Function EncodeString

src/brpc/details/hpack.cpp:568–604

use template to remove dead branches.

template <bool LOWERCASE> // use template to remove dead branches.
inline void EncodeString(butil::IOBufAppender* out, const std::string& s,
                         bool huffman_encoding) {
    if (!huffman_encoding) {
        EncodeInteger(out, 0x00, 7, s.size());
        if (LOWERCASE) {
            for (size_t i = 0; i < s.size(); ++i) {
                out->push_back(butil::ascii_tolower(s[i]));
            }
        } else {
            out->append(s);
        }
        return;
    }
    // Calculate length of encoded string
    uint32_t bit_len = 0;
    if (LOWERCASE) {
        for (size_t i = 0; i < s.size(); ++i) {
            bit_len += s_huffman_table[(uint8_t)butil::ascii_tolower(s[i])].bit_len;
        }
    } else {
        for (size_t i = 0; i < s.size(); ++i) {
            bit_len += s_huffman_table[(uint8_t)s[i]].bit_len;
        }
    }
    EncodeInteger(out, 0x80, 7, (bit_len >> 3) + !!(bit_len & 7));
    HuffmanEncoder e(out, s_huffman_table);
    if (LOWERCASE) {
        for (size_t i = 0; i < s.size(); ++i) {
            e.Encode(butil::ascii_tolower(s[i]));
        }
    } else {
        for (size_t i = 0; i < s.size(); ++i) {
            e.Encode(s[i]);
        }
    }
    e.EndStream();
}

inline ssize_t DecodeString(butil::IOBufBytesIterator& iter, std::string* out) {
    if (iter == NULL) {