" as string Chart3DShaderSourceVS;
-  #resource "Shaders/chart3d_ps.hlsl" as string Chart3DShaderSourcePS;
-#endif
+// We currently only support MQL.
+#ifdef __MQL__
+
+  #include "../../Indicator/IndicatorData.h"
+  #include "../../Indicators/Price/Indi_MA.h"
+  #include "../../Refs.mqh"
+  #include "../../Serializer/SerializerConverter.h"
+  #include "../../Serializer/SerializerJson.h"
+  #include "../../Storage/Instances.h"
+  #include "../Chart/Bar.struct.h"
+  #include "Chart3DCandles.h"
+  #include "Chart3DType.h"
+  #include "Cube.h"
+  #include "Device.h"
+  #include "Interface.h"
+
+  #ifdef __MQL5__
+    // Resource variables.
+    #resource "Shaders/chart3d_vs.hlsl" as string Chart3DShaderSourceVS;
+    #resource "Shaders/chart3d_ps.hlsl" as string Chart3DShaderSourcePS;
+  #endif
 
 typedef BarOHLC (*Chart3DPriceFetcher)(ENUM_TIMEFRAMES, int);
 
@@ -100,9 +103,9 @@ class Chart3D : public Dynamic {
     offset.z = 25.0f;
     initialized = false;
     source = _source;
-#ifdef __MQL5__
+  #ifdef __MQL5__
     Interface::AddListener(chart3d_interface_listener, &this);
-#endif
+  #endif
   }
 
   void OnInterfaceEvent(InterfaceEvent& _event) {
@@ -222,10 +225,12 @@ class Chart3D : public Dynamic {
     BarOHLC _ohlc;
     // BarOHLC _ohlc = price_fetcher(PERIOD_CURRENT, 0);  // @fixme: 'price_fetcher' - internal error #%d
 
-#ifdef __debug__
+  #ifdef __debug__
     Print(SerializerConverter::FromObject(_ohlc).ToString<SerializerJson>());
-#endif
+  #endif
 
     _type_renderer.Render(_device);
   }
 };
+
+#endif
diff --git a/Platform/Chart3D/Device.h b/Platform/Chart3D/Device.h
index 741561a51..85ceefe12 100644
--- a/Platform/Chart3D/Device.h
+++ b/Platform/Chart3D/Device.h
@@ -26,20 +26,23 @@
  */
 
 #ifndef __MQL__
-// Allows the preprocessor to include a header file when it is needed.
-#pragma once
+  // Allows the preprocessor to include a header file when it is needed.
+  #pragma once
 #endif
 
-#include "../../Refs.mqh"
-#include "../../Util.h"
-#include "Frontend.h"
-#include "IndexBuffer.h"
-#include "Material.h"
-#include "Math.h"
-#include "Mesh.h"
-#include "Shader.h"
-#include "ShaderVertexLayout.struct.h"
-#include "VertexBuffer.h"
+// We currently only support MQL.
+#ifdef __MQL__
+
+  #include "../../Refs.mqh"
+  #include "../../Util.h"
+  #include "Frontend.h"
+  #include "IndexBuffer.h"
+  #include "Material.h"
+  #include "Math.h"
+  #include "Mesh.h"
+  #include "Shader.h"
+  #include "ShaderVertexLayout.struct.h"
+  #include "VertexBuffer.h"
 
 enum GFX_DRAW_TEXT_FLAGS { GFX_DRAW_TEXT_FLAG_NONE, GFX_DRAW_TEXT_FLAG_2D_COORD_X, GFX_DRAW_TEXT_FLAG_2D_COORD_Y };
 
