-- |An 'RdfParser' implementation for the Turtle format
-- .
module Text.RDF.RDF4H.TurtleParser(
TurtleParser(TurtleParser)
)
where
import Data.RDF.Types
import Data.RDF.Namespace
import Text.RDF.RDF4H.ParserUtils
import Text.Parsec
import Text.Parsec.Text
import qualified Data.Map as Map
import qualified Data.Text as T
import qualified Data.Text.IO as TIO
import Data.Sequence(Seq, (|>))
import qualified Data.Sequence as Seq
import qualified Data.Foldable as F
import Data.Char (isDigit)
import Control.Monad
import Data.Maybe (fromMaybe)
-- |An 'RdfParser' implementation for parsing RDF in the
-- Turtle format. It takes optional arguments representing the base URL to use
-- for resolving relative URLs in the document (may be overridden in the document
-- itself using the \@base directive), and the URL to use for the document itself
-- for resolving references to <> in the document.
-- To use this parser, pass a 'TurtleParser' value as the first argument to any of
-- the 'parseString', 'parseFile', or 'parseURL' methods of the 'RdfParser' type
-- class.
data TurtleParser = TurtleParser (Maybe BaseUrl) (Maybe T.Text)
-- |'TurtleParser' is an instance of 'RdfParser'.
instance RdfParser TurtleParser where
parseString (TurtleParser bUrl dUrl) = parseString' bUrl dUrl
parseFile (TurtleParser bUrl dUrl) = parseFile' bUrl dUrl
parseURL (TurtleParser bUrl dUrl) = parseURL' bUrl dUrl
type ParseState =
(Maybe BaseUrl, -- the current BaseUrl, may be Nothing initially, but not after it is once set
Maybe T.Text, -- the docUrl, which never changes and is used to resolve <> in the document.
Int, -- the id counter, containing the value of the next id to be used
PrefixMappings, -- the mappings from prefix to URI that are encountered while parsing
[Subject], -- stack of current subject nodes, if we have parsed a subject but not finished the triple
[Predicate], -- stack of current predicate nodes, if we've parsed a predicate but not finished the triple
[Bool], -- a stack of values to indicate that we're processing a (possibly nested) collection; top True indicates just started (on first element)
Seq Triple) -- the triples encountered while parsing; always added to on the right side
t_turtleDoc :: GenParser ParseState (Seq Triple, PrefixMappings)
t_turtleDoc =
many t_statement >> (eof > "eof") >> getState >>= \(_, _, _, pms, _, _, _, ts) -> return (ts, pms)
t_statement :: GenParser ParseState ()
t_statement = d <|> t <|> void (many1 t_ws > "blankline-whitespace")
where
d = void
(try t_directive >> (many t_ws > "directive-whitespace1") >>
(char '.' > "end-of-directive-period") >>
(many t_ws > "directive-whitespace2"))
t = void
(t_triples >> (many t_ws > "triple-whitespace1") >>
(char '.' > "end-of-triple-period") >>
(many t_ws > "triple-whitespace2"))
t_triples :: GenParser ParseState ()
t_triples = t_subject >> (many1 t_ws > "subject-predicate-whitespace") >> t_predicateObjectList >> resetSubjectPredicate
t_directive :: GenParser ParseState ()
t_directive = t_prefixID <|> t_base
t_resource :: GenParser ParseState T.Text
t_resource = try t_uriref <|> t_qname
t_prefixID :: GenParser ParseState ()
t_prefixID =
do try (string "@prefix" > "@prefix-directive")
pre <- (many1 t_ws > "whitespace-after-@prefix") >> option T.empty t_prefixName
char ':' >> (many1 t_ws > "whitespace-after-@prefix-colon")
