FTXUI/src/ftxui/screen/wcwidth.cpp

// Copyright 2020 Arthur Sonzogni. All rights reserved.
// Use of this source code is governed by the MIT license that can be found in
// the LICENSE file.

/*
 * This is an implementation of wcwidth() and wcswidth() (defined in
 * IEEE Std 1002.1-2001) for Unicode.
 *
 * http://www.opengroup.org/onlinepubs/007904975/functions/wcwidth.html
 * http://www.opengroup.org/onlinepubs/007904975/functions/wcswidth.html
 *
 * In fixed-width output devices, Latin characters all occupy a single
 * "cell" position of equal width, whereas ideographic CJK characters
 * occupy two such cells. Interoperability between terminal-line
 * applications and (teletype-style) character terminals using the
 * UTF-8 encoding requires agreement on which character should advance
 * the cursor by how many cell positions. No established formal
 * standards exist at present on which Unicode character shall occupy
 * how many cell positions on character terminals. These routines are
 * a first attempt of defining such behavior based on simple rules
 * applied to data provided by the Unicode Consortium.
 *
 * For some graphical characters, the Unicode standard explicitly
 * defines a character-cell width via the definition of the East Asian
 * FullWidth (F), Wide (W), Half-width (H), and Narrow (Na) classes.
 * In all these cases, there is no ambiguity about which width a
 * terminal shall use. For characters in the East Asian Ambiguous (A)
 * class, the width choice depends purely on a preference of backward
 * compatibility with either historic CJK or Western practice.
 * Choosing single-width for these characters is easy to justify as
 * the appropriate long-term solution, as the CJK practice of
 * displaying these characters as double-width comes from historic
 * implementation simplicity (8-bit encoded characters were displayed
 * single-width and 16-bit ones double-width, even for Greek,
 * Cyrillic, etc.) and not any typographic considerations.
 *
 * Much less clear is the choice of width for the Not East Asian
 * (Neutral) class. Existing practice does not dictate a width for any
 * of these characters. It would nevertheless make sense
 * typographically to allocate two character cells to characters such
 * as for instance EM SPACE or VOLUME INTEGRAL, which cannot be
 * represented adequately with a single-width glyph. The following
 * routines at present merely assign a single-cell width to all
 * neutral characters, in the interest of simplicity. This is not
 * entirely satisfactory and should be reconsidered before
 * establishing a formal standard in this area. At the moment, the
 * decision which Not East Asian (Neutral) characters should be
 * represented by double-width glyphs cannot yet be answered by
 * applying a simple rule from the Unicode database content. Setting
 * up a proper standard for the behavior of UTF-8 character terminals
 * will require a careful analysis not only of each Unicode character,
 * but also of each presentation form, something the author of these
 * routines has avoided to do so far.
 *
 * http://www.unicode.org/unicode/reports/tr11/
 *
 * Markus Kuhn -- 2007-05-26 (Unicode 5.0)
 *
 * Permission to use, copy, modify, and distribute this software
 * for any purpose and without fee is hereby granted. The author
 * disclaims all warranties with regard to this software.
 *
 * Latest version: http://www.cl.cam.ac.uk/~mgk25/ucs/wcwidth.c
 */

#include <wchar.h>

#include "ftxui/screen/string.hpp"

namespace ftxui {

namespace {
struct interval {
  int first;
  int last;
};

/* auxiliary function for binary search in interval table */
int bisearch(wchar_t ucs, const struct interval* table, int max) {
  int min = 0;
  int mid;

  if (ucs < table[0].first || ucs > table[max].last)
    return 0;
  while (max >= min) {
    mid = (min + max) / 2;
    if (ucs > table[mid].last)
      min = mid + 1;
    else if (ucs < table[mid].first)
      max = mid - 1;
    else
      return 1;
  }

  return 0;
}
}  // namespace

/* The following two functions define the column width of an ISO 10646
 * character as follows:
 *
 *    - The null character (U+0000) has a column width of 0.
 *
 *    - Other C0/C1 control characters and DEL will lead to a return
 *      value of -1.
 *
 *    - Non-spacing and enclosing combining characters (general
 *      category code Mn or Me in the Unicode database) have a
 *      column width of 0.
 *
 *    - SOFT HYPHEN (U+00AD) has a column width of 1.
 *
 *    - Other format characters (general category code Cf in the Unicode
 *      database) and ZERO WIDTH SPACE (U+200B) have a column width of 0.
 *
 *    - Hangul Jamo medial vowels and final consonants (U+1160-U+11FF)
 *      have a column width of 0.
 *
 *    - Spacing characters in the East Asian Wide (W) or East Asian
 *      Full-width (F) category as defined in Unicode Technical
 *      Report #11 have a column width of 2.
 *
 *    - All remaining characters (including all printable
 *      ISO 8859-1 and WGL4 characters, Unicode control characters,
 *      etc.) have a column width of 1.
 *
 * This implementation assumes that wchar_t characters are encoded
 * in ISO 10646.
 */

