streaming_json.h

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// Copyright (c) 2024 anabrid GmbH
// Contact: https://www.anabrid.com/licensing/
// SPDX-License-Identifier: MIT OR GPL-2.0-or-later
 
#pragma once
 
#include <Arduino.h>
 
namespace utils {
 
 
  class StreamingJson {
    bool _needs_comma = false;
 
  public:
    Print& output;
    StreamingJson(Print& output) : output(output) {}
 
    void check_comma() {
      if(_needs_comma) output.print(',');
      _needs_comma = false;
    }
    void needs_comma() { _needs_comma = true; }
 
    void begin_dict() { output.print('{'); _needs_comma = false; }
    void end_dict()   { output.print('}'); needs_comma(); }
    void begin_list() { output.print('['); _needs_comma = false; }
    void end_list()   { output.print(']'); needs_comma(); }
 
    void begin_str(char quote='"') { output.print(quote); }
    void end_str(char quote='"') { output.print(quote); }
 
    void key(const char* str, char quote='"') {
      check_comma();
      begin_str(quote);
      output.print(str);
      end_str(quote);
      output.print(':');
    }
 
    void key(const std::string& str) { key(str.c_str()); }
 
    // value types
 
    void val(const char* str, char quote='"') {
      check_comma();
      begin_str(quote);
      output.print(str);
      end_str(quote);
      needs_comma();
    }
 
    void val(const std::string& str) { val(str.c_str()); }
 
    void val(bool b) {
       check_comma();
       output.print(b ? "true" : "false");
       needs_comma();
    }
 
    // should ensure things do not behave as strings...
    template<typename V>
    void val(V i) {
       check_comma();
       output.print(i);
       needs_comma();
    }
 
    void null() {
       check_comma();
       output.print("null");
       needs_comma();
    }
 
    void json(const char* str) {
      check_comma();
      output.print(str);
      needs_comma();
    }
 
    // Shorthands
 
    template<typename V> void kv(const char* _key, V _val) { key(_key); val(_val); }
 
    void endln() {
      output.println();
      output.flush();
    }
 
    // scope handlers
  };
 
}