语法分析.cpp

慎重使用

#include "string.h"
#include "stdio.h"
#include "ctype.h"
#include "dos.h"
#define SPACE 0
#define LETTER 1
#define DIGIT 2
#define OTHER 3
#define FOR 1000
#define TO 1001
#define DO 1002
#define THEN 1003
#define IF 1004
#define ELSE 1005
#define BEGIN 1006
#define END 1007
#define REPEAT 1008
#define UNTIL 1009
#define TRUE 1
#define FALSE 0
#define MAXANA 100    
/*输入字串的最大长度*/
#define MAXRESVL 10   
/*保留字的最大长度*/
#define MAXRESERVE 20  /*保留字个数*/
typedef struct{
char str[10];
}lastwd;
         /*  保留字        标志符      常数     操作符    界符  */
int lastwdkeywd[MAXRESERVE],
flagwd[20],intwd[20],oprwd[20],jief[20],errwd[20];
int ckeywd=0,cflagwd=0,cintwd=0,coprwd=0,cjief=0,cerrwd=0;/*计数*/
int curpos=0; /* 搜索串当前位置*/
/*声明函数*/
char getachar(char *,int);      
 /*此函数用于从字串*的int取一字符*/
int analyse(char);             
 /*此函数用于分析字符*/
int analy(char *);                
/*此函数用于分析字串(关键字还是其他)*/
int writefile(char *,char *);    
  /*写入分析结果:char *属于int类*/
int writech(char *,char );
char anawd[MAXRESVL];
struct date today;
struct time now;
/*-------main()--------------------*/
main()
{char anastr[MAXANA];    /* 放待分析串*/
FILE *ff;
char curch;                   /*当前字符*/
int count=0,kindch,kindwd; 
/*count 用来记录已搜索字符个数,kindch用来返回字符类型*/
 int writeok,i;   
  for(i=0;i<MAXRESVL;i++)
  anawd[i]='';/*kindwd用来返回字串类型*/
printf("输入分析串：(<100 char)");
gets(anastr);
strcat(anastr,"$$");
printf("\n正在分析字符串:: ");
printf("\n%s,%d",anastr,strlen(anastr));   /*技巧：设置结束标志'$'*/
while(getachar(anastr,curpos)!='$'&&curpos<=strlen(anastr))/*如未结束，则进行分析*/
{nextch:
anawd[count]=getachar(anastr,curpos);
curch=getachar(anastr,curpos);
kindch=analyse(curch); /*对当前字符分析*/
switch(kindch)
{
case LETTER:            /*为字母*/
curpos++;
count++;
curch=getachar(anastr,curpos);
kindch=analyse(curch); /*对当前字符分析*/
if(kindch==SPACE)    
 {kindwd=analy(anawd); 
/*函数analy()对分离出的单词anawd分析*/
  if(kindwd!=0)
  {strcpy(keywd[ckeywd].str,anawd);
   writeok=writefile("类型：关键字，",anawd);/*写入分析结果*/
    if(writeok==0)/*如写失败，则现场显示*/
      {
        printf("类型：关键字，%s\n",kindwd,anawd);
       }
   ckeywd++;
   for(i=0;i<MAXRESVL;i++)
    anawd[i]='';
   count=0;
  }
else if(kindwd==0)
 {strcpy(flagwd[cflagwd].str,anawd);
  writeok=writefile("类型：变量，",anawd);/*写入分析结果*/
    if(writeok==0)/*如写失败，则现场显示*/
      {
        printf("类型：变量，%s\n",kindwd,anawd);
       }
    cflagwd++;
   for(i=0;i<MAXRESVL;i++)
    anawd[i]='';
   count=0;
  }
    }  /*******SPACE***/
else if(kindch==OTHER)                 /*========i=========== */
 {kindwd=analy(anawd); /*函数analy()对分离出的单词anawd分析*/
  if(kindwd!=0)
  {strcpy(keywd[ckeywd].str,anawd);
   writeok=writefile("类型：关键字，",anawd);/*写入分析结果*/
    if(writeok==0)/*如写失败，则现场显示*/
      {
        printf("类型：关键字，%s\n",kindwd,anawd);
       }
    ckeywd++;
   }
   if(kindwd==0)
   {strcpy(flagwd[cflagwd].str,anawd);
   writeok=writefile("类型：标志符，",anawd);/*写入分析结果*/
    if(writeok==0)/*如写失败，则现场显示*/
      {
        printf("类型：标志符，%s\n",kindwd,anawd);
       }
    cflagwd++;
   }
    for(i=0;i<MAXRESVL;i++)
    anawd[i]='';
   count=0;
  }
else if(kindch==DIGIT)                 
{
do{
curch=getachar(anastr,curpos);
anawd[count]=curch;   /*x5 */
      count++;
       curpos++;          /* curch='=' */
 }while(analyse(getachar(anastr,curpos))!=SPACE&&analyse(getachar(anastr,curpos))!=OTHER);
    writeok=writefile("类型：变量, ",anawd);/*写入分析结果*/
    if(writeok==0)/*如写失败，则现场显示*/
      {
        printf("类型：变量, %s\n",anawd);
       }
    strcpy(flagwd[cflagwd].str,anawd);
    cflagwd++;
   for(i=0;i<MAXRESVL;i++)
  anawd[i]='';
 count=0;                         
}
else goto nextch;
    /*case LETTER: */
break;

