[utf16js.git] / utf16.js

/* utf16js - easy interfaces for Unicode compliance
 * Copyright (C) 2012  Jay Freeman (saurik)
*/

/* Modified BSD License {{{ */
/*
 *        Redistribution and use in source and binary
 * forms, with or without modification, are permitted
 * provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the
 *    above copyright notice, this list of conditions
 *    and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the
 *    above copyright notice, this list of conditions
 *    and the following disclaimer in the documentation
 *    and/or other materials provided with the
 *    distribution.
 * 3. The name of the author may not be used to endorse
 *    or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS''
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING,
 * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
 * TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/* }}} */

if (typeof define !== 'function') { var define = require('amdefine')(module) }

define([], function() {

var utf16 = function(string) {
    this.string = string;
    this.length = utf16.strlen(string);
};

utf16.decode = function(string, points) {
    if (typeof points === "undefined")
        points = [];

    for (var i = 0, e = string.length; i != e; ++i) {
        var unit = string.charCodeAt(i);
        var part = unit & 0xfc00;
        if (part == 0xdc00)
            return null;
        else if (part != 0xd800)
            points.push(unit);
        else if (++i == e)
            return null;
        else {
            var next = string.charCodeAt(i);
            if ((next & 0xfc00) != 0xdc00)
                return null;
            points.push(0x10000 | (unit & 0x03ff) << 10 | next & 0x03ff);
        }
    }

    return points;
};

utf16.encode = function(points) {
    var units = [];
    for (var i = 0, e = points.length; i != e; ++i) {
        var point = points[i];
        if (point < 0x10000)
            units.push(point);
        else {
            point -= 0x10000;
            units.push(0xd800 | (0xffc00 & point) >> 10, 0xdc00 | 0x03ff & point);
        }
    } return String.fromCharCode.apply(String, units);
};

utf16.fromCharCode = function() {
    return new utf16(utf16.encode(arguments), arguments.length);
};

utf16.adjust = function(mode, string, after) {
    var before = after.slice();
    var offset = 0, index = 0;

    var check = function() {
        var from = mode ? index : offset;
        var to = mode ? offset : index;

        for (var o = 0, l = after.length; o != l; ++o)
            if (before[o] == from) {
                before[o] = null;
                after[o] = to;
            }
    };

    for (var e = string.length; index != e; ++index) {
        check();

        var unit = string.charCodeAt(index);
        var part = unit & 0xfc00;

        if (part == 0xdc00)
            return null;
        else if (part != 0xd800);
        else if (++index == e)
            return null;
        else {
            var next = string.charCodeAt(index);
            if ((next & 0xfc00) != 0xdc00)
                return null;
        }

        ++offset;
    }

    check();
    return after;
};

utf16.point2unit = function(string, offsets) {
    return utf16.adjust(false, string, offsets);
};

utf16.unit2point = function(string, offsets) {
    return utf16.adjust(true, string, offsets);
};

utf16.charAt = function(string, offset) {
    return utf16.substring(string, offset, offset + 1);
};

utf16.charCodeAt = function(string, offset) {
    var char = utf16.charAt(string, offset);
    if (char.length != 2)
        return char.charCodeAt(0);
    return 0x10000 | (char.charCodeAt(0) & 0x03ff) << 10 | char.charCodeAt(1) & 0x03ff
};

utf16.strlen = function(string) {
    return utf16.unit2point(string, [string.length])[0];
};

utf16.substr = function(string, start, length) {
    var stop;
    if (typeof length !== "undefined")
        stop = start + length;
    return utf16.substring(string, start, stop);
};

utf16.substring = function(string, start, stop) {
    var range = utf16.point2unit(string, [start, stop]);
    return string.substring(range[0], range[1]);
};

utf16.prototype.charAt = function(index) {
    return new utf16(utf16.charAt(this.string, index));
};

utf16.prototype.charCodeAt = function(index) {
    return utf16.charCodeAt(this.string, index);
};

utf16.prototype.substr = function(start, length) {
    return new utf16(utf16.substr(this.string, start, length));
};

utf16.prototype.substring = function(start, end) {
    return new utf16(utf16.substring(this.string, start, end));
};

utf16.prototype.toString = function() {
    return this.string;
};

return utf16;

});