uriFrag <- t_uriref
(bUrl, dUrl, _, PrefixMappings pms, _, _, _, _) <- getState
updatePMs $ Just (PrefixMappings $ Map.insert pre (absolutizeUrl bUrl dUrl uriFrag) pms)
return ()
t_base :: GenParser ParseState ()
t_base =
do try (string "@base" > "@base-directive")
many1 t_ws > "whitespace-after-@base"
urlFrag <- t_uriref
bUrl <- currBaseUrl
dUrl <- currDocUrl
updateBaseUrl (Just $ Just $ newBaseUrl bUrl (absolutizeUrl bUrl dUrl urlFrag))
t_verb :: GenParser ParseState ()
t_verb = (try t_predicate <|> (char 'a' >> return rdfTypeNode)) >>= pushPred
t_predicate :: GenParser ParseState Node
t_predicate = liftM UNode (t_resource > "resource")
t_nodeID :: GenParser ParseState T.Text
t_nodeID = do { try (string "_:"); cs <- t_name; return $! "_:" `T.append` cs }
t_qname :: GenParser ParseState T.Text
t_qname =
do pre <- option T.empty (try t_prefixName)
char ':'
name <- option T.empty t_name
(bUrl, _, _, pms, _, _, _, _) <- getState
return $ resolveQName bUrl pre pms `T.append` name
t_subject :: GenParser ParseState ()
t_subject =
simpleBNode <|>
resource <|>
nodeId <|>
between (char '[') (char ']') poList
where
resource = liftM UNode (t_resource > "subject resource") >>= pushSubj
nodeId = liftM BNode (t_nodeID > "subject nodeID") >>= pushSubj
simpleBNode = try (string "[]") >> nextIdCounter >>= pushSubj . BNodeGen
poList = void
(nextIdCounter >>= pushSubj . BNodeGen >> many t_ws >>
t_predicateObjectList >>
many t_ws)
-- verb ws+ objectList ( ws* ';' ws* verb ws+ objectList )* (ws* ';')?
t_predicateObjectList :: GenParser ParseState ()
t_predicateObjectList =
do t_verb > "verb" -- pushes pred onto pred stack
many1 t_ws > "polist-whitespace-after-verb"
t_objectList > "polist-objectList"
many (try (many t_ws >> char ';') >> many t_ws >> t_verb >> many1 t_ws >> t_objectList >> popPred)
popPred -- pop off the predicate pushed by 1st t_verb
return ()
t_objectList :: GenParser ParseState ()
t_objectList = -- t_object actually adds the triples
void
((t_object > "object") >>
many (try (many t_ws >> char ',' >> many t_ws >> t_object)))
t_object :: GenParser ParseState ()
t_object =
do inColl <- isInColl -- whether this object is in a collection
onFirstItem <- onCollFirstItem -- whether we're on the first item of the collection
let processObject = (t_literal >>= addTripleForObject) <|>
(liftM UNode t_resource >>= addTripleForObject) <|>
blank_as_obj <|> t_collection
case (inColl, onFirstItem) of
(False, _) -> processObject
(True, True) -> liftM BNodeGen nextIdCounter >>= \bSubj -> addTripleForObject bSubj >>
pushSubj bSubj >> pushPred rdfFirstNode >> processObject >> collFirstItemProcessed
(True, False) -> liftM BNodeGen nextIdCounter >>= \bSubj -> pushPred rdfRestNode >>
addTripleForObject bSubj >> popPred >> popSubj >>
pushSubj bSubj >> processObject
-- collection: '(' ws* itemList? ws* ')'
-- itemList: object (ws+ object)*
t_collection:: GenParser ParseState ()
t_collection =
-- ( object1 object2 ) is short for:
-- [ rdf:first object1; rdf:rest [ rdf:first object2; rdf:rest rdf:nil ] ]
-- ( ) is short for the resource: rdf:nil
between (char '(') (char ')') $
do beginColl
many t_ws
emptyColl <- option True (try t_object >> many t_ws >> return False)
if emptyColl then void (addTripleForObject rdfNilNode) else
void
(many (many t_ws >> try t_object >> many t_ws) >> popPred >>
pushPred rdfRestNode >>
