718 lines
26 KiB
Plaintext
718 lines
26 KiB
Plaintext
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The parser uses a separate lexer for two reasons:
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1. sql syntax is very awkward to parse, the separate lexer makes it
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easier to handle this in most places (in some places it makes it
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harder or impossible, the fix is to switch to something better than
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parsec)
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2. using a separate lexer gives a huge speed boost because it reduces
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backtracking. (We could get this by making the parsing code a lot more
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complex also.)
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3. we can test the lexer relatively exhaustively, then even when we
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don't do nearly as comprehensive testing on the syntax level, we still
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have a relatively high assurance of the low level of bugs. This is
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much more difficult to get parity with when testing the syntax parser
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directly without the separately testing lexing stage.
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> -- | Lexer for SQL.
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> {-# LANGUAGE TupleSections #-}
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> module Language.SQL.SimpleSQL.Lex
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> (Token(..)
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> ,lexSQL
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> ,prettyToken
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> ,prettyTokens
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> ,ParseError(..)
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> ,Dialect(..)
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> ,tokenListWillPrintAndLex
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> ) where
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> import Language.SQL.SimpleSQL.Dialect
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> import Text.Parsec (option,string,manyTill,anyChar
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> ,try,string,many1,oneOf,digit,(<|>),choice,char,eof
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> ,many,runParser,lookAhead,satisfy
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> ,setPosition,getPosition
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> ,setSourceColumn,setSourceLine
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> ,sourceName, setSourceName
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> ,sourceLine, sourceColumn
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> ,notFollowedBy)
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> import Language.SQL.SimpleSQL.Combinators
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> import Language.SQL.SimpleSQL.Errors
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> import Control.Applicative hiding ((<|>), many)
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> import Data.Char
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> import Control.Monad
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> import Prelude hiding (takeWhile)
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> import Text.Parsec.String (Parser)
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> import Data.Maybe
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> -- | Represents a lexed token
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> data Token
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> -- | A symbol (in ansi dialect) is one of the following
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> --
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> -- * multi char symbols <> \<= \>= != ||
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> -- * single char symbols: * + - < > ^ / % ~ & | ? ( ) [ ] , ; ( )
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> --
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> = Symbol String
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>
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> -- | This is an identifier or keyword. The first field is
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> -- the quotes used, or nothing if no quotes were used. The quotes
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> -- can be " or u& or something dialect specific like []
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> | Identifier (Maybe (String,String)) String
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>
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> -- | This is a prefixed variable symbol, such as :var, @var or #var
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> -- (only :var is used in ansi dialect)
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> | PrefixedVariable Char String
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>
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> -- | This is a positional arg identifier e.g. $1
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> | PositionalArg Int
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>
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> -- | This is a string literal. The first two fields are the --
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> -- start and end quotes, which are usually both ', but can be
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> -- the character set (one of nNbBxX, or u&, U&), or a dialect
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> -- specific string quoting (such as $$ in postgres)
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> | SqlString String String String
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>
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> -- | A number literal (integral or otherwise), stored in original format
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> -- unchanged
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> | SqlNumber String
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>
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> -- | Whitespace, one or more of space, tab or newline.
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> | Whitespace String
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>
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> -- | A commented line using --, contains every character starting with the
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> -- \'--\' and including the terminating newline character if there is one
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> -- - this will be missing if the last line in the source is a line comment
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> -- with no trailing newline
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> | LineComment String
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>
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> -- | A block comment, \/* stuff *\/, includes the comment delimiters
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> | BlockComment String
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>
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> deriving (Eq,Show)
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> -- | Pretty printing, if you lex a bunch of tokens, then pretty
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> -- print them, should should get back exactly the same string
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> prettyToken :: Dialect -> Token -> String
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> prettyToken _ (Symbol s) = s
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> prettyToken _ (Identifier Nothing t) = t
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> prettyToken _ (Identifier (Just (q1,q2)) t) = q1 ++ t ++ q2
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> prettyToken _ (PrefixedVariable c p) = c:p
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> prettyToken _ (PositionalArg p) = '$':show p
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> prettyToken _ (SqlString s e t) = s ++ t ++ e
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> prettyToken _ (SqlNumber r) = r
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> prettyToken _ (Whitespace t) = t
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> prettyToken _ (LineComment l) = l
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> prettyToken _ (BlockComment c) = c
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> prettyTokens :: Dialect -> [Token] -> String
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> prettyTokens d ts = concat $ map (prettyToken d) ts
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TODO: try to make all parsers applicative only
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> -- | Lex some SQL to a list of tokens.
