语法分析.cpp

编译原理语法分析器课程设计完美版 里面有详细的说明和程序

//提供一个编译原理的语义分析程序  你可以直接复制 用TC进行调试
#include "stdio.h"
#include "string.h"
#include  <malloc.h>
#include <conio.h>
#include "stdlib.h"

char prog[100],token[8],ch;
char *rwtab[6]={"begin","if","then","while","do","end"};
int syn,p,m,n,sum,q;
int kk;
//四元式表的结构如下：
struct 
{
	char result1[8];
	char ag11[8];
	char op1[8];
	char ag21[8];
}quad[20];


char *factor();
char *expression();
int yucu();
char *term();
int statement();
int lrparser();
char *newtemp();
void scaner();
void emit(char *result,char *ag1,char *op,char *ag2);


void main()
{ 
	FILE *fp1,*fp2;

	if((fp1=fopen("输入.txt","rt"))==NULL) 
	{ 
		printf("Cannot open 输入.txt\n"); 
		getch(); 
		exit(1); 
	} 
	if((fp2=fopen("输出.txt","wt+"))==NULL) 
	{ 
		printf("Cannot create 输出.txt FILE.strike any key exit"); 
		getch(); 
		exit(1); 
	} 

	int j;
	q=p=kk=0;
	p=0;
	//printf("Please Input a String(end with '#'):\n");
	while(ch!='#')
	{
        ch = fgetc(fp1);
		if(ch == EOF)
		{
			printf("文件为空，请检查后再尝试!");
			return ;
		}
			
		prog[p++]=ch;
	}
	if(prog[p]=='#')
	{
		printf("输入的待分析的串不是以'#'结尾,请修改之后再尝试!\n");
		return;
	}
	p=0;
    char buffer1[200] = {0};
	sprintf(buffer1,"词法分析结果如下:\n");
	fputs(buffer1,fp2);
	//printf("词法分析结果如下:\n");
    do
	{
		scaner();
		switch(syn)
		{
		case 11:
			//printf("(%d,%d)\n",syn,sum);
            sprintf(buffer1,"(%d, %d) \n",syn,sum);
		    fputs(buffer1,fp2);
			break;
		default:
			//printf("(%d,%s)\n",syn,token);
			sprintf(buffer1,"(%d, %s)\n",syn,token);
		    fputs(buffer1,fp2);
			break;
		}
	}while(syn!=0);
	printf("\n");
    
	p=0;
	char  buffer[200]={0};
	sprintf(buffer,"语法分析结果如下:（以四元式形式输出）\n");
	fputs(buffer,fp2);
     //printf("语法分析结果如下:（以四元式形式输出）\n");
	scaner();//扫描函数
	lrparser();
	if(q>19)
		printf(" to long sentense!\n");
	else 
	{
	
       
		for (j=0;j<q;j++)
		{
			//printf("( %s, %s, %s, %s) \n\n",quad[j].op1,quad[j].ag11,quad[j].ag21,quad[j].result1);
			sprintf(buffer,"( %s, %s, %s, %s) \n\n",quad[j].op1,quad[j].ag11,quad[j].ag21,quad[j].result1);
		    fputs(buffer,fp2);
		}
	}
printf("已把相应的词法和语法的结果保存到相应的文件中，请查阅!\n");
	fclose(fp1);
	fclose(fp2);
}
int lrparser()
{
	int schain=0;
	kk=0;
	if (syn==1) //得到begin
	{ 
		scaner();//扫描下个字符
		schain=yucu();
		if(syn==6)//得到end
		{ 
			scaner();//扫描下个字符
			if((syn==0)&&(kk==0))  //得到#
				printf("Success!\n");
		}
		else 
		{
			if(kk!=1)
			printf("short of 'end' !\n");
			kk=1;
			getch();
			exit(0);
		}
	}
	else 
	{ 
		printf("short of 'begin' !\n");
		kk=1;
		getch();
		exit(0);
	}
	return (schain);
}
int yucu()
{ 
	int schain=0;
	schain=statement();
	while(syn==26)
	{ 
		scaner();
		schain=statement();
	}
	return (schain);
}
int statement()
{ 
	char tt[8],eplace[8];
	int schain=0;
	if (syn==10)
	{
		strcpy(tt,token); //tt中保存的是第一个字符
		scaner();
		if(syn==18)    //检测到=号
		{
			scaner();
			strcpy(eplace,expression());
			emit(tt,eplace,"=","__");
			schain=0;
		}
		else 
		{ 
			printf("short of sign ':=' !\n");
			kk=1;
			getch();
			exit(0);
		}
		return (schain);
	}
}
char *expression()
{ 
	char *tp,*ep2,*eplace,*tt;
	tp=(char *)malloc(12);
	ep2=(char *)malloc(12);
	eplace=(char *)malloc(12);
	tt=(char *)malloc(12);

