108 lines
2.9 KiB
JavaScript
108 lines
2.9 KiB
JavaScript
/**
|
|
* Copyright (c) 2013-present, Facebook, Inc.
|
|
* All rights reserved.
|
|
*
|
|
* This source code is licensed under the BSD-style license found in the
|
|
* LICENSE file in the root directory of this source tree. An additional grant
|
|
* of patent rights can be found in the PATENTS file in the same directory.
|
|
*
|
|
* @typechecks
|
|
*
|
|
*/
|
|
|
|
/**
|
|
* Constants to represent text directionality
|
|
*
|
|
* Also defines a *global* direciton, to be used in bidi algorithms as a
|
|
* default fallback direciton, when no better direction is found or provided.
|
|
*
|
|
* NOTE: Use `setGlobalDir()`, or update `initGlobalDir()`, to set the initial
|
|
* global direction value based on the application.
|
|
*
|
|
* Part of the implementation of Unicode Bidirectional Algorithm (UBA)
|
|
* Unicode Standard Annex #9 (UAX9)
|
|
* http://www.unicode.org/reports/tr9/
|
|
*/
|
|
|
|
'use strict';
|
|
|
|
var invariant = require('./invariant');
|
|
|
|
var NEUTRAL = 'NEUTRAL'; // No strong direction
|
|
var LTR = 'LTR'; // Left-to-Right direction
|
|
var RTL = 'RTL'; // Right-to-Left direction
|
|
|
|
var globalDir = null;
|
|
|
|
// == Helpers ==
|
|
|
|
/**
|
|
* Check if a directionality value is a Strong one
|
|
*/
|
|
function isStrong(dir) {
|
|
return dir === LTR || dir === RTL;
|
|
}
|
|
|
|
/**
|
|
* Get string value to be used for `dir` HTML attribute or `direction` CSS
|
|
* property.
|
|
*/
|
|
function getHTMLDir(dir) {
|
|
!isStrong(dir) ? process.env.NODE_ENV !== 'production' ? invariant(false, '`dir` must be a strong direction to be converted to HTML Direction') : invariant(false) : void 0;
|
|
return dir === LTR ? 'ltr' : 'rtl';
|
|
}
|
|
|
|
/**
|
|
* Get string value to be used for `dir` HTML attribute or `direction` CSS
|
|
* property, but returns null if `dir` has same value as `otherDir`.
|
|
* `null`.
|
|
*/
|
|
function getHTMLDirIfDifferent(dir, otherDir) {
|
|
!isStrong(dir) ? process.env.NODE_ENV !== 'production' ? invariant(false, '`dir` must be a strong direction to be converted to HTML Direction') : invariant(false) : void 0;
|
|
!isStrong(otherDir) ? process.env.NODE_ENV !== 'production' ? invariant(false, '`otherDir` must be a strong direction to be converted to HTML Direction') : invariant(false) : void 0;
|
|
return dir === otherDir ? null : getHTMLDir(dir);
|
|
}
|
|
|
|
// == Global Direction ==
|
|
|
|
/**
|
|
* Set the global direction.
|
|
*/
|
|
function setGlobalDir(dir) {
|
|
globalDir = dir;
|
|
}
|
|
|
|
/**
|
|
* Initialize the global direction
|
|
*/
|
|
function initGlobalDir() {
|
|
setGlobalDir(LTR);
|
|
}
|
|
|
|
/**
|
|
* Get the global direction
|
|
*/
|
|
function getGlobalDir() {
|
|
if (!globalDir) {
|
|
this.initGlobalDir();
|
|
}
|
|
!globalDir ? process.env.NODE_ENV !== 'production' ? invariant(false, 'Global direction not set.') : invariant(false) : void 0;
|
|
return globalDir;
|
|
}
|
|
|
|
var UnicodeBidiDirection = {
|
|
// Values
|
|
NEUTRAL: NEUTRAL,
|
|
LTR: LTR,
|
|
RTL: RTL,
|
|
// Helpers
|
|
isStrong: isStrong,
|
|
getHTMLDir: getHTMLDir,
|
|
getHTMLDirIfDifferent: getHTMLDirIfDifferent,
|
|
// Global Direction
|
|
setGlobalDir: setGlobalDir,
|
|
initGlobalDir: initGlobalDir,
|
|
getGlobalDir: getGlobalDir
|
|
};
|
|
|
|
module.exports = UnicodeBidiDirection; |