44ec3cd · project-m36 · git.iko.soy

git.iko.soy/project-m36

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implement undefine Tutorial D operator

44ec3cdAgentM12 years ago

RelationExpr.hs+11−1

compare with master

unifiedsplit

@@ -170,7 +170,14 @@ setRelVar relVarName rel = do

170 Nothing -> do

171 put $ DatabaseContext (inclusionDependencies state) newRelVars

172 return Nothing

173−

173+

174+-- it is not an error to delete a relvar which does not exist, just like it is not an error to insert a pre-existing tuple into a relation

175+deleteRelVar :: String -> DatabaseState (Maybe RelationalError)

176+deleteRelVar relVarName = do

177+ state <- get

178+ let newRelVars = M.delete relVarName (relationVariables state)

179+ put $ DatabaseContext (inclusionDependencies state) newRelVars

180+ return Nothing

174

181

175evalContextExpr :: DatabaseExpr -> DatabaseState (Maybe RelationalError)

182evalContextExpr :: DatabaseExpr -> DatabaseState (Maybe RelationalError)

176evalContextExpr (Define relVarName attrs) = do

183evalContextExpr (Define relVarName attrs) = do

@@ -180,6 +187,9 @@ evalContextExpr (Define relVarName attrs) = do

180 False -> setRelVar relVarName emptyRelation

187 False -> setRelVar relVarName emptyRelation

181 where

188 where

182 emptyRelation = Relation attrs HS.empty

189 emptyRelation = Relation attrs HS.empty

190+

191+evalContextExpr (Undefine relVarName) = do

192+ deleteRelVar relVarName

183

193

184evalContextExpr (Assign relVarName expr) = do

194evalContextExpr (Assign relVarName expr) = do

185 -- in the future, it would be nice to get types from the RelationalExpr instead of needing to evaluate it

195 -- in the future, it would be nice to get types from the RelationalExpr instead of needing to evaluate it

TutorialDInterpreter.hs+7

@@ -177,6 +177,7 @@ databaseExpr = insertP

177 <|> updateP

178 <|> constraintP

179 <|> defineP

180+ <|> undefineP

180 <|> assignP

181 <|> assignP

181

182

182multipleDatabaseExpr :: Parser DatabaseExpr

183multipleDatabaseExpr :: Parser DatabaseExpr

@@ -200,6 +201,12 @@ defineP = do

200 attributes <- makeAttributes

201 attributes <- makeAttributes

201 return $ Define relVarName attributes

202 return $ Define relVarName attributes

202

203

204+undefineP :: Parser DatabaseExpr

205+undefineP = do

206+ reservedOp "undefine"

207+ relVarName <- identifier

208+ return $ Undefine relVarName

209+

203deleteP :: Parser DatabaseExpr

210deleteP :: Parser DatabaseExpr

204deleteP = do

211deleteP = do

205 reservedOp "delete"

212 reservedOp "delete"

TutorialDInterpreterTest.hs+4−1

@@ -30,6 +30,7 @@ main = do

30 ("x:=true where true and true", Right relationTrue),

31 ("x:=true=true", Right relationTrue),

32 ("x:=true=false", Right relationFalse),

33+ ("x:=true; undefine x", Right relationTrue),

33 ("x:=relation {b int, a char}; insert x relation{tuple{b int(5), a char(\"spam\")}}", mkRelation simpleCAttributes (HS.fromList [RelationTuple $ M.fromList [("a", StringAtom "spam"), ("b", IntAtom 5)]])),

34 ("x:=relation {b int, a char}; insert x relation{tuple{b int(5), a char(\"spam\")}}", mkRelation simpleCAttributes (HS.fromList [RelationTuple $ M.fromList [("a", StringAtom "spam"), ("b", IntAtom 5)]])),

34 ("x:=relation{tuple{b int(5),a char(\"spam\")},tuple{b int(6),a char(\"sam\")}}; delete x where b=6", mkRelation simpleCAttributes $ HS.fromList [RelationTuple $ M.fromList [("a", StringAtom "spam"), ("b", IntAtom 5)]])

35 ("x:=relation{tuple{b int(5),a char(\"spam\")},tuple{b int(6),a char(\"sam\")}}; delete x where b=6", mkRelation simpleCAttributes $ HS.fromList [RelationTuple $ M.fromList [("a", StringAtom "spam"), ("b", IntAtom 5)]])

35 ]

36 ]

@@ -50,4 +51,6 @@ assertTutdEqual databaseContext tutd expected = assertEqual tutd interpreted exp

50 where

51 where

51 interpreted = case interpret databaseContext tutd of

52 interpreted = case interpret databaseContext tutd of

52 (Just err, _) -> Left err

53 (Just err, _) -> Left err

53− (Nothing, context) -> Right $ (relationVariables context) M.! "x"

54+ (Nothing, context) -> case M.lookup "x" (relationVariables context) of

55+ Nothing -> Left $ RelVarNotDefinedError "x"

56+ Just rel -> Right rel