cpp1.cpp

语法分析程序 必须先编写一个program的文本文件 再对该文本文件的程序进行语法分析

#include <iostream>
#include <string>
#include <fstream>
using namespace std;

int code[100];
int sym,flag=1,m=0;//flag判断错误，1为真，0为假。sym当前字符
bool isNum(char );
bool isWrd(char );
int isKeywrd(char s[]); 
int isDoublewrd(char c);

/*==============语法分析函数======================*/
int program();
void proghead();
void block();
int consexpl();
void consdefi();
int conssuff();
int varexl();
void vandefi();
int idsuff();
int varssuff();
void typeil();
int procdefi();
void procedh();
int argument();
int procsuff();
int sentence();
void assipro();
int suffix();
void ifsent();
void whilsent();
void read();
void write();
int exprsuff();
void compsent();
int sentsuff();
void conditio();
void express();
int termsuff();
void term();
int factsuff();
void factor();
void addoper();
void muloper();
int respoper();

const char Key1[]={'p','r','o','g','r','a','m'}; 
const char Key2[]="const";   
const char Key3[]="var";   
const char Key4[]="integer";   
const char Key5[]="long";   
const char Key6[]="procedure";
const char Key7[]="if";
const char Key8[]="then";
const char Key9[]="while";
const char Key10[]="do";
const char Key11[]="read";
const char Key12[]="write";
const char Key13[]="begin";
const char Key14[]="end";
const char Key15[]="odd";

bool isNumch(char c)
{
	return (c>='0' && c<='9');
}

bool isWrdch(char c)
{
	return (c>='a' && c<='z');
}

int isKeywrd(char s[])
{
	int i=0;
	while(s[i]==Key1[i] && (s[i]!=0 && Key1[i]!=0)) i++;
	if(s[i]==Key1[i]) return 1;
	else 
	{
		i=0; 
		while(s[i]==Key2[i] && (s[i]!=0 && Key2[i]!=0)) i++;
		if(s[i]==Key2[i]) return 2;
		else
		{
			i=0;
	 		while(s[i]==Key3[i] && (s[i]!=0 && Key3[i]!=0)) i++;
	     	if(s[i]==Key3[i]) return 3;
			else
			{
				i=0;
	 	    	while(s[i]==Key4[i] && (s[i]!=0 && Key4[i]!=0)) i++;
	        	if(s[i]==Key4[i]) return 4;
				else
				{
					i=0;
	 	         	while(s[i]==Key5[i] && (s[i]!=0 && Key5[i]!=0)) i++;
	            	if(s[i]==Key5[i]) return 5;
					else 
					{
						i=0;
	 	            	while(s[i]==Key6[i] && (s[i]!=0 && Key6[i]!=0)) i++;
	                    if(s[i]==Key6[i]) return 6;
						else
						{
							i=0;
	 	                	while(s[i]==Key7[i] && (s[i]!=0 && Key7[i]!=0)) i++;
	                     	if(s[i]==Key7[i]) return 7;
							else
							{
								i=0;
	 	                    	while(s[i]==Key8[i] && (s[i]!=0 && Key8[i]!=0)) i++;
	                            if(s[i]==Key8[i]) return 8;
					        	else
								{
									i=0;
	 	                         	while(s[i]==Key9[i] && (s[i]!=0 && Key9[i]!=0)) i++;
	                                if(s[i]==Key9[i]) return 9;
					            	else
									{
										i=0;
	 	                                while(s[i]==Key10[i] && (s[i]!=0 && Key10[i]!=0)) i++;
	                                    if(s[i]==Key10[i]) return 10;
				                		else
										{
											while(s[i]==Key11[i] && (s[i]!=0 && Key11[i]!=0)) i++;
	                                        if(s[i]==Key11[i]) return 11;
				                	    	else
											{
												while(s[i]==Key12[i] && (s[i]!=0 && Key12[i]!=0)) i++;
	                                            if(s[i]==Key12[i]) return 11;
				                	        	else
												{
													while(s[i]==Key13[i] && (s[i]!=0 && Key13[i]!=0)) i++;
	                                                if(s[i]==Key13[i]) return 13;
				                	            	else
													{
														while(s[i]==Key14[i] && (s[i]!=0 && Key14[i]!=0)) i++;
	                                                    if(s[i]==Key14[i]) return 14;
				                	                	else
														{
															while(s[i]==Key15[i] && (s[i]!=0 && Key15[i]!=0)) i++;
	                                                        if(s[i]==Key15[i]) return 15;
				                	                      	else return 0;
														}
													}
												}
											}
										}
									}
								}
							}
						}
					}
				}
			}
		}
	}
}

