Output_a_simple_translate.txt

int a=0;
int print(int a)
{
	int num=printf("%d\n",a);
	num = num -1;
	return num;
}
//==========================================

int id = number ; int id ( int id ) { int id = id ( stringval , id ) ; id = id - number ; return id ; } $ 

Reducing TYPE -> int 		
Reducing EXPRESSION -> number 
Reducing VAR_DECLARATION -> TYPE id = EXPRESSION 
Reducing TYPE -> int 
Reducing TYPE -> int 
Reducing TYPE -> int 
Reducing EXPRESSION -> stringval 
Reducing EXPRESSION -> id 
Reducing CALL_STATEMENT -> id ( EXPRESSION , EXPRESSION ) 
Reducing EXPRESSION -> CALL_STATEMENT 
Reducing VAR_DECLARATION -> TYPE id = EXPRESSION 
Reducing EXPRESSION -> id 
Reducing EXPRESSION -> number 
Reducing EXPRESSION -> EXPRESSION - EXPRESSION 
Reducing ASSIGNMENT -> id = EXPRESSION 
Reducing EXPRESSION -> id 
Reducing RETURN_STATEMENT -> return EXPRESSION 
Reducing FUN_DEFINITION -> TYPE id ( TYPE id ) { VAR_DECLARATION ; ASSIGNMENT ; RETURN_STATEMENT ; } 
Reducing C -> VAR_DECLARATION ; FUN_DEFINITION 
ACCEPT

0.init
{
	符号表集合为S
//DEPRECATED	当前符号表下标为is,代码流下标ig			//每一个genTemp都将is加1,每一个genCode都将ig加1
	用is,ig指代当前上下文中,最初进入翻译时的符号表开始和代码开始,用 gis,gig代表全局的
	符号栈为T(记录三元组  <文法符号的属性,在符号表中的开始下标bis,在代码流中的起始下标big>)
		存放临时的属性
			临时的属性包括立即值
		存放一个指向符号表i的第j个符号的引用
		用键 refType: 0表示立即值, 1表示在符号表中
			refType=IN_SYMBOL_TABLE时,index为其下标
		临时属性将会被简单复制,引用属性也会被简单复制
	代码流G
	符号表切换指令映射ST(记录 <代码起始,动作,参数>) //用于在四元式代码生成时,从0下标开始处理,每次遇到一个下标如果映射中存在动作就执行.通常来说,每个起始代码只有一个符号表指令动作
}
1.
Reducing TYPE -> int 	
{
	$0 = makeAttribute()	//构造一个临时属性,不在符号表中使用
	$0.type = type
	$0.val = int
	push(<$0,is,ig>)
}
2.
Reducing EXPRESSION -> number 
{
	$0 = makeAttribute()
	$0.type = int
	$0.imval = number.lexval	//对立即数赋值
	push(<$0,is,ig>)
}
3.
Reducing VAR_DECLARATION -> TYPE id = EXPRESSION 
{
	$2=pop()
	$1=pop()
//	pid = findSymbol($id.string) //需要用到id的string表达式
//	if(pid!=NULL) error("redefinition")		//现在,定义总是成功的,检查重定义要留到后面进行
	if($1.type!=$2.type ) error("invalid assignment between conflicting types")
	else
		pid=genSymbol($id.name)  //with desired name
		pid.type = $1.type
		genCode('=',id.name,$2,_)
		push(<makeAttribute(type=var_declare),is,gs>)
}
4.
Reducing TYPE -> int 
{
	$0 = makeAttribute()	//构造一个临时属性,不在符号表中使用
	$0.type = type
	$0.val = int
	push(<$0,is,ig>)
}
5.
Reducing TYPE -> int 
{
	$0 = makeAttribute()	//构造一个临时属性,不在符号表中使用
	$0.type = type
	$0.val = int
	push(<$0,is,ig>)
}
6.
Reducing TYPE -> int 
{
	$0 = makeAttribute()	//构造一个临时属性,不在符号表中使用
	$0.type = type
	$0.val = int
	push(<$0,is,ig>)
}
7.
Reducing EXPRESSION -> stringval 
{
	$0=genTemp()
	$0.type=string
	$0.val=stringval.strRefIndex
	push(<$0.name,is,gs>)
}
8.
Reducing EXPRESSION -> id 
{
//	pid = findNearstSymbol(id.string)		//不需要查找符号表的位置,我们只知道有这个引用即可
//	if(pid==NULL) //  === error("undefined reference")  ==> 修改成 下面的样式
//	{
//		pid=requirePredefinedSymbol(id.string)
//	}
	push(<id.name,is,gs>)
}
9.
Reducing CALL_STATEMENT -> id ( EXPRESSION , EXPRESSION ) 
{
		$2=pop()
		$1=pop()
		args=[$2,$1]
		hasError=false
		for(i=0;i<pid.args.length;i++)
			if(args[i][0].type!=pid.args[i])
				hasError=true
				error(....)
				break
			else
				genCode(param,args[i].addr,_,_)
		if(!hasError)
			if(pid.hasreturn)
				res=genTemp()
				copy(pid.rtype,res.type)
				genCode(call,pid,_,res)
				push(<res,is,gs>)
			else
				res=makeAttribute()
				res.type=void
				genCode(call,pid.addr,_,_)
				push(<res,is,gs>) //无论如何,总是要在值栈中push一个变量的值
}
		
10.		
Reducing EXPRESSION -> CALL_STATEMENT 
{
	$1=pop()
	$0=makeAttribute()
	copy($1,$0)
	push($0)
	//可以优化为
	// do nothing
}
11.
Reducing VAR_DECLARATION -> TYPE id = EXPRESSION 
{
	$2=pop()
	$1=pop()
	pid = findSymbol($id.string) //需要用到id的string表达式
	if(pid!=NULL) error("redefinition")
	else if($1.type!=$2.type ) error("invalid assignment between conflicting types")
	else
		pid=genSymbol($id.string)
		pid.type = $1.type
		genCode('=',pid.addr,$1.imval,_)
		push(makeAttribute(type=var_declare))
}
12.
Reducing EXPRESSION -> id 
13.
Reducing EXPRESSION -> number 
14.
Reducing EXPRESSION -> EXPRESSION - EXPRESSION 
15.
Reducing ASSIGNMENT -> id = EXPRESSION 
{
	$1=pop()
	pid = findSymbol(id.name)
	if(pid==NULL)error("undefined reference")
	else if(pid.type!=$1.type)error("assignment between conficting types")
	else
		genCode(=,$1.addr,_,pid.addr)
		push(pid)
}
16.
Reducing EXPRESSION -> id 
17.
Reducing RETURN_STATEMENT -> return EXPRESSION 
{
	//参数不匹配怎么办,后面再检查
	$1=pop()
	$0=makeAttribute()
	copy($1,$0)
	genCode('return',_,_,$0.addr)
	push($0)
}
18.
Reducing FUN_DEFINITION -> TYPE id ( TYPE id ) { VAR_DECLARATION ; ASSIGNMENT ; RETURN_STATEMENT ; } 
{
	$5=pop()
	$4=pop()
	$3=pop()
	$2=pop()
	$1=pop()
	
	if($5.type!=$1.type)error("return conficted type,expected not returned")
	else
		$0=makeAttribute()
		$0.type=fundeclare
	push($0)
}
19.
Reducing C -> VAR_DECLARATION ; FUN_DEFINITION 
{
	//nothing
}
20.
ACCEPT