addTripleForObject rdfNilNode >>
popPred)
finishColl
return ()
blank_as_obj :: GenParser ParseState ()
blank_as_obj =
-- if a node id, like _:a1, then create a BNode and add the triple
(liftM BNode t_nodeID >>= addTripleForObject) <|>
-- if a simple blank like [], do likewise
(genBlank >>= addTripleForObject) <|>
-- if a blank containing a predicateObjectList, like [ :b :c; :b :d ]
poList
where
genBlank = liftM BNodeGen (try (string "[]") >> nextIdCounter)
poList = between (char '[') (char ']') $
liftM BNodeGen nextIdCounter >>= \bSubj -> -- generate new bnode
void
(addTripleForObject bSubj >> -- add triple with bnode as object
many t_ws >> pushSubj bSubj >> -- push bnode as new subject
t_predicateObjectList >> popSubj >> many t_ws) -- process polist, which uses bnode as subj, then pop bnode
rdfTypeNode, rdfNilNode, rdfFirstNode, rdfRestNode :: Node
rdfTypeNode = UNode $ mkUri rdf "type"
rdfNilNode = UNode $ mkUri rdf "nil"
rdfFirstNode = UNode $ mkUri rdf "first"
rdfRestNode = UNode $ mkUri rdf "rest"
xsdIntUri, xsdDoubleUri, xsdDecimalUri, xsdBooleanUri :: T.Text
xsdIntUri = mkUri xsd "integer"
xsdDoubleUri = mkUri xsd "double"
xsdDecimalUri = mkUri xsd "decimal"
xsdBooleanUri = mkUri xsd "boolean"
t_literal :: GenParser ParseState Node
t_literal =
try str_literal <|>
liftM (`mkLNode` xsdIntUri) (try t_integer) <|>
liftM (`mkLNode` xsdDoubleUri) (try t_double) <|>
liftM (`mkLNode` xsdDecimalUri) (try t_decimal) <|>
liftM (`mkLNode` xsdBooleanUri) t_boolean
where
mkLNode :: T.Text -> T.Text -> Node
mkLNode bsType bs' = LNode (typedL bsType bs')
str_literal :: GenParser ParseState Node
str_literal =
do str <- t_quotedString > "quotedString"
liftM (LNode . typedL str)
(try (count 2 (char '^')) >> t_resource) <|>
liftM (lnode . plainLL str) (char '@' >> t_language) <|>
return (lnode $ plainL str)
t_quotedString :: GenParser ParseState T.Text
t_quotedString = t_longString <|> t_string
-- a non-long string: any number of scharacters (echaracter without ") inside doublequotes.
t_string :: GenParser ParseState T.Text
t_string = liftM T.concat (between (char '"') (char '"') (many t_scharacter))
t_longString :: GenParser ParseState T.Text
t_longString =
do
try tripleQuote
strVal <- liftM T.concat (many longString_char)
tripleQuote
return strVal
where
tripleQuote = count 3 (char '"')
t_integer :: GenParser ParseState T.Text
t_integer =
do sign <- sign_parser > "+-"
ds <- many1 digit > "digit"
notFollowedBy (char '.')
-- integer must be in canonical format, with no leading plus sign or leading zero
return $! ( T.pack sign `T.append` T.pack ds)
t_double :: GenParser ParseState T.Text
t_double =
do sign <- sign_parser > "+-"
rest <- try (do { ds <- many1 digit > "digit"; char '.'; ds' <- many digit > "digit"; e <- t_exponent > "exponent"; return ( T.pack ds `T.snoc` '.' `T.append` T.pack ds' `T.append` e) }) <|>
try (do { char '.'; ds <- many1 digit > "digit"; e <- t_exponent > "exponent"; return ('.' `T.cons` T.pack ds `T.append` e) }) <|>
try (do { ds <- many1 digit > "digit"; e <- t_exponent > "exponent"; return ( T.pack ds `T.append` e) })
return $! T.pack sign `T.append` rest
sign_parser :: GenParser ParseState String
sign_parser = option "" (oneOf "-+" >>= (\c -> return [c]))
t_decimal :: GenParser ParseState T.Text
t_decimal =
do sign <- sign_parser
