finalcut/src/fstring.cpp

/***********************************************************************
* fstring.cpp - Unicode string class with UTF-8 support                *
*                                                                      *
* This file is part of the FINAL CUT widget toolkit                    *
*                                                                      *
* Copyright 2012-2021 Markus Gans                                      *
*                                                                      *
* FINAL CUT is free software; you can redistribute it and/or modify    *
* it under the terms of the GNU Lesser General Public License as       *
* published by the Free Software Foundation; either version 3 of       *
* the License, or (at your option) any later version.                  *
*                                                                      *
* FINAL CUT is distributed in the hope that it will be useful, but     *
* WITHOUT ANY WARRANTY; without even the implied warranty of           *
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the        *
* GNU Lesser General Public License for more details.                  *
*                                                                      *
* You should have received a copy of the GNU Lesser General Public     *
* License along with this program.  If not, see                        *
* <http://www.gnu.org/licenses/>.                                      *
***********************************************************************/

#include <algorithm>
#include <string>
#include <utility>
#include <vector>

#include "final/fapplication.h"
#include "final/flog.h"
#include "final/fstring.h"

namespace finalcut
{

// static class attributes
wchar_t       FString::null_char{L'\0'};
const wchar_t FString::const_null_char{L'\0'};

//----------------------------------------------------------------------
// class FString
//----------------------------------------------------------------------

// constructors and destructor
//----------------------------------------------------------------------
FString::FString (int len)
{
  if ( len > 0 )
    string = std::wstring(std::size_t(len), L'\0');
}

//----------------------------------------------------------------------
FString::FString (std::size_t len)
  : string{std::wstring(len, L'\0')}
{ }

//----------------------------------------------------------------------
FString::FString (std::size_t len, wchar_t c)
  : string{std::wstring(len, c)}
{ }

//----------------------------------------------------------------------
FString::FString (std::size_t len, const UniChar& c)
 : FString(len, wchar_t(c))
{ }

//----------------------------------------------------------------------
FString::FString (const FString& s)  // copy constructor
{
  if ( ! s.isEmpty() )
  {
    std::wstring copy(s.string);
    _assign (copy);
  }
}

//----------------------------------------------------------------------
FString::FString (FString&& s) noexcept  // move constructor
  : string{s.string}
{
  s.string.clear();
}

//----------------------------------------------------------------------
FString::FString (const std::wstring& s)
{
  if ( ! s.empty() )
  {
    std::wstring str(s);
    _assign (str);
  }
}

//----------------------------------------------------------------------
FString::FString (const wchar_t s[])
{
  if ( s )
  {
    std::wstring str(s);
    _assign (str);
  }
}

//----------------------------------------------------------------------
FString::FString (const std::string& s)
{
  if ( ! s.empty() )
  {
    auto wide_string = _toWideString(s.c_str());
    _assign(wide_string);
  }
}

//----------------------------------------------------------------------
FString::FString (const char s[])
{
  if ( s )
  {
    auto wide_string = _toWideString(s);
    _assign(wide_string);
  }
}

//----------------------------------------------------------------------
FString::FString (const UniChar& c)
{
  std::wstring str{ static_cast<wchar_t>(c) };
  _assign (str);
}

//----------------------------------------------------------------------
FString::FString (const wchar_t c)
{
  if ( c )
  {
    std::wstring str{ c };
    _assign (str);
  }
}

//----------------------------------------------------------------------
FString::FString (const char c)
{
  if ( c )
  {
    std::wstring str{ wchar_t(c & 0xff) };
    _assign (str);
  }
}

//----------------------------------------------------------------------
FString::~FString() = default;  // destructor


// FString operators
//----------------------------------------------------------------------
FString& FString::operator = (const FString& s)
{
  if ( &s != this )
  {
    std::wstring str{s.string};
    _assign (str);
  }

  return *this;
}

//----------------------------------------------------------------------
FString& FString::operator = (FString&& s) noexcept
{
  if ( &s != this )
  {
    string = s.string;
    s.string.clear();
  }

  return *this;
}

//----------------------------------------------------------------------
const FString& FString::operator += (const FString& s)
{
  string.append(s.string);
  return *this;
}

//----------------------------------------------------------------------
FString& FString::operator << (const FString& s)
{
  string.append(s.string);
  return *this;
}

//----------------------------------------------------------------------
FString& FString::operator << (const UniChar& c)
{
  FString s{static_cast<wchar_t>(c)};
  string.append(s.string);
  return *this;
}

