jieshi4.cpp

词法分析将字符串分解为三个部分

 //bianyi8.cpp : 定义控制台应用程序的入口点。
//
#include "stdafx.h"
#include <string>
#include <list>
#include <map>
#include <vector>


using namespace std;



class Object
{
protected:
//	list < map<string,Object* > >list1;
	map<string,Object*>map1;
	map<string,Object*>::iterator it;
public:
	void regist(string str,Object * object)
{
	map1[str]=object;
//	list1.push_back(map1);
}
	virtual Object* findbyname(string str1)
	{
		 it=map1.find(str1);
		 return it->second;
	}

		
	virtual int getparament( string str)
	{
		return 0;
	}
};



class Moto :public Object
{
public:
	virtual int getparament(string str)
	{
		if(str=="stop")
		{
			return 0;
		}
		else
			return 1;

	}
};

class Image :public Object
{
public:
	virtual int getparament(string str)
	{
		if(str=="stop")
		{
			return 0;
		}
		else
			return 1;

	}
};


class Explain
{
public:
	Explain()
	{
		fatherposition=0;
		sonposition=0;
//		strinfo="(moto_x_stop&&moto_y_stop)||moto_y_run";
//		len=strinfo.length();
	}
protected:
int len;
//string strinfo;
string::size_type fatherposition,sonposition;
string  strinforson;
string  strinforgrandson[5];
char curr_tok;
double number_value;
//double left;

public:
double expression(string strinfo);
double expr();
double term();
double prim();
void get_token(string strinfo);
};

Object * object=new Object;
Explain *explain=new Explain;
string strinfo="(!moto_x_run&&moto_y_stop)||image_y_stop";

double Explain::expression(string strinfo)
{
	explain->get_token(strinfo);
	double x=explain->expr();
	return x;
}

void Explain::get_token(string strinfo)
{
	if(fatherposition==string::npos)
	{
		curr_tok='=';
		return;
	}
	switch(strinfo[fatherposition])
	 {
   	   case'!':
		   fatherposition++;
		   curr_tok='!';
		   break;
		case'(':
		   fatherposition++;
		   curr_tok='(';
		   break;
	    case')':
		   fatherposition++;
		   curr_tok=')';
		   break;
		case'|':
		   fatherposition++;
		   fatherposition++;
		   curr_tok='|';
		   break;
		 case'&':
		   fatherposition++;
		   fatherposition++;
		   curr_tok='&';
		   break;
		 default:

        string stralpha="ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
		string strsymbol="|&!";

        int firstsymbol = strinfo.find_first_of(strsymbol,fatherposition); 
        if(firstsymbol == string::npos) 
		{ 
                strinforson=strinfo.substr();
        } 
        strinforson=strinfo.substr(fatherposition, firstsymbol - fatherposition);
		fatherposition=firstsymbol;
        
		for(int i=0;i<strinforson.length();i++)
		{
       	int firstunderline=strinforson.find('_',sonposition);
        if(firstunderline == string::npos) 
		{ 
			strinforgrandson[i]=strinforson.substr();              
                break;
        } 
		strinforgrandson[i]=strinforson.substr(0, firstunderline);
		strinforson=strinforson.erase ( 0 , firstunderline+1 );
		}
			Object * newobject;	
	       newobject=object->findbyname(strinforgrandson[0]);
		   number_value=newobject->getparament(strinforgrandson[2]);
		   curr_tok='0';
	 }
}

double Explain::expr()
{
	double left=prim();
	for(;;)
		switch(curr_tok){
			case '|':
				get_token(strinfo);
				left=left||expr();
				break;
			case '&':
				get_token(strinfo);
				left=left&&expr();
				break;
			default:
				return left;
		}
}



double Explain::prim()
{
	double p;
for(;;)
	switch(curr_tok){
			case '!':
				get_token(strinfo);
				p=!prim();
				break;
			case '0':
			{
				double v=number_value;
				get_token(strinfo);
				return v;
			}
		    case '(':
			{
				get_token(strinfo);
				double e=expr();
				get_token(strinfo);//可以在这里直接加‘）’控制
				if(curr_tok!=')'){};
				return e;
			}
			default:
				return p;
	}
}


int _tmain(int argc, _TCHAR* argv[])
{
   	string str1="moto";
	Moto moto;
	object->regist("moto",&moto);
	Image image;
	object->regist("image",&image);
//	explain->get_token(strinfo);
//	cout<<explain->expr()<<"\n";
	cout<<explain->expression(strinfo);
	return 0;
}