rest <- try (do ds <- many digit > "digit"; char '.'; ds' <- option "" (many digit); return (ds ++ ('.':ds')))
<|> try (do { char '.'; ds <- many1 digit > "digit"; return ('.':ds) })
<|> many1 digit > "digit"
return $ T.pack sign `T.append` T.pack rest
t_exponent :: GenParser ParseState T.Text
t_exponent = do e <- oneOf "eE"
s <- option "" (oneOf "-+" >>= \c -> return [c])
ds <- many1 digit;
return $! (e `T.cons` ( T.pack s `T.append` T.pack ds))
t_boolean :: GenParser ParseState T.Text
t_boolean =
try (liftM T.pack (string "true") <|>
liftM T.pack (string "false"))
t_comment :: GenParser ParseState ()
t_comment =
void (char '#' >> many (satisfy (\ c -> c /= '\n' && c /= '\r')))
t_ws :: GenParser ParseState ()
t_ws =
(void (try (char '\t' <|> char '\n' <|> char '\r' <|> char ' '))
<|> try t_comment)
> "whitespace-or-comment"
t_language :: GenParser ParseState T.Text
t_language =
do initial <- many1 lower;
rest <- many (do {char '-'; cs <- many1 (lower <|> digit); return ( T.pack ('-':cs))})
return $! ( T.pack initial `T.append` T.concat rest)
identifier :: GenParser ParseState Char -> GenParser ParseState Char -> GenParser ParseState T.Text
identifier initial rest = initial >>= \i -> many rest >>= \r -> return ( T.pack (i:r))
t_prefixName :: GenParser ParseState T.Text
t_prefixName = identifier t_nameStartCharMinusUnderscore t_nameChar
t_name :: GenParser ParseState T.Text
t_name = identifier t_nameStartChar t_nameChar
t_uriref :: GenParser ParseState T.Text
t_uriref = between (char '<') (char '>') t_relativeURI
t_relativeURI :: GenParser ParseState T.Text
t_relativeURI =
do frag <- liftM (T.pack . concat) (many t_ucharacter)
bUrl <- currBaseUrl
dUrl <- currDocUrl
return $ absolutizeUrl bUrl dUrl frag
-- We make this String rather than T.Text because we want
-- t_relativeURI (the only place it's used) to have chars so that
-- when it creates a T.Text it can all be in one chunk.
t_ucharacter :: GenParser ParseState String
t_ucharacter =
try (liftM T.unpack unicode_escape) <|>
try (string "\\>") <|>
liftM T.unpack (non_ctrl_char_except ">")
t_nameChar :: GenParser ParseState Char
t_nameChar = t_nameStartChar <|> char '-' <|> char '\x00B7' <|> satisfy f
where
f = flip in_range [('0', '9'), ('\x0300', '\x036F'), ('\x203F', '\x2040')]
longString_char :: GenParser ParseState T.Text
longString_char =
specialChar <|> -- \r|\n|\t as single char
try escapedChar <|> -- an backslash-escaped tab, newline, linefeed, backslash or doublequote
try twoDoubleQuote <|> -- two doublequotes not followed by a doublequote
try oneDoubleQuote <|> -- a single doublequote
safeNonCtrlChar <|> -- anything but a single backslash or doublequote
try unicode_escape -- a unicode escape sequence (\uxxxx or \Uxxxxxxxx)
where
specialChar = oneOf "\t\n\r" >>= bs1
escapedChar =
do char '\\'
(char 't' >> bs1 '\t') <|> (char 'n' >> bs1 '\n') <|> (char 'r' >> bs1 '\r') <|>
(char '\\' >> bs1 '\\') <|> (char '"' >> bs1 '"')
twoDoubleQuote = string "\"\"" >> notFollowedBy (char '"') >> bs "\"\""
oneDoubleQuote = char '"' >> notFollowedBy (char '"') >> bs1 '"'
safeNonCtrlChar = non_ctrl_char_except "\\\""
bs1 :: Char -> GenParser ParseState T.Text
bs1 = return . T.singleton
bs :: String -> GenParser ParseState T.Text
bs = return . T.pack
t_nameStartChar :: GenParser ParseState Char
t_nameStartChar = char '_' <|> t_nameStartCharMinusUnderscore
