Diogo BiazusandJoe Nelson
df6cbc4afa
* Replace Prelude import for Protolude in middleware * Remove qualifier from Text type * Replace Prelude for Protolude, replace 'cs' for 'toS' calls, also change some name bindings * Replace Prelude in main for Protolude. Replace error calls for panic calls. Also replace cs for toS * Replace Prelude for Protolude * Replace Prelude for Protolude in OpenAPI
72 lines
1.9 KiB
Haskell
72 lines
1.9 KiB
Haskell
module PostgREST.RangeQuery (
|
|
rangeParse
|
|
, rangeRequested
|
|
, rangeLimit
|
|
, rangeOffset
|
|
, restrictRange
|
|
, rangeGeq
|
|
, allRange
|
|
, NonnegRange
|
|
) where
|
|
|
|
|
|
import Control.Applicative
|
|
import Network.HTTP.Types.Header
|
|
|
|
import qualified Data.ByteString.Char8 as BS
|
|
import Data.Ranged.Boundaries
|
|
import Data.Ranged.Ranges
|
|
|
|
import Text.Regex.TDFA ((=~))
|
|
|
|
import Data.List (lookup)
|
|
|
|
import Protolude
|
|
|
|
type NonnegRange = Range Integer
|
|
|
|
rangeParse :: BS.ByteString -> NonnegRange
|
|
rangeParse range = do
|
|
let rangeRegex = "^([0-9]+)-([0-9]*)$" :: BS.ByteString
|
|
|
|
case listToMaybe (range =~ rangeRegex :: [[BS.ByteString]]) of
|
|
Just parsedRange ->
|
|
let [_, mLower, mUpper] = readMaybe . toS <$> parsedRange
|
|
lower = fromMaybe emptyRange (rangeGeq <$> mLower)
|
|
upper = fromMaybe allRange (rangeLeq <$> mUpper) in
|
|
rangeIntersection lower upper
|
|
Nothing -> allRange
|
|
|
|
rangeRequested :: RequestHeaders -> NonnegRange
|
|
rangeRequested headers = fromMaybe allRange $
|
|
rangeParse <$> lookup hRange headers
|
|
|
|
restrictRange :: Maybe Integer -> NonnegRange -> NonnegRange
|
|
restrictRange Nothing r = r
|
|
restrictRange (Just limit) r =
|
|
rangeIntersection r $
|
|
Range BoundaryBelowAll (BoundaryAbove $ rangeOffset r + limit - 1)
|
|
|
|
rangeLimit :: NonnegRange -> Maybe Integer
|
|
rangeLimit range =
|
|
case [rangeLower range, rangeUpper range] of
|
|
[BoundaryBelow lower, BoundaryAbove upper] -> Just (1 + upper - lower)
|
|
_ -> Nothing
|
|
|
|
rangeOffset :: NonnegRange -> Integer
|
|
rangeOffset range =
|
|
case rangeLower range of
|
|
BoundaryBelow lower -> lower
|
|
_ -> panic "range without lower bound" -- should never happen
|
|
|
|
rangeGeq :: Integer -> NonnegRange
|
|
rangeGeq n =
|
|
Range (BoundaryBelow n) BoundaryAboveAll
|
|
|
|
allRange :: NonnegRange
|
|
allRange = rangeGeq 0
|
|
|
|
rangeLeq :: Integer -> NonnegRange
|
|
rangeLeq n =
|
|
Range BoundaryBelowAll (BoundaryAbove n)
|