text: // Copyright (c) 2009-2010 Satoshi Nakamoto
  // Copyright (c) 2009-2014 The Bitcoin developers
  // Copyright (c) 2017 The PIVX Developers 
  // Distributed under the MIT software license, see the accompanying
  // file COPYING or http://www.opensource.org/licenses/mit-license.php.
  
  /**
   * Utilities for converting data from/to strings.
   */
  #ifndef BITCOIN_UTILSTRENCODINGS_H
  #define BITCOIN_UTILSTRENCODINGS_H
  
  #include "allocators.h"
  #include <stdint.h>
  #include <string>
  #include <vector>
  
  #define BEGIN(a) ((char*)&(a))
  #define END(a) ((char*)&((&(a))[1]))
  #define UBEGIN(a) ((unsigned char*)&(a))
  #define UEND(a) ((unsigned char*)&((&(a))[1]))
  #define ARRAYLEN(array) (sizeof(array) / sizeof((array)[0]))
  
  /** This is needed because the foreach macro can't get over the comma in pair<t1, t2> */
  #define PAIRTYPE(t1, t2) std::pair<t1, t2>
  
  /** Used by SanitizeString() */
  enum SafeChars
  {
      SAFE_CHARS_DEFAULT, //!< The full set of allowed chars
      SAFE_CHARS_UA_COMMENT, //!< BIP-0014 subset
      SAFE_CHARS_FILENAME, //!< Chars allowed in filenames
  };
  
  /**
  * Remove unsafe chars. Safe chars chosen to allow simple messages/URLs/email
  * addresses, but avoid anything even possibly remotely dangerous like & or >
  * @param[in] str    The string to sanitize
  * @param[in] rule   The set of safe chars to choose (default: least restrictive)
  * @return           A new string without unsafe chars
  */
  std::string SanitizeString(const std::string& str, int rule = SAFE_CHARS_DEFAULT);
  std::vector<unsigned char> ParseHex(const char* psz);
  std::vector<unsigned char> ParseHex(const std::string& str);
  signed char HexDigit(char c);
  bool IsHex(const std::string& str);
  std::vector<unsigned char> DecodeBase64(const char* p, bool* pfInvalid = NULL);
  std::string DecodeBase64(const std::string& str);
  std::string EncodeBase64(const unsigned char* pch, size_t len);
  std::string EncodeBase64(const std::string& str);
  SecureString DecodeBase64Secure(const SecureString& input);
  SecureString EncodeBase64Secure(const SecureString& input);
  std::vector<unsigned char> DecodeBase32(const char* p, bool* pfInvalid = NULL);
  std::string DecodeBase32(const std::string& str);
  std::string EncodeBase32(const unsigned char* pch, size_t len);
  std::string EncodeBase32(const std::string& str);
  
  std::string i64tostr(int64_t n);
  std::string itostr(int n);
  int64_t atoi64(const char* psz);
  int64_t atoi64(const std::string& str);
  int atoi(const std::string& str);
  
  /**
   * Convert string to signed 32-bit integer with strict parse error feedback.
   * @returns true if the entire string could be parsed as valid integer,
   *   false if not the entire string could be parsed or when overflow or underflow occurred.
   */
  bool ParseInt32(const std::string& str, int32_t *out);
  
  /**
   * Convert string to signed 64-bit integer with strict parse error feedback.
   * @returns true if the entire string could be parsed as valid integer,
   *   false if not the entire string could be parsed or when overflow or underflow occurred.
   */
  bool ParseInt64(const std::string& str, int64_t *out);
  
  /**
   * Convert string to double with strict parse error feedback.
   * @returns true if the entire string could be parsed as valid double,
   *   false if not the entire string could be parsed or when overflow or underflow occurred.
   */
  bool ParseDouble(const std::string& str, double *out);
  
  template <typename T>
  std::string HexStr(const T itbegin, const T itend, bool fSpaces = false)
  {
      std::string rv;
      static const char hexmap[16] = {'0', '1', '2', '3', '4', '5', '6', '7',
          '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'};
      rv.reserve((itend - itbegin) * 3);
      for (T it = itbegin; it < itend; ++it) {
          unsigned char val = (unsigned char)(*it);
          if (fSpaces && it != itbegin)
              rv.push_back(' ');
          rv.push_back(hexmap[val >> 4]);
          rv.push_back(hexmap[val & 15]);
      }
  
      return rv;
  }
  
  template <typename T>
  inline std::string HexStr(const T& vch, bool fSpaces = false)
  {
      return HexStr(vch.begin(), vch.end(), fSpaces);
  }
  
  /** Reverse the endianess of a string */
  inline std::string ReverseEndianString(std::string in)
  {
      std::string out = "";
      unsigned int s = in.size();
      for (unsigned int i = 0; i < s; i += 2) {
          out += in.substr(s - i - 2, 2);
      }
  
      return out;
  }
  
  /**
   * Format a paragraph of text to a fixed width, adding spaces for
   * indentation to any added line.
   */
  std::string FormatParagraph(const std::string in, size_t width = 79, size_t indent = 0);
  
  /**
   * Timing-attack-resistant comparison.
   * Takes time proportional to length
   * of first argument.
   */
  template <typename T>
  bool TimingResistantEqual(const T& a, const T& b)
  {
      if (b.size() == 0) return a.size() == 0;
      size_t accumulator = a.size() ^ b.size();
      for (size_t i = 0; i < a.size(); i++)
          accumulator |= a[i] ^ b[i % b.size()];
      return accumulator == 0;
  }
  
  #endif // BITCOIN_UTILSTRENCODINGS_H
  