//語法、語義分析及代碼生成
#include <stdio.h>
#include <ctype.h>
#include <conio.h>
#define maxvartablep 500//定義符號表的容量
int TESTparse();
int program();
int compound_stat();
int statement();
int expression_stat();
int expression();
int bool_expr();
int additive_expr();
int term();
int factor();
int if_stat();
int while_stat();
int for_stat();
int write_stat();
int read_stat();
int declaration_stat();
int declaration_list();
int statement_list();
int compound_stat();
int name_def(char *name);
char token[20],token1[40];//token保存單詞符號，token1保存單詞值
extern char Scanout[300],Codeout[300]; //保存詞法分析輸出文件名
FILE *fp,*fout; //用于指向輸入輸出文件的指針
struct{//定義符號表結構
     char name[8];
     int address;
}vartable[maxvartablep];//改符號表最多容納maxvartablep個記錄
int vartablep=0,labelp=0,datap=0;

//插入符號表動作@name-def↓n, t的程序如下：
int name_def(char *name)
{    
	int i,es=0;
    if (vartablep>=maxvartablep) return(21);
	for(i=vartablep-1;i==0;i--)//查符號表
	{ 
		if (strcmp(vartable[i].name,name)==0)
		{
			es=22;//22表示變量重復聲明
			break;
		}
	}
	if (es>0)   return(es);
	strcpy(vartable[vartablep].name,name);
	vartable[vartablep].address=datap;
	datap++;//分配一個單元，數據區指針加1
	vartablep++;	
	return(es);
}
//查詢符號表返回地址
int lookup(char *name,int *paddress)
{
	int i,es=0;
	for(i=0;i<vartablep;i++)
	{
		if (strcmp(vartable[i].name,name)==0)
		{
           *paddress=vartable[i].address;
		   return(es);
		}
	}
     es=23;//變量沒有聲明
	 return(es);
}

//語法、語義分析及代碼生成程序
int TESTparse()
{
	int es=0;
	if((fp=fopen(Scanout,"r"))==NULL)
	{  
      printf("\n打開%s錯誤!\n",Scanout);
	  es=10;
	  return(es);
	}
	printf("請輸入目標文件名（包括路徑）：");
    scanf("%s",Codeout);
	if((fout=fopen(Codeout,"w"))==NULL)
	{  
      printf("\n創建%s錯誤!\n",Codeout);
	  es=10;
	  return(es);
	}
	if (es==0) es=program();
	printf("==語法、語義分析及代碼生成程序結果==\n");
	switch(es)
	{
		case 0: printf("語法、語義分析成功并抽象機匯編生成代碼!\n");break;	
		case 10: printf("打開文件 %s失敗!\n",Scanout);break;
		case 1: printf("缺少{!\n");break;
		case 2: printf("缺少}!\n");break;
		case 3: printf("缺少標識符!\n");break;
		case 4: printf("少分號!\n");break;
		case 5: printf("缺少(!\n");break;
		case 6: printf("缺少)!\n");break;
		case 7: printf("缺少操作數!\n");break;
		case 21: printf("符號表溢出!\n");break;
		case 22: printf("變量重復定義!\n");break;
		case 23: printf("變量未聲明!\n");break;
		
	}
	fclose(fp);
	fclose(fout);
	return(es);
}

//program::={<declaration_list><statement_list>}
int program()
{ 
   int es=0,i;
   fscanf(fp,"%s %s\n",token,token1);
   printf("%s %s\n",token,token1);
   if(strcmp(token,"{"))//判斷是否'{'
   {
	   es=1;
	   return(es);
   }
   fscanf(fp,"%s %s\n",&token,&token1);
   printf("%s %s\n",token,token1);
   es=declaration_list();
   if (es>0) return(es);
   printf("     符號表\n");
   printf("     名字       地址\n");
   for(i=0;i<vartablep;i++)
	   printf("      %s   %d\n",vartable[i].name,vartable[i].address);
   es=statement_list();
   if (es>0) return(es);
   if(strcmp(token,"}"))//判斷是否'}'
   {
	   es=2;
	   return(es);
   }
   fprintf(fout,"        STOP\n");//產生停止指令
   return(es);
}

//<declaration_list>::=
//<declaration_list><declaration_stat>|<declaration_stat>
//改成<declaration_list>::={<declaration_stat>}
int declaration_list()
{
	int es=0;
	while (strcmp(token,"int")==0)
	{
		es=declaration_stat();
		if (es>0) return(es);
	}
	return(es);
}

//<declaration_stat>↓vartablep,datap,codep ->int ID↑n@name-def↓n,t;
int declaration_stat()
{
	int es=0;      
	fscanf(fp,"%s %s\n",&token,&token1);printf("%s %s\n",token,token1);
	if (strcmp(token,"ID"))	return(es=3);  //不是標識符
	es=name_def(token1);//插入符號表
	if (es>0) return(es);
	fscanf(fp,"%s %s\n",&token,&token1);printf("%s %s\n",token,token1);
	if (strcmp(token,";") )	return(es=4);		
	fscanf(fp,"%s %s\n",&token,&token1);printf("%s %s\n",token,token1);
	return(es);
}