//----------------------------------------------------------------------
FString& FString::operator << (const wchar_t c)
{
  FString s{c};
  string.append(s.string);
  return *this;
}

//----------------------------------------------------------------------
FString& FString::operator << (const char c)
{
  FString s{c};
  string.append(s.string);
  return *this;
}

//----------------------------------------------------------------------
const FString& FString::operator >> (FString& s) const
{
  s.string.append(string);
  return *this;
}

//----------------------------------------------------------------------
const FString& FString::operator >> (std::wstring& s) const
{
  s += string;
  return *this;
}

//----------------------------------------------------------------------
const FString& FString::operator >> (std::string& s) const
{
  s.append(toString());
  return *this;
}

//----------------------------------------------------------------------
const FString& FString::operator >> (wchar_t& c) const
{
  c = ( ! isEmpty() ) ? string[0] : L'\0';
  return *this;
}

//----------------------------------------------------------------------
const FString& FString::operator >> (char& c) const
{
  c = ( ! isEmpty() ) ? char(string[0] & 0xff) : '\0';
  return *this;
}

//----------------------------------------------------------------------
const FString& FString::operator >> (sInt16& num) const
{
  num = toShort();
  return *this;
}

//----------------------------------------------------------------------
const FString& FString::operator >> (uInt16& num) const
{
  num = toUShort();
  return *this;
}

//----------------------------------------------------------------------
const FString& FString::operator >> (sInt32& num) const
{
  num = toInt();
  return *this;
}

//----------------------------------------------------------------------
const FString& FString::operator >> (uInt32& num) const
{
  num = toUInt();
  return *this;
}

//----------------------------------------------------------------------
const FString& FString::operator >> (sInt64& num) const
{
  num = toLong();
  return *this;
}

//----------------------------------------------------------------------
const FString& FString::operator >> (uInt64& num) const
{
  num = toULong();
  return *this;
}

//----------------------------------------------------------------------
const FString& FString::operator >> (double& num) const
{
  num = toDouble();
  return *this;
}

//----------------------------------------------------------------------
const FString& FString::operator >> (float& num) const
{
  num = toFloat();
  return *this;
}

//----------------------------------------------------------------------
FString::operator bool () const
{
  return ! isEmpty();
}

//----------------------------------------------------------------------
const FString& FString::operator () () const
{
  return *this;
}


// public methods of FString
//----------------------------------------------------------------------
FString FString::clear()
{
  string.clear();
  return *this;
}

//----------------------------------------------------------------------
const wchar_t* FString::wc_str() const
{
  // Returns a constant wide character string

  return string.c_str();
}

//----------------------------------------------------------------------
wchar_t* FString::wc_str()
{
  // Returns a wide character string

  return const_cast<wchar_t*>(string.c_str());
}

//----------------------------------------------------------------------
const char* FString::c_str() const
{
  // Returns a constant c-string

  if ( ! isEmpty() )
  {
    char_string = _toCharString(string);
    return char_string.c_str();
  }
  else
    return "";
}

//----------------------------------------------------------------------
char* FString::c_str()
{
  // Returns a c-string

  if ( ! isEmpty() )
  {
    char_string = _toCharString(string);
    return const_cast<char*>(char_string.c_str());
  }
  else
    return const_cast<char*>("");
}

//----------------------------------------------------------------------
std::string FString::toString() const
{
  return c_str();
}

//----------------------------------------------------------------------
FString FString::toLower() const
{
  FString s{*this};
  auto to_lower = [] (wchar_t& c)
                  {
                    c = wchar_t(std::towlower(std::wint_t(c)));
                  };
  std::for_each (s.begin(), s.end(), to_lower);
  return s;
}

//----------------------------------------------------------------------
FString FString::toUpper() const
{
  FString s{*this};
  auto to_upper = [] (wchar_t& c)
                  {
                    c = wchar_t(std::towupper(std::wint_t(c)));
                  };
  std::for_each (s.begin(), s.end(), to_upper);
  return s;
}

