73 lines
1.6 KiB
JavaScript
73 lines
1.6 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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/**
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* Given any node return the first leaf node without children.
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*
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* @param {DOMElement|DOMTextNode} node
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* @return {DOMElement|DOMTextNode}
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*/
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function getLeafNode(node) {
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while (node && node.firstChild) {
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node = node.firstChild;
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}
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return node;
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}
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/**
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* Get the next sibling within a container. This will walk up the
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* DOM if a node's siblings have been exhausted.
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*
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* @param {DOMElement|DOMTextNode} node
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* @return {?DOMElement|DOMTextNode}
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*/
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function getSiblingNode(node) {
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while (node) {
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if (node.nextSibling) {
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return node.nextSibling;
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}
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node = node.parentNode;
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}
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}
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/**
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* Get object describing the nodes which contain characters at offset.
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*
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* @param {DOMElement|DOMTextNode} root
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* @param {number} offset
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* @return {?object}
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*/
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function getNodeForCharacterOffset(root, offset) {
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var node = getLeafNode(root);
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var nodeStart = 0;
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var nodeEnd = 0;
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while (node) {
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if (node.nodeType === 3) {
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nodeEnd = nodeStart + node.textContent.length;
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if (nodeStart <= offset && nodeEnd >= offset) {
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return {
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node: node,
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offset: offset - nodeStart
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};
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}
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nodeStart = nodeEnd;
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}
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node = getLeafNode(getSiblingNode(node));
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}
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}
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module.exports = getNodeForCharacterOffset;
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