//<statement_list>::=<statement_list><statement>|<statement>
//改成<statement_list>::={<statement>}
int statement_list()
{
	int es=0;
	while (strcmp(token,"}"))
	{
		es=statement();
		if (es>0) return(es);
	}
	return(es);
}

//<statement>::= <if_stat>|<while_stat>|<for_stat>
//               |<compound_stat> |<expression_stat>

int statement()
{
	int es=0;
	if (es==0 && strcmp(token,"if")==0) es=if_stat();//<IF語句>
	if (es==0 && strcmp(token,"while")==0) es=while_stat();//<while語句>
	if (es==0 && strcmp(token,"for")==0) es=for_stat();//<for語句>
	//可在此處添加do語句調用
	if (es==0 && strcmp(token,"read")==0) es=read_stat();//<read語句>
	if (es==0 && strcmp(token,"write")==0) es=write_stat();//<write語句>
	if (es==0 && strcmp(token,"{")==0) es=compound_stat();//<復合語句>
	if (es==0 && (strcmp(token,"ID")==0||strcmp(token,"NUM")==0)) es=expression_stat();//<表達式語句>
	return(es);
}

//<IF_stat>::= if (<expr>) <statement > [else < statement >]
/*
if (<expression>)@BRF↑label1 <statement > @BR↑label2 @SETlabel↓label1 
                  [ else < statement >] @SETlabel↓label2

其中動作符號的含義如下
  @BRF↑label1 ：輸出 BRF label1, 
  @BR↑label2：輸出 BR label2, 
  @SETlabel↓label1：設置標號label1 
  @SETlabel↓label2：設置標號label2
*/
int if_stat(){
	int es=0,label1,label2;  //if
	fscanf(fp,"%s %s\n",&token,&token1);
	printf("%s %s\n",token,token1);
	if (strcmp(token,"(")) 	return(es=5);  //少左括號
	fscanf(fp,"%s %s\n",&token,&token1);
	printf("%s %s\n",token,token1);
	es=expression();
	if (es>0) return(es);
	if (strcmp(token,")"))  return(es=6); //少右括號
	label1=labelp++;//用label1記住條件為假時要轉向的標號
	fprintf(fout,"        BRF LABEL%d\n",label1);//輸出假轉移指令
	fscanf(fp,"%s %s\n",&token,&token1);
	printf("%s %s\n",token,token1);
	es=statement(); 
	if (es>0) return(es);
	label2=labelp++;//用label2記住要轉向的標號
	fprintf(fout,"        BR LABEL%d\n",label2);//輸出無條件轉移指令
	fprintf(fout,"LABEL%d:\n",label1);//設置label1記住的標號
	if (strcmp(token,"else")==0)//else部分處理
	{  
		fscanf(fp,"%s %s\n",&token,&token1);
		printf("%s %s\n",token,token1);
		es=statement(); 
	    if (es>0) return(es);
	}
	fprintf(fout,"LABEL%d:\n",label2);//設置label2記住的標號
	return(es);
}

//<while_stat>::= while (<expr >) < statement >
//<while_stat>::=while @SET↑labellabel1(<expression>) @BRF↑label2 
//				<statement >@BR↓label1 @SETlabel↓label2
//動作解釋如下：
//@SETlabel↑label1：設置標號label1
//@BRF↑label2 ：輸出 BRF label2,
//@BR↓label1：輸出 BR label1,
//@SETlabel↓label2：設置標號label2
int while_stat()
{
	int es=0,label1,label2;  
	label1=labelp++;
	fprintf(fout,"LABEL%d:\n",label1);//設置label1標號
	fscanf(fp,"%s %s\n",&token,&token1);
	printf("%s %s\n",token,token1);
	if (strcmp(token,"("))  return(es=5);  //少左括號
	fscanf(fp,"%s %s\n",&token,&token1);
	printf("%s %s\n",token,token1);
	es=expression();
	if (es>0) return(es);
	if (strcmp(token,")"))  return(es=6); //少右括號
	label2=labelp++;
	fprintf(fout,"        BRF LABEL%d\n",label2);//輸出假轉移指令
	fscanf(fp,"%s %s\n",&token,&token1);
	printf("%s %s\n",token,token1);
	es=statement();
	if (es>0) return(es);
	fprintf(fout,"        BR LABEL%d\n",label1);//輸出無條件轉移指令
	fprintf(fout,"LABEL%d:\n",label2);//設置label2標號
	return(es);
}

//<for_stat>::= for(<expr>,<expr>,<expr>)<statement>
/*
<for_stat>::=for (<expression>;
             @SETlabel↑label1< expression >@BRF↑label2@BR↑label3;
             @SETlabel↑label4 < expression >@BR↓label1) 
             @SETlabel↓label3 <語句 >@BR↓label4@SETlabel↓label2 
動作解釋：
1.	@SETlabel↓label1：設置標號label1
2.	@BRF↑label2 ：輸出 BRF label2,
3.	@BR↑label3：輸出 BR label3,
4.	@SETlabel↓label4：設置標號label4