//----------------------------------------------------------------------
sInt16 FString::toShort() const
{
  const long num = toLong();

  if ( num > SHRT_MAX )
    throw std::overflow_error ("overflow");

  if ( num < SHRT_MIN )
    throw std::underflow_error ("underflow");

  return static_cast<sInt16>(num);
}

//----------------------------------------------------------------------
uInt16 FString::toUShort() const
{
  const uLong num = toULong();

  if ( num > USHRT_MAX )
    throw std::overflow_error ("overflow");

  return static_cast<uInt16>(num);
}

//----------------------------------------------------------------------
int FString::toInt() const
{
  const long num = toLong();

  if ( num > INT_MAX )
    throw std::overflow_error ("overflow");

  if ( num < INT_MIN )
    throw std::underflow_error ("underflow");

  return static_cast<int>(num);
}

//----------------------------------------------------------------------
uInt FString::toUInt() const
{
  const uLong num = toULong();

  if ( num > UINT_MAX )
    throw std::overflow_error ("overflow");

  return static_cast<uInt>(num);
}

//----------------------------------------------------------------------
long FString::toLong() const
{
  bool neg{false};
  long num{0};
  long tenth_limit{LONG_MAX / 10};
  long tenth_limit_digit{LONG_MAX % 10};
  const FString s{trim()};
  const wchar_t* p = s.string.c_str();

  if ( ! p )
    throw std::invalid_argument ("null value");

  if ( ! *p )
    throw std::invalid_argument ("empty value");

  if ( *p == L'-' )
  {
    p++;
    neg = true;
    tenth_limit = -(LONG_MIN / 10);
    tenth_limit_digit += 1;
  }
  else if ( *p == L'+' )
  {
    p++;
  }

  while ( std::iswdigit(std::wint_t(*p)) )
  {
    auto d = uChar(*p - L'0');

    if ( num > tenth_limit
      || (num == tenth_limit && d > tenth_limit_digit) )
    {
      if ( neg )
        throw std::underflow_error ("underflow");
      else
        throw std::overflow_error ("overflow");
    }

    num = (num << 3) + (num << 1) + d;  // (10 * num) + d
    p++;
  }

  if ( *p != L'\0' && ! std::iswdigit(std::wint_t(*p)) )
    throw std::invalid_argument ("no valid number");

  if ( neg )
    num = (~num) + 1;

  return num;
}

//----------------------------------------------------------------------
uLong FString::toULong() const
{
  uLong num{0};
  const uLong tenth_limit{ULONG_MAX / 10};
  const uLong tenth_limit_digit{ULONG_MAX % 10};
  const FString s{trim()};
  const wchar_t* p = s.string.c_str();

  if ( ! p )
    throw std::invalid_argument ("null value");

  if ( ! *p )
    throw std::invalid_argument ("empty value");

  if ( *p == L'-' )
  {
    throw std::underflow_error ("underflow");
  }
  else if ( *p == L'+' )
  {
    p++;
  }

  while ( std::iswdigit(std::wint_t(*p)) )
  {
    const auto d = uChar(*p - L'0');

    if ( num > tenth_limit
      || (num == tenth_limit && d > tenth_limit_digit) )
    {
      throw std::overflow_error ("overflow");
    }

    num = (num << 3) + (num << 1) + d;  // (10 * num) + d
    p++;
  }

  if ( *p != L'\0' && ! std::iswdigit(std::wint_t(*p)) )
    throw std::invalid_argument ("no valid number");

  return num;
}

//----------------------------------------------------------------------
float FString::toFloat() const
{
  const double num = toDouble();

  if ( num > double(FLT_MAX) || num < double(-FLT_MAX) )
    throw std::overflow_error ("overflow");

  if ( std::fabs(num) < double(FLT_EPSILON) )  // num == 0.0f
    throw std::underflow_error ("underflow");

  return static_cast<float>(num);
}

//----------------------------------------------------------------------
double FString::toDouble() const
{
  if ( isEmpty() )
    throw std::invalid_argument ("null value");

  wchar_t* p{};
  const double ret = std::wcstod(string.c_str(), &p);

  if ( p != nullptr && *p != L'\0' )
    throw std::invalid_argument ("no valid floating point value");

  if ( errno == ERANGE )
  {
    if ( ret >= HUGE_VAL || ret <= -HUGE_VAL )
      throw std::overflow_error ("overflow");

    if ( std::fabs(ret) < DBL_EPSILON )  // ret == 0.0l
      throw std::underflow_error ("underflow");
  }

  return ret;
}

//----------------------------------------------------------------------
FString FString::ltrim() const
{
  // Handle empty string
  if ( isEmpty() )
    return *this;

  auto iter = string.begin();
  const auto last = string.end();

  while ( iter != last && std::iswspace(std::wint_t(*iter)) )
    ++iter;

  if ( iter != last )
    return std::wstring(iter, last);
  else
    return {};
}

//----------------------------------------------------------------------
FString FString::rtrim() const
{
  // Handle empty string
  if ( isEmpty() )
    return *this;

  const auto first = string.begin();
  auto iter = string.end() - 1;

  while ( iter != first && std::iswspace(std::wint_t(*iter)) )
    --iter;

  if ( first != iter )
    return std::wstring(first, iter + 1);
  else
    return {};
}

