69 lines
2.2 KiB
JavaScript
69 lines
2.2 KiB
JavaScript
'use strict';
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/**
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* This code is mostly from the old Etherpad. Please help us to comment this code.
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* This helps other people to understand this code better and helps them to improve it.
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* TL;DR COMMENTS ON THIS FILE ARE HIGHLY APPRECIATED
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*/
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/**
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* Copyright 2009 Google Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS-IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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const isNodeText = (node) => (node.nodeType === 3);
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const getAssoc = (obj, name) => obj[`_magicdom_${name}`];
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const setAssoc = (obj, name, value) => {
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// note that in IE designMode, properties of a node can get
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// copied to new nodes that are spawned during editing; also,
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// properties representable in HTML text can survive copy-and-paste
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obj[`_magicdom_${name}`] = value;
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};
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// "func" is a function over 0..(numItems-1) that is monotonically
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// "increasing" with index (false, then true). Finds the boundary
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// between false and true, a number between 0 and numItems inclusive.
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const binarySearch = (numItems, func) => {
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if (numItems < 1) return 0;
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if (func(0)) return 0;
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if (!func(numItems - 1)) return numItems;
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let low = 0; // func(low) is always false
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let high = numItems - 1; // func(high) is always true
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while ((high - low) > 1) {
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const x = Math.floor((low + high) / 2); // x != low, x != high
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if (func(x)) high = x;
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else low = x;
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}
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return high;
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};
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const binarySearchInfinite = (expectedLength, func) => {
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let i = 0;
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while (!func(i)) i += expectedLength;
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return binarySearch(i, func);
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};
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const noop = () => {};
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exports.isNodeText = isNodeText;
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exports.getAssoc = getAssoc;
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exports.setAssoc = setAssoc;
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exports.binarySearch = binarySearch;
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exports.binarySearchInfinite = binarySearchInfinite;
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exports.noop = noop;
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