JsonParserByLeo/Src/JsonBuilder.mqh

//+------------------------------------------------------------------+
//|                                                  JsonBuilder.mqh |
//|                                  Copyright 2026, Niquel Mendoza. |
//|                                            https://www.mql5.com/ |
//+------------------------------------------------------------------+
#property copyright "Copyright 2026, Niquel Mendoza."
#property link      "https://www.mql5.com/"
#property strict

#ifndef JSONPARSERBYLEO_SRC_JSONBUILDER_MQH
#define JSONPARSERBYLEO_SRC_JSONBUILDER_MQH

namespace TSN
{
//+------------------------------------------------------------------+
//| Escape lookup tables (index = char code 0..127)                  |
//| g_arr_jsonb_type_c: 0 = safe (copy as-is)                        |
//|           1 = two-char escape: backslash + g_arr_jsonb_next_c[c] |
//|           2 = \u00XX hex escape                                  |
//+------------------------------------------------------------------+
const uchar g_arr_jsonb_type_c[128] =
 {
  2, 2, 2, 2, 2, 2, 2, 2, // 0x00-0x07
  1, 1, 1, 2, 1, 1, 2, 2, // 0x08-0x0F  (\b=8,\t=9,\n=10, \f=12,\r=13)
  2, 2, 2, 2, 2, 2, 2, 2, // 0x10-0x17
  2, 2, 2, 2, 2, 2, 2, 2, // 0x18-0x1F
  0, 0, 1, 0, 0, 0, 0, 0, // 0x20-0x27  ('"'=34)
  0, 0, 0, 0, 0, 0, 0, 0, // 0x28-0x2F
  0, 0, 0, 0, 0, 0, 0, 0, // 0x30-0x37
  0, 0, 0, 0, 0, 0, 0, 0, // 0x38-0x3F
  0, 0, 0, 0, 0, 0, 0, 0, // 0x40-0x47
  0, 0, 0, 0, 0, 0, 0, 0, // 0x48-0x4F
  0, 0, 0, 0, 0, 0, 0, 0, // 0x50-0x57
  0, 0, 0, 0, 1, 0, 0, 0, // 0x58-0x5F  ('\\'=92)
  0, 0, 0, 0, 0, 0, 0, 0, // 0x60-0x67
  0, 0, 0, 0, 0, 0, 0, 0, // 0x68-0x6F
  0, 0, 0, 0, 0, 0, 0, 0, // 0x70-0x77
  0, 0, 0, 0, 0, 0, 0, 0 // 0x78-0x7F
 };

//--- Second char of two-char escape (only valid where g_arr_jsonb_type_c==1)
const uchar g_arr_jsonb_next_c[128] =
 {
  0, 0, 0, 0, 0, 0, 0, 0, // 0x00-0x07
  'b', 't', 'n', 0, 'f', 'r', 0, 0, // 0x08-0x0F
  0, 0, 0, 0, 0, 0, 0, 0, // 0x10-0x17
  0, 0, 0, 0, 0, 0, 0, 0, // 0x18-0x1F
  0, 0, '"', 0, 0, 0, 0, 0, // 0x20-0x27
  0, 0, 0, 0, 0, 0, 0, 0, // 0x28-0x2F
  0, 0, 0, 0, 0, 0, 0, 0, // 0x30-0x37
  0, 0, 0, 0, 0, 0, 0, 0, // 0x38-0x3F
  0, 0, 0, 0, 0, 0, 0, 0, // 0x40-0x47
  0, 0, 0, 0, 0, 0, 0, 0, // 0x48-0x4F
  0, 0, 0, 0, 0, 0, 0, 0, // 0x50-0x57
  0, 0, 0, 0, '\\', 0, 0, 0, // 0x58-0x5F
  0, 0, 0, 0, 0, 0, 0, 0, // 0x60-0x67
  0, 0, 0, 0, 0, 0, 0, 0, // 0x68-0x6F
  0, 0, 0, 0, 0, 0, 0, 0, // 0x70-0x77
  0, 0, 0, 0, 0, 0, 0, 0 // 0x78-0x7F
 };

//+------------------------------------------------------------------+
//|                                                                  |
//+------------------------------------------------------------------+
#define JSONBUILDER_EXPAND(need) if(m_pos + (need) >= m_cap) { m_cap += (need) + 4096; ArrayResize(m_buf, m_cap, m_cap); }

//+------------------------------------------------------------------+
//|                                                                  |
//+------------------------------------------------------------------+
class CJsonBuilder
 {
public:
  uchar              m_buf[];
  int                m_pos;

private:
  int                m_cap;
  bool               m_stack_first[64];
  int                m_sp;

