www.pudn.com > WordScanner.rar > WordScanner.cpp
#include "stdio.h"
#include "stdlib.h"
#include "ctype.h"
#include "string.h"
#include "SymbolTable.h" //符号表
#include "WordClass.h" //分类表
#define OK 1
#define ERROR 2
bool word_scanner(FILE * fp);//词法分析
int lookup(char * ptoken);
int out(int id, char * pchar);
int num_of_line=1;
char TOKEN[20]; //读入字符的缓冲区
id_struct * id_head=NULL; //全局变量，指向标识符结构体链表的开始
FILE *fpw;
void main()
{
printf("This is a word analysiser!\n");
printf("编码\t单词\n");
FILE *fp;
fp=fopen("测试程序.txt","r"); //读取测试程序分析
fpw=fopen("词法分析结果.txt","w");//保存分析结果的文件
fprintf(fpw,"%s\t%s\n","编码","单词");
word_scanner(fp); //词法分析
fclose(fp); //关闭打开的文件
}
bool word_scanner(FILE * fp)//词法分析过程
{
bool end_file=false;
char ch;
int p_token=0; //标识TOKEN当前的位置
id_struct * kw_cur_position=id_head; //标识符当前位置指针
const_struct * int_cur_position=const_head; //常数当前位置指针
ch=fgetc(fp);
while(!end_file)
{
//处理部分，为了方便，假设标识符与保留字间以空格分隔
if(isalpha(ch)) //判断是否为字母
{
//若为字母,必为标识符或保留字
p_token=0;
TOKEN[p_token]=ch;
p_token++;
ch=fgetc(fp); //读取下一个字符
while(isalnum(ch))
{
//为数字或字母
TOKEN[p_token]=ch;
p_token++;
ch=fgetc(fp);
}
TOKEN[p_token]='\0';
fseek(fp,-1,1); //将文件指针从当前位置上移一个位置
int is_keyword;
is_keyword=lookup(TOKEN); //检查是否为保留字
if(is_keyword)
{
//是保留字
out(key_word_table[is_keyword-1].id ,key_word_table[is_keyword-1].name );
}
else
{
//是标识符
//将其加入到标识符链表中，并输出相应信息
id_struct * kw_next_position=NULL;
if(kw_cur_position==NULL)
{
//开始时
char pchar[20];
for(int i=0;i<20;i++)
{
pchar[i]=TOKEN[i];
}
id_head=(id_struct *)malloc(sizeof(id_struct));
id_head->id =12;
id_head->p =pchar;
id_head->next =NULL;
kw_cur_position=id_head;
out(id_head->id ,id_head->p );
}
else
{
//非开始位置
char pchar[20];
for(int i=0;i<20;i++)
{
pchar[i]=TOKEN[i];
}
kw_next_position=(id_struct *)malloc(sizeof(id_struct));
kw_next_position->id =12;
kw_next_position->p =pchar;
kw_next_position->next =NULL;
kw_cur_position->next =kw_next_position;
kw_cur_position=kw_next_position;
out(kw_cur_position->id ,kw_cur_position->p );
}
}//处理完关键字和保留字
}
else
{
//分析开始符号为非字母的单词
if(isdigit(ch))
{
//如果为数字
p_token=0;
TOKEN[p_token]=ch;
ch=fgetc(fp);
p_token++;
while(isdigit(ch))
{
//继续读取数字
TOKEN[p_token]=ch;
p_token++;
ch=fgetc(fp);
}
TOKEN[p_token]='\0';
fseek(fp,-1,1);
//加到常数链表中
const_struct * int_next_position=NULL;
if(const_head==NULL)
{
//如果链表为空
const_head=(const_struct *)malloc(sizeof(const_struct));
const_head->id =13;
const_head->value =TOKEN;
const_head->next =NULL;
int_cur_position=const_head;
out(const_head->id ,const_head->value );
}
else
{
//链表不为空
int_next_position=(const_struct *)malloc(sizeof(const_struct));
int_next_position->id =13;
int_next_position->value =TOKEN;
int_next_position->next =NULL;
int_cur_position->next =int_next_position;
int_cur_position=int_next_position;