//----------------------------------------------------------------------
FString FString::trim() const
{
  // Handle NULL and empty string
  if ( isEmpty() )
    return *this;

  const FString s{ltrim()};
  return s.rtrim();
}

//----------------------------------------------------------------------
FString FString::left (std::size_t len) const
{
  // Handle empty and too long strings
  if ( isEmpty() || len > getLength() )
    return *this;

  return string.substr(0, len);
}

//----------------------------------------------------------------------
FString FString::right (std::size_t len) const
{
  // Handle empty and too long strings
  if ( isEmpty() || len > getLength() )
    return *this;

  return string.substr(string.size() - len, len);
}

//----------------------------------------------------------------------
FString FString::mid (std::size_t pos, std::size_t len) const
{
  // Handle empty string
  if ( isEmpty() )
    return *this;

  if ( pos == 0 )
    pos = 1;

  auto length = string.length();

  if ( pos <= length && pos + len > length )
    len = length - pos + 1;

  if ( pos > length || pos + len - 1 > length || len == 0 )
    return {};

  auto first = string.begin() + static_cast<difference_type>(pos) - 1;
  auto last = first + static_cast<difference_type>(len);
  return std::wstring(first, last);
}

//----------------------------------------------------------------------
FStringList FString::split (const FString& delimiter) const
{
  if ( isEmpty() )
    return {};

  const FString s{*this};
  FStringList string_list{};
  auto delimiter_length = delimiter.getLength();
  std::wstring::size_type first = 0;
  std::wstring::size_type last;

  while ( (last = s.string.find(delimiter.string, first)) != std::wstring::npos )
  {
    string_list.emplace_back(std::wstring(s.string, first, last - first));
    first = last + delimiter_length;
  }

  string_list.emplace_back(std::wstring(s.string, first));
  return string_list;
}

//----------------------------------------------------------------------
FString& FString::setString (const FString& s)
{
  std::wstring str{s.string};
  _assign (str);
  return *this;
}

//----------------------------------------------------------------------
FString& FString::setNumber (sInt64 num)
{
  std::array<wchar_t, 30> buf{};
  wchar_t* s = &buf[29];  // Pointer to the last character
  auto abs_num = static_cast<uInt64>(num);

  if ( num < 0 )
    abs_num = static_cast<uInt64>(-num);

  *s = '\0';

  do
  {
    *--s = L"0123456789"[abs_num % 10];
    abs_num /= 10;
  }
  while ( abs_num );

  if ( num < 0 )
    *--s = '-';

  std::wstring str{s};
  _assign (str);
  return *this;
}

//----------------------------------------------------------------------
FString& FString::setNumber (uInt64 num)
{
  wchar_t buf[30]{};
  wchar_t* s = &buf[29];  // Pointer to the last character
  *s = '\0';

  do
  {
    *--s = L"0123456789"[num % 10];
    num /= 10;
  }
  while ( num );

  std::wstring str{s};
  _assign (str);
  return *this;
}

//----------------------------------------------------------------------
FString& FString::setNumber (lDouble f_num, int precision)
{
  std::array<wchar_t, 20> format{};  // = "%.<precision>Lg"
  wchar_t* s = &format[0];
  *s++ = L'%';
  *s++ = L'.';

  // The precision can not have more than 2 digits
  if ( precision > 99 )
    precision = 99;

  if ( precision >= 10 )
  {
    // The precision value is 2 digits long
    *s++ = precision / 10 + L'0';
    *s++ = precision % 10 + L'0';
  }
  else
  {
    // The precision value has only 1 digit
    *s++ = precision + L'0';
  }

  *s++ = L'L';
  *s++ = L'g';
  *s = L'\0';

  return sprintf(format.data(), f_num);
}

//----------------------------------------------------------------------
FString& FString::setFormatedNumber (sInt64 num, char separator)
{
  int n{0};
  std::array<wchar_t, 30> buf{};
  wchar_t* s = &buf[29];  // Pointer to the last character
  auto abs_num = static_cast<uInt64>(num);

  if ( separator == 0 )
    separator = ' ';

  if ( num < 0 )
    abs_num = static_cast<uInt64>(-num);

