module PostgREST.Parsers
where
import Control.Applicative hiding ((<$>))
import Data.Monoid
import Data.String.Conversions (cs)
import Data.Text (Text)
import Data.Tree
import PostgREST.Types
import Text.ParserCombinators.Parsec hiding (many, (<|>))
import PostgREST.QueryBuilder (operators)
pRequestSelect :: Text -> Parser ReadRequest
pRequestSelect rootNodeName = do
fieldTree <- pFieldForest
return $ foldr treeEntry (Node (Select [] [rootNodeName] [] Nothing, (rootNodeName, Nothing)) []) fieldTree
where
treeEntry :: Tree SelectItem -> ReadRequest -> ReadRequest
treeEntry (Node fld@((fn, _),_) fldForest) (Node (q, i) rForest) =
case fldForest of
[] -> Node (q {select=fld:select q}, i) rForest
_ -> Node (q, i) (foldr treeEntry (Node (Select [] [fn] [] Nothing, (fn, Nothing)) []) fldForest:rForest)
pRequestFilter :: (String, String) -> Either ParseError (Path, Filter)
pRequestFilter (k, v) = (,) <$> path <*> (Filter <$> fld <*> op <*> val)
where
treePath = parse pTreePath ("failed to parser tree path (" ++ k ++ ")") k
opVal = parse pOpValueExp ("failed to parse filter (" ++ v ++ ")") v
path = fst <$> treePath
fld = snd <$> treePath
op = fst <$> opVal
val = snd <$> opVal
ws :: Parser Text
ws = cs <$> many (oneOf " \t")
lexeme :: Parser a -> Parser a
lexeme p = ws *> p <* ws
pTreePath :: Parser (Path,Field)
pTreePath = do
p <- pFieldName `sepBy1` pDelimiter
jp <- optionMaybe pJsonPath
let pp = map cs p
jpp = map cs <$> jp
return (init pp, (last pp, jpp))
pFieldForest :: Parser [Tree SelectItem]
pFieldForest = pFieldTree `sepBy1` lexeme (char ',')
pFieldTree :: Parser (Tree SelectItem)
pFieldTree = try (Node <$> pSelect <*> between (char '{') (char '}') pFieldForest)
<|> Node <$> pSelect <*> pure []
pStar :: Parser Text
pStar = cs <$> (string "*" *> pure ("*"::String))
pFieldName :: Parser Text
pFieldName = cs <$> (many1 (letter <|> digit <|> oneOf "_")
<?> "field name (* or [a..z0..9_])")
pJsonPathStep :: Parser Text
pJsonPathStep = cs <$> try (string "->" *> pFieldName)
pJsonPath :: Parser [Text]
pJsonPath = (++) <$> many pJsonPathStep <*> ( (:[]) <$> (string "->>" *> pFieldName) )
pField :: Parser Field
pField = lexeme $ (,) <$> pFieldName <*> optionMaybe pJsonPath
pSelect :: Parser SelectItem
pSelect = lexeme $
try ((,) <$> pField <*>((cs <$>) <$> optionMaybe (string "::" *> many letter)) )
<|> do
s <- pStar
return ((s, Nothing), Nothing)
pOperator :: Parser Operator
pOperator = cs <$> (pOp <?> "operator (eq, gt, ...)")
where pOp = foldl (<|>) empty $ map (try . string . cs . fst) operators
pValue :: Parser FValue
pValue = VText <$> (cs <$> many anyChar)
pDelimiter :: Parser Char
pDelimiter = char '.' <?> "delimiter (.)"
pOperatiorWithNegation :: Parser Operator
pOperatiorWithNegation = try ( (<>) <$> ( cs <$> string "not." ) <*> pOperator) <|> pOperator
pOpValueExp :: Parser (Operator, FValue)
pOpValueExp = (,) <$> pOperatiorWithNegation <*> (pDelimiter *> pValue)
pOrder :: Parser [OrderTerm]
pOrder = lexeme pOrderTerm `sepBy` char ','
pOrderTerm :: Parser OrderTerm
pOrderTerm =
try ( do
c <- pFieldName
_ <- pDelimiter
d <- (string "asc" *> pure OrderAsc)
<|> (string "desc" *> pure OrderDesc)
nls <- optionMaybe (pDelimiter *> (
try(string "nullslast" *> pure OrderNullsLast)
<|> try(string "nullsfirst" *> pure OrderNullsFirst)
))
return $ OrderTerm c d nls
)
<|> OrderTerm <$> (cs <$> pFieldName) <*> pure OrderAsc <*> pure Nothing