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-- PxsltParser
--
-- CVS: $Id: PxsltParser.hs,v 1.11 2004/02/23 08:19:27 thor Exp $
--
-- Copyright (C) 2003 Tom Moertel <tom@moertel.com>
-- Licensed under the terms of the GNU General Public License.
-- See the LICENSE file in the project distribution for details.
module PxsltParser (pxslParser) where
import Text.ParserCombinators.Parsec
import PxsltParserTerms
import XmlString
pxslParser :: Parser [Statement]
pxslParser = do
sts <- many (statement (-1) <?> "top-level statement")
eof
return sts
statement :: Int -> Parser Statement
statement col = (try empty <|> nonEmpty) <?> "statement"
where
nonEmpty = do
hspaces
indent <- getSourceColumn
if indent <= col
then pzero
else ((pxslComment >> statement col)
<|> xmlComment <|> literal <|> element
<|> try macroRef <|> try macroDef <|> macroApp)
empty :: Parser Statement
empty = blankLine >> return Empty
pxslComment :: Parser ()
pxslComment = do
char '#'
manyTill anyChar (skip newline <|> eof)
return ()
xmlComment :: Parser Statement
xmlComment = do
ctx <- getSourceContext
string "--" <?> "comment delimiter"
text <- manyTill anyChar (skip newline <|> eof)
return (Comment ctx text)
literal :: Parser Statement
literal = do
ctx <- getSourceContext
xstr <- quotedXmlString
hspaces
optional newline
return (Literal ctx xstr)
element :: Parser Statement
element = do
ctx@(_, col) <- getSourceContext
name <- xmlName <?> "element name"
hspaces
posnArgs <- exprList <?> "positional arguments"
nvpArgs <- nameValuePairList <?> "named arguments"
children <- subStatements col
hspaces
return (Element ctx name posnArgs nvpArgs children)
where
exprList = many $ try (do optional lineContinuation
e <- argExpr; hspaces; return e)
subStatements col = many (try (statement col <?> "children statements"))
macroRef :: Parser Statement
macroRef = do
ctx@(_, col) <- getSourceContext
string ",," <?> ",, introducing macro reference"
name <- xmlName <?> "macro name"
hspaces
posnArgs <- exprList <?> "positional arguments"
nvpArgs <- nameValuePairList <?> "named arguments"
children <- subStatements col <?> "BODY argument"
hspaces
return (MacroRef ctx name posnArgs nvpArgs children)
where
exprList = many $ try (do optional lineContinuation
e <- argExpr; hspaces; return e)
subStatements col = many (try (statement col <?> "children statements"))
macroDef :: Parser Statement
macroDef = do
ctx@(_, col) <- getSourceContext
char ',' <?> ", introducing macro defn"
name <- (hspace >> return "") <|> xmlName <?> "macro name"
parmNames <- xmlNameList <?> "parameter list"
char '=' <?> "= [macro defn]"
many1 space -- we require at least one space to disambiguate
-- from macro application ",test var=val"
bodyStatements <- subStatements col <?> "macro defn body"
hspaces
return (MacroDef ctx name parmNames bodyStatements)
where
xmlNameList = many $ try (optional lineContinuation >> xmlName)
subStatements col = many (try (statement col <?> "macro body statement"))
macroApp :: Parser Statement
macroApp = do
ctx@(_, col) <- getSourceContext
char ',' <?> ", introducing macro application"
name <- xmlName <?> "macro name"
hspaces
posnArgs <- exprList <?> "positional arguments"
nvpArgs <- nameValuePairList <?> "named arguments"
children <- subStatements col <?> "BODY argument"
hspaces
return (MacroApp ctx name posnArgs nvpArgs children)
where
exprList = many $ try (do optional lineContinuation
e <- argExpr; hspaces; return e)
subStatements col = many (try (statement col <?> "children statements"))
nameValuePairList :: Parser [(String, [Statement])]
nameValuePairList = many (do optional lineContinuation
nvp <- nameValuePair
optional lineContinuation <|> hspaces1
return nvp)
where
nameValuePair = do
try (char '-' >> notFollowedBy (char '-')) <?> "-name=value pair"
optName <- xmlName <?> "name for -name=value pair"
spacesDelimited (char '=') <?> "equals sign for -name=value pair"
optValue <- expr <?> "value for -name=value pair"
hspaces
return (optName, optValue)
expr :: Parser [Statement]
expr = (exprList <|> exprSingle) <?> "expression"
where
exprSingle = do
ctx <- getSourceContext
lit <- quotedXmlString <|> rawString
return [Literal ctx lit]
exprList = do
pxp <- parenExpr <|> evalExpr
pxps <- option [] expr
return (pxp ++ pxps)
rawString = do
str <- many1 rawChar
return (XSCdata str)
rawChar :: Parser Char
rawChar = do
notFollowedBy space
try ((try (string ")>") >> unexpected ")>")
<|> return ())
anyChar
evalExpr :: Parser [Statement]
evalExpr = do
ctx <- getSourceContext
try (string "<(") <?> "opening <( for eval exprssion"
spaces -- layout starts at next non-whitespace char
sts <- many (statement (-1)) <?> "eval-expression statements"
spaces
string ")>" <?> "closing )> for eval expression"
return [Eval ctx sts]
parenExpr :: Parser [Statement]
parenExpr = pexp <?> "parenthesized expression"
where
pexp = do
ctx <- getSourceContext
middle <- inBetweenParens
return [Literal ctx . XSMixed $ middle]
inBetweenParens = do
gexp <- between (char '(') (char ')') generalExpr
return $ "(" ++ gexp ++ ")"
generalExpr = do
pieces <- many (inBetweenParens <|> many1 (noneOf "()"))
return (concat pieces)
argExpr :: Parser [Statement]
argExpr = do
ctx <- getSourceContext
e <- ((notFollowedBy (oneOf "-<)" <|> newline) >> expr) <|> evalExpr)
<?> "argument expression"
return e
xmlName :: Parser String
xmlName = do
firstChar <- letter <|> oneOf "_:"
rest <- many (letter <|> digit <|> oneOf ".-_:")
hspaces
return (firstChar : rest)
quotedXmlString :: Parser XmlString
quotedXmlString = do
char '<'
cdataLiteral <|> mixedLiteral
where
cdataLiteral = do
char '{'
txt <- manyTill anyChar (string "}>")
return (XSCdata txt)
mixedLiteral = do
char '<'
txt <- manyTill anyChar (try (string ">>" >> notFollowedBy (char '>')))
return (XSMixed txt)
hspaces :: Parser ()
hspaces = skipMany hspace
hspaces1 :: Parser ()
hspaces1 = skipMany1 hspace
hspace :: Parser Char
hspace = char ' '
blankLine :: Parser ()
blankLine = skipMany hspace >> newline >> return ()
lineContinuation :: Parser ()
lineContinuation = (char '\\' >> newline >> hspaces) <?> "line continuation"
getSourceColumn :: Parser Int
getSourceColumn = getPosition >>= return . sourceColumn
getSourceLine :: Parser Int
getSourceLine = getPosition >>= return . sourceLine
getSourceContext :: Parser SourceContext
getSourceContext = do
line <- getSourceLine
col <- getSourceColumn
return (line, col)
skip :: Parser a -> Parser ()
skip a = a >> return ()
-- | Allows any amount of whitespace (including none) on either side
-- of parser 'p'.
spacesDelimited :: Parser a -> Parser a
spacesDelimited p = do spaces; val <- p; spaces; return val
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