Libraries: A powerful and feature-rich JSON library for MQL5, designed to bring a modern development experience similar to Python/JS

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A powerful and feature-rich JSON library for MQL5, designed to bring a modern development experience similar to Python/JS:

A powerful and feature-rich JSON library for MQL5, designed to bring a modern development experience similar to Python/JS

Author: Dao Liang Ding

[Le Minh Duc]

Thank you for sharing your work. I'm curious—how does your library compare to Sergeev’s Json Lib in terms of performance or capabilities?

[hini]

Thank you very much for sharing the code!

[hini]

Advanced Query 4 Verification failed, is this normal?

[hini]

To resolve the issue of validation failure in Advanced Query 4, replace this function in JsonPath.mqh.

   void EvaluatePath(const MQL5_Json::JsonNode &root, const string &path, MQL5_Json::JsonNode &out_nodes[], MQL5_Json::JsonError &error)
   {
      MQL5_Json::JsonNode current_nodes[];
      if(root.IsValid())
      {
         ArrayResize(current_nodes,1);
         current_nodes[0] = root;
      }
      Tokenizer tokenizer(path);
      while(true)
      {
         Tokenizer::Token token = tokenizer.NextToken();
         if(token.type == Tokenizer::Eof) break;
         if(token.type == Tokenizer::Error)
         {
            error.message = "Invalid JSONPath token";
            error.context = token.str_val;
            return;
         }
         if(token.type == Tokenizer::Root || token.type == Tokenizer::Dot) continue;
         MQL5_Json::JsonNode next_gen_nodes[];
         for(int i=0; i < ArraySize(current_nodes); i++)
         {
            MQL5_Json::JsonNode current_node = current_nodes[i];
            if(!current_node.IsValid()) continue;
            if(token.type == Tokenizer::Ddot)  // Deep scan from current node
            {
               // Add current node if it has children that will be processed next
               if(current_node.IsObject() || current_node.IsArray())
               {
                  int s=ArraySize(next_gen_nodes);
                  ArrayResize(next_gen_nodes,s+1);
                  next_gen_nodes[s]=current_node;
               }
            }
            else if(token.type == Tokenizer::Id || token.type == Tokenizer::Str)
            {
               if(current_node.IsObject())
               {
                  MQL5_Json::JsonNode child=current_node.Get(token.str_val);
                  if(child.IsValid())
                  {
                     int s=ArraySize(next_gen_nodes);
                     ArrayResize(next_gen_nodes,s+1);
                     next_gen_nodes[s]=child;
                  }
               }
               else if(current_node.IsArray())
               {
                  for(int j=0; j<current_node.Size();j++)
                  {
                     MQL5_Json::JsonNode item=current_node.At(j);
                     if(item.IsObject())
                     {
                        MQL5_Json::JsonNode child=item.Get(token.str_val);
                        if(child.IsValid())
                        {
                           int s=ArraySize(next_gen_nodes);
                           ArrayResize(next_gen_nodes,s+1);
                           next_gen_nodes[s]=child;
                        }
                     }
                  }
               }
            }
            else if(token.type == Tokenizer::Lbr)  // [index] or [*]
            {
               Tokenizer::Token next_token = tokenizer.NextToken();
               if(next_token.type == Tokenizer::Wild) // [*] 
               {
                  Tokenizer::Token rbr_token = tokenizer.NextToken();
                  if(rbr_token.type == Tokenizer::Rbr)
                  {
                     if(current_node.IsArray())
                     {
                        for(int j=0; j<current_node.Size(); j++)
                        {
                           MQL5_Json::JsonNode child=current_node.At(j);
                           if(child.IsValid())
                           {
                              int s=ArraySize(next_gen_nodes);
                              ArrayResize(next_gen_nodes,s+1);
                              next_gen_nodes[s]=child;
                           }
                        }
                     }
                  }
               }
               else if(next_token.type == Tokenizer::Num) // [index] 
               {
                  Tokenizer::Token rbr_token = tokenizer.NextToken();
                  if(rbr_token.type == Tokenizer::Rbr)
                  {
                     if(current_node.IsArray())
                     {
                        int index = (int)next_token.num_val;
                        if(index >= 0 && index < current_node.Size())
                        {
                           MQL5_Json::JsonNode child=current_node.At(index);
                           if(child.IsValid())
                           {
                              int s=ArraySize(next_gen_nodes);
                              ArrayResize(next_gen_nodes,s+1);
                              next_gen_nodes[s]=child;
                           }
                        }
                     }
                  }
               }
               else
               {
                  error.message = "Invalid array access syntax";
                  error.context = "Expected [*] or [index]";
                  return;
               }
            }
            else if(token.type == Tokenizer::Wild)
            {
               if(current_node.IsObject())
               {
                  string k[];
                  current_node.GetKeys(k);
                  for(int j=0;j<ArraySize(k);j++)
                  {
                     MQL5_Json::JsonNode child=current_node.Get(k[j]);
                     if(child.IsValid())
                     {
                        int s=ArraySize(next_gen_nodes);
                        ArrayResize(next_gen_nodes,s+1);
                        next_gen_nodes[s]=child;
                     }
                  }
               }
               else if(current_node.IsArray())
               {
                  for(int j=0; j<current_node.Size(); j++)
                  {
                     MQL5_Json::JsonNode child=current_node.At(j);
                     if(child.IsValid())
                     {
                        int s=ArraySize(next_gen_nodes);
                        ArrayResize(next_gen_nodes,s+1);
                        next_gen_nodes[s]=child;
                     }
                  }
               }
            }
         }
         // [THE FIX] Replace illegal ArrayCopy with a compliant `for` loop
         int size = ArraySize(next_gen_nodes);
         ArrayResize(current_nodes, size);
         for(int i=0; i<size; i++) current_nodes[i] = next_gen_nodes[i];
      }
      // [THE FIX] Replace illegal ArrayCopy with a compliant `for` loop
      int size_out = ArraySize(current_nodes);
      ArrayResize(out_nodes, size_out);
      for(int i=0; i<size_out; i++) out_nodes[i] = current_nodes[i];
   }