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|
module Grasp.Parser (
parseGrasp
) where
import Control.Applicative( some )
import Text.ParserCombinators.Parsec
import qualified Grasp.Graph as G
parseGrasp :: String -> Either ParseError GraspProgram
parseGrasp input =
parse removeComments "error" input >>=
parse graspDOT "error" >>=
return . G.construct
-- removes comments but otherwise leaves input unchanged
removeComments = gline `sepEndBy` eol >>= return . concat
eol = try (string "\r\n")
<|> try (string "\n\r")
<|> try (string "\n")
<|> try (string "\r")
<?> "end of line"
gline = many thing >>= return . concat
thing = try (some (noneOf "\r\n\"/#"))
<|> try (quotedString >>= return . ("\"" ++) . (++ "\""))
<|> try singleLineComment
<|> try multiLineComment
<|> (anyChar >>= return . (:[]) )
singleLineComment =
(string "//" >> many (noneOf "\r\n") >> return "")
<|> (string "#" >> many (noneOf "\r\n") >> return "")
multiLineComment = do
string "/*"
many (noneOf "*" <|> (char '*' >> notFollowedBy (char '/') >> return '*'))
return ""
-- parses a DOT graph language file into the data for a grasp program
graspDOT = do
optional strict
graphType
optional ident
openBrace
(n,e) <- stmtList ([],[])
closeBrace
many blankLine
eof
return (n,e)
strict = caseInsensitiveString "strict" >>= (\x -> whiteSpace >> return x)
graphType = try (caseInsensitiveString "digraph" >>= (\x -> whiteSpace >> return x)) <?> "digraph"
ident = ((try alphaNumString)
<|> (try numeral)
<|> (try quotedString)) >>= (\x -> whiteSpace >> return x)
<?> "ID"
stmtList (n,e) =
try (whiteSpace >> node >>= (\x -> stmtList (x:n,e)) )
<|> try (whiteSpace >> edge >>= (\x -> stmtList (n,x:e)) )
<|> try (whiteSpace >> attr >> stmtList (n,e))
<|> try (whiteSpace >> subgraph >>= (\(x,y) -> stmtList ((reverse x) ++ n, (reverse y) ++ e)) )
<|> try (blankLine >> stmtList (n,e))
<|> return (reverse n, reverse e)
blankLine = whiteSpace >> eol
alphaNumString = do
a <- nonDigitChar
b <- many alphaNumChar
return (a:b)
nonDigitChar = letter <|> char '_'
alphaNumChar = alphaNum <|> char '_'
numeral = try negativeNum <|> positiveNum
negativeNum = char '-' >> positiveNum >>= return . ('-':)
positiveNum = try pointNum <|> try floatNum <|> wholeNum
pointNum = char '.' >> some digit >>= return . ('.':)
wholeNum = some digit
floatNum = do { a <- some digit; char '.'; b <- many digit; return (a ++ "." ++ b)}
quotedString = do
char '\"'
s <- some quotedChar
char '\"'
return s
quotedChar = noneOf "\"\r\n" <|> try (char '\\' >> char '\"')
node = do
n <- ident
a <- attrList
optional (char ';')
whiteSpace
return (n,a)
edge = do
a <- ident
edgeOp
b <- ident
c <- attrList
optional (char ';')
whiteSpace
return (a,b,c)
edgeOp = string "->" >> whiteSpace >> return "->"
attr = attrType >> attrList >> optional (char ';') >> whiteSpace
attrType = (caseInsensitiveString "graph"
<|> caseInsensitiveString "node"
<|> caseInsensitiveString "edge") >>= (\x -> whiteSpace >> return x)
attrList = do
a <- many aList
let r = filter (\x -> fst x == "label") (concat a)
case (length r) of
0 -> fail "expected node/edge label"
1 -> return . snd . head $ r
_ -> fail "unexpected multiple labels for single node/edge"
aList = do
openBracket
a <- many equAttr
closeBracket
whiteSpace
return a
equAttr = do
e <- equ
optional (char ';' <|> char ',')
whiteSpace
return e
equ = do
a <- ident
equalsChar
b <- ident
return (a,b)
subgraph = do
optional (caseInsensitiveString "subgraph" >> optional ident)
openBrace
(n,e) <- stmtList ([],[])
closeBrace
optional (char ';')
whiteSpace
return (n,e)
openBrace = char '{' >> whiteSpace >> return '{'
closeBrace = char '}' >> whiteSpace >> return '}'
openBracket = char '[' >> whiteSpace >> return '['
closeBracket = char ']' >> whiteSpace >> return ']'
equalsChar = char '='
caseInsensitiveChar c = char (toLower c) <|> char (toUpper c)
caseInsensitiveString s = mapM caseInsensitiveChar s
whiteSpace = many (oneOf " \t")
|
