react app

react-app/node_modules/react/lib/FallbackCompositionState.js

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+/**
+ * Copyright 2013-2015, 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.
+ *
+ * @providesModule FallbackCompositionState
+ * @typechecks static-only
+ */
+
+'use strict';
+
+var PooledClass = require("./PooledClass");
+
+var assign = require("./Object.assign");
+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, {
+  /**
+   * 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;