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> lexSQL :: Dialect
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> -- ^ dialect of SQL to use
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> -> FilePath
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> -- ^ filename to use in error messages
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> -> Maybe (Int,Int)
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> -- ^ line number and column number of the first character
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> -- in the source to use in error messages
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> -> String
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> -- ^ the SQL source to lex
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> -> Either ParseError [((String,Int,Int),Token)]
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> lexSQL dialect fn' p src =
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> let (l',c') = fromMaybe (1,1) p
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> in either (Left . convParseError src) Right
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> $ runParser (setPos (fn',l',c') *> many (sqlToken dialect) <* eof) () fn' src
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> where
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> setPos (fn,l,c) = do
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> fmap (flip setSourceName fn
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> . flip setSourceLine l
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> . flip setSourceColumn c) getPosition
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> >>= setPosition
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> -- | parser for a sql token
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> sqlToken :: Dialect -> Parser ((String,Int,Int),Token)
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> sqlToken d = do
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> p' <- getPosition
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> let p = (sourceName p',sourceLine p', sourceColumn p')
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The order of parsers is important: strings and quoted identifiers can
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start out looking like normal identifiers, so we try to parse these
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first and use a little bit of try. Line and block comments start like
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symbols, so we try these before symbol. Numbers can start with a . so
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this is also tried before symbol (a .1 will be parsed as a number, but
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. otherwise will be parsed as a symbol).
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> (p,) <$> choice [sqlString d
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> ,identifier d
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> ,lineComment d
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> ,blockComment d
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> ,sqlNumber d
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> ,positionalArg d
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> ,dontParseEndBlockComment d
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> ,prefixedVariable d
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> ,symbol d
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> ,sqlWhitespace d]
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Parses identifiers:
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simple_identifier_23
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u&"unicode quoted identifier"
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"quoted identifier"
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"quoted identifier "" with double quote char"
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`mysql quoted identifier`
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> identifier :: Dialect -> Parser Token
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> identifier d =
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> choice
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> [quotedIden
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> ,unicodeQuotedIden
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> ,regularIden
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> ,guard (diBackquotedIden d) >> mySqlQuotedIden
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> ,guard (diSquareBracketQuotedIden d) >> sqlServerQuotedIden
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> ]
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> where
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> regularIden = Identifier Nothing <$> identifierString
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> quotedIden = Identifier (Just ("\"","\"")) <$> qidenPart
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> mySqlQuotedIden = Identifier (Just ("`","`"))
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> <$> (char '`' *> takeWhile1 (/='`') <* char '`')
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> sqlServerQuotedIden = Identifier (Just ("[","]"))
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> <$> (char '[' *> takeWhile1 (`notElem` "[]") <* char ']')
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> -- try is used here to avoid a conflict with identifiers
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> -- and quoted strings which also start with a 'u'
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> unicodeQuotedIden = Identifier
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> <$> (f <$> try (oneOf "uU" <* string "&"))
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> <*> qidenPart
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> where f x = Just (x: "&\"", "\"")
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> qidenPart = char '"' *> qidenSuffix ""
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> qidenSuffix t = do
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> s <- takeTill (=='"')
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> void $ char '"'
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> -- deal with "" as literal double quote character
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> choice [do
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> void $ char '"'
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> qidenSuffix $ concat [t,s,"\"\""]
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> ,return $ concat [t,s]]
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This parses a valid identifier without quotes.
