simdjson-simdjson/include/simdjson/dom/serialization.h

#ifndef SIMDJSON_SERIALIZATION_H
#define SIMDJSON_SERIALIZATION_H

#include "simdjson/dom/base.h"
#include "simdjson/dom/element.h"
#include "simdjson/dom/object.h"

#include <vector>

namespace simdjson {

/**
 * The string_builder template and mini_formatter class
 * are not part of  our public API and are subject to change
 * at any time!
 */
namespace internal {

template<class formatter>
class base_formatter {
public:
  /** Add a comma **/
  simdjson_inline void comma();
  /** Start an array, prints [ **/
  simdjson_inline void start_array();
  /** End an array, prints ] **/
  simdjson_inline void end_array();
  /** Start an array, prints { **/
  simdjson_inline void start_object();
  /** Start an array, prints } **/
  simdjson_inline void end_object();
  /** Prints a true **/
  simdjson_inline void true_atom();
  /** Prints a false **/
  simdjson_inline void false_atom();
  /** Prints a null **/
  simdjson_inline void null_atom();
  /** Prints a number **/
  simdjson_inline void number(int64_t x);
  /** Prints a number **/
  simdjson_inline void number(uint64_t x);
  /** Prints a number **/
  simdjson_inline void number(double x);
  /** Prints a key (string + colon) **/
  simdjson_inline void key(std::string_view unescaped);
  /** Prints a string. The string is escaped as needed. **/
  simdjson_inline void string(std::string_view unescaped);
  /** Clears out the content. **/
  simdjson_inline void clear();
  /**
   * Get access to the buffer, it is owned by the instance, but
   * the user can make a copy.
   **/
  simdjson_inline std::string_view str() const;

  /** Prints one character **/
  simdjson_inline void one_char(char c);

  simdjson_inline void call_print_newline() {
      static_cast<formatter*>(this)->print_newline();
  }

  simdjson_inline void call_print_indents(size_t depth) {
      static_cast<formatter*>(this)->print_indents(depth);
  }

  simdjson_inline void call_print_space() {
      static_cast<formatter*>(this)->print_space();
  }

protected:
  // implementation details (subject to change)
  /** Backing buffer **/
  std::vector<char> buffer{}; // not ideal!
};


/**
 * @private This is the class that we expect to use with the string_builder
 * template. It tries to produce a compact version of the JSON element
 * as quickly as possible.
 */
class mini_formatter : public base_formatter<mini_formatter> {
public:
  simdjson_inline void print_newline();

  simdjson_inline void print_indents(size_t depth);

  simdjson_inline void print_space();
};

class pretty_formatter : public base_formatter<pretty_formatter> {
public:
  simdjson_inline void print_newline();

  simdjson_inline void print_indents(size_t depth);

  simdjson_inline void print_space();

protected:
  int indent_step = 4;
};

/**
 * @private The string_builder template allows us to construct
 * a string from a document element. It is parametrized
 * by a "formatter" which handles the details. Thus
 * the string_builder template could support both minification
 * and prettification, and various other tradeoffs.
 */
template <class formatter = mini_formatter>
class string_builder {
public:
  /** Construct an initially empty builder, would print the empty string **/
  string_builder() = default;
  /** Append an element to the builder (to be printed) **/
  inline void append(simdjson::dom::element value);
  /** Append an array to the builder (to be printed) **/
  inline void append(simdjson::dom::array value);
  /** Append an object to the builder (to be printed) **/
  inline void append(simdjson::dom::object value);
  /** Reset the builder (so that it would print the empty string) **/
  simdjson_inline void clear();
  /**
   * Get access to the string. The string_view is owned by the builder
   * and it is invalid to use it after the string_builder has been
   * destroyed.
   * However you can make a copy of the string_view on memory that you
   * own.
   */
  simdjson_inline std::string_view str() const;
  /** Append a key_value_pair to the builder (to be printed) **/
  simdjson_inline void append(simdjson::dom::key_value_pair value);
private:
  formatter format{};
};

} // internal

namespace dom {

/**
 * Print JSON to an output stream.
 *
 * @param out The output stream.
 * @param value The element.
 * @throw if there is an error with the underlying output stream. simdjson itself will not throw.
 */
inline std::ostream& operator<<(std::ostream& out, simdjson::dom::element value);
#if SIMDJSON_EXCEPTIONS
inline std::ostream& operator<<(std::ostream& out, simdjson::simdjson_result<simdjson::dom::element> x);
#endif
/**
 * Print JSON to an output stream.
 *
 * @param out The output stream.
 * @param value The array.
 * @throw if there is an error with the underlying output stream. simdjson itself will not throw.
 */
inline std::ostream& operator<<(std::ostream& out, simdjson::dom::array value);
#if SIMDJSON_EXCEPTIONS
inline std::ostream& operator<<(std::ostream& out, simdjson::simdjson_result<simdjson::dom::array> x);
#endif
/**
 * Print JSON to an output stream.
 *
 * @param out The output stream.
 * @param value The object.
 * @throw if there is an error with the underlying output stream. simdjson itself will not throw.
 */
inline std::ostream& operator<<(std::ostream& out, simdjson::dom::object value);
#if SIMDJSON_EXCEPTIONS
inline std::ostream& operator<<(std::ostream& out,  simdjson::simdjson_result<simdjson::dom::object> x);
#endif
} // namespace dom

/**
 * Converts JSON to a string.
 *
 *   dom::parser parser;
 *   element doc = parser.parse("   [ 1 , 2 , 3 ] "_padded);
 *   cout << to_string(doc) << endl; // prints [1,2,3]
 *
 */
template <class T>
std::string to_string(T x)   {
    // in C++, to_string is standard: http://www.cplusplus.com/reference/string/to_string/
    // Currently minify and to_string are identical but in the future, they may
    // differ.
    simdjson::internal::string_builder<> sb;
    sb.append(x);
    std::string_view answer = sb.str();
    return std::string(answer.data(), answer.size());
}
#if SIMDJSON_EXCEPTIONS
template <class T>
std::string to_string(simdjson_result<T> x) {
    if (x.error()) { throw simdjson_error(x.error()); }
    return to_string(x.value());
}
#endif

/**
 * Minifies a JSON element or document, printing the smallest possible valid JSON.
 *
 *   dom::parser parser;
 *   element doc = parser.parse("   [ 1 , 2 , 3 ] "_padded);
 *   cout << minify(doc) << endl; // prints [1,2,3]
 *
 */
template <class T>
std::string minify(T x)  {
  return to_string(x);
}

#if SIMDJSON_EXCEPTIONS
template <class T>
std::string minify(simdjson_result<T> x) {
    if (x.error()) { throw simdjson_error(x.error()); }
    return to_string(x.value());
}
#endif

/**
 * Prettifies a JSON element or document, printing the valid JSON with indentation.
 *
 *   dom::parser parser;
 *   element doc = parser.parse("   [ 1 , 2 , 3 ] "_padded);
 *
 *   // Prints:
 *   // {
 *   //     [
 *   //         1,
 *   //         2,
 *   //         3
 *   //     ]
 *   // }
 *   cout << prettify(doc) << endl;
 *
 */
template <class T>
std::string prettify(T x)  {
    simdjson::internal::string_builder<simdjson::internal::pretty_formatter> sb;
    sb.append(x);
    std::string_view answer = sb.str();
    return std::string(answer.data(), answer.size());
}

#if SIMDJSON_EXCEPTIONS
template <class T>
std::string prettify(simdjson_result<T> x) {
    if (x.error()) { throw simdjson_error(x.error()); }
    return to_string(x.value());
}
#endif

} // namespace simdjson


#endif