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/**
* Copyright 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.
*
*/
'use strict';
var _assign = require('object-assign');
var PooledClass = require('./PooledClass');
var getTextContentAccessor = require('./getTextContentAccessor');
/**
* This helper class stores information about text content of a target node,
* allowing comparison of content before and after a given event.
*
* Identify the node where selection currently begins, then observe
* both its text content and its current position in the DOM. Since the
* browser may natively replace the target node during composition, we can
* use its position to find its replacement.
*
* @param {DOMEventTarget} root
*/
function FallbackCompositionState(root) {
this._root = root;
this._startText = this.getText();
this._fallbackText = null;
}
_assign(FallbackCompositionState.prototype, {
destructor: function () {
this._root = null;
this._startText = null;
this._fallbackText = null;
},
/**
* Get current text of input.
*
* @return {string}
*/
getText: function () {
if ('value' in this._root) {
return this._root.value;
}
return this._root[getTextContentAccessor()];
},
/**
* Determine the differing substring between the initially stored
* text content and the current content.
*
* @return {string}
*/
getData: function () {
if (this._fallbackText) {
return this._fallbackText;
}
var start;
var startValue = this._startText;
var startLength = startValue.length;
var end;
var endValue = this.getText();
var endLength = endValue.length;
for (start = 0; start < startLength; start++) {
if (startValue[start] !== endValue[start]) {
break;
}
}
var minEnd = startLength - start;
for (end = 1; end <= minEnd; end++) {
if (startValue[startLength - end] !== endValue[endLength - end]) {
break;
}
}
var sliceTail = end > 1 ? 1 - end : undefined;
this._fallbackText = endValue.slice(start, sliceTail);
return this._fallbackText;
}
});
PooledClass.addPoolingTo(FallbackCompositionState);
module.exports = FallbackCompositionState;
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