t_nameStartCharMinusUnderscore :: GenParser ParseState Char
t_nameStartCharMinusUnderscore = try $ satisfy $ flip in_range blocks
where
blocks = [('A', 'Z'), ('a', 'z'), ('\x00C0', '\x00D6'),
('\x00D8', '\x00F6'), ('\x00F8', '\x02FF'),
('\x0370', '\x037D'), ('\x037F', '\x1FFF'),
('\x200C', '\x200D'), ('\x2070', '\x218F'),
('\x2C00', '\x2FEF'), ('\x3001', '\xD7FF'),
('\xF900', '\xFDCF'), ('\xFDF0', '\xFFFD'),
('\x10000', '\xEFFFF')]
t_hex :: GenParser ParseState Char
t_hex = satisfy (\c -> isDigit c || (c >= 'A' && c <= 'F')) > "hexadecimal digit"
-- characters used in (non-long) strings; any echaracters except ", or an escaped \"
-- echaracter - #x22 ) | '\"'
t_scharacter :: GenParser ParseState T.Text
t_scharacter =
(try (string "\\\"") >> return (T.singleton '"'))
<|> try (do {char '\\';
(char 't' >> return (T.singleton '\t')) <|>
(char 'n' >> return (T.singleton '\n')) <|>
(char 'r' >> return (T.singleton '\r'))}) -- echaracter part 1
<|> unicode_escape
<|> (non_ctrl_char_except "\\\"" >>= \s -> return $! s) -- echaracter part 2 minus "
unicode_escape :: GenParser ParseState T.Text
unicode_escape =
(char '\\' >> return (T.singleton '\\')) >>
((char '\\' >> return "\\\\") <|>
(char 'u' >> count 4 t_hex >>= \cs -> return $! "\\u" `T.append` T.pack cs) <|>
(char 'U' >> count 8 t_hex >>= \cs -> return $! "\\U" `T.append` T.pack cs))
non_ctrl_char_except :: String -> GenParser ParseState T.Text
non_ctrl_char_except cs =
liftM T.singleton
(satisfy (\ c -> c <= '\1114111' && (c >= ' ' && c `notElem` cs)))
{-# INLINE in_range #-}
in_range :: Char -> [(Char, Char)] -> Bool
in_range c = any (\(c1, c2) -> c >= c1 && c <= c2)
-- Resolve a prefix using the given prefix mappings and base URL. If the prefix is
-- empty, then the base URL will be used if there is a base URL and if the map
-- does not contain an entry for the empty prefix.
resolveQName :: Maybe BaseUrl -> T.Text -> PrefixMappings -> T.Text
resolveQName mbaseUrl prefix (PrefixMappings pms') =
case (mbaseUrl, T.null prefix) of
(Just (BaseUrl base), True) -> Map.findWithDefault base T.empty pms'
(Nothing, True) -> err1
(_, _ ) -> Map.findWithDefault err2 prefix pms'
where
err1 = error "Cannot resolve empty QName prefix to a Base URL."
err2 = error ("Cannot resolve QName prefix: " ++ T.unpack prefix)
-- Resolve a URL fragment found on the right side of a prefix mapping by converting it to an absolute URL if possible.
absolutizeUrl :: Maybe BaseUrl -> Maybe T.Text -> T.Text -> T.Text
absolutizeUrl mbUrl mdUrl urlFrag =
if isAbsoluteUri urlFrag then urlFrag else
(case (mbUrl, mdUrl) of
(Nothing, Nothing) -> urlFrag
(Just (BaseUrl bUrl), Nothing) -> bUrl `T.append` urlFrag
(Nothing, Just dUrl) -> if isHash urlFrag then
dUrl `T.append` urlFrag else urlFrag
(Just (BaseUrl bUrl), Just dUrl) -> (if isHash urlFrag then dUrl
else bUrl)
`T.append` urlFrag)
where
isHash bs' = T.length bs' == 1 && T.head bs' == '#'
{-# INLINE isAbsoluteUri #-}
isAbsoluteUri :: T.Text -> Bool
isAbsoluteUri = T.isInfixOf (T.pack [':'])
newBaseUrl :: Maybe BaseUrl -> T.Text -> BaseUrl
newBaseUrl Nothing url = BaseUrl url
newBaseUrl (Just (BaseUrl bUrl)) url = BaseUrl $! mkAbsoluteUrl bUrl url
{-# INLINE mkAbsoluteUrl #-}
-- Make an absolute URL by returning as is if already an absolute URL and otherwise
-- appending the URL to the given base URL.
