Fix handling of empty statements.

Language/SQL/SimpleSQL/Parse.lhs

@@ -1450,14 +1450,14 @@ TODO: change style
 > topLevelQueryExpr = queryExpr <??> (id <$ semi)
 
 > topLevelStatement :: Parser Statement
-> topLevelStatement = statement <??> (id <$ semi)
+> topLevelStatement = statement
 
 -------------------------
 
 = Statements
 
-> statement :: Parser Statement
+> statementWithoutSemicolon :: Parser Statement
-> statement = choice
+> statementWithoutSemicolon = choice
 >     [keyword_ "create" *> choice [createSchema
 >                                  ,createTable
 >                                  ,createView
@@ -1488,6 +1488,9 @@ TODO: change style
 >     ,revoke
 >     ,SelectStatement <$> queryExpr
 >     ]
+>
+> statement :: Parser Statement
+> statement = statementWithoutSemicolon <* optional semi <|> semi *> pure EmptyStatement
 
 > createSchema :: Parser Statement
 > createSchema = keyword_ "schema" >>
@@ -1895,12 +1898,8 @@ wrapper to parse a series of statements. They must be separated by
 semicolon, but for the last statement, the trailing semicolon is
 optional.
 
-TODO: change style
-
 > statements :: Parser [Statement]
-> statements = (:[]) <$> statement
+> statements = many statement
->              >>= optionSuffix ((semi *>) . pure)
->              >>= optionSuffix (\p -> (p++) <$> statements)
 
 ----------------------------------------------
 

Language/SQL/SimpleSQL/Pretty.lhs

@@ -35,14 +35,22 @@ Try to do this when this code is ported to a modern pretty printing lib.
 > prettyScalarExpr :: Dialect -> ScalarExpr -> String
 > prettyScalarExpr d = render . scalarExpr d
 
+> -- | A terminating semicolon.
+> terminator :: Doc
+> terminator = text ";\n"
+
 > -- | Convert a statement ast to concrete syntax.
 > prettyStatement :: Dialect -> Statement -> String
-> prettyStatement d = render . statement d
+> prettyStatement _ EmptyStatement = render terminator
+> prettyStatement d s = render (statement d s)
 
 > -- | Convert a list of statements to concrete syntax. A semicolon
 > -- is inserted after each statement.
 > prettyStatements :: Dialect -> [Statement] -> String
-> prettyStatements d = render . vcat . map ((<> text ";\n") . statement d)
+> prettyStatements d = render . vcat . map prettyStatementWithSemicolon
+>   where
+>     prettyStatementWithSemicolon :: Statement -> Doc
+>     prettyStatementWithSemicolon s = statement d s <> terminator
 
 = scalar expressions
 
@@ -641,6 +649,7 @@ Try to do this when this code is ported to a modern pretty printing lib.
 
 
 > statement _ (StatementComment cs) = vcat $ map comment cs
+> statement _ EmptyStatement = empty
 
 
 == sessions

Language/SQL/SimpleSQL/Syntax.lhs

@@ -530,6 +530,7 @@ I'm not sure if this is valid syntax or not.
 >   | SetTransform
 >   | SetCollation -}
 >   | StatementComment [Comment]
+>   | EmptyStatement
 >     deriving (Eq,Show,Read,Data,Typeable)
 
 > data DropBehaviour =

simple-sql-parser.cabal

@@ -85,7 +85,8 @@ Test-Suite Tests
                        Language.SQL.SimpleSQL.Tpch,
                        Language.SQL.SimpleSQL.ScalarExprs,
                        Language.SQL.SimpleSQL.LexerTests,
-                       Language.SQL.SimpleSQL.CustomDialect
+                       Language.SQL.SimpleSQL.CustomDialect,
+                       Language.SQL.SimpleSQL.EmptyStatement
   ghc-options:         -threaded
 
 executable SimpleSqlParserTool

tools/Language/SQL/SimpleSQL/EmptyStatement.lhs

@@ -0,0 +1,18 @@
+> module Language.SQL.SimpleSQL.EmptyStatement where
+>
+> import Language.SQL.SimpleSQL.Syntax
+> import Language.SQL.SimpleSQL.TestTypes
+>
+> emptyStatementTests :: TestItem
+> emptyStatementTests = Group "empty statement"
+>   [ TestStatement ansi2011 ";" EmptyStatement
+>   , TestStatements ansi2011 ";" [EmptyStatement]
+>   , TestStatements ansi2011 ";;" [EmptyStatement, EmptyStatement]
+>   , TestStatements ansi2011 ";;;" [EmptyStatement, EmptyStatement, EmptyStatement]
+>   , TestStatement ansi2011 "/* comment */ ;" EmptyStatement
+>   , TestStatements ansi2011 "/* comment */ ;" [EmptyStatement]
+>   , TestStatements ansi2011 "/* comment */ ; /* comment */ ;"
+>       [EmptyStatement, EmptyStatement]
+>   , TestStatements ansi2011 "/* comment */ ; /* comment */ ; /* comment */ ;"
+>       [EmptyStatement, EmptyStatement, EmptyStatement]
+>   ]

tools/Language/SQL/SimpleSQL/Tests.lhs

@@ -29,6 +29,7 @@ test data to the Test.Framework tests.
 > import Language.SQL.SimpleSQL.Odbc
 > import Language.SQL.SimpleSQL.Tpch
 > import Language.SQL.SimpleSQL.LexerTests
+> import Language.SQL.SimpleSQL.EmptyStatement
 
 > import Language.SQL.SimpleSQL.SQL2011Queries
 > import Language.SQL.SimpleSQL.SQL2011AccessControl
@@ -64,6 +65,7 @@ order on the generated documentation.
 >     ,mySQLTests
 >     ,oracleTests
 >     ,customDialectTests
+>     ,emptyStatementTests
 >     ]
 
 > tests :: T.TestTree