@@ -165,10 +168,10 @@ class Device : public Dynamic {
     VertexBuffer* _buff = CreateVertexBuffer();
     // Unfortunately we can't make this method virtual.
     if (dynamic_cast<MTDXVertexBuffer*>(_buff) != NULL) {
-// MT5's DirectX.
-#ifdef __debug__
+  // MT5's DirectX.
+  #ifdef __debug__
       Print("Filling vertex buffer via MTDXVertexBuffer");
-#endif
+  #endif
       ((MTDXVertexBuffer*)_buff).Fill<T>(data);
     } else {
       Alert("Unsupported vertex buffer device target");
@@ -196,9 +199,9 @@ class Device : public Dynamic {
    */
   template <typename T>
   void Render(Mesh<T>* _mesh, Shader* _vs = NULL, Shader* _ps = NULL) {
-#ifdef __debug__
+  #ifdef __debug__
     Print("Rendering mesh");
-#endif
+  #endif
     VertexBuffer* _vertices;
     IndexBuffer* _indices;
     _mesh.GetBuffers(&this, _vertices, _indices);
@@ -321,3 +324,5 @@ class Device : public Dynamic {
    */
   virtual void ClearBuffer(ENUM_CLEAR_BUFFER_TYPE _type, unsigned int _color) = NULL;
 };
+
+#endif
diff --git a/Platform/Chart3D/Devices/MTDX/MTDXDevice.h b/Platform/Chart3D/Devices/MTDX/MTDXDevice.h
index aa82926c8..82a505d2b 100644
--- a/Platform/Chart3D/Devices/MTDX/MTDXDevice.h
+++ b/Platform/Chart3D/Devices/MTDX/MTDXDevice.h
@@ -26,11 +26,14 @@
  */
 
 #ifndef __MQL__
-// Allows the preprocessor to include a header file when it is needed.
-#pragma once
+  // Allows the preprocessor to include a header file when it is needed.
+  #pragma once
 #endif
 
-#include "../../Device.h"
+// We currently only support MQL.
+#ifdef __MQL__
+
+  #include "../../Device.h"
 
 class MTDXDevice : public Device {
  public:
@@ -38,14 +41,14 @@ class MTDXDevice : public Device {
    * Initializes graphics device.
    */
   bool Init(Frontend* _frontend) {
-#ifdef __debug__
+  #ifdef __debug__
     Print("MTDXDevice: DXContextCreate: width = ", _frontend.Width(), ", height = ", _frontend.Height());
-#endif
+  #endif
     context = DXContextCreate(_frontend.Width(), _frontend.Height());
-#ifdef __debug__
+  #ifdef __debug__
     Print("LastError: ", GetLastError());
     Print("MTDXDevice: context = ", context);
-#endif
+  #endif
     _frontend.Init();
     return true;
   }
@@ -87,14 +90,14 @@ class MTDXDevice : public Device {
       _dx_color.z = 1.0f / 255.0f * ((_color & 0x000000FF) >> 0);
       _dx_color.w = 1.0f / 255.0f * ((_color & 0xFF000000) >> 24);
       DXContextClearColors(context, _dx_color);
-#ifdef __debug__
+  #ifdef __debug__
       Print("DXContextClearColors: LastError: ", GetLastError());
-#endif
+  #endif
     } else if (_type == CLEAR_BUFFER_TYPE_DEPTH) {
       DXContextClearDepth(context);
-#ifdef __debug__
+  #ifdef __debug__
       Print("DXContextClearDepth: LastError: ", GetLastError());
-#endif
+  #endif
     }
   }
 
@@ -140,19 +143,21 @@ class MTDXDevice : public Device {
     _vertices.Select();
     if (_indices == NULL) {
       if (!DXDraw(context)) {
-#ifdef __debug__
+  #ifdef __debug__
         Print("Can't draw!");
-#endif
+  #endif
       }
-#ifdef __debug__
+  #ifdef __debug__
       Print("DXDraw: LastError: ", GetLastError());
-#endif
+  #endif
     } else {
       _indices.Select();
       DXDrawIndexed(context);
-#ifdef __debug__
+  #ifdef __debug__
       Print("DXDrawIndexed: LastError: ", GetLastError());
-#endif
+  #endif
     }
   }
 };
+
+#endif
diff --git a/Platform/Chart3D/Face.h b/Platform/Chart3D/Face.h
index 59f394b26..4969db0d2 100644
--- a/Platform/Chart3D/Face.h
+++ b/Platform/Chart3D/Face.h
@@ -26,11 +26,14 @@
  */
 
 #ifndef __MQL__
-// Allows the preprocessor to include a header file when it is needed.
-#pragma once
+  // Allows the preprocessor to include a header file when it is needed.
+  #pragma once
 #endif
 
-#include "Math.h"
+// We currently only support MQL.
+#ifdef __MQL__
+
+  #include "Math.h"
 
