Mini Shell

"use strict"

var defaults = require('defaults')
var combining = require('./combining')

var DEFAULTS = {
  nul: 0,
  control: 0
}

module.exports = function wcwidth(str) {
  return wcswidth(str, DEFAULTS)
}

module.exports.config = function(opts) {
  opts = defaults(opts || {}, DEFAULTS)
  return function wcwidth(str) {
    return wcswidth(str, opts)
  }
}

/*
 *  The following 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 characters are encoded in ISO 10646.
*/

function wcswidth(str, opts) {
  if (typeof str !== 'string') return wcwidth(str, opts)

  var s = 0
  for (var i = 0; i < str.length; i++) {
    var n = wcwidth(str.charCodeAt(i), opts)
    if (n < 0) return -1
    s += n
  }

  return s
}

function wcwidth(ucs, opts) {
  // test for 8-bit control characters
  if (ucs === 0) return opts.nul
  if (ucs < 32 || (ucs >= 0x7f && ucs < 0xa0)) return opts.control

  // binary search in table of non-spacing characters
  if (bisearch(ucs)) 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)));
}

function bisearch(ucs) {
  var min = 0
  var max = combining.length - 1
  var mid

  if (ucs < combining[0][0] || ucs > combining[max][1]) return false

  while (max >= min) {
    mid = Math.floor((min + max) / 2)
    if (ucs > combining[mid][1]) min = mid + 1
    else if (ucs < combining[mid][0]) max = mid - 1
    else return true
  }

  return false
}