jsoncpp/include/json/writer.h

// Copyright 2007-2010 Baptiste Lepilleur
// Distributed under MIT license, or public domain if desired and
// recognized in your jurisdiction.
// See file LICENSE for detail or copy at http://jsoncpp.sourceforge.net/LICENSE

#ifndef JSON_WRITER_H_INCLUDED
#define JSON_WRITER_H_INCLUDED

#if !defined(JSON_IS_AMALGAMATION)
#include "value.h"
#endif // if !defined(JSON_IS_AMALGAMATION)
#include <vector>
#include <string>

// Disable warning C4251: <data member>: <type> needs to have dll-interface to
// be used by...
#if defined(JSONCPP_DISABLE_DLL_INTERFACE_WARNING)
#pragma warning(push)
#pragma warning(disable : 4251)
#endif // if defined(JSONCPP_DISABLE_DLL_INTERFACE_WARNING)

namespace Json {

class Value;

/** \brief Abstract class for writers.
 */
class JSON_API Writer {
public:
  virtual ~Writer();

  virtual std::string write(const Value &root) = 0;
};

/** \brief Outputs a Value in <a HREF="http://www.json.org">JSON</a> format
 *without formatting (not human friendly).
 *
 * The JSON document is written in a single line. It is not intended for 'human'
 *consumption,
 * but may be usefull to support feature such as RPC where bandwith is limited.
 * \sa Reader, Value
 */
class JSON_API FastWriter : public Writer {
public:
  FastWriter();
  virtual ~FastWriter() {}

  void enableYAMLCompatibility();

  /** \brief Drop the "null" string from the writer's output for nullValues.
   * Strictly speaking, this is not valid JSON. But when the output is being
   * fed to a browser's Javascript, it makes for smaller output and the
   * browser can handle the output just fine.
   */
  void dropNullPlaceholders();

  void omitEndingLineFeed();

public: // overridden from Writer
  virtual std::string write(const Value &root);

private:
  void writeValue(const Value &value);

  std::string document_;
  bool yamlCompatiblityEnabled_;
  bool dropNullPlaceholders_;
  bool omitEndingLineFeed_;
};

/** \brief Writes a Value in <a HREF="http://www.json.org">JSON</a> format in a
 *human friendly way.
 *
 * The rules for line break and indent are as follow:
 * - Object value:
 *     - if empty then print {} without indent and line break
 *     - if not empty the print '{', line break & indent, print one value per
 *line
 *       and then unindent and line break and print '}'.
 * - Array value:
 *     - if empty then print [] without indent and line break
 *     - if the array contains no object value, empty array or some other value
 *types,
 *       and all the values fit on one lines, then print the array on a single
 *line.
 *     - otherwise, it the values do not fit on one line, or the array contains
 *       object or non empty array, then print one value per line.
 *
 * If the Value have comments then they are outputed according to their
 *#CommentPlacement.
 *
 * \sa Reader, Value, Value::setComment()
 */
class JSON_API StyledWriter : public Writer {
public:
  StyledWriter();
  virtual ~StyledWriter() {}

public: // overridden from Writer
  /** \brief Serialize a Value in <a HREF="http://www.json.org">JSON</a> format.
   * \param root Value to serialize.
   * \return String containing the JSON document that represents the root value.
   */
  virtual std::string write(const Value &root);

private:
  void writeValue(const Value &value);
  void writeArrayValue(const Value &value);
  bool isMultineArray(const Value &value);
  void pushValue(const std::string &value);
  void writeIndent();
  void writeWithIndent(const std::string &value);
  void indent();
  void unindent();
  void writeCommentBeforeValue(const Value &root);
  void writeCommentAfterValueOnSameLine(const Value &root);
  bool hasCommentForValue(const Value &value);
  static std::string normalizeEOL(const std::string &text);

  typedef std::vector<std::string> ChildValues;

  ChildValues childValues_;
  std::string document_;
  std::string indentString_;
  int rightMargin_;
  int indentSize_;
  bool addChildValues_;
};

/** \brief Writes a Value in <a HREF="http://www.json.org">JSON</a> format in a
 human friendly way,
     to a stream rather than to a string.
 *
 * The rules for line break and indent are as follow:
 * - Object value:
 *     - if empty then print {} without indent and line break
 *     - if not empty the print '{', line break & indent, print one value per
 line
 *       and then unindent and line break and print '}'.
 * - Array value:
 *     - if empty then print [] without indent and line break
 *     - if the array contains no object value, empty array or some other value
 types,
 *       and all the values fit on one lines, then print the array on a single
 line.
 *     - otherwise, it the values do not fit on one line, or the array contains
 *       object or non empty array, then print one value per line.
 *
 * If the Value have comments then they are outputed according to their
 #CommentPlacement.
 *
 * \param indentation Each level will be indented by this amount extra.
 * \sa Reader, Value, Value::setComment()
 */
class JSON_API StyledStreamWriter {
public:
  StyledStreamWriter(std::string indentation = "\t");
  ~StyledStreamWriter() {}

public:
  /** \brief Serialize a Value in <a HREF="http://www.json.org">JSON</a> format.
   * \param out Stream to write to. (Can be ostringstream, e.g.)
   * \param root Value to serialize.
   * \note There is no point in deriving from Writer, since write() should not
   * return a value.
   */
  void write(std::ostream &out, const Value &root);

private:
  void writeValue(const Value &value);
  void writeArrayValue(const Value &value);
  bool isMultineArray(const Value &value);
  void pushValue(const std::string &value);
  void writeIndent();
  void writeWithIndent(const std::string &value);
  void indent();
  void unindent();
  void writeCommentBeforeValue(const Value &root);
  void writeCommentAfterValueOnSameLine(const Value &root);
  bool hasCommentForValue(const Value &value);
  static std::string normalizeEOL(const std::string &text);

  typedef std::vector<std::string> ChildValues;

  ChildValues childValues_;
  std::ostream *document_;
  std::string indentString_;
  int rightMargin_;
  std::string indentation_;
  bool addChildValues_;
};

#if defined(JSON_HAS_INT64)
std::string JSON_API valueToString(Int value);
std::string JSON_API valueToString(UInt value);
#endif // if defined(JSON_HAS_INT64)
std::string JSON_API valueToString(LargestInt value);
std::string JSON_API valueToString(LargestUInt value);
std::string JSON_API valueToString(double value);
std::string JSON_API valueToString(bool value);
std::string JSON_API valueToQuotedString(const char *value);

/// \brief Output using the StyledStreamWriter.
/// \see Json::operator>>()
JSON_API std::ostream &operator<<(std::ostream &, const Value &root);

} // namespace Json

#if defined(JSONCPP_DISABLE_DLL_INTERFACE_WARNING)
#pragma warning(pop)
#endif // if defined(JSONCPP_DISABLE_DLL_INTERFACE_WARNING)

#endif // JSON_WRITER_H_INCLUDED