mkAbsoluteUrl :: T.Text -> T.Text -> T.Text
mkAbsoluteUrl base url =
if isAbsoluteUri url then url else base `T.append` url
currBaseUrl :: GenParser ParseState (Maybe BaseUrl)
currBaseUrl = getState >>= \(bUrl, _, _, _, _, _, _, _) -> return bUrl
currDocUrl :: GenParser ParseState (Maybe T.Text)
currDocUrl = getState >>= \(_, dUrl, _, _, _, _, _, _) -> return dUrl
pushSubj :: Subject -> GenParser ParseState ()
pushSubj s = getState >>= \(bUrl, dUrl, i, pms, ss, ps, cs, ts) ->
setState (bUrl, dUrl, i, pms, s:ss, ps, cs, ts)
popSubj :: GenParser ParseState Subject
popSubj = getState >>= \(bUrl, dUrl, i, pms, ss, ps, cs, ts) ->
setState (bUrl, dUrl, i, pms, tail ss, ps, cs, ts) >>
when (null ss) (error "Cannot pop subject off empty stack.") >>
return (head ss)
pushPred :: Predicate -> GenParser ParseState ()
pushPred p = getState >>= \(bUrl, dUrl, i, pms, ss, ps, cs, ts) ->
setState (bUrl, dUrl, i, pms, ss, p:ps, cs, ts)
popPred :: GenParser ParseState Predicate
popPred = getState >>= \(bUrl, dUrl, i, pms, ss, ps, cs, ts) ->
setState (bUrl, dUrl, i, pms, ss, tail ps, cs, ts) >>
when (null ps) (error "Cannot pop predicate off empty stack.") >>
return (head ps)
isInColl :: GenParser ParseState Bool
isInColl = getState >>= \(_, _, _, _, _, _, cs, _) -> return . not . null $ cs
updateBaseUrl :: Maybe (Maybe BaseUrl) -> GenParser ParseState ()
updateBaseUrl val = _modifyState val no no no no no
-- combines get_current and increment into a single function
nextIdCounter :: GenParser ParseState Int
nextIdCounter = getState >>= \(bUrl, dUrl, i, pms, s, p, cs, ts) ->
setState (bUrl, dUrl, i+1, pms, s, p, cs, ts) >> return i
updatePMs :: Maybe PrefixMappings -> GenParser ParseState ()
updatePMs val = _modifyState no no val no no no
-- Register that we have begun processing a collection
beginColl :: GenParser ParseState ()
beginColl = getState >>= \(bUrl, dUrl, i, pms, s, p, cs, ts) ->
setState (bUrl, dUrl, i, pms, s, p, True:cs, ts)
onCollFirstItem :: GenParser ParseState Bool
onCollFirstItem = getState >>= \(_, _, _, _, _, _, cs, _) -> return (not (null cs) && head cs)
collFirstItemProcessed :: GenParser ParseState ()
collFirstItemProcessed = getState >>= \(bUrl, dUrl, i, pms, s, p, _:cs, ts) ->
setState (bUrl, dUrl, i, pms, s, p, False:cs, ts)
-- Register that a collection is finished being processed; the bool value
-- in the monad is *not* the value that was popped from the stack, but whether
-- we are still processing a parent collection or have finished processing
-- all collections and are no longer in a collection at all.
finishColl :: GenParser ParseState Bool
finishColl = getState >>= \(bUrl, dUrl, i, pms, s, p, cs, ts) ->
let cs' = drop 1 cs
in setState (bUrl, dUrl, i, pms, s, p, cs', ts) >> return (not $ null cs')
-- Alias for Nothing for use with _modifyState calls, which can get very long with
-- many Nothing values.
no :: Maybe a
no = Nothing
-- Update the subject and predicate values of the ParseState to Nothing.
resetSubjectPredicate :: GenParser ParseState ()
resetSubjectPredicate =
getState >>= \(bUrl, dUrl, n, pms, _, _, cs, ts) ->
setState (bUrl, dUrl, n, pms, [], [], cs, ts)
-- Modifies the current parser state by updating any state values among the parameters
-- that have non-Nothing values.