int wchar_width(wchar_t ucs) {
  /* sorted list of non-overlapping intervals of non-spacing characters */
  /* generated by "uniset +cat=Me +cat=Mn +cat=Cf -00AD +1160-11FF +200B c" */
  static const struct interval combining[] = {
      {0x0300, 0x036F},   {0x0483, 0x0486},   {0x0488, 0x0489},
      {0x0591, 0x05BD},   {0x05BF, 0x05BF},   {0x05C1, 0x05C2},
      {0x05C4, 0x05C5},   {0x05C7, 0x05C7},   {0x0600, 0x0603},
      {0x0610, 0x0615},   {0x064B, 0x065E},   {0x0670, 0x0670},
      {0x06D6, 0x06E4},   {0x06E7, 0x06E8},   {0x06EA, 0x06ED},
      {0x070F, 0x070F},   {0x0711, 0x0711},   {0x0730, 0x074A},
      {0x07A6, 0x07B0},   {0x07EB, 0x07F3},   {0x0901, 0x0902},
      {0x093C, 0x093C},   {0x0941, 0x0948},   {0x094D, 0x094D},
      {0x0951, 0x0954},   {0x0962, 0x0963},   {0x0981, 0x0981},
      {0x09BC, 0x09BC},   {0x09C1, 0x09C4},   {0x09CD, 0x09CD},
      {0x09E2, 0x09E3},   {0x0A01, 0x0A02},   {0x0A3C, 0x0A3C},
      {0x0A41, 0x0A42},   {0x0A47, 0x0A48},   {0x0A4B, 0x0A4D},
      {0x0A70, 0x0A71},   {0x0A81, 0x0A82},   {0x0ABC, 0x0ABC},
      {0x0AC1, 0x0AC5},   {0x0AC7, 0x0AC8},   {0x0ACD, 0x0ACD},
      {0x0AE2, 0x0AE3},   {0x0B01, 0x0B01},   {0x0B3C, 0x0B3C},
      {0x0B3F, 0x0B3F},   {0x0B41, 0x0B43},   {0x0B4D, 0x0B4D},
      {0x0B56, 0x0B56},   {0x0B82, 0x0B82},   {0x0BC0, 0x0BC0},
      {0x0BCD, 0x0BCD},   {0x0C3E, 0x0C40},   {0x0C46, 0x0C48},
      {0x0C4A, 0x0C4D},   {0x0C55, 0x0C56},   {0x0CBC, 0x0CBC},
      {0x0CBF, 0x0CBF},   {0x0CC6, 0x0CC6},   {0x0CCC, 0x0CCD},
      {0x0CE2, 0x0CE3},   {0x0D41, 0x0D43},   {0x0D4D, 0x0D4D},
      {0x0DCA, 0x0DCA},   {0x0DD2, 0x0DD4},   {0x0DD6, 0x0DD6},
      {0x0E31, 0x0E31},   {0x0E34, 0x0E3A},   {0x0E47, 0x0E4E},
      {0x0EB1, 0x0EB1},   {0x0EB4, 0x0EB9},   {0x0EBB, 0x0EBC},
      {0x0EC8, 0x0ECD},   {0x0F18, 0x0F19},   {0x0F35, 0x0F35},
      {0x0F37, 0x0F37},   {0x0F39, 0x0F39},   {0x0F71, 0x0F7E},
      {0x0F80, 0x0F84},   {0x0F86, 0x0F87},   {0x0F90, 0x0F97},
      {0x0F99, 0x0FBC},   {0x0FC6, 0x0FC6},   {0x102D, 0x1030},
      {0x1032, 0x1032},   {0x1036, 0x1037},   {0x1039, 0x1039},
      {0x1058, 0x1059},   {0x1160, 0x11FF},   {0x135F, 0x135F},
      {0x1712, 0x1714},   {0x1732, 0x1734},   {0x1752, 0x1753},
      {0x1772, 0x1773},   {0x17B4, 0x17B5},   {0x17B7, 0x17BD},
      {0x17C6, 0x17C6},   {0x17C9, 0x17D3},   {0x17DD, 0x17DD},
      {0x180B, 0x180D},   {0x18A9, 0x18A9},   {0x1920, 0x1922},
      {0x1927, 0x1928},   {0x1932, 0x1932},   {0x1939, 0x193B},
      {0x1A17, 0x1A18},   {0x1B00, 0x1B03},   {0x1B34, 0x1B34},
      {0x1B36, 0x1B3A},   {0x1B3C, 0x1B3C},   {0x1B42, 0x1B42},
      {0x1B6B, 0x1B73},   {0x1DC0, 0x1DCA},   {0x1DFE, 0x1DFF},
      {0x200B, 0x200F},   {0x202A, 0x202E},   {0x2060, 0x2063},
      {0x206A, 0x206F},   {0x20D0, 0x20EF},   {0x302A, 0x302F},
      {0x3099, 0x309A},   {0xA806, 0xA806},   {0xA80B, 0xA80B},
      {0xA825, 0xA826},   {0xFB1E, 0xFB1E},   {0xFE00, 0xFE0F},
      {0xFE20, 0xFE23},   {0xFEFF, 0xFEFF},   {0xFFF9, 0xFFFB},
      {0x10A01, 0x10A03}, {0x10A05, 0x10A06}, {0x10A0C, 0x10A0F},
      {0x10A38, 0x10A3A}, {0x10A3F, 0x10A3F}, {0x1D167, 0x1D169},
      {0x1D173, 0x1D182}, {0x1D185, 0x1D18B}, {0x1D1AA, 0x1D1AD},
      {0x1D242, 0x1D244}, {0xE0001, 0xE0001}, {0xE0020, 0xE007F},
      {0xE0100, 0xE01EF}};

