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|
module Haddock.Backends.Hyperlinker.Parser
( parse
, Token(..), TokenType(..)
, Position(..), Span(..)
) where
import Data.Char
import Data.List
data Token = Token
{ tkType :: TokenType
, tkValue :: String
, tkSpan :: Span
}
data Position = Position
{ posRow :: !Int
, posCol :: !Int
}
data Span = Span
{ spStart :: Position
, spEnd :: Position
}
data TokenType
= TkIdentifier
| TkKeyword
| TkString
| TkChar
| TkNumber
| TkOperator
| TkGlyph
| TkSpecial
| TkSpace
| TkComment
| TkCpp
| TkPragma
| TkUnknown
deriving (Eq)
parse :: String -> [Token]
parse = tokenize . tag . chunk
chunk :: String -> [String]
chunk [] = []
chunk str@(c:_)
| isSpace c = chunk' $ span isSpace str
chunk str
| "--" `isPrefixOf` str = chunk' $ spanToNewline str
| "{-" `isPrefixOf` str = chunk' $ chunkComment 0 str
| otherwise = chunk' $ head $ lex str
chunk' :: (String, String) -> [String]
chunk' (c, rest) = c:(chunk rest)
spanToNewline :: String -> (String, String)
spanToNewline [] = ([], [])
spanToNewline ('\\':'\n':str) =
let (str', rest) = spanToNewline str
in ('\\':'\n':str', rest)
spanToNewline str@('\n':_) = ("", str)
spanToNewline (c:str) =
let (str', rest) = spanToNewline str
in (c:str', rest)
chunkComment :: Int -> String -> (String, String)
chunkComment _ [] = ("", "")
chunkComment depth ('{':'-':str) =
let (c, rest) = chunkComment (depth + 1) str
in ("{-" ++ c, rest)
chunkComment depth ('-':'}':str)
| depth == 1 = ("-}", str)
| otherwise =
let (c, rest) = chunkComment (depth - 1) str
in ("-}" ++ c, rest)
chunkComment depth (e:str) =
let (c, rest) = chunkComment depth str
in (e:c, rest)
tag :: [String] -> [(Span, String)]
tag =
reverse . snd . foldl aux (Position 1 1, [])
where
aux (pos, cs) str =
let pos' = foldl move pos str
in (pos', (Span pos pos', str):cs)
move pos '\n' = pos { posRow = posRow pos + 1, posCol = 1 }
move pos _ = pos { posCol = posCol pos + 1 }
tokenize :: [(Span, String)] -> [Token]
tokenize =
map aux
where
aux (sp, str) = Token
{ tkType = classify str
, tkValue = str
, tkSpan = sp
}
classify :: String -> TokenType
classify str
| "--" `isPrefixOf` str = TkComment
| "{-#" `isPrefixOf` str = TkPragma
| "{-" `isPrefixOf` str = TkComment
classify (c:_)
| isSpace c = TkSpace
| isDigit c = TkNumber
| c `elem` special = TkSpecial
| c == '#' = TkCpp
| c == '"' = TkString
| c == '\'' = TkChar
classify str
| str `elem` keywords = TkKeyword
| str `elem` glyphs = TkGlyph
| all (`elem` symbols) str = TkOperator
| isIdentifier str = TkIdentifier
| otherwise = TkUnknown
keywords :: [String]
keywords =
[ "as"
, "case"
, "class"
, "data"
, "default"
, "deriving"
, "do"
, "else"
, "hiding"
, "if"
, "import"
, "in"
, "infix"
, "infixl"
, "infixr"
, "instance"
, "let"
, "module"
, "newtype"
, "of"
, "qualified"
, "then"
, "type"
, "where"
, "forall"
, "mdo"
]
glyphs :: [String]
glyphs =
[ ".."
, ":"
, "::"
, "="
, "\\"
, "|"
, "<-"
, "->"
, "@"
, "~"
, "~#"
, "=>"
, "-"
, "!"
]
special :: [Char]
special = "()[]{},;`"
-- TODO: Add support for any Unicode symbol or punctuation.
-- source: http://stackoverflow.com/questions/10548170/what-characters-are-permitted-for-haskell-operators
symbols :: [Char]
symbols = "!#$%&*+./<=>?@\\^|-~:"
isIdentifier :: String -> Bool
isIdentifier (s:str)
| (isLower' s || isUpper s) && all isAlphaNum' str = True
where
isLower' c = isLower c || c == '_'
isAlphaNum' c = isAlphaNum c || c == '_' || c == '\''
isIdentifier _ = False
|
