77 lines
2.0 KiB
ReStructuredText
77 lines
2.0 KiB
ReStructuredText
Examples
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========
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Extracting a number from input
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------------------------------
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::
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std::optional<std::string_view> extract_number(std::string_view s) noexcept {
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if (auto m = ctre::match<"[a-z]+([0-9]+)">(s)) {
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return m.get<1>().to_view();
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} else {
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return std::nullopt;
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}
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}
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`link to compiler explorer <https://gcc.godbolt.org/z/5U67_e>`_
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Extracting values from date
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---------------------------
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::
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struct date { std::string_view year; std::string_view month; std::string_view day; };
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std::optional<date> extract_date(std::string_view s) noexcept {
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using namespace ctre::literals;
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if (auto [whole, year, month, day] = ctre::match<"(\\d{4})/(\\d{1,2})/(\\d{1,2})">(s); whole) {
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return date{year, month, day};
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} else {
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return std::nullopt;
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}
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}
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//static_assert(extract_date("2018/08/27"sv).has_value());
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//static_assert((*extract_date("2018/08/27"sv)).year == "2018"sv);
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//static_assert((*extract_date("2018/08/27"sv)).month == "08"sv);
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//static_assert((*extract_date("2018/08/27"sv)).day == "27"sv);
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`link to compiler explorer <https://gcc.godbolt.org/z/x64CVp>`_
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Lexer
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-----
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::
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enum class type {
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unknown, identifier, number
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};
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struct lex_item {
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type t;
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std::string_view c;
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};
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std::optional<lex_item> lexer(std::string_view v) noexcept {
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if (auto [m,id,num] = ctre::match<"([a-z]+)|([0-9]+)">(v); m) {
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if (id) {
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return lex_item{type::identifier, id};
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} else if (num) {
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return lex_item{type::number, num};
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}
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}
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return std::nullopt;
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}
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`link to compiler explorer <https://gcc.godbolt.org/z/PKTiCC>`_
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Range over input
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----------------
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This support is preliminary and probably the API will be changed.
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::
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auto input = "123,456,768"sv;
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for (auto match: ctre::range<"([0-9]+),?">(input)) {
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std::cout << std::string_view{match.get<0>()} << "\n";
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} |