out(int_cur_position->id ,int_cur_position->value );
}
}//分析完常数
else
{
//分析各类界符
switch(ch)
{
case '+':
printf("%d\t%s\n",14,"+");
fprintf(fpw,"%d\t%s\n",14,"+");
break;
case '-':
//需要保证为无符号整数
// ch=fgetc(fp);
// if(isdigit(ch))
// {
//输入了负数
// printf("%s%d%s\n","The scanner finds negtive at line ",num_of_line," in this program,please check it!");
// fprintf(fpw,"%s%d%s\n","The scanner finds negtive at line ",num_of_line," in this program,please check it!");
// }
// else
// {
//运算符
printf("%d\t%s\n",15,"-");
fprintf(fpw,"%d\t%s\n",15,"-");
// }
break;
case '*':
printf("%d\t%s\n",16,"*");
fprintf(fpw,"%d\t%s\n",16,"*");
break;
case ';':
printf("%d\t%s\n",17,";");
fprintf(fpw,"%d\t%s\n",17,";");
break;
case '(':
printf("%d\t%s\n",18,"(");
fprintf(fpw,"%d\t%s\n",18,"(");
break;
case ')':
printf("%d\t%s\n",19,")");
fprintf(fpw,"%d\t%s\n",19,")");
break;
case '=':
printf("%d\t%s\n",22,"=");
fprintf(fpw,"%d\t%s\n",22,"=");
break;
case '>':
ch=fgetc(fp);
if(ch=='=')
{
printf("%d\t%s\n",24,">=");
fprintf(fpw,"%d\t%s\n",24,">=");
}
else
{
fseek(fp,-1,1);
printf("%d\t%s\n",23,">");
fprintf(fpw,"%d\t%s\n",23,">");
}
break;
case '<':
ch=fgetc(fp);
if(ch=='=')
{
printf("%d\t%s\n",21,"<=");
fprintf(fpw,"%d\t%s\n",21,"<=");
}
else
{
if(ch=='>')
{
printf("%d\t%s\n",25,"<>");
fprintf(fpw,"%d\t%s\n",25,"<>");
}
else
{
fseek(fp,-1,1);
printf("%d\t%s\n",20,"<");
fprintf(fpw,"%d\t%s\n",20,"<");
}
}
break;
case ':':
ch=fgetc(fp);
if(ch=='=')
{
printf("%d\t%s\n",27,":=");
fprintf(fpw,"%d\t%s\n",27,":=");
}
else
{
fseek(fp,-1,1);
printf("%d\t%s\n",26,":");
fprintf(fpw,"%d\t%s\n",26,":");
}
break;
case '/':
ch=fgetc(fp);
if(ch=='*')
{
//处理注释部分
//循环读入，直到遇到*/为止
bool is_end=false;
int thefirst=1;
while(!is_end)
{
if(thefirst)
{
ch=fgetc(fp);
thefirst=0;
}
while(ch!='*')
{
ch=fgetc(fp);
}
ch=fgetc(fp);
if(ch=='/')
{
//到注释尾
is_end=true;
}
}
}
else
{
fseek(fp,-1,1);
printf("%d\t%s\n",28,"/");
fprintf(fpw,"%d\t%s\n",28,"/");
}
break;
case ' ':
//不进行特殊处理
break;
case '\r':
break;
case '\n':
num_of_line++;
break;
default:
if(isprint(ch))
{
printf("%s%d%s\n","There is a error at line ",num_of_line," !");
printf("%s%c%s\n","The symbol '",ch,"' is not a acceptable symbol!");
fprintf(fpw,"%s%d%s\n","There is a error at line ",num_of_line," !");
fprintf(fpw,"%s%c%s\n","The symbol ",ch," is not a acceptable symbol!");
//exit(0); //暂时按退出处理
}
//exit(0); //暂时按退出处理
break;
}
}
}//else
if(feof(fp)!=0)
{
//文件结束
end_file=true;
}
else
{
//读取下一个字符
ch=fgetc(fp);
}
}//while
return OK;
}
int lookup(char * ptoken)
{
//查询给的字符串是否为保留字
//若是，返回保留字位置，
//否则，返回0
for(int i=0;i<11;i++)
{
if(0==strcmp(key_word_table[i].name,ptoken))
{
//返回位置
return i+1;
}
}
return 0;
}
int out(int id, char * pchar)
{
//以二元组的形式输出id和pchar指向的内容
printf("%d\t%s\n",id,pchar);
fprintf(fpw,"%d\t%s\n",id,pchar);
return 1;
};