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스택 처리, 토큰 처리

 

MiniCalculator.h

#pragma region 스택 처리
#define STACK_SIZE 20

int stack[STACK_SIZE];
int top;

void Push(int n)
{
	if (top >= STACK_SIZE)
	{
		throw std::out_of_range("stack");
	}

	stack[top++] = n;
}

int Pop()
{
	if (top <= 0)
	{
		throw std::out_of_range("stack");
	}

	return stack[--top];
}

int Peek()
{
	if (top <= 0)
	{
		throw std::out_of_range("stack");
	}

	return stack[top - 1];
}
#pragma endregion


#pragma region 토큰 처리
char* current;
int ch{ ' ' };

int NextCharacter()
{
	if (*current == '\0')
	{
		return '\0';
	}

	return *current++;
}

Token NextToken()
{
	// 공백 스킵
	while (isspace(ch))
	{
		ch = NextCharacter();
	};

	if (isdigit(ch))
	{
		int num{ 0 };
		do 
		{
			num = num * 10 + (ch - '0');
			ch = NextCharacter();
		} while (isdigit(ch));
		return Token(TokenKind::Int, num);
	}
	
	if (islower(ch))
	{
		int num{ ch - 'a' };
		ch = NextCharacter();
		return Token(TokenKind::VariableName, num);
	}

	TokenKind tokenKind{ TokenKind::Others };

	switch (ch)
	{
	case '(':
		tokenKind = TokenKind::LeftParenthesis;
		break;
	case ')':
		tokenKind = TokenKind::RightParenthesis;
		break;
	case '+':
		tokenKind = TokenKind::Plus;
		break;
	case '-':
		tokenKind = TokenKind::Minus;
		break;
	case '*':
		tokenKind = TokenKind::Multiply;
		break;
	case '/':
		tokenKind = TokenKind::Divide;
		break;
	case '=':
		tokenKind = TokenKind::Assign;
		break;
	case '?':
		tokenKind = TokenKind::Print;
		break;
	case '\0':
		tokenKind = TokenKind::EndOfToken;
		break;
	}

	ch = NextCharacter();

	return Token(tokenKind);
}
#pragma endregion

 

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