int isDoublewrd(char c)
{
	int x;
	switch(c)
	{
	case '+': x=16;break;
	case '-': x=17;break;
	case '*': x=18;break;
	case '/': x=19;break;
	case '=': x=20;break;
	case '<': x=22;break;
	case '>': x=24;break;
	case ',': x=26;break;
	case '.': x=27;break;
	case ';': x=28;break;
	case ':': x=29;break;
	case '(': x=31;break;
	case ')': x=32;break;
	case '#': x=35;break;
	default: x=0;
	}
	return x;
}


int cifa()
{
	ifstream fin("program.txt");
	char ch;
	char str[25]={0};
	int n,i,val,k=0;
	while(!fin.eof())
	{
		ch=fin.get();
		if(ch==' ' || ch=='\n') continue;
		else if(isWrdch(ch)) 
		{
			n=0;
			while(isWrdch(ch) || isNumch(ch))
			{	 
				if(n<20)
				{
					str[n]=ch;
					n=n+1;
					ch=fin.get();
				}
				else ch=fin.get();
			}
			if(i=isKeywrd(str)) 
			{
				cout<<i<<endl;
				code[k]=i;
				k++;
			}
			else 
			{
				cout<<"34"<<' '<<str<<endl;
				code[k]=34;
				k++;
			}
			if(i=isDoublewrd(ch))
			{
				cout<<i<<endl;
				code[k]=i;
				k++;
			}
			i=0;
			while(str[i]!=0) {str[i]=0;i++;}
		}
		else if(isNumch(ch)) 
		{
			val=0;
			while(isNumch(ch))
			{
				val=val*10+ch-'0';
				ch=fin.get();
			}
			cout<<"33"<<' '<<val<<endl;
			code[k]=33;
			k++;
			if(i=isDoublewrd(ch)) 
			{
				cout<<i<<endl;
				code[k]=i;
				k++;
			}
			i=0;
		}
		else if(isDoublewrd(ch))
		{
			cout<<isDoublewrd(ch)<<endl;
			code[k]=isDoublewrd(ch);
			k++;
		}
	}
	return k;
}
void getword() //************读取字符
{
	sym=code[m];
	m++;
}
void error() //******************判断错误位置
{
	flag=0;
	int t=m-1;
	cout<<"位置："<<t+1<<"代码:"<<code[t]<<" "<<"出错"<<endl;
	exit(0);
}

/*=========================================================*/
int program()
{
	getword();
	proghead();
	block();
	if(sym==27) return 0;
	else error();
}
void proghead()
{
	 if(sym==1) 
	 {
		 getword();
		 if(sym==34) 
		 {
			 getword();
			 if(sym==28) getword();
			 else error();
		 }
		 else error();
	 }
	 else error();
}
void block()
{
	consexpl();
	varexl();
	procdefi();
	compsent();
}
int consexpl()
{
	if(sym==2)
	{
		getword();
		consdefi();
		conssuff();
	}
	else return 0;
}
void consdefi()
{
	 if(sym==34) 
	 {
		 getword();
		 if(sym==20) 
		 {
			 getword();
			 if(sym==33) getword();
			 else error();
		 }
		 else error();
	 }
	 else error();
}
int conssuff()
 {
	 if(sym==26) 
	 {
		 getword();
		 consdefi();
		 conssuff();
	 }
	 else return 0;
 }
int varexl()
 {
	 if(sym==3)
	 {
		 getword();
		 vandefi();
		 varssuff();
	 }
	 else return 0; 
 }
void vandefi()
{
	if(sym==34) 
	 {
		getword(); 
		idsuff();
		if(sym==29) 
		 {
			 getword();
			 typeil();
			 if(sym==28) getword();
			 else error();
		 }
		 else error();
	 }
	 else error();

