词法分析器.h

进行语法的分析

//#include "stdafx.h"
#include "stdio.h"
#include "iostream.h"
#include "ctype.h"
#include "string.h"
typedef struct
{
	int num;
	char word[20];
}key;
int line=1,column=0,c; 
char str[20];   
key keyword[15]=  
{
	{1,"PROGRAM"},{2,"CONST"},{3,"VAR"},
	{4,"INTEGER"},{5,"LONG"},{6,"PROCEDURE"},
	{7,"IF"},{8,"THEN"},{9,"WHILE"},
	{10,"DO"},{11,"READ"},{12,"WRITE"},
	{13,"BEGIN"},{14,"END"},{15,"ODD"}
};
/*void output(int m,char * s)  
{
	cout<<"["<<m<<","<<s<<"]"<<' '<<line<<' '<<column-strlen(s)+1<<endl;
}*/
char getch(FILE * fp)  
{
	char ch;
	ch=fgetc(fp);
	if(ch=='\n') 
	{
		line=line+1;
		column=0;      
	}
	else
	{
		column=column+1;
		c=column;
	}
	return ch;
}
void seek(FILE *fp,char ch)  
{
	if(ch=='\n')
	{
		line=line-1;
        column=c;
	}
	else
	{
		column=column-1;
		c=column;
	}
	fseek(fp,-1,1);
}
int compare(char *s1) 
{ 
	int i;
	for(i=0;i<20;i++)
	{
		if(strcmp(s1,keyword[i].word)==0)
			return keyword[i].num;
	}
	return -1;
}
int getsym(FILE * fp)  
{
	char ch;
	int n,m;
	int val;
	ch=getch(fp);
	while(ch==' ')ch=getch(fp);
	if(isalpha(ch)) 
	{
		n=0;
		while(isalnum(ch))
		{
			if(n<20)
			{
				str[n]=ch;
				n=n+1;
			}
			ch=getch(fp);
		}
		seek(fp,ch);
		str[n]='\0';
		m=compare(str);
		if(m!=-1)
		{
			//output(m,keyword[m-1].word); 
			return m;
		}
		else
		{
			//output(34,str);
			return 34;
		}
	}
	/*else if(isdigit(ch))
	{
		val=0;
		int i=0;
		while(isdigit(ch))
		{
			val=val*10+ch-'0';
			ch=getch(fp);
			i=i+1;
		}
		seek(fp,ch);
		cout<<'['<<33<<','<<val<<']'<<line<<' '<<column-i+1<<endl; 
		return 33;
	}*/
	else if(isdigit(ch))
    {
		 str[0]=ch;
		 ch=getch(fp);
		 n=1;
		 while(isdigit(ch))
		 {
			str[n]=ch;
			n++;
			ch=getch(fp);
		 }
		 str[n]='\0';
		 seek(fp,ch);
		 //output(33,str);
		 return 33;
    }
	else         
		switch(ch)
	{
        case '+'://output(16,"+");
			str[0]='+';
			str[1]='\0';
			return 16;break;    
        case '-'://output(17,"-");
			str[0]='-';
			str[1]='\0';
			return 17;break;
		case '*'://output(18,"*");
			str[0]='*';
			str[1]='\0';
			return 18;break;
		case '/'://output(19,"/");
			str[0]='/';
			str[1]='\0';
			return 19;break;
		case '='://output(20,"=");
			str[0]='=';
			str[1]='\0';
			return 20;break;
		case ','://output(26,",");
			str[0]=',';
			str[1]='\0';
			return 26;break;
		case '.'://output(27,".");
			str[0]='.';
			str[1]='\0';
			return 27;break;
		case ';'://output(28,";");
			str[0]=';';
			str[1]='\0';
			return 28;break;
		case '('://output(31,"(");
			str[0]='(';
			str[1]='\0';
			return 31;break;
		case ')'://output(32,")");
			str[0]=')';
			str[1]='\0';
			return 32;break;
		case '#'://output(35,"#");
			str[0]='#';
			str[1]='\0';
			return 35;break;
		case '<':         
			str[0]=ch;
			ch=getch(fp);
			if(ch=='>')
			{
				str[1]=ch;
				str[2]='\0';
				//output(21,str);
				return 21;
			}
			else 
			{
				if(ch=='=')
				{
					str[1]=ch;
					str[2]='\0';
					//output(23,str);
					return 23;
				}
				else 
				{
					str[1]='\0';
					seek(fp,ch);
					//output(22,str);
					return 22;
				}
			}
			break;	
		case '>':
			str[0]=ch;
			ch=getch(fp);		
			if(ch=='=') 
			{
				str[1]=ch;
				str[2]='\0';
				//output(25,str);
				return 25;
			}
			else 
			{
				str[1]='\0';
				seek(fp,ch);
				//output(24,str);
				return 24;
			}
			break;
		case ':':
			str[0]=ch;
			ch=getch(fp);
			if(ch=='=')
			{
				str[1]=ch;
				str[2]='\0';
				//output(30,str);
				return 30;
			}
			else 
			{
				str[1]='\0';
				seek(fp,ch);
				//output(29,str);
				return 29;
			}
			break;
		default: 
			{ 
				if(ch!=EOF&&ch!=' '&&ch!='\n')
				{
					cout<<"ERROR: "<<ch<<" line: "<<line<<" column: "<<column<<endl;
					return -1;
				}
				else 
					return 0;
			}
	}
}
/*int main()
{
	FILE *fp;
    char wenjian[30];
    cout<<"Please input the file you want to transform:";
    cin>>wenjian;
    fp=fopen(wenjian,"r");
    while(!feof(fp))
    {
		getsym(fp);
    }
	return 0;
}*/