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/**
* Copyright (c) 2013-present, Facebook, Inc.
*
* This source code is licensed under the MIT license found in the
* LICENSE file in the root directory of this source tree.
*
* @typechecks
*
*/
/**
* Stateful API for text direction detection
*
* This class can be used in applications where you need to detect the
* direction of a sequence of text blocks, where each direction shall be used
* as the fallback direction for the next one.
*
* NOTE: A default direction, if not provided, is set based on the global
* direction, as defined by `UnicodeBidiDirection`.
*
* == Example ==
* ```
* var UnicodeBidiService = require('UnicodeBidiService');
*
* var bidiService = new UnicodeBidiService();
*
* ...
*
* bidiService.reset();
* for (var para in paragraphs) {
* var dir = bidiService.getDirection(para);
* ...
* }
* ```
*
* Part of our implementation of Unicode Bidirectional Algorithm (UBA)
* Unicode Standard Annex #9 (UAX9)
* http://www.unicode.org/reports/tr9/
*/
'use strict';
function _classCallCheck(instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } }
var UnicodeBidi = require('./UnicodeBidi');
var UnicodeBidiDirection = require('./UnicodeBidiDirection');
var invariant = require('./invariant');
var UnicodeBidiService = function () {
/**
* Stateful class for paragraph direction detection
*
* @param defaultDir Default direction of the service
*/
function UnicodeBidiService(defaultDir) {
_classCallCheck(this, UnicodeBidiService);
if (!defaultDir) {
defaultDir = UnicodeBidiDirection.getGlobalDir();
} else {
!UnicodeBidiDirection.isStrong(defaultDir) ? process.env.NODE_ENV !== 'production' ? invariant(false, 'Default direction must be a strong direction (LTR or RTL)') : invariant(false) : void 0;
}
this._defaultDir = defaultDir;
this.reset();
}
/**
* Reset the internal state
*
* Instead of creating a new instance, you can just reset() your instance
* everytime you start a new loop.
*/
UnicodeBidiService.prototype.reset = function reset() {
this._lastDir = this._defaultDir;
};
/**
* Returns the direction of a block of text, and remembers it as the
* fall-back direction for the next paragraph.
*
* @param str A text block, e.g. paragraph, table cell, tag
* @return The resolved direction
*/
UnicodeBidiService.prototype.getDirection = function getDirection(str) {
this._lastDir = UnicodeBidi.getDirection(str, this._lastDir);
return this._lastDir;
};
return UnicodeBidiService;
}();
module.exports = UnicodeBidiService;
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