main.c

输入一个DO-WHILE的语句,进行词法分析,词法分析器利用超前搜索,状态转换等方法,将源程序转化成为一个一个的单词符号二元式,如果词法分析无误,则进入语法分析部分,使用简单优先法进行文法分析,为每个

#include "stdio.h"
#include "Parse.h"
#include "Global.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <malloc.h>
#include <ctype.h>
#include <conio.h>
#define NULL 0
#define OK 1
#define size 100
FILE *fp;
char ch;
char *keyword[6]={"begin","else","end","if","then","var"};
char *comparison[5]={"<","<=",">",">=","<>"};
char *equal[1]={"="};
char *interpunction[10]={",",";",":=",".","(",")","+","-","*","/"};
char *now[2]={"while","do"};
int flag[1]={1};
char buffer[10][100];
int inc=-1;

bool search(char searchstr[],int wordtype)
{
       int i;
       switch (wordtype)
       {
             case 1:for(i=0;i<=5;i++)
					{
                        if(strcmp(keyword[i],searchstr)==0)
                         return(true);
                              
                     }
				 break;
   
              case 2: for(i=0;i<=4;i++)
                           {
                            if(strcmp(comparison[i],searchstr)==0)
                             return(true);
                           }
				  break;
              case 3: for(i=0;i<=9;i++)
                           {
                            if(strcmp(interpunction[i],searchstr)==0)
                             return(true);
                           }
				  break;
              case 4:for(i=0;i<=1;i++)
					 {
                             if(strcmp(now[i],searchstr)==0)
                             return(true);
					 }
				  break;
			  case 5:{
                             if(strcmp(equal[0],searchstr)==0)
                             return(true);
					 }
				  break;
       }
                         return(false);
}

char letterprocess (char ch)//字母处理函数                       
{
   int i=-1,j=1;
   char letter[20];
   while (isalnum(ch)!=0)
   {
     letter[++i]=ch;
     ch=fgetc(fp);
   }
 letter[i+1]='\0';
 if (search(letter,1))
 {
	 printf("<%s,->\n",letter);printf("aaaaa");
     flag[0]=0;
 }
 else if(search(letter,4))
	 printf("<%s,->\n",letter);
 else
 {
  printf("<indentifier,%s>\n",letter);
  strcpy(buffer[++inc],letter);
 }
 return(ch);
}

char numberprocess(char ch)//数字处理程序
{
    int i=-1;
    char num[20];
//	printf("该文法不在此次考虑中\n");
	flag[0]=0;
    while (isdigit(ch)!=0)
    {
        num[++i]=ch;
        ch=fgetc(fp);
    }
    if(isalpha(ch)!=0)
    {
       while(isspace(ch)==0)
       {
          num[++i]=ch;
          ch=fgetc(fp);
       }
       num[i+1]='\0';
       printf("错误！非法标识符：%s\n",num);
       goto u;
     }
       num[i+1]='\0';
       printf("<num,%s>\n",num);
       u: return(ch);
}

char otherprocess(char ch)
{
    int i=-1;
    char other[20];
    if (isspace(ch)!=0)
    {
        ch=fgetc(fp);
        goto u;
    }
    while ((isspace(ch)==0)&&(isalnum(ch)==0))
    {
        other[++i]=ch;
        ch=fgetc(fp);
    }
    other[i+1]='\0';
    if (search(other,3))
	{
		printf("<relop,%s>\n",other);
		flag[0]=0;
	}
    else
    if (search(other,2))
	{
		printf("<%s,->\n",other);
        strcpy(buffer[++inc],other);
	}
    else if(search(other,5))
		printf("<%s,->\n",other);
    else 
    printf("错误！非法字符：%s\n",other);
    u: return (ch);
 }

void cifa() 
{
	char str;
    printf(" ********** 词法分析器 **********\n");
    if ((fp=fopen("lj.txt","r"))==NULL)
    printf("源程序无法打开！\n");
    else
    {
       str =fgetc(fp);
       while (str!=EOF)
       {
           if (isalpha(str)!=0)
           str=letterprocess(str);
           else
           {
              if (isdigit(str)!=0)
              str=numberprocess(str);
              else
              str=otherprocess(str);
            }
                            
	   };
       printf("词法分析结束！\n");
       printf("  ********** 语法分析器 **********\n");
    }
      
}

/* 
    Get string from user, and
  store the value into the global variable Buff  */
void InputString()
{
    int len = 0;
	printf("表达式文法为: ");
    printf(GRAMMAR);
    printf("\n Please input any string to parse:\n");
    scanf("%s", Buff);
    len = strlen(Buff);
    Buff[len] = '#';
    Buff[len+1] = 0;
}

void main()
{
    printf(" DO-WHILE循环语句的翻译\n ");
    printf("循环语句的格式为：DO <赋值语句> WHILE <表达式>\n ");
    printf("翻译的语句:do c=a+1 while a>b\n ");
	cifa();
	InputString();
    Parse();
    getch();
    printf(" \n  (1) (+,a,1,c)\n ");
	printf(" (2) (>,a,b,t0)\n ");
	printf(" (3) (=,t0,true,1)\n ");
	printf(" (4) (-,-,-,-)\n ");
}