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> identifierString :: Parser String
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> identifierString =
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> startsWith (\c -> c == '_' || isAlpha c) isIdentifierChar
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this can be moved to the dialect at some point
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> isIdentifierChar :: Char -> Bool
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> isIdentifierChar c = c == '_' || isAlphaNum c
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use try because : and @ can be part of other things also
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> prefixedVariable :: Dialect -> Parser Token
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> prefixedVariable d = try $ choice
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> [PrefixedVariable <$> char ':' <*> identifierString
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> ,guard (diAtIdentifier d) >>
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> PrefixedVariable <$> char '@' <*> identifierString
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> ,guard (diHashIdentifier d) >>
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> PrefixedVariable <$> char '#' <*> identifierString
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> ]
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> positionalArg :: Dialect -> Parser Token
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> positionalArg d =
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> guard (diPositionalArg d) >>
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> -- use try to avoid ambiguities with other syntax which starts with dollar
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> PositionalArg <$> try (char '$' *> (read <$> many1 digit))
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Parse a SQL string. Examples:
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'basic string'
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'string with '' a quote'
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n'international text'
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b'binary string'
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x'hexidecimal string'
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> sqlString :: Dialect -> Parser Token
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> sqlString d = dollarString <|> csString <|> normalString
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> where
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> dollarString = do
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> guard $ diDollarString d
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> -- use try because of ambiguity with symbols and with
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> -- positional arg
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> delim <- (\x -> concat ["$",x,"$"])
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> <$> try (char '$' *> option "" identifierString <* char '$')
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> SqlString delim delim <$> manyTill anyChar (try $ string delim)
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> normalString = SqlString "'" "'" <$> (char '\'' *> normalStringSuffix False "")
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> normalStringSuffix allowBackslash t = do
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> s <- takeTill $ if allowBackslash
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> then (`elem` "'\\")
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> else (== '\'')
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> -- deal with '' or \' as literal quote character
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> choice [do
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> ctu <- choice ["''" <$ try (string "''")
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> ,"\\'" <$ string "\\'"
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> ,"\\" <$ char '\\']
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> normalStringSuffix allowBackslash $ concat [t,s,ctu]
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> ,concat [t,s] <$ char '\'']
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> -- try is used to to avoid conflicts with
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> -- identifiers which can start with n,b,x,u
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> -- once we read the quote type and the starting '
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> -- then we commit to a string
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> -- it's possible that this will reject some valid syntax
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> -- but only pathalogical stuff, and I think the improved
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> -- error messages and user predictability make it a good
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> -- pragmatic choice
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> csString
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> | diEString d =
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> choice [SqlString <$> try (string "e'" <|> string "E'")
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> <*> return "'" <*> normalStringSuffix True ""
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> ,csString']
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> | otherwise = csString'
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> csString' = SqlString
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> <$> try cs
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> <*> return "'"
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> <*> normalStringSuffix False ""
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> csPrefixes = "nNbBxX"
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> cs = choice $ (map (\x -> string ([x] ++ "'")) csPrefixes)
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> ++ [string "u&'"
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> ,string "U&'"]
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numbers
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digits
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digits.[digits][e[+-]digits]
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[digits].digits[e[+-]digits]
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digitse[+-]digits
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where digits is one or more decimal digits (0 through 9). At least one
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digit must be before or after the decimal point, if one is used. At
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least one digit must follow the exponent marker (e), if one is
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present. There cannot be any spaces or other characters embedded in
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the constant. Note that any leading plus or minus sign is not actually
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considered part of the constant; it is an operator applied to the
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constant.
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> sqlNumber :: Dialect -> Parser Token
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> sqlNumber d =
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> SqlNumber <$> completeNumber
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> -- this is for definitely avoiding possibly ambiguous source
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> <* choice [-- special case to allow e.g. 1..2
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> guard (diPostgresSymbols d)
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> *> (void $ lookAhead $ try $ string "..")
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> <|> void (notFollowedBy (oneOf "eE."))
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> ,notFollowedBy (oneOf "eE.")
