C++ string_view::find方法代码示例

/// Deconstruct a "URI" string into the "fllename" part (returned) and turn
/// the "query" part into a series of pairs of id and value. For example,
///     deconstruct_uri("foo.tif?bar=1&blah=\"hello world\"", args) 
/// would be expected to return "foo.tif" and *args would contain two
/// pairs: ("foo","1") and ("bar","\"hello world\"").
static string_view
deconstruct_uri (string_view uri,
                 std::vector<std::pair<string_view,string_view> > *args=NULL)
{
    if (args)
        args->clear ();
    size_t arg_start = uri.find ('?');
    if (arg_start == string_view::npos)
        return uri;
    string_view argstring = uri.substr (arg_start+1);
    string_view filename = uri.substr (0, arg_start);
    if (! args)
        return filename;
    while (! argstring.empty()) {
        string_view id = Strutil::parse_until (argstring, "=&");
        string_view value;
        if (! id.size())
            break;
        if (! Strutil::parse_char (argstring, '=') || argstring.empty())
            break;
        if (argstring[0] == '\"')
            Strutil::parse_string (argstring, value, true, Strutil::KeepQuotes);
        else
            value = Strutil::parse_until (argstring, "&\t\r\n");
        args->push_back (std::make_pair(id, value));
        Strutil::parse_char (argstring, '&');
    }
    return filename;
}

config_option::config_option(string_view category, string_view name,
                             string_view description, const meta_state* meta,
                             void* value)
    : meta_(meta),
      value_(value) {
  using std::copy;
  using std::accumulate;
  auto comma = name.find(',');
  auto long_name = name.substr(0, comma);
  auto short_names = comma == string_view::npos ? string_view{}
                                                : name.substr(comma + 1);
  auto total_size = [](std::initializer_list<string_view> xs) {
    return (xs.size() - 1) // one separator between all fields
           + accumulate(xs.begin(), xs.end(), size_t{0},
                        [](size_t x, string_view sv) { return x + sv.size(); });
  };
  auto ts = total_size({category, long_name, short_names, description});
  CAF_ASSERT(ts <= std::numeric_limits<uint16_t>::max());
  buf_size_ = static_cast<uint16_t>(ts);
  buf_.reset(new char[ts]);
  // fille the buffer with "<category>.<long-name>,<short-name>,<descriptions>"
  auto first = buf_.get();
  auto i = first;
  auto pos = [&] {
    return static_cast<uint16_t>(std::distance(first, i));
  };
  // <category>.
  i = copy(category.begin(), category.end(), i);
  category_separator_ = pos();
  *i++ = '.';
  // <long-name>,
  i = copy(long_name.begin(), long_name.end(), i);
  long_name_separator_ = pos();
  *i++ = ',';
  // <short-names>,
  i = copy(short_names.begin(), short_names.end(), i);
  short_names_separator_ = pos();
  *i++ = ',';
  // <description>
  i = copy(description.begin(), description.end(), i);
  CAF_ASSERT(pos() == buf_size_);
}

static lng_line_type parse_lng_line(const string_view str, bool ParseLabels, string_view& Label, string_view& Data)
{
	Label = {};
	Data = {};

	//-- "Text"
	if (starts_with(str, L'"'))
	{
		Data = str.substr(1, str.size() - (ends_with(str, L'"')? 2 : 1));
		return lng_line_type::text;
	}

	//-- //[Label]
	if (ParseLabels)
	{
		const auto Prefix = L"//["sv, Suffix = L"]"sv;
		if (starts_with(str, Prefix) && ends_with(str, Suffix))
		{
			Label = str.substr(Prefix.size(), str.size() - Prefix.size() - Suffix.size());
			return lng_line_type::label;
		}
	}

	//-- MLabel="Text"
	if (ParseLabels && !str.empty() && str.back() == L'"')
	{
		const auto eq_pos = str.find(L'=');
		if (eq_pos != str.npos && std::iswalpha(str[0]))
		{
			const auto Value = trim(str.substr(eq_pos + 1));

			if (starts_with(Value, L'"'))
			{
				Label = trim(str.substr(0, eq_pos));
				Data = Value.substr(1, Value.size() - 2);
				return lng_line_type::both;
			}
		}
	}

	return lng_line_type::none;
}

static void parse_lng_line(const string_view str, string& label, string& data, bool& have_data)
{
	have_data = false;

	//-- //[Label]
	if (starts_with(str, L"//["sv) && ends_with(str, L"]"sv))
	{
		const auto LabelView = str.substr(3, str.size() - 3 - 1);
		//-- //[Label=0]
		assign(label, LabelView.substr(0, LabelView.find(L'=')));
		return;
	}

	//-- "Text"
	if (starts_with(str, L'"'))
	{
		have_data = true;
		assign(data, str.substr(1));
		if (!data.empty() && data.back() == L'"')
			data.pop_back();
		return;
	}

	//-- MLabel="Text"
	if (!str.empty() && str.back() == L'"')
	{
		const auto eq_pos = str.find(L'=');
		if (eq_pos != string::npos && InRange(L'A', upper(str[0]), L'Z'))
		{
			assign(data, trim(str.substr(eq_pos + 1)));
			if (data.size() > 1 && data[0] == L'"')
			{
				assign(label, trim(str.substr(0, eq_pos)));
				have_data = true;
				data.pop_back();
				data.erase(0, 1);
			}
		}
	}
}

void f2(const string_view str) {
  cout << str.substr(str.find("D"), 3) << endl;
}