lua: built-in module datetime

* created a new Tarantool built-in module `datetime`;
* register cdef types for this module;
* export some `dt_*` functions from `c-dt` library;
* lua implementationis of `asctime` and `strftime`;
* datetime parsing unit tests, with and withput timezones;
* c test for reversible strftime roundtrip;

Part of tarantool#5941

src/CMakeLists.txt

@@ -51,6 +51,8 @@ lua_source(lua_sources ../third_party/luafun/fun.lua)
 lua_source(lua_sources lua/httpc.lua)
 lua_source(lua_sources lua/iconv.lua)
 lua_source(lua_sources lua/swim.lua)
+lua_source(lua_sources lua/datetime.lua)
+
 # LuaJIT jit.* library
 lua_source(lua_sources ${LUAJIT_SOURCE_ROOT}/src/jit/bc.lua)
 lua_source(lua_sources ${LUAJIT_SOURCE_ROOT}/src/jit/bcsave.lua)

src/exports.h

@@ -531,3 +531,24 @@ EXPORT(uri_format)
 EXPORT(uri_parse)
 EXPORT(uuid_nil)
 EXPORT(uuid_unpack)
+EXPORT(dt_from_rdn)
+EXPORT(dt_from_yd)
+EXPORT(dt_from_ymd)
+EXPORT(dt_from_yqd)
+EXPORT(dt_from_ywd)
+EXPORT(dt_to_yd)
+EXPORT(dt_to_ymd)
+EXPORT(dt_to_yqd)
+EXPORT(dt_to_ywd)
+EXPORT(dt_rdn)
+EXPORT(dt_dow)
+EXPORT(dt_parse_iso_date)
+EXPORT(dt_parse_iso_time)
+EXPORT(dt_parse_iso_time_basic)
+EXPORT(dt_parse_iso_time_extended)
+EXPORT(dt_parse_iso_zone)
+EXPORT(dt_parse_iso_zone_basic)
+EXPORT(dt_parse_iso_zone_extended)
+EXPORT(dt_parse_iso_zone_lenient)
+EXPORT(dt_from_struct_tm)
+EXPORT(dt_to_struct_tm)

src/lib/core/datetime.h

@@ -0,0 +1,61 @@
+#pragma once
+/*
+ * Copyright 2021, Tarantool AUTHORS, please see AUTHORS file.
+ *
+ * Redistribution and use in source and binary forms, with or
+ * without modification, are permitted provided that the following
+ * conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above
+ *    copyright notice, this list of conditions and the
+ *    following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above
+ *    copyright notice, this list of conditions and the following
+ *    disclaimer in the documentation and/or other materials
+ *    provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY <COPYRIGHT HOLDER> ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+ * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
+ * <COPYRIGHT HOLDER> OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
+ * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
+ * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
+ * THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <c-dt/dt_core.h>
+#include <stdint.h>
+#include <stdbool.h>
+
+#if defined(__cplusplus)
+extern "C" {
+#endif /* defined(__cplusplus) */
+
+/**
+ * datetime structure consisting of:
+ */
+struct datetime_t {
+	int64_t secs;	///< seconds since epoch
+	int32_t nsec;	///< nanoseconds if any
+	int32_t offset; ///< offset in minutes from GMT
+};
+
+/**
+ * Date/time delta structure
+ */
+struct datetime_interval_t {
+	int64_t secs; ///< relative seconds delta
+	int32_t nsec; ///< nanoseconds delta
+};
+
+#if defined(__cplusplus)
+} /* extern "C" */
+#endif /* defined(__cplusplus) */
+