b12e7ab · typeable/postgresql-simple

git.iko.soy/typeable/postgresql-simple

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Explicit handling of accumulator in fold

b12e7abTimo von Holtz11 years ago

src/Database/PostgreSQL/Simple.hs+17−14

compare with master

unifiedsplit

@@ -122,7 +122,7 @@ import Data.ByteString.Builder

122 ( Builder, byteString, char8, intDec )

123import Control.Applicative ((<$>))

124import Control.Exception as E

125−import Control.Monad (foldM, unless, when, forM_)

125+import Control.Monad (unless)

126import Data.ByteString (ByteString)

127import Data.Int (Int64)

128import Data.List (intersperse)

@@ -142,7 +142,6 @@ import qualified Database.PostgreSQL.LibPQ as PQ

142import qualified Data.ByteString.Char8 as B

143import Control.Monad.Trans.Reader

144import Control.Monad.Trans.State.Strict

145−import qualified Control.Monad.Trans.State.Strict as SL

146import Control.Monad.IO.Class (liftIO)

145import Control.Monad.IO.Class (liftIO)

147

146

148

147

@@ -581,22 +580,26 @@ doFold FoldOptions{..} parser conn _template q a0 f = do

581 <> byteString " FROM "

580 <> byteString " FROM "

582 <> byteString name

581 <> byteString name

583 )

582 )

584− loop = do

583+ loop a = do

585 result <- liftIO (exec conn q)

584 result <- liftIO (exec conn q)

586 status <- liftIO (PQ.resultStatus result)

585 status <- liftIO (PQ.resultStatus result)

587 case status of

586 case status of

588 PQ.TuplesOk -> do

587 PQ.TuplesOk -> do

589 nrows <- liftIO (PQ.ntuples result)

588 nrows <- liftIO (PQ.ntuples result)

590 ncols <- liftIO (PQ.nfields result)

589 ncols <- liftIO (PQ.nfields result)

591− when (nrows > 0) $ do

590+ if nrows > 0

592− forM_ [0..(nrows-1)] $ \row -> do

591+ then do

593− x <- liftIO (getRowWith parser row ncols conn (Query q) result)

592+ a' <- innerLoop 0 nrows ncols result a

594− a <- get

595− a' <- liftIO (f a x)

596− put a'

597− loop

593+ loop a'

594+ else return a

598 _ -> liftIO (throwResultError "fold" result status)

595 _ -> liftIO (throwResultError "fold" result status)

596+ innerLoop row nrows ncols result a

597+ | row < nrows = do

598+ x <- getRowWith parser row ncols conn result

599+ a' <- f a x

600+ innerLoop (row+1) nrows ncols result a'

601+ | otherwise = return a

599− in SL.execStateT loop a0

602+ in loop a0

600

603

601-- FIXME: choose the Automatic chunkSize more intelligently

604-- FIXME: choose the Automatic chunkSize more intelligently

602-- One possibility is to use the type of the results, although this

605-- One possibility is to use the type of the results, although this

@@ -670,7 +673,7 @@ finishQueryWith parser conn q result = do

670 nrows <- PQ.ntuples result

673 nrows <- PQ.ntuples result

671 ncols <- PQ.nfields result

674 ncols <- PQ.nfields result

672 forM' 0 (nrows-1) $ \row ->

675 forM' 0 (nrows-1) $ \row ->

673− getRowWith parser row ncols conn q result

676+ getRowWith parser row ncols conn result

674 PQ.CopyOut ->

677 PQ.CopyOut ->

675 throwIO $ QueryError "query: COPY TO is not supported" q

678 throwIO $ QueryError "query: COPY TO is not supported" q

676 PQ.CopyIn ->

679 PQ.CopyIn ->

@@ -679,8 +682,8 @@ finishQueryWith parser conn q result = do

679 PQ.NonfatalError -> throwResultError "query" result status

682 PQ.NonfatalError -> throwResultError "query" result status

680 PQ.FatalError -> throwResultError "query" result status

683 PQ.FatalError -> throwResultError "query" result status

681

684

682−getRowWith :: RowParser r -> PQ.Row -> PQ.Column -> Connection -> Query -> PQ.Result -> IO r

685+getRowWith :: RowParser r -> PQ.Row -> PQ.Column -> Connection -> PQ.Result -> IO r

683−getRowWith parser row ncols conn q result = do

686+getRowWith parser row ncols conn result = do

684 let rw = Row row result

687 let rw = Row row result

685 let unCol (PQ.Col x) = fromIntegral x :: Int

688 let unCol (PQ.Col x) = fromIntegral x :: Int

686 okvc <- runConversion (runStateT (runReaderT (unRP parser) rw) 0) conn

689 okvc <- runConversion (runStateT (runReaderT (unRP parser) rw) 0) conn