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lib: splitSpan: return no spans for an empty datespan

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Fixes an issue where a bounded budget could wrongly appear in a
disjoint report period.
This commit is contained in:
Simon Michael 2018-03-29 18:09:15 +01:00
parent 4d562ef068
commit d060398484
1 changed files with 18 additions and 3 deletions
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21
hledger-lib/Hledger/Data/Dates.hs
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@ -149,8 +149,12 @@ spanEnd (DateSpan _ d) = d
spansSpan :: [DateSpan] -> DateSpan
spansSpan spans = DateSpan (maybe Nothing spanStart $ headMay spans) (maybe Nothing spanEnd $ lastMay spans)
-- | Split a DateSpan into one or more consecutive whole spans of the specified length which enclose it.
-- | Split a DateSpan into consecutive whole spans of the specified interval
-- which fully encompass the original span (and a little more when necessary).
-- If no interval is specified, the original span is returned.
-- If the original span is the null date span, ie unbounded, the null date span is returned.
-- If the original span is empty, eg if the end date is <= the start date, no spans are returned.
--
--
-- ==== Examples:
-- >>> let t i d1 d2 = splitSpan i $ mkdatespan d1 d2
@ -161,9 +165,9 @@ spansSpan spans = DateSpan (maybe Nothing spanStart $ headMay spans) (maybe Noth
-- >>> splitSpan (Quarters 1) nulldatespan
-- [DateSpan -]
-- >>> t (Days 1) "2008/01/01" "2008/01/01" -- an empty datespan
-- [DateSpan 2008/01/01-2007/12/31]
-- []
-- >>> t (Quarters 1) "2008/01/01" "2008/01/01"
-- [DateSpan 2008/01/01-2007/12/31]
-- []
-- >>> t (Months 1) "2008/01/01" "2008/04/01"
-- [DateSpan 2008/01,DateSpan 2008/02,DateSpan 2008/03]
-- >>> t (Months 2) "2008/01/01" "2008/04/01"
@ -185,6 +189,7 @@ spansSpan spans = DateSpan (maybe Nothing spanStart $ headMay spans) (maybe Noth
--
splitSpan :: Interval -> DateSpan -> [DateSpan]
splitSpan _ (DateSpan Nothing Nothing) = [DateSpan Nothing Nothing]
splitSpan _ s | isEmptySpan s = []
splitSpan NoInterval s = [s]
splitSpan (Days n) s = splitspan startofday (applyN n nextday) s
splitSpan (Weeks n) s = splitspan startofweek (applyN n nextweek) s
@ -222,6 +227,12 @@ daysInSpan :: DateSpan -> Maybe Integer
daysInSpan (DateSpan (Just d1) (Just d2)) = Just $ diffDays d2 d1
daysInSpan _ = Nothing
-- | Is this an empty span, ie closed with the end date on or before the start date ?
isEmptySpan :: DateSpan -> Bool
isEmptySpan s = case daysInSpan s of
Just n -> n < 1
Nothing -> False
-- | Does the span include the given date ?
spanContainsDate :: DateSpan -> Day -> Bool
spanContainsDate (DateSpan Nothing Nothing) _ = True
@ -240,6 +251,10 @@ spansIntersect [d] = d
spansIntersect (d:ds) = d `spanIntersect` (spansIntersect ds)
-- | Calculate the intersection of two datespans.
--
-- For non-intersecting spans, gives an empty span beginning on the second's start date:
-- >>> mkdatespan "2018-01-01" "2018-01-03" `spanIntersect` mkdatespan "2018-01-03" "2018-01-05"
-- DateSpan 2018/01/03-2018/01/02
spanIntersect (DateSpan b1 e1) (DateSpan b2 e2) = DateSpan b e
where
b = latest b1 b2