diff options
| -rw-r--r-- | lib/stdlib/src/calendar.erl | 39 | ||||
| -rw-r--r-- | lib/stdlib/test/calendar_SUITE.erl | 14 |
2 files changed, 41 insertions, 12 deletions
diff --git a/lib/stdlib/src/calendar.erl b/lib/stdlib/src/calendar.erl index bb5d450cd6..3a083d9fda 100644 --- a/lib/stdlib/src/calendar.erl +++ b/lib/stdlib/src/calendar.erl @@ -529,24 +529,41 @@ valid_date({Y, M, D}) -> %% day_to_year(DayOfEpoch) = {Year, DayOfYear} %% -%% The idea here is to first guess a year, and then adjust. Although -%% the implementation is recursive, at most 1 or 2 recursive steps +%% The idea here is to first set the upper and lower bounds for a year, +%% and then adjust a range by interpolation search. Although complexity +%% of the algorithm is log(log(n)), at most 1 or 2 recursive steps %% are taken. -%% If DayOfEpoch is very large, we need far more than 1 or 2 iterations, -%% since we just subtract a yearful of days at a time until we're there. %% -spec day_to_year(non_neg_integer()) -> {year(), day_of_year()}. day_to_year(DayOfEpoch) when DayOfEpoch >= 0 -> - Y0 = DayOfEpoch div ?DAYS_PER_YEAR, - {Y1, D1} = dty(Y0, DayOfEpoch, dy(Y0)), + YMax = DayOfEpoch div ?DAYS_PER_YEAR, + YMin = DayOfEpoch div ?DAYS_PER_LEAP_YEAR, + {Y1, D1} = dty(YMin, YMax, DayOfEpoch, dy(YMin), dy(YMax)), {Y1, DayOfEpoch - D1}. --spec dty(year(), non_neg_integer(), non_neg_integer()) -> +-spec dty(year(), year(), non_neg_integer(), non_neg_integer(), + non_neg_integer()) -> {year(), non_neg_integer()}. -dty(Y, D1, D2) when D1 < D2 -> - dty(Y-1, D1, dy(Y-1)); -dty(Y, _D1, D2) -> - {Y, D2}. +dty(Min, Max, _D1, DMin, _DMax) when Min == Max -> + {Min, DMin}; +dty(Min, Max, D1, DMin, DMax) -> + Diff = Max - Min, + Mid = Min + (Diff * (D1 - DMin)) div (DMax - DMin), + MidLength = + case is_leap_year(Mid) of + true -> ?DAYS_PER_LEAP_YEAR; + false -> ?DAYS_PER_YEAR + end, + case dy(Mid) of + D2 when D1 < D2 -> + NewMax = Mid - 1, + dty(Min, NewMax, D1, DMin, dy(NewMax)); + D2 when D1 - D2 >= MidLength -> + NewMin = Mid + 1, + dty(NewMin, Max, D1, dy(NewMin), DMax); + D2 -> + {Mid, D2} + end. %% %% The Gregorian days of the iso week 01 day 1 for a given year. diff --git a/lib/stdlib/test/calendar_SUITE.erl b/lib/stdlib/test/calendar_SUITE.erl index df62c0921d..c6d9dbca4a 100644 --- a/lib/stdlib/test/calendar_SUITE.erl +++ b/lib/stdlib/test/calendar_SUITE.erl @@ -24,6 +24,7 @@ -export([all/0, suite/0,groups/0,init_per_suite/1, end_per_suite/1, init_per_group/2,end_per_group/2, gregorian_days/1, + big_gregorian_days/1, gregorian_seconds/1, day_of_the_week/1, day_of_the_week_calibrate/1, @@ -36,13 +37,16 @@ -define(START_YEAR, 1947). -define(END_YEAR, 2012). +-define(BIG_START_YEAR, 20000000). +-define(BIG_END_YEAR, 20000020). + suite() -> [{ct_hooks,[ts_install_cth]}]. all() -> [gregorian_days, gregorian_seconds, day_of_the_week, day_of_the_week_calibrate, leap_years, last_day_of_the_month, local_time_to_universal_time_dst, - iso_week_number, system_time, rfc3339]. + iso_week_number, system_time, rfc3339, big_gregorian_days]. groups() -> []. @@ -67,6 +71,14 @@ gregorian_days(Config) when is_list(Config) -> MaxDays = calendar:date_to_gregorian_days({?END_YEAR, 1, 1}), check_gregorian_days(Days, MaxDays). +%% Tests that date_to_gregorian_days and gregorian_days_to_date +%% are each others inverses from ?BIG_START_YEAR-01-01 up to ?BIG_END_YEAR-01-01. +%% At the same time valid_date is tested. +big_gregorian_days(Config) when is_list(Config) -> + Days = calendar:date_to_gregorian_days({?BIG_START_YEAR, 1, 1}), + MaxDays = calendar:date_to_gregorian_days({?BIG_END_YEAR, 1, 1}), + check_gregorian_days(Days, MaxDays). + %% Tests that datetime_to_gregorian_seconds and %% gregorian_seconds_to_date are each others inverses for a sampled %% number of seconds from ?START_YEAR-01-01 up to ?END_YEAR-01-01: We check |