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flattening algorithm needs to be reworked.

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also, datetime methods aren't consistent in their naming and return values.
This commit is contained in:
aj
2010-11-10 03:18:57 -08:00
parent d84a0c1822
commit e48e793a36
5 changed files with 107 additions and 69 deletions
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3
src/ezic.erl
View File

@@ -49,7 +49,8 @@ load(Folder) ->
dev_start() ->
ezic:load(filename:join("priv","tzdata")).
ezic:load(filename:join("priv","tzdata")),
ezic_flatten:flatten().
test() ->

39
src/ezic_date.erl
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@@ -5,8 +5,10 @@
-export([
normalize/1
% rule-specific
for_rule/2
, for_rule/2
, for_rule_utc/4
@@ -19,6 +21,7 @@
, add_seconds/2
, add_offset/2
, all_times/3
, m1s/1
% comparisons
, compare/2
@@ -32,6 +35,20 @@
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% converts any sane date part into a complete datetime
% USED EXCLUSIVELY FOR COMPARISONS. The resulting "datetime" values may not
% represent true dates or times.
normalize(A) when is_atom(A) ->
A;
normalize(Y) when is_integer(Y) ->
{{Y,1,1}, #tztime{}};
normalize(Date={Y,M,D})
when is_integer(Y), is_integer(M), is_integer(D) ->
{Date, #tztime{}};
normalize(R={{Y,M,D}, #tztime{}}) ->
R.
% returns RELATIVE {Y,M,D} for a rule and Year
for_rule(#rule{in=M, on=D, at=At}, Y) when is_integer(D) ->
{{Y,M,D}, At};
@@ -97,6 +114,11 @@ add_offset(Datetime, Offset) ->
% returns {WallTime, StdTime, UtcTime}
% where each is a datetime tuple: {{Y,M,D}{HH,MM,SS}}
% @todo ensure X is in list: max, maximum, min, minimum, current, ...?
all_times(X,_,_) when is_atom(X) ->
{X,X,X};
% universal time given
all_times({Date, #tztime{time=UTCTime, flag=Flag}}, Offset, DSTOffset)
when Flag=:=u; Flag=:=g; Flag=:=z ->
@@ -153,6 +175,8 @@ when is_integer(Y1), is_integer(Y2)
DT1 =< DT2.
% returns true if DT1 =:= DT2. False otherwise
% both times are assumed to be in the same zone/DST context
equal(DT1={{Y1,M1,D1},{HH1,MM1,SS1}}, DT2={{Y2,M2,D2},{HH2,MM2,SS2}})
@@ -238,6 +262,19 @@ add_days_in_month(Days, Date={Y,M,D}) ->
end
end.
m1s(D= {{Y,M,D},{HH,MM,SS}})
when is_integer(Y), is_integer(M), is_integer(D)
, is_integer(HH), is_integer(MM), is_integer(SS) ->
calendar:gregorian_seconds_to_datetime(calendar:datetime_to_gregorian_seconds(D) - 1).
% @todo type checking
m1s(W,S,U) when is_tuple(W), is_tuple(S), is_tuple(U) ->
{m1s(W), m1s(S), m1s(U)}.