  *s = L'\0';

  do
  {
    *--s = L"0123456789"[abs_num % 10];
    abs_num /= 10;
    n++;

    if ( abs_num && n % 3 == 0 )
      *--s = separator;
  }
  while ( abs_num );

  if ( num < 0 )
    *--s = '-';

  std::wstring str{s};
  _assign (str);
  return *this;
}

//----------------------------------------------------------------------
FString& FString::setFormatedNumber (uInt64 num, char separator)
{
  int n{0};
  wchar_t buf[30]{};
  wchar_t* s = &buf[29];  // Pointer to the last character
  *s = L'\0';

  if ( separator == 0 )
    separator = ' ';

  do
  {
    *--s = L"0123456789"[num % 10];
    num /= 10;
    n++;

    if ( num && n % 3 == 0 )
      *--s = separator;
  }
  while ( num );

  std::wstring str{s};
  _assign (str);
  return *this;
}

// FString operators
//----------------------------------------------------------------------
bool FString::operator < (const FString& s) const
{
  return string < s.string;
}

//----------------------------------------------------------------------
bool FString::operator <= (const FString& s) const
{
  return string <= s.string;
}

//----------------------------------------------------------------------
bool FString::operator == (const FString& s) const
{
  return string == s.string;
}

//----------------------------------------------------------------------
bool FString::operator != (const FString& s) const
{
  return ! ( *this == s );
}

//----------------------------------------------------------------------
bool FString::operator >= (const FString& s) const
{
  return string >= s.string;
}

//----------------------------------------------------------------------
bool FString::operator > (const FString& s) const
{
  return string > s.string;
}

//----------------------------------------------------------------------
const FString& FString::insert (const FString& s, int pos)
{
  if ( isNegative(pos) || uInt(pos) > string.length() )
    throw std::out_of_range("");

  string.insert(uInt(pos), s.string, 0 , s.getLength());
  return *this;
}

//----------------------------------------------------------------------
const FString& FString::insert (const FString& s, std::size_t pos)
{
  if ( pos > string.length() )
    throw std::out_of_range("");

  string.insert(uInt(pos), s.string, 0 , s.getLength());
  return *this;
}

//----------------------------------------------------------------------
FString FString::replace (const FString& from, const FString& to) const
{
  // Handle empty strings
  if ( isEmpty() || from.isEmpty() )
    return *this;

  FString s{*this};
  std::wstring::size_type pos{};

  while ( (pos = s.string.find(from.string, pos)) != std::wstring::npos )
  {
     s.string.replace (pos, from.getLength(), to.string);
     pos += to.getLength();
  }

  return s;
}

//----------------------------------------------------------------------
FString FString::replaceControlCodes() const
{
  FString s{*this};

  for (auto&& c : s)
  {
    if ( c <= L'\x1f' )
    {
      c += L'\x2400';
    }
    else if ( c == L'\x7f' )
    {
      c = L'\x2421';
    }
    else if ( c >= L'\x80' && c <= L'\x9f' )
    {
      c = L' ';
    }
    else if ( ! std::iswprint(std::wint_t(c)) )
      c = L' ';
  }

  return s;
}

//----------------------------------------------------------------------
FString FString::expandTabs (int tabstop) const
{
  if ( tabstop <= 0 )
    return *this;

  FString outstr{};
  const auto tab_split = split(L"\t");
  const auto last = tab_split.end() - 1;
  auto iter = tab_split.begin();

  while ( iter != tab_split.end() )
  {
    if ( iter != last )
    {
      const auto len = iter->getLength();
      const auto tab_len = std::size_t(tabstop);
      outstr += *iter + std::wstring(tab_len - (len % tab_len), L' ');
    }
    else
      outstr += *iter;