 // Face flags.
 enum ENUM_FACE_FLAGS { FACE_FLAGS_NONE, FACE_FLAGS_TRIANGLE, FACE_FLAGS_QUAD };
@@ -99,3 +102,5 @@ struct Face {
     }
   }
 };
+
+#endif
diff --git a/Platform/Chart3D/Frontend.h b/Platform/Chart3D/Frontend.h
index a5bc188eb..d681b1552 100644
--- a/Platform/Chart3D/Frontend.h
+++ b/Platform/Chart3D/Frontend.h
@@ -26,8 +26,8 @@
  */
 
 #ifndef __MQL__
-// Allows the preprocessor to include a header file when it is needed.
-#pragma once
+  // Allows the preprocessor to include a header file when it is needed.
+  #pragma once
 #endif
 
 #include "../../Refs.mqh"
@@ -61,32 +61,32 @@ class Frontend : public Dynamic {
   /**
    * Initializes canvas.
    */
-  virtual bool Init() = NULL;
+  virtual bool Init() = 0;
 
   /**
    * Deinitializes canvas.
    */
-  virtual bool Deinit() = NULL;
+  virtual bool Deinit() = 0;
 
   /**
    * Executed before render starts.
    */
-  virtual void RenderBegin(int context) = NULL;
+  virtual void RenderBegin(int context) = 0;
 
   /**
    * Executed after render ends.
    */
-  virtual void RenderEnd(int context) = NULL;
+  virtual void RenderEnd(int context) = 0;
 
   /**
    * Returns canvas' width.
    */
-  virtual int Width() = NULL;
+  virtual int Width() = 0;
 
   /**
    * Returns canvas' height.
    */
-  virtual int Height() = NULL;
+  virtual int Height() = 0;
 
   /**
    * Enqueues text to be drawn directly into the pixel buffer. Queue will be processed in the Device::End() method.
diff --git a/Platform/Chart3D/IndexBuffer.h b/Platform/Chart3D/IndexBuffer.h
index 7392f7731..3eb7f7395 100644
--- a/Platform/Chart3D/IndexBuffer.h
+++ b/Platform/Chart3D/IndexBuffer.h
@@ -26,8 +26,8 @@
  */
 
 #ifndef __MQL__
-// Allows the preprocessor to include a header file when it is needed.
-#pragma once
+  // Allows the preprocessor to include a header file when it is needed.
+  #pragma once
 #endif
 
 #include "../../Refs.mqh"
@@ -54,15 +54,15 @@ class IndexBuffer : public Dynamic {
   /**
    * Creates index buffer.
    */
-  virtual bool Create(VOID_DATA(_data)) = NULL;
+  virtual bool Create(VOID_DATA(_data)) = 0;
 
   /**
    * Fills index buffer with indices.
    */
-  virtual void Fill(ARRAY_REF(unsigned int, _indices)) = NULL;
+  virtual void Fill(ARRAY_REF(unsigned int, _indices)) = 0;
 
   /**
    * Activates index buffer for rendering.
    */
-  virtual void Select() = NULL;
+  virtual void Select() = 0;
 };
diff --git a/Platform/Chart3D/Math.h b/Platform/Chart3D/Math.h
index 25cd12e1d..69a0e3947 100644
--- a/Platform/Chart3D/Math.h
+++ b/Platform/Chart3D/Math.h
@@ -4,34 +4,38 @@
 //|                                             https://www.mql5.com |
 //+------------------------------------------------------------------+
 #ifndef __MQL__
-// Allows the preprocessor to include a header file when it is needed.
-#pragma once
+  // Allows the preprocessor to include a header file when it is needed.
+  #pragma once
 #endif
 