	strcpy(eplace,term());

	while((syn==13)||(syn==14))
	{ 
		if (syn==13)
			strcpy(tt,"+");
		else
			strcpy(tt,"-");

		scaner();
		strcpy(ep2,term());
		strcpy(tp,newtemp());
		emit(tp,eplace,tt,ep2);
		strcpy(eplace,tp);
	}
	return (eplace);
}
char *term()
{ 
	char *tp,*ep2,*eplace,*tt;
	tp=(char *)malloc(12);
	ep2=(char *)malloc(12);
	eplace=(char *)malloc(12);
	tt=(char *)malloc(12);

	strcpy(eplace,factor());

	while((syn==15)||(syn==16))
	{
		if (syn==15)
			strcpy(tt,"*");
		else 
			strcpy(tt,"/");
		scaner();
		strcpy(ep2,factor());
		strcpy(tp,newtemp());
		emit(tp,eplace,tt,ep2);
		strcpy(eplace,tp);
	}
	return (eplace);
}
char *factor()
{ 
	char *fplace;
	fplace=(char *)malloc(12);
	strcpy(fplace,"");

	if(syn==10)  //得到字符
	{ 
		strcpy(fplace,token);
		scaner();
	}
	else if(syn==11) //得到数字
	{
		itoa(sum,fplace,10);
		scaner();
	}
	else if(syn==27) //得到)
	{ 
		scaner();
		fplace=expression();
		if(syn==28) //得到(
			scaner();
		else
		{ 
			printf("error on ')' !\n");
			kk=1;
			getch();
			exit(0);
		}
	}
	else 
	{ 
		printf("error on '(' !\n");
		kk=1;
		getch();
		exit(0);
	}
	return (fplace);
}
//该函数回送一个新的临时变量名，临时变量名产生的顺序为T1,T2...
char *newtemp()
{ 
	char *p;
	char m[8];
	p=(char *)malloc(8);

	kk++;
	itoa(kk,m,10);
	strcpy(p+1,m);
	p[0]='t';
	return(p); //设置中间变量名放在一个字符数组中，字符数组的第一个字符为t第二个字符为m表示的数值
}
void scaner()
{ 
	sum=0;
	///for(m=0;m<8;m++)
		//token[m++]=NULL;
	memset(token,0,8);
	m=0;
	ch=prog[p++];
	while(ch==' ')
		ch=prog[p++];
	if(((ch<='z')&&(ch>='a'))||((ch<='Z')&&(ch>='A')))
	{ 
		while(((ch<='z')&&(ch>='a'))||((ch<='Z')&&(ch>='A'))||((ch>='0')&&(ch<='9')))
		{
			token[m++]=ch;
			ch=prog[p++];
		}
		p--;
		syn=10;
		token[m++]='\0';
		for(n=0;n<6;n++)
			if(strcmp(token,rwtab[n])==0)
			{
				syn=n+1;
				break;
			}
	}
	else if((ch>='0')&&(ch<='9'))
	{ 
		while((ch>='0')&&(ch<='9'))
		{
			sum=sum*10+ch-'0';
			ch=prog[p++];
		}
		p--;
		syn=11;
	}
	else switch(ch)
	{ 
case '<':m=0;
	ch=prog[p++];
	if(ch=='>')
	{  
		syn=21;
	}
	else if(ch=='=')
	{  
		syn=22;
	}
	else
	{ 
		syn=20;
		p--;
	}
	break;
case '>':m=0;
	ch=prog[p++];
	if(ch=='=')
	{
		syn=24;
	}
	else
	{ 
		syn=23;
		p--;
	}
	break;
case ':':m=0;
	token[m++] = ch;
	ch=prog[p++];
	if(ch=='=')
	{ 
		syn=18;
		token[m++] = ch;
	}
	else
	{
		syn=17;
		p--;
	}
	break;
	
case '+': syn=13;token[0] = ch; break;
case '-': syn=14;token[0] = ch; break;
case '*': syn=15;token[0] = ch;break;
case '/': syn=16;token[0] = ch;break;
case '(': syn=27;token[0] = ch;break;
case ')': syn=28;token[0] = ch;break;
case '=': syn=25;token[0] = ch;break;
case ';': syn=26;token[0] = ch;break;
case '#': syn=0;token[0] =  ch;break;
default: syn=-1;break;
	}
}
//该函数是生成一个三地址语句送到四元式表中
void emit(char *result,char *ag1,char *op,char *ag2)
{ 
	strcpy(quad[q].result1,result);
	strcpy(quad[q].ag11,ag1);
	strcpy(quad[q].op1,op);
	strcpy(quad[q].ag21,ag2);
	q++; //统计有多少个四元式
}