  //---
  void               PutRaw(const string& s);
  void               PutRaw(const uchar& s[]);
  void               PutRawNoRef(const string s);
  void               PutEncodedStr(const string& s);

public:
                     CJsonBuilder(int initial_cap = 1024);
                    ~CJsonBuilder() {}

  //---
  void               Clear();

  //---
  __forceinline string Build() const { return CharArrayToString(m_buf, 0, m_pos, CP_UTF8); }


  //--- Structure
  CJsonBuilder*      Obj();
  CJsonBuilder*      EndObj();
  CJsonBuilder*      Arr();
  CJsonBuilder*      EndArr();

  //--- Key / Values
  CJsonBuilder*      Key(const string& k);
  CJsonBuilder*      ValS(const string& v);
  CJsonBuilder*      ValSNoRef(const string v);
  CJsonBuilder*      Val(int v);
  CJsonBuilder*      Val(long v);
  CJsonBuilder*      Val(double v);
  CJsonBuilder*      Val(bool v);
  CJsonBuilder*      ValidJson(const uchar& v[]);
  CJsonBuilder*      ValidJson(const string& fragment);
  CJsonBuilder*      ValidJsonNoRef(const string fragment);
  CJsonBuilder*      Null();
 };

//+------------------------------------------------------------------+
//|                                                                  |
//+------------------------------------------------------------------+
CJsonBuilder::CJsonBuilder(int initial_cap)
 {
  m_cap = initial_cap;
  ArrayResize(m_buf, m_cap);
  m_pos = 0;
  m_sp = 0;
  m_stack_first[0] = true;
 }

//+------------------------------------------------------------------+
//|                                                                  |
//+------------------------------------------------------------------+
#define JSON_BUILDER_PUT(c) \
  JSONBUILDER_EXPAND(1) \
  m_buf[m_pos++] = c;  \

//---
#define JSON_BUILDER_COMMA \
  if(!m_stack_first[m_sp]) \
   { \
    JSON_BUILDER_PUT(',') \
   } \
  m_stack_first[m_sp] = false;

//+------------------------------------------------------------------+
//|                                                                  |
//+------------------------------------------------------------------+
void CJsonBuilder::Clear()
 {
  m_pos = 0;
  m_sp = 0;
  m_stack_first[0] = true;
 }


//+------------------------------------------------------------------+
void CJsonBuilder::PutRaw(const uchar& s[])
 {
//---
  const int l = ArraySize(s);
  const int max_bytes = l * 4 + 1;
  JSONBUILDER_EXPAND(max_bytes)

//---
  m_pos += ArrayCopy(m_buf, s, 0, m_pos, WHOLE_ARRAY);
 }

//+------------------------------------------------------------------+
void CJsonBuilder::PutRaw(const string& s)
 {
//---
  const int l = StringLen(s);
  const int max_bytes = l * 4 + 1;
  JSONBUILDER_EXPAND(max_bytes)

//---
  int written = StringToCharArray(s, m_buf, m_pos, WHOLE_ARRAY, CP_UTF8);
  if(written > 0 && m_buf[m_pos + written - 1] == 0)
    written--;
  m_pos += written;
 }

//+------------------------------------------------------------------+
void CJsonBuilder::PutRawNoRef(const string s)
 {
//---
  const int l = StringLen(s);
  const int max_bytes = l * 4 + 1;
  JSONBUILDER_EXPAND(max_bytes)

//---
  int written = StringToCharArray(s, m_buf, m_pos, WHOLE_ARRAY, CP_UTF8);
  if(written > 0 && m_buf[m_pos + written - 1] == 0)
    written--;
  m_pos += written;
 }

//+------------------------------------------------------------------+
void CJsonBuilder::PutEncodedStr(const string& s)
 {
//---
  JSON_BUILDER_PUT('"')

//---
  const int l = StringLen(s);

//---
  for(int i = 0; i < l; i++)
   {
    //---
    const ushort c = s[i];

    //---
    if(c >= 128)
     {
      //--- UTF-8 multibyte
      uchar temp[];
      int tlen = StringToCharArray(ShortToString(c), temp, 0, WHOLE_ARRAY, CP_UTF8);
      if(tlen > 0 && temp[tlen - 1] == 0)
        tlen--;
      JSONBUILDER_EXPAND(tlen)
      ArrayCopy(m_buf, temp, m_pos, 0, tlen);
      m_pos += tlen;
      continue;
     }

