mirror of
https://github.com/GrammaticalFramework/gf-core.git
synced 2026-04-09 04:59:31 -06:00
135 lines
3.8 KiB
Haskell
135 lines
3.8 KiB
Haskell
-- -*- haskell -*-
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-- This Alex file was machine-generated by the BNF converter
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{
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module Transfer.Syntax.Lex where
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import Transfer.ErrM
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}
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$l = [a-zA-Z\192 - \255] # [\215 \247] -- isolatin1 letter FIXME
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$c = [A-Z\192-\221] # [\215] -- capital isolatin1 letter FIXME
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$s = [a-z\222-\255] # [\247] -- small isolatin1 letter FIXME
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$d = [0-9] -- digit
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$i = [$l $d _ '] -- identifier character
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$u = [\0-\255] -- universal: any character
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@rsyms = -- reserved words consisting of special symbols
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\; | \: | \{ | \} | \= | \( | \) | \_ | \- \> | \\ | \| \| | \& \& | \= \= | \/ \= | \< | \< \= | \> | \> \= | \+ | \- | \* | \/ | \% | \.
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:-
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"--" [.]* ; -- Toss single line comments
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"{-" ([$u # \-] | \- [$u # \}])* ("-")+ "}" ;
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$white+ ;
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@rsyms { tok (\p s -> PT p (TS $ share s)) }
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$l $i* { tok (\p s -> PT p (eitherResIdent (TV . share) s)) }
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\" ([$u # [\" \\ \n]] | (\\ (\" | \\ | \' | n | t)))* \"{ tok (\p s -> PT p (TL $ share $ unescapeInitTail s)) }
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$d+ { tok (\p s -> PT p (TI $ share s)) }
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{
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tok f p s = f p s
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share :: String -> String
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share = id
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data Tok =
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TS !String -- reserved words
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| TL !String -- string literals
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| TI !String -- integer literals
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| TV !String -- identifiers
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| TD !String -- double precision float literals
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| TC !String -- character literals
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deriving (Eq,Show,Ord)
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data Token =
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PT Posn Tok
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| Err Posn
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deriving (Eq,Show,Ord)
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tokenPos (PT (Pn _ l _) _ :_) = "line " ++ show l
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tokenPos (Err (Pn _ l _) :_) = "line " ++ show l
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tokenPos _ = "end of file"
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posLineCol (Pn _ l c) = (l,c)
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mkPosToken t@(PT p _) = (posLineCol p, prToken t)
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prToken t = case t of
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PT _ (TS s) -> s
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PT _ (TI s) -> s
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PT _ (TV s) -> s
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PT _ (TD s) -> s
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PT _ (TC s) -> s
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_ -> show t
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data BTree = N | B String Tok BTree BTree deriving (Show)
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eitherResIdent :: (String -> Tok) -> String -> Tok
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eitherResIdent tv s = treeFind resWords
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where
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treeFind N = tv s
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treeFind (B a t left right) | s < a = treeFind left
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| s > a = treeFind right
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| s == a = t
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resWords = b "import" (b "derive" (b "case" (b "Type" N N) (b "data" N N)) (b "if" (b "else" N N) N)) (b "of" (b "let" (b "in" N N) N) (b "where" (b "then" N N) N))
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where b s = B s (TS s)
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unescapeInitTail :: String -> String
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unescapeInitTail = unesc . tail where
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unesc s = case s of
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'\\':c:cs | elem c ['\"', '\\', '\''] -> c : unesc cs
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'\\':'n':cs -> '\n' : unesc cs
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'\\':'t':cs -> '\t' : unesc cs
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'"':[] -> []
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c:cs -> c : unesc cs
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_ -> []
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-------------------------------------------------------------------
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-- Alex wrapper code.
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-- A modified "posn" wrapper.
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-------------------------------------------------------------------
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data Posn = Pn !Int !Int !Int
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deriving (Eq, Show,Ord)
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alexStartPos :: Posn
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alexStartPos = Pn 0 1 1
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alexMove :: Posn -> Char -> Posn
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alexMove (Pn a l c) '\t' = Pn (a+1) l (((c+7) `div` 8)*8+1)
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alexMove (Pn a l c) '\n' = Pn (a+1) (l+1) 1
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alexMove (Pn a l c) _ = Pn (a+1) l (c+1)
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type AlexInput = (Posn, -- current position,
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Char, -- previous char
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String) -- current input string
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tokens :: String -> [Token]
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tokens str = go (alexStartPos, '\n', str)
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where
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go :: (Posn, Char, String) -> [Token]
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go inp@(pos, _, str) =
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case alexScan inp 0 of
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AlexEOF -> []
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AlexError (pos, _, _) -> fail $ show pos ++ ": lexical error"
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AlexSkip inp' len -> go inp'
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AlexToken inp' len act -> act pos (take len str) : (go inp')
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alexGetChar :: AlexInput -> Maybe (Char,AlexInput)
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alexGetChar (p, c, []) = Nothing
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alexGetChar (p, _, (c:s)) =
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let p' = alexMove p c
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in p' `seq` Just (c, (p', c, s))
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alexInputPrevChar :: AlexInput -> Char
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alexInputPrevChar (p, c, s) = c
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}
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