  /* test for 8-bit control characters */
  if (ucs == 0)
    return 0;
  if (ucs < 32 || (ucs >= 0x7f && ucs < 0xa0))
    return -1;

  /* binary search in table of non-spacing characters */
  if (bisearch(ucs, combining, sizeof(combining) / sizeof(struct interval) - 1))
    return 0;

  /* if we arrive here, ucs is not a combining or C0/C1 control character */

  return 1 +
         (ucs >= 0x1100 &&
          (ucs <= 0x115f || /* Hangul Jamo init. consonants */
           ucs == 0x2329 || ucs == 0x232a ||
           (ucs >= 0x2e80 && ucs <= 0xa4cf && ucs != 0x303f) || /* CJK ... Yi */
           (ucs >= 0xac00 && ucs <= 0xd7a3) || /* Hangul Syllables */
           (ucs >= 0xf900 &&
            ucs <= 0xfaff) || /* CJK Compatibility Ideographs */
           (ucs >= 0xfe10 && ucs <= 0xfe19) || /* Vertical forms */
           (ucs >= 0xfe30 && ucs <= 0xfe6f) || /* CJK Compatibility Forms */
           (ucs >= 0xff00 && ucs <= 0xff60) || /* Fullwidth Forms */
           (ucs >= 0xffe0 && ucs <= 0xffe6) ||
           (ucs >= 0x20000 && ucs <= 0x2fffd) ||
           (ucs >= 0x30000 && ucs <= 0x3fffd)));
}

