101 lines
3.2 KiB
JavaScript
101 lines
3.2 KiB
JavaScript
/**
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* @file pathJoin.js
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* @author mengke01
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* @date
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* @description
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* 求路径的并集
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*/
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define(
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function (require) {
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var join2Path = require('./join/join2Path');
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var Relation = require('./join/relation');
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/**
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* 求路径交集、并集、差集
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*
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* @param {Array} paths 路径集合
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* @param {number} relation 关系
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* @return {Array} 合并后的路径
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*/
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function pathJoin(paths, relation) {
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if (paths.length === 1) {
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if (relation === Relation.intersect) {
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return [];
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}
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return paths;
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}
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else if (paths.length === 2) {
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return join2Path(paths[0], paths[1], relation);
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}
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// 算法描述：
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// 1. 第一个路径为已选集合，后面依次为待选集合
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// 2. 从已选集合中和待选集合中各取一个轮廓求合并
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// 3. 如果有合并项目，则除去已选集合和待选集合中的路径，把新路径加入待选集合，继续2
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// 否则将待选集合中的当前路径加入已选集合，继续2
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// 4. 继续2、3步骤直到待选集合为空
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// 已选集合
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var startPaths = [paths[0]];
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var leftPath = paths.slice(1);
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var curPath;
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// 两个轮廓如果是由同一个合并生成的，则不需要进行比较了
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// 这里用位来标记是哪个路径分割出来的
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var joinFlag = 0;
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// 将路径放入leftPath，并打上标记
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var putToResult = function (path) {
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path.joinFlag = (path.joinFlag || 0) + (1 << joinFlag);
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leftPath.push(path);
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};
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while (curPath = leftPath.shift()) {
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for (var i = 0, l = startPaths.length; i < l; i++) {
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if (curPath.joinFlag && startPaths[i].joinFlag && (curPath.joinFlag & startPaths[i].joinFlag)) {
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continue;
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}
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var result = join2Path(curPath, startPaths[i], relation);
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// 相交关系，有个无交集则返回空
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if (relation === Relation.intersect && !result.length) {
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return [];
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}
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// 原样返回,继续比较
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if (result.length === 2 && result[0] === curPath && result[1] === startPaths[i]) {
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continue;
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}
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// 否则分割出来的点，加入待选集合
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else {
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startPaths.splice(i, 1);
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joinFlag++;
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result.forEach(putToResult);
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break;
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}
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}
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// 没有找到
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if (i === l) {
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startPaths.push(curPath);
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}
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else if (!startPaths.length) {
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startPaths.push(leftPath.shift());
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}
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}
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return startPaths;
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}
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pathJoin.Relation = Relation;
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return pathJoin;
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}
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);
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