    //--- ASCII lookup
    const uchar esc = g_arr_jsonb_type_c[c];
    if(esc == 0)
     {
      JSONBUILDER_EXPAND(1)
      m_buf[m_pos++] = (uchar)c;
     }
    else
      if(esc == 1)
       {
        JSONBUILDER_EXPAND(2)
        m_buf[m_pos++] = '\\';
        m_buf[m_pos++] = g_arr_jsonb_next_c[c];
       }
      else // esc == 2: \u00XX
       {
        JSONBUILDER_EXPAND(6)
        m_buf[m_pos++] = '\\';
        m_buf[m_pos++] = 'u';
        m_buf[m_pos++] = '0';
        m_buf[m_pos++] = '0';

        //---
        uchar t = uchar((c >> 4) & 0xF);
        m_buf[m_pos++] = (uchar)(t < 10 ? '0' + t : 'a' + t - 10);
        t = uchar(c & 0xF);
        m_buf[m_pos++] = (uchar)(t < 10 ? '0' + t : 'a' + t - 10);
       }
   }

//---
  JSON_BUILDER_PUT('"')
 }

//+------------------------------------------------------------------+
CJsonBuilder* CJsonBuilder::Obj()
 {
  JSON_BUILDER_COMMA
  JSON_BUILDER_PUT('{')
  if(m_sp < 63)
   {
    m_sp++;
    m_stack_first[m_sp] = true;
   }
  return &this;
 }

//+------------------------------------------------------------------+
CJsonBuilder* CJsonBuilder::EndObj()
 {
  if(m_sp > 0)
    m_sp--;
  JSON_BUILDER_PUT('}')
  m_stack_first[m_sp] = false;
  return &this;
 }

//+------------------------------------------------------------------+
CJsonBuilder* CJsonBuilder::Arr()
 {
  JSON_BUILDER_COMMA
  JSON_BUILDER_PUT('[')
  if(m_sp < 63)
   {
    m_sp++;
    m_stack_first[m_sp] = true;
   }
  return &this;
 }

//+------------------------------------------------------------------+
CJsonBuilder* CJsonBuilder::EndArr()
 {
  if(m_sp > 0)
    m_sp--;
  JSON_BUILDER_PUT(']')
  m_stack_first[m_sp] = false;
  return &this;
 }

//+------------------------------------------------------------------+
CJsonBuilder* CJsonBuilder::Key(const string& k)
 {
  JSON_BUILDER_COMMA
  PutEncodedStr(k);
  JSON_BUILDER_PUT(':')
  m_stack_first[m_sp] = true;
  return &this;
 }

//+------------------------------------------------------------------+
CJsonBuilder* CJsonBuilder::ValS(const string& v)
 {
  JSON_BUILDER_COMMA
  PutEncodedStr(v);
  return &this;
 }

//+------------------------------------------------------------------+
CJsonBuilder* CJsonBuilder::ValSNoRef(const string v)
 {
  JSON_BUILDER_COMMA
  PutEncodedStr(v);
  return &this;
 }

//+------------------------------------------------------------------+
CJsonBuilder* CJsonBuilder::Val(int v)
 {
  JSON_BUILDER_COMMA
  PutRawNoRef((string)v);
  return &this;
 }

//+------------------------------------------------------------------+
CJsonBuilder* CJsonBuilder::Val(long v)
 {
  JSON_BUILDER_COMMA
  PutRawNoRef((string)v);
  return &this;
 }

//+------------------------------------------------------------------+
CJsonBuilder* CJsonBuilder::Val(double v)
 {
  JSON_BUILDER_COMMA
  PutRawNoRef((string)v);
  return &this;
 }



//+------------------------------------------------------------------+
CJsonBuilder* CJsonBuilder::Val(bool v)
 {
  JSON_BUILDER_COMMA
  PutRawNoRef(v ? "true" : "false");
  return &this;
 }


//+------------------------------------------------------------------+
CJsonBuilder* CJsonBuilder::ValidJson(const uchar& v[])
 {
  JSON_BUILDER_COMMA
  PutRaw(v);
  return &this;
 }

//+------------------------------------------------------------------+
CJsonBuilder* CJsonBuilder::ValidJson(const string& fragment)
 {
  JSON_BUILDER_COMMA
  PutRaw(fragment);
  return &this;
 }

//+------------------------------------------------------------------+
CJsonBuilder* CJsonBuilder::ValidJsonNoRef(const string fragment)
 {
  JSON_BUILDER_COMMA
  PutRaw(fragment);
  return &this;
 }


//+------------------------------------------------------------------+
CJsonBuilder* CJsonBuilder::Null()
 {
  JSON_BUILDER_COMMA
  PutRaw("null");
  return &this;
 }

//---
CJsonBuilder g_json_builder;

} // namespace TSN
//+------------------------------------------------------------------+
#endif // JSONPARSERBYLEO_SRC_JSONBUILDER_MQH