 #ifdef __MQL__
-#property copyright "Copyright 2019,MetaQuotes Software Corp."
-#property link "https://www.mql5.com"
+  #property copyright "Copyright 2019,MetaQuotes Software Corp."
+  #property link "https://www.mql5.com"
 #endif
+
+// We currently only support MQL.
+#ifdef __MQL__
+
 //+------------------------------------------------------------------+
-//| DirectX Math Routines                                            |
-//+------------------------------------------------------------------+
-//| Ported from C++ code of ReactOS, written by David Adam           |
-//| and Tony Wasserka                                                |
-//|                                                                  |
-//| https://doxygen.reactos.org/de/d57/                              |
-//| dll_2directx_2wine_2d3dx9__36_2math_8c_source.html               |
-//|                                                                  |
-//| Copyright (C) 2007 David Adam                                    |
-//| Copyright (C) 2007 Tony Wasserka                                 |
-//+------------------------------------------------------------------+
-#define DX_PI 3.1415926535897932384626f
-#define DX_PI_DIV2 1.5707963267948966192313f
-#define DX_PI_DIV3 1.0471975511965977461542f
-#define DX_PI_DIV4 0.7853981633974483096156f
-#define DX_PI_DIV6 0.5235987755982988730771f
-#define DX_PI_MUL2 6.2831853071795864769253f
-#define DXSH_MINORDER 2
-#define DXSH_MAXORDER 6
+  //| DirectX Math Routines                                            |
+  //+------------------------------------------------------------------+
+  //| Ported from C++ code of ReactOS, written by David Adam           |
+  //| and Tony Wasserka                                                |
+  //|                                                                  |
+  //| https://doxygen.reactos.org/de/d57/                              |
+  //| dll_2directx_2wine_2d3dx9__36_2math_8c_source.html               |
+  //|                                                                  |
+  //| Copyright (C) 2007 David Adam                                    |
+  //| Copyright (C) 2007 Tony Wasserka                                 |
+  //+------------------------------------------------------------------+
+  #define DX_PI 3.1415926535897932384626f
+  #define DX_PI_DIV2 1.5707963267948966192313f
+  #define DX_PI_DIV3 1.0471975511965977461542f
+  #define DX_PI_DIV4 0.7853981633974483096156f
+  #define DX_PI_DIV6 0.5235987755982988730771f
+  #define DX_PI_MUL2 6.2831853071795864769253f
+  #define DXSH_MINORDER 2
+  #define DXSH_MAXORDER 6
 //+------------------------------------------------------------------+
 //| Preliminary declarations                                         |
 //+------------------------------------------------------------------+
@@ -1442,7 +1446,7 @@ void DXMatrixAffineTransformation2D(DXMatrix &out, float scaling, const DXVector
   out.m[3][0] += translation.x;
   out.m[3][1] += translation.y;
 }
-#define D3DERR_INVALIDCALL -2005530516
+  #define D3DERR_INVALIDCALL -2005530516
 //#define S_OK                 0;
 //+------------------------------------------------------------------+
 //| Breaks down a general 3D transformation _matrix into its scalar,  |
@@ -3150,7 +3154,7 @@ void DXSHRotate(float &out[], int order, const DXMatrix &_matrix, const float &i
     return;
   }
 
-#ifdef __MQL5__
+  #ifdef __MQL5__
   if ((float)fabs(_matrix.m[2][2]) != 1.0f) {
     sinb = (float)sqrt(1.0f - _matrix.m[2][2] * _matrix.m[2][2]);
     alpha = (float)atan2(_matrix.m[2][1] / sinb, _matrix.m[2][0] / sinb);
@@ -3161,12 +3165,12 @@ void DXSHRotate(float &out[], int order, const DXMatrix &_matrix, const float &i
     beta = 0.0f;
     gamma = 0.0f;
   }
-#else
+  #else
   alpha = 0.0f;
   beta = 0.0f;
   gamma = 0.0f;
   sinb = 0.0f;
-#endif
+  #endif
 
   //---
   DXSHRotateZ(temp, order, gamma, in);
@@ -3230,3 +3234,5 @@ float DXScalarLerp(const float val1, const float val2, float s) { return ((1 - s
 //+---------------------------------------------------------------------+
 float DXScalarBiasScale(const float val, const float bias, const float scale) { return ((val + bias) * scale); }
 //+------------------------------------------------------------------+
+
+#endif
diff --git a/Platform/Chart3D/Shader.h b/Platform/Chart3D/Shader.h
index 8bfc3de25..6b5d9cfca 100644
--- a/Platform/Chart3D/Shader.h
+++ b/Platform/Chart3D/Shader.h
@@ -26,11 +26,14 @@
  */
 