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> ]
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> where
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> completeNumber =
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> (int <??> (pp dot <??.> pp int)
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> -- try is used in case we read a dot
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> -- and it isn't part of a number
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> -- if there are any following digits, then we commit
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> -- to it being a number and not something else
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> <|> try ((++) <$> dot <*> int))
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> <??> pp expon
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> int = many1 digit
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> -- make sure we don't parse two adjacent dots in a number
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> -- special case for postgresql, we backtrack if we see two adjacent dots
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> -- to parse 1..2, but in other dialects we commit to the failure
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> dot = let p = string "." <* notFollowedBy (char '.')
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> in if diPostgresSymbols d
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> then try p
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> else p
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> expon = (:) <$> oneOf "eE" <*> sInt
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> sInt = (++) <$> option "" (string "+" <|> string "-") <*> int
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> pp = (<$$> (++))
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Symbols
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A symbol is an operator, or one of the misc symbols which include:
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. .. := : :: ( ) ? ; , { } (for odbc)
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The postgresql operator syntax allows a huge range of operators
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compared with ansi and other dialects
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> symbol :: Dialect -> Parser Token
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> symbol d = Symbol <$> choice (concat
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> [dots
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> ,if diPostgresSymbols d
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> then postgresExtraSymbols
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> else []
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> ,miscSymbol
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> ,if diOdbc d then odbcSymbol else []
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> ,if diPostgresSymbols d
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> then generalizedPostgresqlOperator
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> else basicAnsiOps
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> ])
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> where
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> dots = [many1 (char '.')]
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> odbcSymbol = [string "{", string "}"]
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> postgresExtraSymbols =
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> [try (string ":=")
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> -- parse :: and : and avoid allowing ::: or more
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> ,try (string "::" <* notFollowedBy (char ':'))
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> ,try (string ":" <* notFollowedBy (char ':'))]
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> miscSymbol = map (string . (:[])) $
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> case () of
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> _ | diSqlServerSymbols d -> ",;():?"
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> | diPostgresSymbols d -> "[],;()"
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> | otherwise -> "[],;():?"
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try is used because most of the first characters of the two character
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symbols can also be part of a single character symbol
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> basicAnsiOps = map (try . string) [">=","<=","!=","<>"]
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> ++ map (string . (:[])) "+-^*/%~&<>="
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> ++ pipes
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> pipes = -- what about using many1 (char '|'), then it will
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> -- fail in the parser? Not sure exactly how
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> -- standalone the lexer should be
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> [char '|' *>
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> choice ["||" <$ char '|' <* notFollowedBy (char '|')
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> ,return "|"]]
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postgresql generalized operators
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this includes the custom operators that postgres supports,
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plus all the standard operators which could be custom operators
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according to their grammar
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rules
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An operator name is a sequence of up to NAMEDATALEN-1 (63 by default) characters from the following list:
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+ - * / < > = ~ ! @ # % ^ & | ` ?
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There are a few restrictions on operator names, however:
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-- and /* cannot appear anywhere in an operator name, since they will be taken as the start of a comment.
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A multiple-character operator name cannot end in + or -, unless the name also contains at least one of these characters:
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~ ! @ # % ^ & | ` ?
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which allows the last character of a multi character symbol to be + or
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-
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> generalizedPostgresqlOperator :: [Parser String]
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> generalizedPostgresqlOperator = [singlePlusMinus,opMoreChars]
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> where
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> allOpSymbols = "+-*/<>=~!@#%^&|`?"
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> -- these are the symbols when if part of a multi character
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> -- operator permit the operator to end with a + or - symbol
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> exceptionOpSymbols = "~!@#%^&|`?"
