94 lines
2.4 KiB
JavaScript
94 lines
2.4 KiB
JavaScript
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/**
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* Copyright 2013-present, Facebook, Inc.
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* All rights reserved.
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*
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* This source code is licensed under the BSD-style license found in the
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* LICENSE file in the root directory of this source tree. An additional grant
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* of patent rights can be found in the PATENTS file in the same directory.
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*
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*/
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'use strict';
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var _assign = require('object-assign');
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var PooledClass = require('./PooledClass');
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var getTextContentAccessor = require('./getTextContentAccessor');
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/**
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* This helper class stores information about text content of a target node,
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* allowing comparison of content before and after a given event.
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*
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* Identify the node where selection currently begins, then observe
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* both its text content and its current position in the DOM. Since the
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* browser may natively replace the target node during composition, we can
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* use its position to find its replacement.
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*
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* @param {DOMEventTarget} root
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*/
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function FallbackCompositionState(root) {
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this._root = root;
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this._startText = this.getText();
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this._fallbackText = null;
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}
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_assign(FallbackCompositionState.prototype, {
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destructor: function () {
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this._root = null;
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this._startText = null;
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this._fallbackText = null;
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},
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/**
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* Get current text of input.
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*
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* @return {string}
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*/
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getText: function () {
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if ('value' in this._root) {
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return this._root.value;
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}
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return this._root[getTextContentAccessor()];
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},
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/**
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* Determine the differing substring between the initially stored
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* text content and the current content.
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*
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* @return {string}
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*/
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getData: function () {
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if (this._fallbackText) {
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return this._fallbackText;
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}
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var start;
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var startValue = this._startText;
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var startLength = startValue.length;
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var end;
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var endValue = this.getText();
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var endLength = endValue.length;
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for (start = 0; start < startLength; start++) {
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if (startValue[start] !== endValue[start]) {
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break;
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}
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}
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var minEnd = startLength - start;
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for (end = 1; end <= minEnd; end++) {
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if (startValue[startLength - end] !== endValue[endLength - end]) {
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break;
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}
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}
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var sliceTail = end > 1 ? 1 - end : undefined;
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this._fallbackText = endValue.slice(start, sliceTail);
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return this._fallbackText;
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}
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});
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PooledClass.addPoolingTo(FallbackCompositionState);
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module.exports = FallbackCompositionState;
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