81
src/ezic_flatten.erl
View File

@@ -1,5 +1,7 @@
-module(ezic_flatten).
-include("include/ezic.hrl").
-include_lib("eunit/include/eunit.hrl").
-define(FLAT(W,S,U), #flatzone{wall_from=W, std_from=S, utc_from=U}).
-define(ENDFLAT(F,W,S,U), F#flatzone{wall_to=W, std_to=S, utc_to=U}).
@@ -19,7 +21,6 @@ flatten() ->
not_done.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% PRIVATE
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@@ -29,43 +30,11 @@ flatten() ->
flatten_zones(Zones) ->
flatten_zones(Zones, []).
make_next_flat(#flatzone{wall_to=W, std_to=S, utc_to=U, offset=O}) ->
make_next_flat({W,S,U}, O);
make_next_flat(EndTimes) ->
make_next_flat(EndTimes, undefined).
make_next_flat({W,S,U}, O) ->
FW= ezic_date:add_seconds(W,1),
FS= ezic_date:add_seconds(S,1),
FU= ezic_date:add_seconds(U,1),
Flat= ?FLAT(FW, FS, FU),
Flat#flatzone{offset=O}.
end_flat(Flat=#flatzone{}, {W,S,U}) ->
?ENDFLAT(Flat,W,S,U).
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% INTERNAL
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
flatten_zones([], Flats) ->
Flats;
flatten_zones([Z1|_]= AllZones, Flats) ->
{CurrentZones, RestZones}= ezic_zone:split_by_name(Z1, AllZones),
SortedZones= lists:sort(fun ezic_zone:sort_ascending/2, CurrentZones),
NewFlats= lists:merge(Flats, flatten_zone_set(SortedZones)),
NewFlats= lists:merge(Flats, flatten_zone_set(CurrentZones)),
flatten_zones(RestZones, NewFlats).
@@ -88,7 +57,12 @@ flatten_zone_set(Zones) ->
% assumes a new zone every time it is called
flatten_zone_set(_, [], Flats) ->
Flats;
flatten_zone_set(FromTimeStub=#flatzone{utc_from=UTCFrom, dstoffset=DSTOffset}, [Z1=#zone{rule=RuleName, until=UntilTime, gmtoff=Offset} | _RestZones], _Flats) ->
flatten_zone_set(FromTimeStub=#flatzone{utc_from=UTCFrom, dstoffset=DSTOffset}
, Zones %[Z1=#zone{rule=RuleName, until=UntilTime, gmtoff=Offset} | _RestZones],
, Flats) ->
{Zone, RestZones}= ezic_zone:next(Zones, UTCFrom, DSTOffset),
#zone{rule=RuleName, until=UntilTime, gmtoff=Offset}=Zone,
%% we have a flatzone with start times, we populate the base offset
FromTime= FromTimeStub#flatzone{offset=Offset},
@@ -97,7 +71,10 @@ flatten_zone_set(FromTimeStub=#flatzone{utc_from=UTCFrom, dstoffset=DSTOffset},
%% we gather all rules that _may_ apply (same year)
Rules= ezic_db:rules(RuleName),
RuleDates= lists:foldl(
%% and add normalized (inaccurate) dates for sorting purposes
%% note this may be empty
RulesWithDates= lists:foldl(
fun(R, Acc)->
case ezic_rule:project_next(R, Offset, DSTOffset, UTCFrom) of
none -> Acc;
@@ -105,11 +82,33 @@ flatten_zone_set(FromTimeStub=#flatzone{utc_from=UTCFrom, dstoffset=DSTOffset},
end
end
,[], Rules),
AllDates= [{ezic_zone:project_end(Z1, DSTOffset), Z1} | RuleDates],
%% tack on the zone w/ date, in case it ends first
ZoneWithDate= {ezic_zone:project_end_utc(Zone, DSTOffset), Zone},
[NextEventWithDate | RestWithDates]= lists:sort(RulesAndZoneWithDates),
?debugVal(NextEventWithDate),
?debugVal(RestWithDates),
{_,NextEvent}= NextEventWithDate,
{EndFlat, NextFlat}= finish_and_start_flat(FromTime, NextEvent, Offset, DSTOffset),
NewFlats= [EndFlat | Flats],
RestZones= [Z || {_,Z} <- RestWithDates],
flatten_zone_set(NextFlat, RestZones, NewFlats).
finish_and_start_flat(Flat=#flatzone{}, Zone=#zone{}, _Offset, DSTOffset) ->
NextStart= {WT, ST, UT}= ezic_zone:project_end(Zone, DSTOffset),
{MWT, MST, MUT}= ezic_date:m1s(NextStart),
EndFlat= ?ENDFLAT(Flat, MWT, MST, MUT),
NextFlat= ?FLAT(WT, ST, UT),
{EndFlat, NextFlat};
finish_and_start_flat(Flat=#flatzone{utc_from=UTCFrom}, Rule=#rule{}, Offset, DSTOffset) ->
not_done.

45
src/ezic_zone.erl
View File

@@ -7,11 +7,11 @@
, current/1
, current_as_of_utc/2
, split_by_name/2
, sort_ascending/2
, sort_descending/2
, offset_sec/1
, project_end/2
, project_end_utc/2
, next/3
]).
@@ -50,16 +50,6 @@ current_as_of_utc(UTCDatetime, TzName) ->
get_zone_utc(_, []) ->
erlang:error(no_current);
get_zone_utc(_UTCDatetime, Zones) ->
_SortedZones= lists:sort(fun sort_descending/2, Zones),
%% [CZone|_]= lists:dropwhile(fun(SZ)-> older_zone_utc(SZ, UTCDatetime) end, SortedZones),
%% CZone.
%% begin with GMT offset.
%% foreach rule (oldest first)
%% see whether until=(standard|wall|utc) time
%%
not_done.
@@ -76,14 +66,6 @@ split_by_name(#zone{name=N}, Zones) ->
, Zones).
sort_descending(#zone{until=U1}, #zone{until=U2}) ->
ezic_date:compare(U2, U1).
sort_ascending(Z1=#zone{}, Z2=#zone{}) ->
not sort_descending(Z1, Z2).
% @bug doesn't normalize times. Times are self-relative (to standard time), and Now may come from any timezone unless we're careful about that.
%% older_zone(#zone{until=Until}, UTCDatetime) ->
%% ezic_date:compare(Until, UTCDatetime).
@@ -98,9 +80,28 @@ offset_sec(Zone) ->
% returns the UTC datetime projected for zone end (given current DST Offset)
project_end(#zone{until=Until, gmtoff=Offset}, DSTOffset) ->
{_,_,UTCDatetime}= ezic_date:all_times(Until, Offset, DSTOffset),
ezic_date:all_times(Until, Offset, DSTOffset).
% returns just the UTC datetime projected for zone end
project_end_utc(Zone=#zone{}, DSTOffset) ->
{_,_,UTCDatetime}= project_end(Zone, DSTOffset),
UTCDatetime.
% returns {Zone, Rest} where Zone is the next zone after UTCFrom,
% subject to the DST offset.
% Note that dst differences *can* change which zone comes next,
% though it's very unlikely (and does not exist in the current tz database files).
% this method covers that event, anyhow.
next(ZoneList, UTCFrom, DSTOff) ->
DatedList= lists:map(
fun(Z=#zone{until=Until, gmtoff=Offset})->
NU= ezic_date:normalize(Until),
{_,_,UTCDt}= ezic_date:all_times(NU, Offset, DSTOff),
{UTCDt, Z}
end
, ZoneList),
[{_,Zone} | DRest]= lists:sort(DatedList),
{Zone, [R || {_,R}<- DRest]}.