C++ StringView::find方法代码示例

// https://tools.ietf.org/html/rfc6455#section-4.1
// "The HTTP version MUST be at least 1.1."
static inline bool headerHasValidHTTPVersion(StringView httpStatusLine)
{
    const char* httpVersionStaticPreambleLiteral = "HTTP/";
    StringView httpVersionStaticPreamble(reinterpret_cast<const LChar*>(httpVersionStaticPreambleLiteral), strlen(httpVersionStaticPreambleLiteral));
    if (!httpStatusLine.startsWith(httpVersionStaticPreamble))
        return false;

    // Check that there is a version number which should be at least three characters after "HTTP/"
    unsigned preambleLength = httpVersionStaticPreamble.length();
    if (httpStatusLine.length() < preambleLength + 3)
        return false;

    auto dotPosition = httpStatusLine.find('.', preambleLength);
    if (dotPosition == notFound)
        return false;

    StringView majorVersionView = httpStatusLine.substring(preambleLength, dotPosition - preambleLength);
    bool isValid;
    int majorVersion = majorVersionView.toIntStrict(isValid);
    if (!isValid)
        return false;

    unsigned minorVersionLength;
    unsigned charactersLeftAfterDotPosition = httpStatusLine.length() - dotPosition;
    for (minorVersionLength = 1; minorVersionLength < charactersLeftAfterDotPosition; minorVersionLength++) {
        if (!isASCIIDigit(httpStatusLine[dotPosition + minorVersionLength]))
            break;
    }
    int minorVersion = (httpStatusLine.substring(dotPosition + 1, minorVersionLength)).toIntStrict(isValid);
    if (!isValid)
        return false;

    return (majorVersion >= 1 && minorVersion >= 1) || majorVersion >= 2;
}

// TODO US-ASCII support only, no UTF-8 support
// While UTF-8 might work in some cases, we do not guarantee full functionality
template <typename StringView> inline auto decompose(const StringView &lhs, const StringView &rhs)
{
    auto const lcs = longest_common_substring(lhs, rhs);

    // trim spaces, transform to lower
    const auto trim = [](StringView view) {
        // we compare suffixes based on this value, it might break UTF chars, but as long as we are
        // consistent in handling, we do not create bad results
        std::string str = boost::to_lower_copy(view.to_string());
        auto front = str.find_first_not_of(" ");

        if (front == std::string::npos)
            return str;

        auto back = str.find_last_not_of(" ");
        return str.substr(front, back - front + 1);
    };

    if (lcs.empty())
    {
        return std::make_tuple(trim(lhs), trim(rhs), std::string(), std::string());
    }

    // find the common substring in both
    auto lhs_pos = lhs.find(lcs);
    auto rhs_pos = rhs.find(lcs);

    BOOST_ASSERT(lhs_pos + lcs.size() <= lhs.size());
    BOOST_ASSERT(rhs_pos + lcs.size() <= rhs.size());

    // prefixes
    auto lhs_prefix = (lhs_pos > 0) ? lhs.substr(0, lhs_pos) : StringView();
    auto rhs_prefix = (rhs_pos > 0) ? rhs.substr(0, rhs_pos) : StringView();

    // suffices
    auto lhs_suffix = lhs.substr(lhs_pos + lcs.size());
    auto rhs_suffix = rhs.substr(rhs_pos + lcs.size());

    return std::make_tuple(trim(lhs_prefix), trim(lhs_suffix), trim(rhs_prefix), trim(rhs_suffix));
}

inline bool requiresNameAnnounced(const StringView &from_name,
                                  const StringView &from_ref,
                                  const StringView &from_pronunciation,
                                  const StringView &from_exits,
                                  const StringView &to_name,
                                  const StringView &to_ref,
                                  const StringView &to_pronunciation,
                                  const StringView &to_exits,
                                  const SuffixTable &suffix_table)
{
    // first is empty and the second is not
    if ((from_name.empty() && from_ref.empty()) && !(to_name.empty() && to_ref.empty()))
        return true;

    // FIXME, handle in profile to begin with?
    // Input for this function should be a struct separating streetname, suffix (e.g. road,
    // boulevard, North, West ...), and a list of references

    // check similarity of names
    const auto names_are_empty = from_name.empty() && to_name.empty();
    const auto name_is_contained =
        boost::starts_with(from_name, to_name) || boost::starts_with(to_name, from_name);

    const auto checkForPrefixOrSuffixChange =
        [](const StringView &first, const StringView &second, const SuffixTable &suffix_table) {
            std::string first_prefix, first_suffix, second_prefix, second_suffix;
            std::tie(first_prefix, first_suffix, second_prefix, second_suffix) =
                decompose(first, second);

            const auto checkTable = [&](const std::string &str) {
                return str.empty() || suffix_table.isSuffix(str);
            };

            return checkTable(first_prefix) && checkTable(first_suffix) &&
                   checkTable(second_prefix) && checkTable(second_suffix);
        };

    const auto is_suffix_change = checkForPrefixOrSuffixChange(from_name, to_name, suffix_table);
    const auto names_are_equal = from_name == to_name || name_is_contained || is_suffix_change;
    const auto name_is_removed = !from_name.empty() && to_name.empty();
    // references are contained in one another
    const auto refs_are_empty = from_ref.empty() && to_ref.empty();
    const auto ref_is_contained =
        from_ref.empty() || to_ref.empty() ||
        (from_ref.find(to_ref) != std::string::npos || to_ref.find(from_ref) != std::string::npos);
    const auto ref_is_removed = !from_ref.empty() && to_ref.empty();

    const auto obvious_change =
        (names_are_empty && refs_are_empty) || (names_are_equal && ref_is_contained) ||
        (names_are_equal && refs_are_empty) || (ref_is_contained && name_is_removed) ||
        (names_are_equal && ref_is_removed) || is_suffix_change;

    const auto needs_announce =
        // " (Ref)" -> "Name " and reverse
        (from_name.empty() && !from_ref.empty() && !to_name.empty() && to_ref.empty()) ||
        (!from_name.empty() && from_ref.empty() && to_name.empty() && !to_ref.empty());

    const auto pronunciation_changes = from_pronunciation != to_pronunciation;

    // when exiting onto ramps, we need to be careful about exit numbers. These can often be only
    // assigned to the first part of the ramp
    //
    //  a . . b . c . . d
    //         ` e . . f
    //
    // could assign the exit number to `be` when exiting `abcd` instead of the full ramp.
    //
    // Issuing a new-name instruction here would result in the turn assuming the short segment to be
    // irrelevant and remove the exit number in a collapse scenario. We don't want to issue any
    // instruction from be-ef, since we only loose the exit number. So we want to make sure that we
    // don't just loose an exit number, when exits change
    const auto exits_change = from_exits != to_exits;
    const auto looses_exit = (names_are_equal && !from_exits.empty() && to_exits.empty());

    return !obvious_change || needs_announce || pronunciation_changes ||
           (exits_change && !looses_exit);
}