}
int idsuff()
{
	if(sym==26)
	{
		getword();
		if(sym==34) getword();
		else flag=0;
		idsuff();
	}
	else return 0;
}
int varssuff()
{
	if(sym==34) 
	{
		vandefi();
		varssuff();
	}
	else return 0;
}
void typeil()
{
	if(sym==4||sym==5) getword(); 
	else error();
}
int procdefi()
{
	if(sym==6)
	{
		procedh();
		block();
		if(sym==28) 
		{
			getword();
		    procsuff();
		}
		else error();
	}
	else return 0;
}
void procedh()
{
     if(sym==6)
	 {
		 getword();
         if(sym==34) 
		 {
			 getword();
			 argument();
		     if(sym==28) getword();
             else error();
		 }
		 else error();
	 }
	 else error();
}
int argument()
{
     if(sym==31)
	 {
		 getword();
		 if(sym==34)
		 {
			 getword();
			 if(sym==29)
			 {
				 getword();
				 typeil();
				 if(sym==32) getword();
				 else error();
			 }
			 else error();
		 }
		 else error();
	 }
	 else return 0;
}
int procsuff()
{
	if(sym==6)
	{
		procedh();
		block();
		if(sym==28) 
		{
			getword();
			procsuff();
		}
		else error();
	}
	else return 0;
}
int sentence()
{
	if(sym==34) assipro();
	else if(sym==7) ifsent();
	else if(sym==9) whilsent();
	else if(sym==11) read();
	else if(sym==12) write();
	else if(sym==13) compsent();
	else return 0;
}
void assipro()
{
	if(sym==34)
	{
		getword();
		suffix();
	}
	else error();
}
int suffix()
{
	if(sym==29)
	{
		getword();
		if(sym==20)
		{
			getword();
			express();
		}
		else error();
	}
	else if(sym==31)
	{
		getword();
		express();
		if(sym==32) getword();
		else error();
	}
	else return 0;
}
void ifsent()
{
	if(sym==7) 
	{
		getword();
		conditio();
		if(sym==8)
		{
			getword();
			sentence();
		}
		else error();

	}
	else error();
}
void whilsent()
{
	if(sym==9)
	{
		getword();
		conditio();
		if(sym==10)
		{
			getword();
			sentence();
		}
		else error();
	}
	else error();
}
void read()
{
	if(sym==11) 
	{
		getword();
		if(sym==31)
		{
			getword();
			if(sym==34)
			{
				getword();
				idsuff();
				if(sym==32) getword();
				else error();
			}
			else error();
		}
		else error();
	}
	else error();
}
void write()
{
	if(sym==12) 
	{
		getword();
		if(sym==31)
		{
			getword();
			express();
			exprsuff();
			if(sym==32) getword();
			else error();
		}
		else error();
	}
	else error();
}
int exprsuff()
{
	if(sym==26)
	{
		getword();
		express();
		exprsuff();

	}
	else return 0;
}
void compsent()
{
	if(sym==13)
	{
		getword();
		sentence();
		sentsuff();
		if(sym==14) getword();
		else error();
	}
	else error();
}
int sentsuff()
{
	if(sym==28)
	{
		getword();
		sentence();
		sentsuff();
	}
	else return 0;
}
void conditio()
{
	if(sym==16||sym==17||sym==34||sym==33||sym==31)
	{
		express();
		respoper();
		express();
	}
	else if(sym==15)
	{
		getword();
		express();
	}
	else error();
}
void express()
{
	if(sym==16||sym==17)
	{
		getword();
		term();
		termsuff();
	}
	else if(sym==34||sym==33||sym==31)
	{
		term();
		termsuff();
	}
	else error();
}


int termsuff()
{
	if(sym==16||sym==17)
	{
		addoper();
		term();
		termsuff();
	}
	else return 0;
}
void term()
{
	if(sym==34||sym==33||sym==31)
	{
		factor();
		factsuff();
	}
	else error();
}
int factsuff()
{
	if(sym==18||sym==19)
	{
		muloper();
		factor();
		factsuff();
	}
	else return 0;
}
void factor()
{
	if(sym==34) getword();
	else if(sym==33) getword();
	else if(sym==31) 
	{
		getword();
		express();
		if(sym==32) getword();
		else error();
	}
	else error();
} 
void addoper()
{
	if(sym==16||sym==17) getword();
	else error();
}
void muloper()
{
	if(sym==18||sym==19) getword();
	else error();
}
int respoper()
{
	if(sym==20) getword();
	else if(sym==22) 
	{
		getword();
		if(sym==20) getword();
        else return 0;
	}
	else if(sym==24)
	{
		getword();
		if(sym==20) getword();
        else return 0;
	}
	else error();
}
/*====================================*/
void main()
{
	int len=cifa();
	cout<<"字符代码为："<<endl;
	for(int i=0;i<len;i++)
	{
		cout<<code[i]<<"  ";
		if((i+1)%10==0) cout<<endl;
	}
	cout<<endl;
	program();
	if(flag==1) cout<<"语法分析正确"<<endl;
	else cout<<"程序错误"<<endl;
}