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> -- special case for parsing a single + or - symbol
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> singlePlusMinus = try $ do
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> c <- oneOf "+-"
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> notFollowedBy $ oneOf allOpSymbols
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> return [c]
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> -- this is used when we are parsing a potentially multi symbol
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> -- operator and we have alread seen one of the 'exception chars'
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> -- and so we can end with a + or -
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> moreOpCharsException = do
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> c <- oneOf (filter (`notElem` "-/*") allOpSymbols)
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> -- make sure we don't parse a comment starting token
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> -- as part of an operator
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> <|> try (char '/' <* notFollowedBy (char '*'))
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> <|> try (char '-' <* notFollowedBy (char '-'))
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> -- and make sure we don't parse a block comment end
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> -- as part of another symbol
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> <|> try (char '*' <* notFollowedBy (char '/'))
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> (c:) <$> option [] moreOpCharsException
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> opMoreChars = choice
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> [-- parse an exception char, now we can finish with a + -
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> (:)
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> <$> oneOf exceptionOpSymbols
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> <*> option [] moreOpCharsException
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> ,(:)
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> <$> (-- parse +, make sure it isn't the last symbol
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> try (char '+' <* lookAhead (oneOf allOpSymbols))
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> <|> -- parse -, make sure it isn't the last symbol
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> -- or the start of a -- comment
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> try (char '-'
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> <* notFollowedBy (char '-')
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> <* lookAhead (oneOf allOpSymbols))
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> <|> -- parse / check it isn't the start of a /* comment
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> try (char '/' <* notFollowedBy (char '*'))
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> <|> -- make sure we don't parse */ as part of a symbol
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> try (char '*' <* notFollowedBy (char '/'))
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> <|> -- any other ansi operator symbol
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> oneOf "<>=")
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> <*> option [] opMoreChars
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> ]
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> sqlWhitespace :: Dialect -> Parser Token
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> sqlWhitespace _ = Whitespace <$> many1 (satisfy isSpace)
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> lineComment :: Dialect -> Parser Token
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> lineComment _ =
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> (\s -> LineComment $ concat ["--",s]) <$>
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> -- try is used here in case we see a - symbol
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> -- once we read two -- then we commit to the comment token
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> (try (string "--") *> (
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> -- todo: there must be a better way to do this
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> conc <$> manyTill anyChar (lookAhead lineCommentEnd) <*> lineCommentEnd))
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> where
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> conc a Nothing = a
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> conc a (Just b) = a ++ b
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> lineCommentEnd =
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> Just "\n" <$ char '\n'
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> <|> Nothing <$ eof
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Try is used in the block comment for the two symbol bits because we
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want to backtrack if we read the first symbol but the second symbol
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isn't there.
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> blockComment :: Dialect -> Parser Token
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> blockComment _ =
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> (\s -> BlockComment $ concat ["/*",s]) <$>
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> (try (string "/*") *> commentSuffix 0)
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> where
|
|
> commentSuffix :: Int -> Parser String
|
|
> commentSuffix n = do
|
|
> -- read until a possible end comment or nested comment
|
|
> x <- takeWhile (\e -> e /= '/' && e /= '*')
|
|
> choice [-- close comment: if the nesting is 0, done
|
|
> -- otherwise recurse on commentSuffix
|
|
> try (string "*/") *> let t = concat [x,"*/"]
|
|
> in if n == 0
|
|
> then return t
|
|
> else (\s -> concat [t,s]) <$> commentSuffix (n - 1)
|
|
> -- nested comment, recurse
|
|
> ,try (string "/*") *> ((\s -> concat [x,"/*",s]) <$> commentSuffix (n + 1))
|
|
> -- not an end comment or nested comment, continue
|
|
> ,(\c s -> x ++ [c] ++ s) <$> anyChar <*> commentSuffix n]
|
|
|
|
|
|
This is to improve user experience: provide an error if we see */
|
|
outside a comment. This could potentially break postgres ops with */
|
|
in them (which is a stupid thing to do). In other cases, the user
|
|
should write * / instead (I can't think of any cases when this would
|
|
be valid syntax though).
