Method parse_escaped

include/boost/json/basic_parser_impl.hpp:1124–1688

template<class Handler>
template<bool StackEmpty_>
const char*
basic_parser<Handler>::
parse_escaped(
    const char* p,
    std::size_t& total,
    std::integral_constant<bool, StackEmpty_> stack_empty,
    bool is_key,
    bool allow_bad_utf16)
{
    constexpr unsigned urc = 0xFFFD; // Unicode replacement character
    auto const ev_too_large = is_key?
        error::key_too_large : error::string_too_large;
    auto const max_size = is_key?
        Handler::max_key_size : Handler::max_string_size;
    int digit;

    //---------------------------------------------------------------
    //
    // To handle escapes, a local temporary buffer accumulates
    // the unescaped result. The algorithm attempts to fill the
    // buffer to capacity before invoking the handler.
    // In some cases the temporary buffer needs to be flushed
    // before it is full:
    // * When the closing double quote is seen
    // * When there in no more input (and more is expected later)
    // A goal of the algorithm is to call the handler as few times
    // as possible. Thus, when the first escape is encountered,
    // the algorithm attempts to fill the temporary buffer first.
    //
    detail::buffer<BOOST_JSON_STACK_BUFFER_SIZE> temp;

    // Unescaped JSON is never larger than its escaped version.
    // To efficiently process only what will fit in the temporary buffer,
    // the size of the input stream is temporarily "clipped" to the size
    // of the temporary buffer.
    // handle escaped character
    detail::clipped_const_stream cs(p, end_);
    cs.clip(temp.max_size());

    if(! stack_empty && ! st_.empty())
    {
        state st;
        st_.pop(st);
        switch(st)
        {
        default: BOOST_JSON_UNREACHABLE();
        case state::str3: goto do_str3;
        case state::str4: goto do_str4;
        case state::str5: goto do_str5;
        case state::str6: goto do_str6;
        case state::str7: goto do_str7;
        case state::sur1: goto do_sur1;
        case state::sur2: goto do_sur2;
        case state::sur3: goto do_sur3;
        case state::sur4: goto do_sur4;
        case state::sur5: goto do_sur5;
        case state::sur6: goto do_sur6;
        }