宏(#define)定义函数妙用_C/C++_编程开发_程序员俱乐部

class StringBuilder
{
public:
    StringBuilder(const char8_t* str);
    virtual ~StringBuilder();
    ...

    virtual StringBuilder& operator<<(const char8_t* value) { return operator+(value); }
    virtual StringBuilder& operator<<(int8_t value);
    virtual StringBuilder& operator<<(int16_t value);
    virtual StringBuilder& operator<<(int32_t value);
    virtual StringBuilder& operator<<(int64_t value);
    virtual StringBuilder& operator<<(uint8_t value);
    virtual StringBuilder& operator<<(uint16_t value);
    virtual StringBuilder& operator<<(uint32_t value);
    virtual StringBuilder& operator<<(uint64_t value);
    virtual StringBuilder& operator<<(double value);
    virtual StringBuilder& operator<<(const void * value);
};

#define OPERATOR_IMPL(Type, Formatter) \
    StringBuilder& StringBuilder::operator<<(Type value) \
    { \
        if ((mSize - mCount) < 64) \
        { \
            if (!grow(64)) \
            { \
                mCount = 0; \
                return *this; \
            } \
        } \
        mCount += blaze_snzprintf(mBuffer + mCount, mSize - mCount, "%"Formatter, value); \
        return *this; \
    }

OPERATOR_IMPL(int8_t, PRId8);
OPERATOR_IMPL(int16_t, PRIi16);
OPERATOR_IMPL(int32_t, PRIi32);
OPERATOR_IMPL(int64_t, PRId64);
OPERATOR_IMPL(uint8_t, PRIu8);
OPERATOR_IMPL(uint16_t, PRIu16);
OPERATOR_IMPL(uint32_t, PRIu32);
OPERATOR_IMPL(uint64_t, PRIu64);
OPERATOR_IMPL(double, "f");
OPERATOR_IMPL(const void *, "p");