while.cpp

一个简单的语法分析器,实现对布尔表达式,算术表达式的分析,以及if语句,FOR语句,WHILE语句,DO_WHILE语句的分析

//分析while循环语句
#include "Parser.h"
int Sen_While()
{
	int RTN_ADDR = lineOfEqu + 1;
	int bool_addr = Bool_Analysis();
	int TRUE_ADDR = EquPush(11, bool_addr, ZERO, 0);
	int FALSE_ADDR = EquPush(6, 0, 0, 0);
	int rtn1 = 0;
	switch(curr_code)
	{
		case 27:                           //标志符,说明是赋值语句
			Sen_Assign();
			rtn1 = expr_rtn_addr;
			break;
		case 12:
			rtn1 = Sen_For();             //for语句
			break;
		case 13:                          //if语句
			rtn1 = Sen_If();
			break;
		case 20:                          //repeat循环语句
			rtn1 = Sen_Repeat();
			break;
		case 26:                          //while循环语句
			rtn1 = Sen_While();
			break;
		case 2:                           //begin
			rtn1 = Begin();
			break;
		default:                          //其他语句为错误
			Error(COMMON_ERROR);
			break;
	}
	BackPatch(TRUE_ADDR, rtn1);
	int JMP_ADDR = EquPush(6, 0, 0, RTN_ADDR);
	BackPatch(FALSE_ADDR, lineOfEqu + 1);
	return RTN_ADDR;
}