    ++iter;
  }

  return outstr;
}

//----------------------------------------------------------------------
FString FString::removeDel() const
{
  FString s{*this};
  std::size_t i{0};
  std::size_t count{0};

  for (auto&& c : s)
  {
    if ( c == 0x7f )
    {
      count++;
    }
    else if ( count > 0 )
    {
      count--;
    }
    else  // count == 0
    {
      s.string[i] = c;
      i++;
    }
  }

  s.string.erase(i);
  return s;
}


//----------------------------------------------------------------------
FString FString::removeBackspaces() const
{
  FString s{*this};
  std::size_t i{0};

  for (auto&& c : s)
  {
    if ( c != L'\b' )
    {
      s.string[i] = c;
      i++;
    }
    else if ( i > 0 )
    {
      i--;
    }
  }

  s.string.erase(i);
  return s;
}

//----------------------------------------------------------------------
const FString& FString::overwrite (const FString& s, int pos)
{
  if ( pos < 0 )
    return overwrite (s, 0);

  return overwrite (s, std::size_t(pos));
}

//----------------------------------------------------------------------
const FString& FString::overwrite (const FString& s, std::size_t pos)
{
  if ( pos > string.length() )
    pos = string.length();

  string.replace(pos, s.getLength(), s.string);
  return *this;
}

//----------------------------------------------------------------------
const FString& FString::remove (std::size_t pos, std::size_t len)
{
  auto length = string.length();

  if ( pos > length )
    return *this;

  if ( pos + len > length )
    len = length - pos;

  string.erase (pos, len);
  return *this;
}

//----------------------------------------------------------------------
bool FString::includes (const FString& s) const
{
  if ( s.isEmpty() )
    return false;

  return string.find(s.string) != std::wstring::npos;
}


// private methods of FString
//----------------------------------------------------------------------
inline void FString::_assign (std::wstring& s)
{
  if ( string == s )
    return;

  s.swap(string);
}

//----------------------------------------------------------------------
inline std::string FString::_toCharString (const std::wstring& s) const
{
  if ( s.empty() )
    return {};

  const wchar_t* src = s.c_str();
  auto state = std::mbstate_t();
  auto size = std::wcsrtombs(nullptr, &src, 0, &state) + 1;

  std::vector<char> dest(size);

  const auto mblength = std::wcsrtombs (dest.data(), &src, size, &state);

  if ( mblength == static_cast<std::size_t>(-1) && errno != EILSEQ )
  {
    return {};
  }

  return dest.data();
}

//----------------------------------------------------------------------
inline std::wstring FString::_toWideString (const std::string& s) const
{
  if ( s.empty() )
    return {};

  const char* src = s.c_str();
  auto state = std::mbstate_t();
  auto size = std::mbsrtowcs(nullptr, &src, 0, &state) + 1;

  if ( size == 0 )  // ...malformed UTF-8 string
    return {};

  std::vector<wchar_t> dest(size);

  const auto wide_length = std::mbsrtowcs (dest.data(), &src, size, &state);

  if ( wide_length == static_cast<std::size_t>(-1) )
  {
    if ( src != s.c_str() )
      return dest.data();
    else
    {
      return {};
    }
  }

  if ( wide_length == size )
    dest[size - 1] = '\0';

  if ( wide_length != 0 )
    return dest.data();
  else
    return {};
}


// FString non-member operators
//----------------------------------------------------------------------
FString operator + (const FString& s1, const FString& s2)
{
  auto tmp = s1.string + s2.string;
  return tmp;
}

//----------------------------------------------------------------------
std::ostream& operator << (std::ostream& outstr, const FString& s)
{
  const auto width = std::size_t(outstr.width());

  if ( s.string.length() > 0 )
  {
    outstr << s._toCharString(s.string).c_str();
  }
  else if ( width > 0 )
  {
    const FString fill_str{width, wchar_t(outstr.fill())};
    outstr << s._toCharString(fill_str.string).c_str();
  }

  return outstr;
}

//----------------------------------------------------------------------
std::istream& operator >> (std::istream& instr, FString& s)
{
  std::array<char, FString::INPBUFFER + 1> buf{};
  instr.getline (buf.data(), FString::INPBUFFER);
  auto wide_string = s._toWideString(buf.data());

  if ( ! wide_string.empty() )
  {
    s._assign (wide_string);
  }

  return instr;
}

//----------------------------------------------------------------------
std::wostream& operator << (std::wostream& outstr, const FString& s)
{
  const auto width = std::size_t(outstr.width());

  if ( s.string.length() > 0 )
  {
    outstr << s.string;
  }
  else if ( width > 0 )
  {
    const FString fill_str{width, outstr.fill()};
    outstr << fill_str.string;
  }

  return outstr;
}

//----------------------------------------------------------------------
std::wistream& operator >> (std::wistream& instr, FString& s)
{
  std::array<wchar_t, FString::INPBUFFER + 1> buf{};
  instr.getline (buf.data(), FString::INPBUFFER);
  std::wstring str(buf.data());
  s._assign (str);
  return instr;
}

}  // namespace finalcut