/*
 * The following functions are the same as mk_wcwidth() and
 * mk_wcswidth(), except that spacing characters in the East Asian
 * Ambiguous (A) category as defined in Unicode Technical Report #11
 * have a column width of 2. This variant might be useful for users of
 * CJK legacy encodings who want to migrate to UCS without changing
 * the traditional terminal character-width behaviour. It is not
 * otherwise recommended for general use.
 */
int wchar_width_cjk(wchar_t ucs) {
  /* sorted list of non-overlapping intervals of East Asian Ambiguous
   * characters, generated by "uniset +WIDTH-A -cat=Me -cat=Mn -cat=Cf c" */
  static const struct interval ambiguous[] = {
      {0x00A1, 0x00A1}, {0x00A4, 0x00A4},   {0x00A7, 0x00A8},
      {0x00AA, 0x00AA}, {0x00AE, 0x00AE},   {0x00B0, 0x00B4},
      {0x00B6, 0x00BA}, {0x00BC, 0x00BF},   {0x00C6, 0x00C6},
      {0x00D0, 0x00D0}, {0x00D7, 0x00D8},   {0x00DE, 0x00E1},
      {0x00E6, 0x00E6}, {0x00E8, 0x00EA},   {0x00EC, 0x00ED},
      {0x00F0, 0x00F0}, {0x00F2, 0x00F3},   {0x00F7, 0x00FA},
      {0x00FC, 0x00FC}, {0x00FE, 0x00FE},   {0x0101, 0x0101},
      {0x0111, 0x0111}, {0x0113, 0x0113},   {0x011B, 0x011B},
      {0x0126, 0x0127}, {0x012B, 0x012B},   {0x0131, 0x0133},
      {0x0138, 0x0138}, {0x013F, 0x0142},   {0x0144, 0x0144},
      {0x0148, 0x014B}, {0x014D, 0x014D},   {0x0152, 0x0153},
      {0x0166, 0x0167}, {0x016B, 0x016B},   {0x01CE, 0x01CE},
      {0x01D0, 0x01D0}, {0x01D2, 0x01D2},   {0x01D4, 0x01D4},
      {0x01D6, 0x01D6}, {0x01D8, 0x01D8},   {0x01DA, 0x01DA},
      {0x01DC, 0x01DC}, {0x0251, 0x0251},   {0x0261, 0x0261},
      {0x02C4, 0x02C4}, {0x02C7, 0x02C7},   {0x02C9, 0x02CB},
      {0x02CD, 0x02CD}, {0x02D0, 0x02D0},   {0x02D8, 0x02DB},
      {0x02DD, 0x02DD}, {0x02DF, 0x02DF},   {0x0391, 0x03A1},
      {0x03A3, 0x03A9}, {0x03B1, 0x03C1},   {0x03C3, 0x03C9},
      {0x0401, 0x0401}, {0x0410, 0x044F},   {0x0451, 0x0451},
      {0x2010, 0x2010}, {0x2013, 0x2016},   {0x2018, 0x2019},
      {0x201C, 0x201D}, {0x2020, 0x2022},   {0x2024, 0x2027},
      {0x2030, 0x2030}, {0x2032, 0x2033},   {0x2035, 0x2035},
      {0x203B, 0x203B}, {0x203E, 0x203E},   {0x2074, 0x2074},
      {0x207F, 0x207F}, {0x2081, 0x2084},   {0x20AC, 0x20AC},
      {0x2103, 0x2103}, {0x2105, 0x2105},   {0x2109, 0x2109},
      {0x2113, 0x2113}, {0x2116, 0x2116},   {0x2121, 0x2122},
      {0x2126, 0x2126}, {0x212B, 0x212B},   {0x2153, 0x2154},
      {0x215B, 0x215E}, {0x2160, 0x216B},   {0x2170, 0x2179},
      {0x2190, 0x2199}, {0x21B8, 0x21B9},   {0x21D2, 0x21D2},
      {0x21D4, 0x21D4}, {0x21E7, 0x21E7},   {0x2200, 0x2200},
      {0x2202, 0x2203}, {0x2207, 0x2208},   {0x220B, 0x220B},
      {0x220F, 0x220F}, {0x2211, 0x2211},   {0x2215, 0x2215},
      {0x221A, 0x221A}, {0x221D, 0x2220},   {0x2223, 0x2223},
      {0x2225, 0x2225}, {0x2227, 0x222C},   {0x222E, 0x222E},
      {0x2234, 0x2237}, {0x223C, 0x223D},   {0x2248, 0x2248},
      {0x224C, 0x224C}, {0x2252, 0x2252},   {0x2260, 0x2261},
      {0x2264, 0x2267}, {0x226A, 0x226B},   {0x226E, 0x226F},
      {0x2282, 0x2283}, {0x2286, 0x2287},   {0x2295, 0x2295},
      {0x2299, 0x2299}, {0x22A5, 0x22A5},   {0x22BF, 0x22BF},
      {0x2312, 0x2312}, {0x2460, 0x24E9},   {0x24EB, 0x254B},
      {0x2550, 0x2573}, {0x2580, 0x258F},   {0x2592, 0x2595},
      {0x25A0, 0x25A1}, {0x25A3, 0x25A9},   {0x25B2, 0x25B3},
      {0x25B6, 0x25B7}, {0x25BC, 0x25BD},   {0x25C0, 0x25C1},
      {0x25C6, 0x25C8}, {0x25CB, 0x25CB},   {0x25CE, 0x25D1},
      {0x25E2, 0x25E5}, {0x25EF, 0x25EF},   {0x2605, 0x2606},
      {0x2609, 0x2609}, {0x260E, 0x260F},   {0x2614, 0x2615},
      {0x261C, 0x261C}, {0x261E, 0x261E},   {0x2640, 0x2640},
      {0x2642, 0x2642}, {0x2660, 0x2661},   {0x2663, 0x2665},
      {0x2667, 0x266A}, {0x266C, 0x266D},   {0x266F, 0x266F},
      {0x273D, 0x273D}, {0x2776, 0x277F},   {0xE000, 0xF8FF},
      {0xFFFD, 0xFFFD}, {0xF0000, 0xFFFFD}, {0x100000, 0x10FFFD}};

  /* binary search in table of non-spacing characters */
  if (bisearch(ucs, ambiguous, sizeof(ambiguous) / sizeof(struct interval) - 1))
    return 2;

  return wchar_width(ucs);
}

int wstring_width(const std::wstring& text) {
  int width = 0;

  for (const wchar_t& it : text) {
    int w = wchar_width(it);
    if (w < 0)
      return -1;
    width += w;
  }
  return width;
}

int wstring_width_cjk(const std::wstring& text) {
  int width = 0;

  for (const wchar_t& it : text) {
    int w = wchar_width_cjk(it);
    if (w < 0)
      return -1;
    width += w;
  }
  return width;
}

}  // namespace ftxui