utf16.js

   1 if (typeof define !== 'function') { var define = require('amdefine')(module) }
   2
   3 define(function(require) {
   4
   5 var utf16 = function(string) {
   6     this.string = string;
   7     this.length = utf16.strlen(string);
   8 };
   9
  10 utf16.decode = function(string, points) {
  11     if (typeof points === "undefined")
  12         points = [];
  13
  14     for (var i = 0, e = string.length; i != e; ++i) {
  15         var unit = string.charCodeAt(i);
  16         var part = unit & 0xfc00;
  17         if (part == 0xdc00)
  18             return null;
  19         else if (part != 0xd800)
  20             points.push(unit);
  21         else if (++i == e)
  22             return null;
  23         else {
  24             var next = string.charCodeAt(i);
  25             if ((next & 0xfc00) != 0xdc00)
  26                 return null;
  27             points.push(0x10000 | (unit & 0x03ff) << 10 | next & 0x03ff);
  28         }
  29     }
  30
  31     return points;
  32 };
  33
  34 utf16.encode = function(points) {
  35     var units = [];
  36     for (var i = 0, e = points.length; i != e; ++i) {
  37         var point = points[i];
  38         if (point < 0x10000)
  39             units.push(point);
  40         else {
  41             point -= 0x10000;
  42             units.push(0xd800 | (0xffc00 & point) >> 10, 0xdc00 | 0x03ff & point);
  43         }
  44     } return String.fromCharCode.apply(String, units);
  45 };
  46
  47 utf16.fromCharCode = function() {
  48     return new utf16(utf16.encode(arguments), arguments.length);
  49 };
  50
  51 utf16.adjust = function(mode, string, after) {
  52     var before = after.slice();
  53     var offset = 0, index = 0;
  54
  55     var check = function() {
  56         var from = mode ? index : offset;
  57         var to = mode ? offset : index;
  58
  59         for (var o = 0, l = after.length; o != l; ++o)
  60             if (before[o] == from) {
  61                 before[o] = null;
  62                 after[o] = to;
  63             }
  64     };
  65
  66     for (var e = string.length; index != e; ++index) {
  67         check();
  68
  69         var unit = string.charCodeAt(index);
  70         var part = unit & 0xfc00;
  71
  72         if (part == 0xdc00)
  73             return null;
  74         else if (part != 0xd800);
  75         else if (++index == e)
  76             return null;
  77         else {
  78             var next = string.charCodeAt(index);
  79             if ((next & 0xfc00) != 0xdc00)
  80                 return null;
  81         }
  82
  83         ++offset;
  84     }
  85
  86     check();
  87     return after;
  88 };
  89
  90 utf16.point2unit = function(string, offsets) {
  91     return utf16.adjust(false, string, offsets);
  92 };
  93
  94 utf16.unit2point = function(string, offsets) {
  95     return utf16.adjust(true, string, offsets);
  96 };
  97
  98 utf16.charAt = function(string, offset) {
  99     return utf16.substring(string, offset, offset + 1);
 100 };
 101
 102 utf16.charCodeAt = function(string, offset) {
 103     var char = utf16.charAt(string, offset);
 104     if (char.length != 2)
 105         return char.charCodeAt(0);
 106     return 0x10000 | (char.charCodeAt(0) & 0x03ff) << 10 | char.charCodeAt(1) & 0x03ff
 107 };
 108
 109 utf16.strlen = function(string) {
 110     return utf16.unit2point(string, [string.length])[0];
 111 };
 112
 113 utf16.substr = function(string, start, length) {
 114     var stop;
 115     if (typeof length !== "undefined")
 116         stop = start + length;
 117     return utf16.substring(string, start, stop);
 118 };
 119
 120 utf16.substring = function(string, start, stop) {
 121     var range = utf16.point2unit(string, [start, stop]);
 122     return string.substring(range[0], range[1]);
 123 };
 124
 125 utf16.prototype.charAt = function(index) {
 126     return new utf16(utf16.charAt(this.string, index));
 127 };
 128
 129 utf16.prototype.charCodeAt = function(index) {
 130     return utf16.charCodeAt(this.string, index);
 131 };
 132
 133 utf16.prototype.substr = function(start, length) {
 134     return new utf16(utf16.substr(this.string, start, length));
 135 };
 136
 137 utf16.prototype.substring = function(start, end) {
 138     return new utf16(utf16.substring(this.string, start, end));
 139 };
 140
 141 utf16.prototype.toString = function() {
 142     return this.string;
 143 };
 144
 145 return utf16;
 146
 147 });