|
|
|
|
> dontParseEndBlockComment :: Dialect -> Parser Token
|
|
> dontParseEndBlockComment _ =
|
|
> -- don't use try, then it should commit to the error
|
|
> try (string "*/") *> fail "comment end without comment start"
|
|
|
|
|
|
Some helper combinators
|
|
|
|
> startsWith :: (Char -> Bool) -> (Char -> Bool) -> Parser String
|
|
> startsWith p ps = do
|
|
> c <- satisfy p
|
|
> choice [(:) c <$> (takeWhile1 ps)
|
|
> ,return [c]]
|
|
|
|
> takeWhile1 :: (Char -> Bool) -> Parser String
|
|
> takeWhile1 p = many1 (satisfy p)
|
|
|
|
> takeWhile :: (Char -> Bool) -> Parser String
|
|
> takeWhile p = many (satisfy p)
|
|
|
|
> takeTill :: (Char -> Bool) -> Parser String
|
|
> takeTill p = manyTill anyChar (peekSatisfy p)
|
|
|
|
> peekSatisfy :: (Char -> Bool) -> Parser ()
|
|
> peekSatisfy p = void $ lookAhead (satisfy p)
|
|
|
|
This utility function will accurately report if the two tokens are
|
|
pretty printed, if they should lex back to the same two tokens. This
|
|
function is used in testing (and can be used in other places), and
|
|
must not be implemented by actually trying to print both tokens and
|
|
then lex them back from a single string (because then we would have
|
|
the risk of thinking two tokens cannot be together when there is bug
|
|
in the lexer, which the testing is supposed to find).
|
|
|
|
maybe do some quick checking to make sure this function only gives
|
|
true negatives: check pairs which return false actually fail to lex or
|
|
give different symbols in return: could use quickcheck for this
|
|
|
|
a good sanity test for this function is to change it to always return
|
|
true, then check that the automated tests return the same number of
|
|
successes. I don't think it succeeds this test at the moment
|
|
|
|
> -- | Utility function to tell you if a list of tokens
|
|
> -- will pretty print then lex back to the same set of tokens.
|
|
> -- Used internally, might be useful for generating SQL via lexical tokens.
|
|
> tokenListWillPrintAndLex :: Dialect -> [Token] -> Bool
|
|
> tokenListWillPrintAndLex _ [] = True
|
|
> tokenListWillPrintAndLex _ [_] = True
|
|
> tokenListWillPrintAndLex d (a:b:xs) =
|
|
> tokensWillPrintAndLex d a b && tokenListWillPrintAndLex d (b:xs)
|
|
|
|
> tokensWillPrintAndLex :: Dialect -> Token -> Token -> Bool
|
|
> tokensWillPrintAndLex d a b
|
|
|
|
a : followed by an identifier character will look like a host param
|
|
followed by = or : makes a different symbol
|
|
|
|
> | Symbol ":" <- a
|
|
> , checkFirstBChar (\x -> isIdentifierChar x || x `elem` ":=") = False
|
|
|
|
two symbols next to eachother will fail if the symbols can combine and
|
|
(possibly just the prefix) look like a different symbol
|
|
|
|
> | diPostgresSymbols d
|
|
> , Symbol a' <- a
|
|
> , Symbol b' <- b
|
|
> , b' `notElem` ["+", "-"] || or (map (`elem` a') "~!@#%^&|`?") = False
|
|
|
|
check two adjacent symbols in non postgres where the combination
|
|
possibilities are much more limited. This is ansi behaviour, it might
|
|
be different when the other dialects are done properly
|
|
|
|
> | Symbol a' <- a
|
|
> , Symbol b' <- b
|
|
> , (a',b') `elem` [("<",">")
|
|
> ,("<","=")
|
|
> ,(">","=")
|
|
> ,("!","=")
|
|
> ,("|","|")
|
|
> ,("||","|")
|
|
> ,("|","||")
|
|
> ,("||","||")
|
|
> ,("<",">=")
|
|
> ] = False
|
|
|
|
two whitespaces will be combined
|
|
|
|
> | Whitespace {} <- a
|
|
> , Whitespace {} <- b = False
|
|
|
|
line comment without a newline at the end will eat the next token
|
|
|
|
> | LineComment {} <- a
|
|
> , checkLastAChar (/='\n') = False
|
|
|
|
check the last character of the first token and the first character of
|
|
the second token forming a comment start or end symbol
|
|
|
|
> | let f '-' '-' = True
|
|
> f '/' '*' = True
|
|
> f '*' '/' = True
|
|
> f _ _ = False
|
|
> in checkBorderChars f = False
|
|
|
|
a symbol will absorb a following .
