should be it

external/duckdb/extension/icu/include/icu-datefunc.hpp

@@ -0,0 +1,87 @@
+//===----------------------------------------------------------------------===//
+//                         DuckDB
+//
+// icu-datefunc.hpp
+//
+//
+//===----------------------------------------------------------------------===//
+
+#pragma once
+
+#include "duckdb.hpp"
+
+#include "duckdb/common/enums/date_part_specifier.hpp"
+#include "duckdb/planner/expression/bound_function_expression.hpp"
+#include "tz_calendar.hpp"
+
+namespace duckdb {
+
+struct ICUDateFunc {
+	struct BindData : public FunctionData {
+		explicit BindData(ClientContext &context);
+		BindData(const string &tz_setting, const string &cal_setting);
+		BindData(const BindData &other);
+
+		string tz_setting;
+		string cal_setting;
+		CalendarPtr calendar;
+
+		bool Equals(const FunctionData &other_p) const override;
+		duckdb::unique_ptr<FunctionData> Copy() const override;
+
+		void InitCalendar();
+	};
+
+	struct CastData : public BoundCastData {
+		explicit CastData(duckdb::unique_ptr<FunctionData> info_p) : info(std::move(info_p)) {
+		}
+
+		duckdb::unique_ptr<BoundCastData> Copy() const override {
+			return make_uniq<CastData>(info->Copy());
+		}
+
+		duckdb::unique_ptr<FunctionData> info;
+	};
+
+	//! Binds a default calendar object for use by the function
+	static duckdb::unique_ptr<FunctionData> Bind(ClientContext &context, ScalarFunction &bound_function,
+	                                             vector<duckdb::unique_ptr<Expression>> &arguments);
+
+	//! Tries to set the time zone for the calendar and returns false if it is not valid.
+	static bool TrySetTimeZone(icu::Calendar *calendar, const string_t &tz_id);
+	//! Sets the time zone for the calendar. Throws if it is not valid
+	static void SetTimeZone(icu::Calendar *calendar, const string_t &tz_id, string *error_message = nullptr);
+	//! Gets the timestamp from the calendar, throwing if it is not in range.
+	static bool TryGetTime(icu::Calendar *calendar, uint64_t micros, timestamp_t &result);
+	//! Gets the timestamp from the calendar, throwing if it is not in range.
+	static timestamp_t GetTime(icu::Calendar *calendar, uint64_t micros = 0);
+	//! Gets the timestamp from the calendar, assuming it is in range.
+	static timestamp_t GetTimeUnsafe(icu::Calendar *calendar, uint64_t micros = 0);
+	//! Sets the calendar to the timestamp, returning the unused µs part
+	static uint64_t SetTime(icu::Calendar *calendar, timestamp_t date);
+	//! Extracts the field from the calendar
+	static int32_t ExtractField(icu::Calendar *calendar, UCalendarDateFields field);
+	//! Subtracts the field of the given date from the calendar
+	static int32_t SubtractField(icu::Calendar *calendar, UCalendarDateFields field, timestamp_t end_date);
+	//! Adds the timestamp and the interval using the calendar
+	static timestamp_t Add(TZCalendar &calendar, timestamp_t timestamp, interval_t interval);
+	//! Subtracts the interval from the timestamp using the calendar
+	static timestamp_t Sub(TZCalendar &calendar, timestamp_t timestamp, interval_t interval);
+	//! Subtracts the latter timestamp from the former timestamp using the calendar
+	static interval_t Sub(TZCalendar &calendar, timestamp_t end_date, timestamp_t start_date);
+	//! Pulls out the bin values from the timestamp assuming it is an instant,
+	//! constructs an ICU timestamp, and then converts that back to a DuckDB instant
+	//! Adding offset doesn't really work around DST because the bin values are ambiguous
+	static timestamp_t FromNaive(icu::Calendar *calendar, timestamp_t naive);
+
+	//! Truncates the calendar time to the given part precision
+	typedef void (*part_trunc_t)(icu::Calendar *calendar, uint64_t &micros);
+	static part_trunc_t TruncationFactory(DatePartSpecifier part);
+	static timestamp_t CurrentMidnight(icu::Calendar *calendar, ExpressionState &state);
+
+	//! Subtracts the two times at the given part precision
+	typedef int64_t (*part_sub_t)(icu::Calendar *calendar, timestamp_t start_date, timestamp_t end_date);
+	static part_sub_t SubtractFactory(DatePartSpecifier part);
+};
+
+} // namespace duckdb