_modifyState :: Maybe (Maybe BaseUrl) -> Maybe (Int -> Int) -> Maybe PrefixMappings ->
Maybe Subject -> Maybe Predicate -> Maybe (Seq Triple) ->
GenParser ParseState ()
_modifyState mb_bUrl mb_n mb_pms mb_subj mb_pred mb_trps =
do (_bUrl, _dUrl, _n, _pms, _s, _p, _cs, _ts) <- getState
setState (fromMaybe _bUrl mb_bUrl,
_dUrl,
maybe _n (const _n) mb_n,
fromMaybe _pms mb_pms,
maybe _s (: _s) mb_subj,
maybe _p (: _p) mb_pred,
_cs,
fromMaybe _ts mb_trps)
addTripleForObject :: Object -> GenParser ParseState ()
addTripleForObject obj =
do (bUrl, dUrl, i, pms, ss, ps, cs, ts) <- getState
when (null ss) $
error $ "No Subject with which to create triple for: " ++ show obj
when (null ps) $
error $ "No Predicate with which to create triple for: " ++ show obj
setState (bUrl, dUrl, i, pms, ss, ps, cs, ts |> Triple (head ss) (head ps) obj)
-- |Parse the document at the given location URL as a Turtle document, using an optional @BaseUrl@
-- as the base URI, and using the given document URL as the URI of the Turtle document itself.
--
-- The @BaseUrl@ is used as the base URI within the document for resolving any relative URI references.
-- It may be changed within the document using the @\@base@ directive. At any given point, the current
-- base URI is the most recent @\@base@ directive, or if none, the @BaseUrl@ given to @parseURL@, or
-- if none given, the document URL given to @parseURL@. For example, if the @BaseUrl@ were
-- @http:\/\/example.org\/@ and a relative URI of @\@ were encountered (with no preceding @\@base@
-- directive), then the relative URI would expand to @http:\/\/example.org\/b@.
--
-- The document URL is for the purpose of resolving references to 'this document' within the document,
-- and may be different than the actual location URL from which the document is retrieved. Any reference
-- to @\<>@ within the document is expanded to the value given here. Additionally, if no @BaseUrl@ is
-- given and no @\@base@ directive has appeared before a relative URI occurs, this value is used as the
-- base URI against which the relative URI is resolved.
--p
-- Returns either a @ParseFailure@ or a new RDF containing the parsed triples.
parseURL' :: forall rdf. (RDF rdf) =>
Maybe BaseUrl -- ^ The optional base URI of the document.
-> Maybe T.Text -- ^ The document URI (i.e., the URI of the document itself); if Nothing, use location URI.
-> String -- ^ The location URI from which to retrieve the Turtle document.
-> IO (Either ParseFailure rdf)
-- ^ The parse result, which is either a @ParseFailure@ or the RDF
-- corresponding to the Turtle document.
parseURL' bUrl docUrl = _parseURL (parseString' bUrl docUrl)
-- |Parse the given file as a Turtle document. The arguments and return type have the same semantics
-- as 'parseURL', except that the last @String@ argument corresponds to a filesystem location rather
-- than a location URI.
--
-- Returns either a @ParseFailure@ or a new RDF containing the parsed triples.
parseFile' :: forall rdf. (RDF rdf) => Maybe BaseUrl -> Maybe T.Text -> String -> IO (Either ParseFailure rdf)
parseFile' bUrl docUrl fpath =
TIO.readFile fpath >>= \bs' -> return $ handleResult bUrl (runParser t_turtleDoc initialState (maybe "" T.unpack docUrl) bs')
where initialState = (bUrl, docUrl, 1, PrefixMappings Map.empty, [], [], [], Seq.empty)
-- |Parse the given string as a Turtle document. The arguments and return type have the same semantics
-- as , except that the last @String@ argument corresponds to the Turtle document itself as
-- a string rather than a location URI.
parseString' :: forall rdf. (RDF rdf) => Maybe BaseUrl -> Maybe T.Text -> T.Text -> Either ParseFailure rdf
parseString' bUrl docUrl ttlStr = handleResult bUrl (runParser t_turtleDoc initialState "" ttlStr)
where initialState = (bUrl, docUrl, 1, PrefixMappings Map.empty, [], [], [], Seq.empty)
handleResult :: RDF rdf => Maybe BaseUrl -> Either ParseError (Seq Triple, PrefixMappings) -> Either ParseFailure rdf
handleResult bUrl result =
case result of
(Left err) -> Left (ParseFailure $ show err)
(Right (ts, pms)) -> Right $! mkRdf (F.toList ts) bUrl pms
_testParseState :: ParseState
_testParseState = (Nothing, Nothing, 1, PrefixMappings Map.empty, [], [], [], Seq.empty)