feat: add temporal literal parsers.

.gitattribute

@@ -0,0 +1,2 @@
+*.ll    text
+*.yy    text

CMakeLists.txt

@@ -18,6 +18,8 @@ option(ENABLE_COVERAGE "enable coverage on debug build" OFF)
 include(GNUInstallDirs)
 
 find_package(mpdecpp REQUIRED)
+find_package(FLEX REQUIRED)
+find_package(BISON 3.6 REQUIRED)
 
 find_package(ICU 60
     COMPONENTS

README.md

@@ -16,7 +16,7 @@ git submodule update --init --recursive
 ```dockerfile
 FROM ubuntu:22.04
 
-RUN apt update -y && apt install -y git build-essential cmake ninja-build libboost-container-dev libboost-stacktrace-dev libicu-dev
+RUN apt update -y && apt install -y git build-essential cmake ninja-build libboost-container-dev libboost-stacktrace-dev libicu-dev flex bison
 ```
 
 optional packages:
@@ -40,6 +40,25 @@ make -j4
 make install # or sudo make install
 ```
 
+#### GNU Bison `>= 3.6`
+
+This project requires GNU Bison `>= 3.6`.
+Please run `bison --version` and check the printed version.
+
+```sh
+# install packages to build bison
+sudo apt update -y
+sudo apt install -y curl m4
+
+curl http://ftp.jaist.ac.jp/pub/GNU/bison/bison-3.6.4.tar.gz | tar zxv
+cd bison-3.6.4
+./configure --prefix=/path/to/install
+make -j4
+make install # or sudo make install
+```
+
+If you install the above to a non-standard path, please specify `-DCMAKE_PREFIX_PATH=</path/to/install>` to cmake.
+
 ## How to build
 
 ```sh

include/takatori/datetime/conversion.h

@@ -0,0 +1,55 @@
+#pragma once
+
+#include <optional>
+#include <string>
+
+#include <takatori/util/either.h>
+
+#include "conversion_info.h"
+
+namespace takatori::datetime {
+
+/**
+ * @brief represents the result of conversion, or error message.
+ * @tparam T the type of conversion result
+ */
+template<class T>
+using conversion_result = util::either<std::string, T>;
+
+/**
+ * @brief parses the given contents as a date.
+ * @details The date format must be `YYYY-MM-DD`.
+ * @param contents the source contents
+ * @return the parsed date information
+ * @return an error message if the conversion was failed
+ */
+[[nodiscard]] conversion_result<date_info> parse_date(std::string const& contents);
+
+/**
+ * @brief parses the given contents as a time of day.
+ * @details The date format must be `hh:mm:ss.SSSSSSSSS`.
+ * @param contents the source contents
+ * @return the parsed time of day information
+ * @return an error message if the conversion was failed
+ */
+[[nodiscard]] conversion_result<time_info> parse_time(std::string const& contents);
+
+/**
+ * @brief parses the given contents as a datetime, with or without zone offset.
+ * @details The date format must be `YY-MM-DD hh:mm:ss.SSSSSSSSS+HH:MM`.
+ * @param contents the source contents
+ * @return the parsed datetime information with or without zone offset
+ * @return an error message if the conversion was failed
+ */
+[[nodiscard]] conversion_result<datetime_info> parse_datetime(std::string const& contents);
+
+/**
+ * @brief parses the given contents as a zone offset.
+ * @details The date format must be `+HH:MM` or just `Z`.
+ * @param contents the source contents
+ * @return the parsed zone offset
+ * @return an error message if the conversion was failed
+ */
+[[nodiscard]] conversion_result<zone_offset_info> parse_zone_offset(std::string const& contents);
+
+} // namespace takatori::datetime

include/takatori/datetime/conversion_info.h

@@ -0,0 +1,76 @@
+#pragma once
+
+#include <chrono>
+#include <optional>
+
+#include <cstdint>
+
+namespace takatori::datetime {
+
+/**
+ * @brief represents date information.
+ */
+struct date_info {
+
+    /// @brief the year field of date.
+    std::uint32_t year {};
+
+    /// @brief the month field of date.
+    std::uint32_t month {};
+
+    /// @brief the day of month field of date.
+    std::uint32_t day {};
+};
+
+/**
+ * @brief represents time of day information.
+ */
+struct time_info {
+
+    /// @brief the sub-second field type.
+    using subsecond_type = std::chrono::duration<std::uint32_t, std::nano>;
+
+    /// @brief the hour field of time of day.
+    std::uint32_t hour {};
+
+    /// @brief the minute field of time of day.
+    std::uint32_t minute {};
+
+    /// @brief the second field of time of day.
+    std::uint32_t second {};
+
+    /// @brief the sub-second field of time of day.
+    subsecond_type subsecond {};
+};
+
+/**
+ * @brief represents timezone offset information.
+ */
+struct zone_offset_info {
+
+    /// @brief the sign of timezone offset.
+    bool plus { true };
+
+    /// @brief the hour field of timezone offset.
+    std::uint32_t hour {};
+
+    /// @brief the minute field of timezone offset.
+    std::uint32_t minute {};
+};
+
+/**
+ * @brief represents datetime information.
+ */
+struct datetime_info {
+
+    /// @brief the date information.
+    date_info date;
+
+    /// @brief the time of day information.
+    time_info time;
+
+    /// @brief the optional timezone offset information.
+    std::optional<zone_offset_info> offset;
+};
+
+} // namespace takatori::datetime