算符优先分析过程 编译原理

算符优先分析过程只考虑算符（终结符）之间的优先关系，分析扫描每个规约式的算符间优先关系。

根据龙书阐述，算符优先分析逐渐淘汰了。orz

但仍然实现之。

示例语法如下：

D->#E#
E->E+T|T
T->T*F|F
F->P$F|P
P->(E)|i

 

main.cpp

#include <iostream>

#include <vector>

#include "grammerin.h"
#include "calculatepriortable.h"
#include "analy.h"
using namespace std;

int main()
{
    vector<vector<char> > sign;
    cout<<"读入语法规则:"<<endl;
    sign=readGrammer();
    /*
    for(int i=0;i<2;++i)
    {
        for(int j=0;j<sign[i].size();++j)
            cout<<sign[i][j]<<" ";
        cout<<endl;
    }
    */
    vector<vector<vector<char> > > vvvc;
    vvvc = createfirstandfollow(sign);
    vector<vector<char> > priortable;
    priortable=createtable(vvvc);

    while(true)
    {
        cout<<endl<<"input: ";
        string s;
        cin>>s;
        inStringAnalyze(s,priortable);
    }
    return 0;
}

 

grammerin.cpp:

#ifndef GRMMERIN_H
#define GRMMERIN_H
#include <vector>
using namespace std;
vector< vector<char> > readGrammer();
vector< vector<char> > readGrammerWithNoPrint();
vector<string> getgrammer();
#endif

grammerin.h:

#include <iostream>
#include <sstream>
#include <string>
#include <fstream>
#include <cstdlib>
#include <vector>
#include <cctype>
#include <algorithm>
#include <map>
#include <set>
#include <cmath>
#include <queue>
#include <cstdio>
#include <cstdlib>
#include <ctime>

using namespace std;

vector< vector<char> > readGrammer()
{


    vector<char> terminatesign,unterminatesign;
    string s,grammer;

    ifstream in("C:\\Users\\lsy\\Desktop\\grammer1.txt");
    if (! in.is_open())
    { cout << "Error opening file"; exit (1); }
    while (!in.eof() )
    {
        char lin[100];
        //in.getline(buffer);
        in.getline(lin,100);
        s+=lin;
        grammer+=s+"\n";

        //cout <<s<< endl;
        int k=s.find_first_of("->");
        for(int i=0;i<k;++i)
        {
            //cout<<s[i]<<endl;
            vector<char>::iterator result = find(unterminatesign.begin(),unterminatesign.end(),s[i]);
            if(result==unterminatesign.end())
                unterminatesign.push_back(s[i]);
        }
        for(int i=k+2;i<s.size();++i)
        {
            //cout<<s[i]<<endl;
            if((s[i]>='A'&&s[i]<='Z')||s[i]==' '||s[i]=='|')
                ;
            else
            {
                vector<char>::iterator result = find(terminatesign.begin(),terminatesign.end(),s[i]);
                if(result==terminatesign.end())
                    terminatesign.push_back(s[i]);
            }
        }

        s="";
    }
    cout<<grammer;
    cout<<endl<<"·ÇÖÕ½á·û£º"<<endl;
    for(int i=0;i<unterminatesign.size();++i)
        cout<<unterminatesign[i]<<" ";
    cout<<endl;
    cout<<"ÖÕ½á·û£º"<<endl;
    for(int i=0;i<terminatesign.size();++i)
        cout<<terminatesign[i]<<" ";
    cout<<endl;
    vector<vector<char> > returnvector;
    returnvector.push_back(unterminatesign);
    returnvector.push_back(terminatesign);
    return returnvector;
}

vector< vector<char> > readGrammerWithNoPrint()
{
    //system("chcp 65001");

    vector<char> terminatesign,unterminatesign;
    string s,grammer;

    ifstream in("C:\\Users\\lsy\\Desktop\\grammer1.txt");
    if (! in.is_open())
    { cout << "Error opening file"; exit (1); }
    while (!in.eof() )
    {
        char lin[100];
        //in.getline(buffer);
        in.getline(lin,100);
        s+=lin;
        grammer+=s+"\n";

        //cout <<s<< endl;
        int k=s.find_first_of("->");
        for(int i=0;i<k;++i)
        {
            //cout<<s[i]<<endl;
            vector<char>::iterator result = find(unterminatesign.begin(),unterminatesign.end(),s[i]);
            if(result==unterminatesign.end())
                unterminatesign.push_back(s[i]);
        }
        for(int i=k+2;i<s.size();++i)
        {
            //cout<<s[i]<<endl;
            if((s[i]>='A'&&s[i]<='Z')||s[i]==' '||s[i]=='|')
                ;
            else
            {
                vector<char>::iterator result = find(terminatesign.begin(),terminatesign.end(),s[i]);
                if(result==terminatesign.end())
                    terminatesign.push_back(s[i]);
            }
        }

        s="";
    }
    vector<vector<char> > returnvector;
    returnvector.push_back(unterminatesign);
    returnvector.push_back(terminatesign);
    return returnvector;
}


vector<string> getgrammer()
{
    string s;
    vector<string> vv;
    ifstream in("C:\\Users\\lsy\\Desktop\\grammer1.txt");
    if (! in.is_open())
    { cout << "Error opening file"; exit (1);