ref-wchar/index.js

A ref "type" implementation of `wchar_t *` (a.k.a. wide string) backed by "node-iconv"

/**
 * Module dependencies.
 */

var ref = require('ref');
var Iconv = require('iconv').Iconv;

/**
 * On Windows they're UTF-16 (2-bytes),
 * but on Unix platform they're UTF-32 (4-bytes).
 *
 * TODO: add a way to optionally enable `-fshort-wchar` for Unix (gcc option).
 */

var size;
if ('win32' == process.platform) {
  size = 2;
} else {
  size = 4;
}

var getter = new Iconv('UTF-' + (8 * size) + ref.endianness, 'UTF-8');
var setter = new Iconv('UTF-8', 'UTF-' + (8 * size) + ref.endianness);


/**
 * The `wchar_t` type.
 */

exports = module.exports = Object.create(ref.types['int' + (8 * size)]);
exports.name = 'wchar_t';
exports.size = size;
exports.indirection = 1;
exports.get = function get (buf, offset) {
  if (offset > 0 || buf.length !== exports.size) {
    offset = offset | 0;
    buf = buf.slice(offset, offset + size);
  }
  return exports.toString(buf);
};
exports.set = function set (buf, offset, val) {
  var _buf = val; // assume val is a Buffer by default
  if (typeof val === 'string') {
    _buf = setter.convert(val[0]);
  } else if (typeof val === 'number') {
    _buf = setter.convert(String.fromCharCode(val));
  } else if (!_buf) {
    throw new TypeError('muss pass a String, Number, or Buffer for `wchar_t`');
  }
  return _buf.copy(buf, offset, 0, size);
};


/**
 * The "wchar_t *" type.
 *
 * We use the "CString" type as a base since it's pretty close to what we
 * actually want. We just have to define custom "get" and "set" functions.
 */

exports.string = Object.create(ref.types.CString);
exports.string.name = 'WCString';
exports.string.get = function get (buf, offset) {
  var _buf = buf.readPointer(offset);
  if (_buf.isNull()) {
    return null;
  }
  var stringBuf = _buf.reinterpretUntilZeros(exports.size);
  return exports.toString(stringBuf);
};
exports.string.set = function set (buf, offset, val) {
  var _buf = val; // val is a Buffer? it better be \0 terminated...
  if ('string' == typeof val) {
    _buf = setter.convert(val + '\0');
  }
  return buf.writePointer(_buf, offset);
};

/**
 * Turns a `wchar_t *` Buffer instance into a JavaScript String instance.
 *
 * @param {Buffer} buffer - buffer instance to serialize
 * @public
 */

exports.toString = function toString (buffer) {
  return getter.convert(buffer).toString('utf8');
};