编写可读代码的艺术之一

《编写可读代码的艺术》,艺术是表达自己内在的欲望 再看看我毕设中的代码，写的真是烂啊 可读代码的艺术包含：

名副其实的命名子解释的注释言简意赅的控制结构

在毕设中遇到的实际问题：

/** * This method evaluates an event against a run, for skip-till-any-match * @param e The event which is being evaluated. * @param r The run which the event is being evaluated against. * @throws CloneNotSupportedException */ public void evaluateEventForSkipTillAny(Event e, Run r) throws CloneNotSupportedException{ boolean checkResult = true; checkResult = this.checkPredicate(e, r);// check predicate if(checkResult){ // the predicate if ok. checkResult = this.checkTimeWindow(e, r); // the time window is ok if(checkResult){// predicate and time window are ok this.buffer.bufferEvent(e);// add the event to buffer int oldState = 0; int newState = 0; Run newRun = this.cloneRun(r); // clone this run oldState = newRun.getCurrentState(); newRun.addEvent(e); // add the event to this run newState = newRun.getCurrentState(); if(oldState != newState){ this.activeRuns.add(newRun); }else{//kleene closure if(newRun.isFull){ //check match and output match if(newRun.checkMatch()){ this.outputMatch(new Match(newRun, this.nfa, this.buffer)); Profiling.totalRunLifeTime += (System.nanoTime() - r.getLifeTimeBegin()); } }else{ //check proceed if(this.checkProceed(newRun)){ Run newerRun = this.cloneRun(newRun); this.activeRuns.add(newRun); newerRun.proceed(); if(newerRun.isComplete()){ this.outputMatch(new Match(r, this.nfa, this.buffer)); Profiling.totalRunLifeTime += (System.nanoTime() - r.getLifeTimeBegin()); }else { this.activeRuns.add(newerRun); } } } } }else{ this.toDeleteRuns.add(r); } } } 先观察上面的代码，计算代码的复杂度 Cyclomatic Complexity(CC循环复杂度)=edges-nodes+2

代码的作用

Created with Raphaël 2.1.0 开始 检测事件 拷贝run，新run添加事件，得到前后状态 添加事件前后边 检测是否输出 输出这棵run的节点 检测是否前进 检测是否完成 输出这棵run的节点 添加run到活动run表 删掉run 结束 yes no yes yes no yes yes no

分析上面方法的作用

检查事件满足NFA当前状态的起始边，如果满足再检查当前状态是否为克林闭包状态，再检查是否要前进

修改为evaluateEventForSkipTillAny(Event e,Run run)的作用是移除/添加/前进对run的三个操作 checkPredicateOptimized(Event e,Run run)的作用是检查事件对run当前状态的所有谓词的检查

public void evaluateEventOptimizedForSkipTillAny(Event e, Run r) throws CloneNotSupportedException{ int checkResult = this.checkPredicateOptimized(e, r); switch(checkResult){ case 1: boolean timeWindow = this.checkTimeWindow(e, r); if(timeWindow){ Run newRun = this.cloneRun(r); this.addRunByPartition(newRun); this.addEventToRun(r, e); }else{ this.toDeleteRuns.add(r); } break; case 2: Run newRun = this.cloneRun(r); this.addRunByPartition(newRun); r.proceed(); this.addEventToRun(r, e); } } /** * Checks the predicate for e against r * 对于run，检测e的谓词,检测结果是0为false，1是take或begin，2是proceed * @param e The current event * @param r The run against which e is evaluated * @return The check result, 0 for false, 1 for take or begin, 2 for proceed */ public int checkPredicateOptimized(Event e, Run r){//0 for false, 1 for take or begin, 2 for proceed int currentState = r.getCurrentState();//当前run的状态 State s = this.nfa.getStates(currentState);//例子会返回run的克林闭包a状态 //检测事件类型 if(!s.getEventType().equalsIgnoreCase(e.getEventType())){// event type check; return 0; } //非克林加检测 if(!s.isKleeneClosure()){ Edge beginEdge = s.getEdges(0); boolean result; //result = firstEdge.evaluatePredicate(e, r, buffer); result = beginEdge.evaluatePredicate(e, r, buffer);// if(result){ return 1; } }else{//克林加情况 //克林加初始化检测，true if(r.isKleeneClosureInitialized()){ boolean result; //当将e加入r当中时，检测run是否需要proceed,他是通过将该事件放入下一个状态中进行计算， //得到下一个状态，如果这个事件满足下个状态的所有谓词，状态从克林闭包状态前进 //例如第一次匹配中，2和3事件到来时返回的false，因为它的volume不满足状态1中的谓词。4事件满足，返回true result = this.checkProceedOptimized(e, r);//proceedEdge.evaluatePredicate(e, r, buffer); if(result){ return 2;//前进 }else{ //take边 Edge takeEdge = s.getEdges(1); //计算take边 result = takeEdge.evaluatePredicate(e, r, buffer); if(result){ //在第一个匹配中，ID为2和3的事件满足，take边 return 1; } } }else{//克林加初始化检测，false Edge beginEdge = s.getEdges(0); boolean result; result = beginEdge.evaluatePredicate(e, r, buffer);// if(result){ return 1; } } } return 0; }

兵哥PPT上编写可读代码的艺术其中包含->言简意赅的控制结构 1. 打平条件分支：用if-else if -else 代替嵌套if 2. 提前返回 3.使用continue

根据这个理论，checkPredicateOptimized()方法可以改为

else if(r.isKleeneClosureInitialized()){} else{}

的结构。 只是一个简单的改进，15行的方法还没做好呢

附上PPT里面的控制言简意赅的控制结构的案例