static inline uint32_t decodeUtf8()

in src/agent/UnicodeEncoding.h [100:151]

• 52 lines of code
• 15 McCabe index (conditional complexity)

static inline uint32_t decodeUtf8(const char *in) {
    const uint32_t kInvalid = static_cast<uint32_t>(-1);
    switch (utf8CharLength(in[0])) {
        case 1: {
            return in[0];
        }
        case 2: {
            if ((in[1] & 0xC0) != 0x80) {
                return kInvalid;
            }
            uint32_t tmp = 0;
            tmp = (in[0] & 0x1F) << 6;
            tmp |= (in[1] & 0x3F);
            return tmp <= 0x7F ? kInvalid : tmp;
        }
        case 3: {
            if ((in[1] & 0xC0) != 0x80 ||
                    (in[2] & 0xC0) != 0x80) {
                return kInvalid;
            }
            uint32_t tmp = 0;
            tmp = (in[0] & 0x0F) << 12;
            tmp |= (in[1] & 0x3F) << 6;
            tmp |= (in[2] & 0x3F);
            if (tmp <= 0x07FF || (tmp >= 0xD800 && tmp <= 0xDFFF)) {
                return kInvalid;
            } else {
                return tmp;
            }
        }
        case 4: {
            if ((in[1] & 0xC0) != 0x80 ||
                    (in[2] & 0xC0) != 0x80 ||
                    (in[3] & 0xC0) != 0x80) {
                return kInvalid;
            }
            uint32_t tmp = 0;
            tmp = (in[0] & 0x07) << 18;
            tmp |= (in[1] & 0x3F) << 12;
            tmp |= (in[2] & 0x3F) << 6;
            tmp |= (in[3] & 0x3F);
            if (tmp <= 0xFFFF || tmp > 0x10FFFF) {
                return kInvalid;
            } else {
                return tmp;
            }
        }
        default: {
            return kInvalid;
        }
    }
}