xing.cpp

编译原理中的词法分析

#include <stdio.h>
#include <string.h>
#include <ctype.h>
#include <iostream.h>
#include <stdlib.h>
//定义单词编码表的数据结构
struct symbolrecord 
{ char symbol[10];
  int id;
} ;

//定义符号表的数据结构
struct entrytype
{ char idname[10];
  int address;
  int type;
};

//定义常数表的数据结构
struct digittype
{ int num;
  int address;
};

//Token字的数据结构
struct tokentype
{ int id;
  int entry;
};

FILE *fp;                       //源文件指针
struct digittype d[10];         //定义常数表，个数指针
struct entrytype a[40];         //定义符号表，个数指针
int k=0,t=0;

//单词编码表初始化
struct symbolrecord s[30]=
{ "func",0,
  "while",1,
  "do",2,
  "If",3,
  "Then",4,
  "Else",5,
  "true",6,
  "false",7,
  "int",8,
  "const",9,
  "{",11,
  "}",12,
  ";",13,
  ",",14,
  "=",15,
  "!",16,
  "&",17,
  "|",18,
  "<",19,
  ">",20,
  "<=",21,
  ">=",22,
  "<>",23,
  "==",24,
  "+",25,
  "*",26,
  "(",27,
  ")",28,
  "id",29};

     
//识别标识符算法
tokentype recogid(char ch)
{ tokentype tokenid;
  FILE *fs;
  int flag,fflag;
  char word[10]={0};
  int i,j;
  i=0;
 
  while(isalpha(ch)||isdigit(ch)) 
	{ word[i]=ch;
      ch=fgetc(fp);
      i=i+1;
	}
  ungetc(ch,fp);
 word[i]='\0';
  for(j=0;j<=8;j++)
	 { flag=strcmp(word, s[j].symbol);
       if(flag==0)                                    //是关键字
		{ tokenid.id=j;
	      tokenid.entry=-1;
		  break;
	   }
     }
  if(flag!=0)
	  
  { for(j=0;j<=k;j++)
	{	fflag=strcmp(a[j].idname,word);
		 if(fflag==0)                                 //在符号表中可以找到
		   { tokenid.id=29;
             tokenid.entry=a[j].address;
			 break;
		  }
	}
    if(fflag!=0)
	
		{ fs=fopen("symbol.txt","a");                 //符号表中不存在的标识符
	      strcpy(a[k].idname, word);
		  a[k].address=k;
		  a[k].type=29;
		  tokenid.id=29;
		  tokenid.entry=k;
		  
		  for(j=0;j<9;j++)
		    fprintf(fs,"%c",word[j]);
          fprintf(fs,"%c",'\t');
          fprintf(fs,"%d",a[k].address);
          fprintf(fs,"%c",'\t');
          fprintf(fs,"%d",a[k].type);
          fprintf(fs,"%c",'\n');
		  fclose(fs);
		  k=k+1;
		}
  }
   
   return tokenid;
}

///识别数字函数
tokentype recogdig(char ch)
{ int flag;
  int i=0,j;
  int num=0;
  tokentype tokenid;
  while(isdigit(ch)) 
	{ num=(ch-48)+num*10;
      ch=fgetc(fp);
      i=i+1;
	}

  for(j=0;j<=t;j++)
	  if(d[j].num==num)
		{ flag=1;
          tokenid.id=9;
          tokenid.entry=d[j].address;
		  break;
		}
  if(flag!=1)
  {  d[t].num=num;
	 d[t].address=t;
     tokenid.id=9;
	 tokenid.entry=t;
	 t=t+1;
  }
  return tokenid;
}


//识别算符和界符函数
tokentype recogdel(char ch)
{ tokentype tokenid;
  switch(ch)	
	{ case'{':tokenid.id=11;break;
      case'}':tokenid.id=12;break;
	  case';':tokenid.id=13;break;
	  case',':tokenid.id=14;break;
	  case'=':ch=fgetc(fp);
	      if(ch=='=') tokenid.id=24;
		  else { tokenid.id=15;
		         ungetc(ch,fp);
				};
		  break;
	  case'!':tokenid.id=16;break;
	  case'&':tokenid.id=17;break;
	  case'|':tokenid.id=18;break;
	  case'<':ch=fgetc(fp);
	      if(ch=='=') tokenid.id=21;
		  else 
			if(ch=='>') tokenid.id=23;
				else{ tokenid.id=19;
		              ungetc(ch,fp);
					};
		  break;
	  case'>':ch=fgetc(fp);
	      if(ch=='=') tokenid.id=22;
		  else { tokenid.id=20;
		         ungetc(ch,fp);
				};
		  break;
	       
	  case'+':tokenid.id=25;break;
	  case'*':tokenid.id=26;break;
	  case'(':tokenid.id=27;break;
	  case')':tokenid.id=28;break;
	}
  tokenid.entry=-1;
 return tokenid;
  }

/////////////////////handlecom函数////////////
tokentype handlecom(char ch)
{ tokentype tokenid;
  char ch1;
  int flag=0;
  if(ch!='*' )
  { tokenid.id=29;
    tokenid.entry=-1;
  }
  else
	{ while(flag==0)
		{ ch1=ch;
          ch=fgetc(fp);
		  if((ch1='*')&&(ch='/'))
                  flag=1;
		}
	}
  return tokenid;
}

///////////sort函数/////////
void sort(char ch)
{ 
  struct tokentype tokenword;
  FILE * fq = fopen("tokenfile.txt","a");
	if(isalpha(ch))
        tokenword=recogid(ch);                  //字母
	else if(isdigit(ch))
		    tokenword=recogdig(ch);             //数字
	     else  if(ch=='/')
			    tokenword=handlecom(ch);
		        else
					tokenword=recogdel(ch);
  printf("%d\t%d\n",tokenword.id,tokenword.entry);

  fprintf(fq,"%d",tokenword.id);
  fprintf(fq,"%c",'\t');
  fprintf(fq,"%d",tokenword.entry); 
  fprintf(fq,"%c",'\n');
  fclose(fq);

}



/////////////scanner函数////////
void scanner()
{ char ch;
  fp=fopen("source.txt","r");
  ch=getc(fp);
  while(ch!=EOF)
	{ if(!isspace(ch))
		{ sort(ch);
          
		}
      ch=fgetc(fp);
	}
  fclose(fp);

}

void main()
{ int i;
  
  printf("token字如下:\n");
  scanner();
  printf("************************************\n");
  printf("符号表如下：\n"); 
  printf("%s\t\t%s\t\t%s\n","idname","address","type");
  for(i=0;i<=k-1;i++)
       printf("%s\t\t%d\t\t%d\n",a[i].idname,a[i].address,a[i].type);
  printf("************************************\n");
  printf("常数表如下：\n"); 
  printf("%s\t\t%s\n","num","address");
  for(i=0;i<=t-1;i++)
       printf("%d\t\t%d\n",d[i].num,d[i].address); 
  cout<<endl;
  system("pause");
}