case DIGIT:/*数字*/
{curpos++;
count++;
curch=getachar(anastr,curpos);
kindch=analyse(curch); /*对当前字符分析*/
if(kindch==DIGIT||kindch==SPACE||kindch==OTHER)
 {if(kindch==DIGIT)
   do{curch=getachar(anastr,curpos);
     anawd[count]=curch;
       count++;
        curpos++;
     }while(analyse(getachar(anastr,curpos))==DIGIT);
   writeok=writefile("类型：数字, ",anawd);/*写入分析结果*/
    if(writeok==0)/*如写失败，则现场显示*/
      {
        printf("类型：数字, %s\n",anawd);
       }
   strcpy(intwd[cintwd].str,anawd);
   cintwd++;
   for(i=0;i<MAXRESVL;i++)
  anawd[i]='';
 count=0;
 }
else 
{printf("变量声明错误！(变量不能以数字开始)");
  do{curch=getachar(anastr,curpos);
anawd[count]=curch;
      count++;
       curpos++;
     }while(analyse(getachar(anastr,curpos++))!=OTHER);
    strcpy(errwd[cerrwd].str,anawd);
    writeok=writefile("类型：错误, ",anawd);/*写入分析结果*/
    if(writeok==0)/*如写失败，则现场显示*/
      {
        printf("类型：错误, %s\n",anawd);
       }
    cerrwd++;
   for(i=0;i<MAXRESVL;i++)
  anawd[i]='';
 curpos--;
 count=0;
goto nextch;
}
}  /*case 数字 */
break;
case SPACE:
 curpos++;
 break;