 #ifndef __MQL__
-// Allows the preprocessor to include a header file when it is needed.
-#pragma once
+  // Allows the preprocessor to include a header file when it is needed.
+  #pragma once
 #endif
 
-#include "../../Refs.mqh"
+// We currently only support MQL.
+#ifdef __MQL__
+
+  #include "../../Refs.mqh"
 
 // Shader type.
 enum ENUM_SHADER_TYPE {
@@ -85,10 +88,10 @@ class Shader : public Dynamic {
   void SetCBuffer(const X& data) {
     // Unfortunately we can't make this method virtual.
     if (dynamic_cast<MTDXShader*>(&this) != NULL) {
-// MT5's DirectX.
-#ifdef __debug__
+  // MT5's DirectX.
+  #ifdef __debug__
       Print("Setting CBuffer data for MT5");
-#endif
+  #endif
       ((MTDXShader*)&this).SetCBuffer(data);
     } else {
       Alert("Unsupported cbuffer device target");
@@ -100,3 +103,5 @@ class Shader : public Dynamic {
    */
   virtual void Select() = NULL;
 };
+
+#endif
diff --git a/Platform/Chart3D/TSR.h b/Platform/Chart3D/TSR.h
index 4ed42dd48..e239a8ed5 100644
--- a/Platform/Chart3D/TSR.h
+++ b/Platform/Chart3D/TSR.h
@@ -26,11 +26,14 @@
  */
 
 #ifndef __MQL__
-// Allows the preprocessor to include a header file when it is needed.
-#pragma once
+  // Allows the preprocessor to include a header file when it is needed.
+  #pragma once
 #endif
 
-#include "Math.h"
+// We currently only support MQL.
+#ifdef __MQL__
+
+  #include "Math.h"
 
 class TSR {
  public:
@@ -65,3 +68,5 @@ class TSR {
     return _mtx_result;
   }
 };
+
+#endif
diff --git a/Platform/Chart3D/Vertex.h b/Platform/Chart3D/Vertex.h
index 65e9248b0..1922a8e62 100644
--- a/Platform/Chart3D/Vertex.h
+++ b/Platform/Chart3D/Vertex.h
@@ -21,11 +21,14 @@
  */
 
 #ifndef __MQL__
-// Allows the preprocessor to include a header file when it is needed.
-#pragma once
+  // Allows the preprocessor to include a header file when it is needed.
+  #pragma once
 #endif
 
-#include "../../Refs.mqh"
+// We currently only support MQL.
+#ifdef __MQL__
+
+  #include "../../Refs.mqh"
 
 /**
  * Generic vertex to be used by meshes.
@@ -56,3 +59,5 @@ const ShaderVertexLayout Vertex::Layout[3] = {
     {"POSITION", 0, GFX_VAR_TYPE_FLOAT, 3, false, sizeof(Vertex), 0},
     {"NORMAL", 0, GFX_VAR_TYPE_FLOAT, 3, false, sizeof(Vertex), sizeof(float) * 3},
     {"COLOR", 0, GFX_VAR_TYPE_FLOAT, 4, false, sizeof(Vertex), sizeof(float) * 6}};
+
+#endif
diff --git a/Std.h b/Std.h
index 789ec31eb..c4a5d6ce1 100644
--- a/Std.h
+++ b/Std.h
@@ -387,15 +387,19 @@ class InvalidEnumValue {
 #endif
       static const T
       value() {
-    return (T)INT_MAX;
+#ifdef __MQL__
+    return (T)NULL;
+#else
+    return std::numeric_limits<T>::max();
+#endif
   }
 };
 
 #ifndef __MQL__
 struct _WRONG_VALUE {
   template <typename T>
-  operator T() {
-    return (T)-1;
+  operator T() const {
+    return std::numeric_limits<T>::max();
   }
 } WRONG_VALUE;
 
@@ -405,10 +409,9 @@ const string _empty_string = "";
 // Converter of NULL_VALUE into expected type. e.g., "int x = NULL_VALUE" will end up with "x = 0".
 struct _NULL_VALUE {
   template <typename T>
-  explicit operator T() const {
-    return (T)0;
+  operator T() const {
+    return std::numeric_limits<T>::max();
   }
-
 } NULL_VALUE;
 
 /**