|
|
TODO: not 100% on this always being bad
|
|
|
|
> | Symbol {} <- a
|
|
> , checkFirstBChar (=='.') = False
|
|
|
|
cannot follow a symbol ending in : with another token starting with :
|
|
|
|
> | let f ':' ':' = True
|
|
> f _ _ = False
|
|
> in checkBorderChars f = False
|
|
|
|
unquoted identifier followed by an identifier letter
|
|
|
|
> | Identifier Nothing _ <- a
|
|
> , checkFirstBChar isIdentifierChar = False
|
|
|
|
a quoted identifier using ", followed by a " will fail
|
|
|
|
> | Identifier (Just (_,"\"")) _ <- a
|
|
> , checkFirstBChar (=='"') = False
|
|
|
|
prefixed variable followed by an identifier char will be absorbed
|
|
|
|
> | PrefixedVariable {} <- a
|
|
> , checkFirstBChar isIdentifierChar = False
|
|
|
|
a positional arg will absorb a following digit
|
|
|
|
> | PositionalArg {} <- a
|
|
> , checkFirstBChar isDigit = False
|
|
|
|
a string ending with ' followed by a token starting with ' will be absorbed
|
|
|
|
> | SqlString _ "'" _ <- a
|
|
> , checkFirstBChar (=='\'') = False
|
|
|
|
a number followed by a . will fail or be absorbed
|
|
|
|
> | SqlNumber {} <- a
|
|
> , checkFirstBChar (=='.') = False
|
|
|
|
a number followed by an e or E will fail or be absorbed
|
|
|
|
> | SqlNumber {} <- a
|
|
> , checkFirstBChar (\x -> x =='e' || x == 'E') = False
|
|
|
|
two numbers next to eachother will fail or be absorbed
|
|
|
|
> | SqlNumber {} <- a
|
|
> , SqlNumber {} <- b = False
|
|
|
|
|
|
> | otherwise = True
|
|
|
|
> where
|
|
> prettya = prettyToken d a
|
|
> prettyb = prettyToken d b
|
|
> -- helper function to run a predicate on the
|
|
> -- last character of the first token and the first
|
|
> -- character of the second token
|
|
> checkBorderChars f
|
|
> | (_:_) <- prettya
|
|
> , (fb:_) <- prettyb
|
|
> , la <- last prettya
|
|
> = f la fb
|
|
> checkBorderChars _ = False
|
|
> checkFirstBChar f = case prettyb of
|
|
> (b':_) -> f b'
|
|
> _ -> False
|
|
> checkLastAChar f = case prettya of
|
|
> (_:_) -> f $ last prettya
|
|
> _ -> False
|
|
|
|
|
|
|
|
|
|
TODO:
|
|
|
|
make the tokenswill print more dialect accurate. Maybe add symbol
|
|
chars and identifier chars to the dialect definition and use them from
|
|
here
|
|
|
|
start adding negative / different parse dialect tests
|
|
|
|
add token tables and tests for oracle, sql server
|
|
review existing tables
|
|
|
|
look for refactoring opportunities, especially the token
|
|
generation tables in the tests
|
|
|
|
do some user documentation on lexing, and lexing/dialects
|
|
|
|
start thinking about a more separated design for the dialect handling
|
|
|
|
lexing tests are starting to take a really long time, so split the
|
|
tests so it is much easier to run all the tests except the lexing
|
|
tests which only need to be run when working on the lexer (which
|
|
should be relatively uncommon), or doing a commit or finishing off a
|
|
series of commits,
|
|
|
|
start writing the error message tests:
|
|
generate/write a large number of syntax errors
|
|
create a table with the source and the error message
|
|
try to compare some different versions of code to compare the
|
|
quality of the error messages by hand
|
|
|
|
get this checked in so improvements and regressions in the error
|
|
message quality can be tracked a little more easily (although it will
|
|
still be manual)
|
|
|
|
try again to add annotation to the ast
|