case OTHER:
/*其他，如：=,:=,{,},;,*,(,),+*/    if(curch=='{'||curch=='}'||curch=='('||curch==')'||curch==';'||curch=='['||curch==']')
    { strcpy(jief[cjief].str,anawd);
writeok=writech("类型：界符,",curch);
/*写入分析结果*/
    if(writeok==0)/*如写失败，则现场显示*/
      {
        printf("类型：界符, %s\n",curch);
       }
 curpos++;
     cjief++;
     for(i=0;i<MAXRESVL;i++)
  anawd[i]='';
 count=0;
 }
  else 
if(curch=='-'||curch=='+'||curch=='*'||curch=='/'||curch=='%'||curch=='<'||curch=='>')
    {strcpy(oprwd[coprwd].str,anawd); 
    writeok=writech("类型：运算符,",curch);/*写入分析结果*/
    if(writeok==0)/*如写失败，则现场显示*/
      {
        printf("类型：运算符, %s\n",curch);
       }
 curpos++;
        coprwd++;
        for(i=0;i<MAXRESVL;i++)
  anawd[i]='';
 count=0;
    }
    else if(curch=='=')
      {curpos++;
   curch=getachar(anastr,curpos);
    if(curch=='=')
    {strcpy(oprwd[coprwd].str,"=="); 
          writeok=writefile("类型：比较符,","==");/*写入分析结果*/
          if(writeok==0)
/*如写失败，则现场显示*/
  {
            printf("类型：比较符, ==\n");
  }
    curpos++;
               coprwd++;
         for(i=0;i<MAXRESVL;i++)
             anawd[i]='';
            count=0;    
         }
     else
{strcpy(oprwd[coprwd].str,anawd);
        writeok=writech("类型：赋值符",'=');/*写入分析结果*/
          if(writeok==0)
/*如写失败，则现场显示*/
    {  printf("类型：赋值符，=\n");
    }
   /*分析当前字符*/ 
     coprwd++;
         for(i=0;i<MAXRESVL;i++)
              anawd[i]='';
             count=0;
           }
 }
   else if(curch==':')
      {curpos++;
   curch=getachar(anastr,curpos);
    if(curch=='=')
    {strcpy(oprwd[coprwd].str,":="); 
          writeok=writefile("类型：赋值符,",":=");/*写入分析结果*/
          if(writeok==0)
/*如写失败，则现场显示*/
  {
            printf("类型：赋值符, :=\n");
  }
    curpos++;
               coprwd++;
                for(i=0;i<MAXRESVL;i++)
              anawd[i]='';
              count=0;
     }
         }
break;
default:Error();
}
}
if(!(ff=fopen("jieg.txt","a")))
{printf("不能写文件jieg.txt！");
}
else{ 
fprintf(ff,"\n-------------简单词法分析器--");
fprintf(ff,"\n\t\t\t设计：计本003 安文政 完成日期:2003/01/09");
getdate(&today);
gettime(&now);
fprintf(ff,"\n 测试日期： %d-%d-%d",today.da_year,today.da_mon,today.da_day);
fprintf(ff,"     测试时间： %02d:%02d:%02d",now.ti_hour,now.ti_min,now.ti_sec);
fprintf(ff,"\n-------------------------------");
fprintf(ff,"\n\t\t分析结果:");
fprintf(ff,"\n 输入的语句：%s ",anastr);
fprintf(ff,"\n ('$$'为系统添加的结束标志)");
fprintf(ff,"\n 保留字:");
for(i=0;i<ckeywd;i++)
fprintf(ff,"  %s ",keywd[i].str);
fprintf(ff,"\n 标志符:");
for(i=0;i<cflagwd;i++)
fprintf(ff,"  %s ",flagwd[i].str);
fprintf(ff,"\n 常数:");
for(i=0;i<cintwd;i++)
fprintf(ff,"  %s ",intwd[i].str);
fprintf(ff,"\n 操作符:");
for(i=0;i<coprwd;i++)
fprintf(ff,"  %s ",oprwd[i].str);
fprintf(ff,"\n 界符:");
for(i=0;i<cjief;i++)
fprintf(ff,"  %s ",jief[i].str);
fprintf(ff,"\n 错误类型:");
if(cerrwd==0)
fprintf(ff,"  无");
else 
for(i=0;i<cerrwd;i++)
fprintf(ff,"  %s ",errwd[i].str);
fclose(ff);
}
printf("\n分析结果已保存于当前目录下的 jieguo.txt!");
printf("\n\t 计本003 安文政 2003/01/09");
}

Error(char *strin)
{
printf(" \n发现非法字符!!\n ");
strcpy(errwd[cerrwd].str,strin);
    cerrwd++;
}

char getachar(char *anastr,int where)       /*此函数从字串*anastr的where取一字符*/
{char ch;
ch=anastr[where];
/*printf("\n%d,%c  in function getachar ",where,ch);*/
return ch;
}
int analyse(char ch) /*此函数用于分析字符*/
{if(isalpha(ch))
{
return LETTER;
}
else if(isdigit(ch))
{
 return DIGIT;
}
else if(isspace(ch))
 
{
return SPACE;}
else return OTHER;
}

int writefile(char *kind,char *str)
{FILE *fp;
if(!(fp=fopen("jieguo.txt","a")))
{printf("不能写文件jieguo.txt！");
return 0;
}
fprintf(fp," %s  %s\n",kind,str);
fclose(fp);
return 1;
}
int writech(char *kind,char str)
{FILE *fp;
if(!(fp=fopen("jieguo.txt","a")))
{printf("不能写文件jieguo.txt！");
return 0;
}
fprintf(fp," %s  %c\n",kind,str);
fclose(fp);
return 1;
}
int analy(char *wd)
{if(!strcmp(wd,"for"))
return FOR;
else if(!strcmp(wd,"do"))
return DO;
else if(!strcmp(wd,"to"))
return TO;
else if(!strcmp(wd,"then"))
return THEN;
else if(!strcmp(wd,"if"))
return IF;
else if(!strcmp(wd,"else"))
return ELSE;
else if(!strcmp(wd,"begin"))
return BEGIN;
else if(!strcmp(wd,"end"))
return END;
else if(!strcmp(wd,"repeat"))
return REPEAT;
else if(!strcmp(wd,"until"))
return UNTIL;
else return 0;
}