analysisproc.cpp

语法分析器

#include "string.h"
#include "stdlib.h"
#include "stdio.h"
#include "iostream"
#define MAX_LENGTH 120
using namespace std;
int index = 0;
char constable[100][MAX_LENGTH];
int constcount = 0;//常数表
char GetChar(char *str){
	char c;
	c = str[index++];

return c;
}
int Oct2Dec(char *str){//转换8进制为10进制
	int i = 0, j = 0;
	int c = 1,sum = 0;
	char ch;
	ch = *(++str);

	while(ch != '\0'){
		i++;
		ch = *(++str);
	}
	ch =*(--str);
	for(j = i;j > 0;j--){
		ch -='0';
		sum+=c*ch;
		c*=8;
		ch = *(--str);
	}
	return sum;
}

int Hex2Dec(char *str){//转换16进制为10进制
	int i = 0, j = 0;
	int c = 1,sum = 0;
	char ch;
	str+=2;
	ch = *str;

	while(ch != '\0'){
		i++;
		ch = *(++str);
	}
	ch =*(--str);
	for(j = i;j > 0;j--){
		if(ch >= '0'&&ch <='9')
		ch -='0';
		else if(ch >= 'a'&&ch <='f'){

			ch -='a';
			ch+=10;
		}
		else if(ch >= 'A'&&ch <='F'){
			
			ch -='A';
			ch+=10;
		}
		sum+=c*ch;
		c*=16;
		ch = *(--str);
	}
	return sum;
}


int InsertConst(char* strToken){
	strcpy(constable[constcount++],strToken);
	puts(constable[constcount]);
	return constcount;
}

void insertID(){

}
void ErrorProc(){
}
int Reserve(char *str){//检查是否为保留字并返回保留字的编号
	int i;
	char *ResTable[] = {""
		,"if"
		,"then"
		,"else"
		,"while"
		,"do"}
	,**pt;
	pt = ResTable;
		
	for(i = 1;i < 6;i++){
		if(strcmp(pt[i],str) == 0)
			return i;


	}
	
	
	return 0;
}

int scan(){
int code,value;
char ch;
char strToken[MAX_LENGTH]={'\0'};
char str[MAX_LENGTH] = "12 asdf 0x if 21 ij ";
int i = 0;
/*
FILE *fp;
fp = fopen("c:\123.txt","r");
if(!fp){
	printf("Can not open file! Program exit\n");
	exit(1);

}
*/

ch = GetChar(str);
do{
	if(ch >='1'&&ch<='9'){				//如果为十进制数
		strToken[i++] = ch;

		ch = GetChar(str);
		while(ch >='0'&&ch<='9'){		//如果是十进制的数的后n位继续填入
			strToken[i++] = ch;
			ch = GetChar(str);
		}
		strToken[i] = '\0';//如果是其他字符尾部置空
		printf("INT10\t%s\n",strToken);
		i = 0;
	//	InsertConst(strToken);
		
	}
	else if(ch == '0'){
		strToken[i++] = ch;
		ch = GetChar(str);
		if(ch == 'x'){//HEX的处理
			strToken[i++] = ch;
			ch = GetChar(str);
			while((ch >= '0'&& ch <= '9')||(ch >='a'&&ch <='f')){
				strToken[i++] = ch;
				ch = GetChar(str);
			}
			strToken[i] = '\0';
			i = 0;
			
			printf("INT16\t%d\n",Hex2Dec(strToken));
			continue;
		//	InsertConst(strToken);
				
		}
		else if(ch >= '0'&& ch <= '7'){ //处理8进制问题
			strToken[i++] = ch;
			ch = GetChar(str);
			while(ch >= '0'&& ch <= '7'){
				strToken[i++] = ch;
				ch = GetChar(str);

			}
			strToken[i] = '\0';
			i = 0;
			
			printf("INT8\t%d\n",Oct2Dec(strToken));
			continue;
			
			//InsertConst(strToken);
		}
		else 
			strToken[i] = '\0';
			i = 0;
			printf("INT10\t%s\n",strToken);
			//InsertConst(strToken);
	}
	else if(ch == '+'||ch == '-'||ch == '*'||ch == '/'||ch == '>'||ch == '<'||ch == '='||ch == '('|| ch == ')'){
		strToken[i++] = ch;//处理运算符
		strToken[i] = '\0';
		printf("%s\t_\n",strToken);
		i = 0;
		ch = GetChar(str);
	}
	else if((ch >= 'a'&& ch <= 'z')||(ch >='A'&&ch <= 'Z')){
		strToken[i++] = ch;

		ch = GetChar(str);
		while((ch >= 'a'&& ch <= 'z')||(ch >='A'&&ch <= 'Z')){		//如果是字母继续填入后n位
			strToken[i++] = ch;
			strToken[i]= '\0';
			if(code = Reserve(strToken))
				break;// 如果是保留字跳出单词的循环
			ch = GetChar(str);


		}
	
		strToken[i] = '\0';//如果是其他字符尾部置空	
		if(code){//对于保留字的处理
			printf("Reserve\t%s\n",strToken);
			ch = GetChar(str);
		}
		else 
			printf("IDN\t%s\n",strToken);
		
		i = 0;
		code = 0;
	}
	else if(ch == ' '){
			ch = GetChar(str);
	}

	
}while(ch);

return 0;
}

void main(){
	char s[100];
	scan();
	

}