Use HashTable to share strings in tokens when parsing GFC files.

src/GF/Canon/LexGFC.hs

@@ -1,7 +1,7 @@
 {-# OPTIONS -fglasgow-exts -cpp #-}
 {-# LINE 3 "LexGFC.x" #-}
 module LexGFC where
-
+import SharedString
 import ErrM
 
 #if __GLASGOW_HASKELL__ >= 503
@@ -35,10 +35,10 @@ alex_accept = listArray (0::Int,14) [[],[],[(AlexAccSkip)],[(AlexAcc (alex_actio
 tok f p s = f p s
 
 data Tok =
-   TS String     -- reserved words
- | TL String     -- string literals
+   TS !String     -- reserved words
+ | TL !String     -- string literals
  | TI String     -- integer literals
- | TV String     -- identifiers
+ | TV !String     -- identifiers    -- H
  | TD String     -- double precision float literals
  | TC String     -- character literals
 
@@ -130,9 +130,9 @@ alexGetChar (p, _, (c:s)) =
 alexInputPrevChar :: AlexInput -> Char
 alexInputPrevChar (p, c, s) = c
 
-alex_action_1 = tok (\p s -> PT p (TS s)) 
-alex_action_2 = tok (\p s -> PT p (eitherResIdent TV s)) 
-alex_action_3 = tok (\p s -> PT p (TL $ unescapeInitTail s)) 
+alex_action_1 = tok (\p s -> PT p (TS (shareString s))) 
+alex_action_2 = tok (\p s -> PT p (eitherResIdent (TV . shareString) s)) 
+alex_action_3 = tok (\p s -> PT p (TL $ shareString $ unescapeInitTail s)) 
 alex_action_4 = tok (\p s -> PT p (TI s))    
 {-# LINE 1 "GenericTemplate.hs" #-}
 {-# LINE 1 "<built-in>" #-}

src/GF/Canon/LexGFC.x

@@ -0,0 +1,131 @@
+-- -*- haskell -*-
+-- This Alex file was machine-generated by the BNF converter
+-- Lines with -- H have been hacked for greater performance
+{
+module LexGFC where
+import SharedString -- H
+import ErrM
+}
+
+
+$l = [a-zA-Z\192 - \255] # [\215 \247]    -- isolatin1 letter FIXME
+$c = [A-Z\192-\221] # [\215]    -- capital isolatin1 letter FIXME
+$s = [a-z\222-\255] # [\247]    -- small isolatin1 letter FIXME
+$d = [0-9]                -- digit
+$i = [$l $d _ ']          -- identifier character
+$u = [\0-\255]          -- universal: any character
+
+@rsyms =    -- reserved words consisting of special symbols
+   \; | \= | \{ | \} | \: | \- \> | \* \* | \[ | \] | \\ | \. | \( | \) | \_ | \< | \> | \$ | \? | \= \> | \! | \+ \+ | \/ | \@ | \+ | \| | \,
+
+:-
+
+$white+ ;
+@rsyms { tok (\p s -> PT p (TS (shareString s))) } -- H
+
+$l $i*   { tok (\p s -> PT p (eitherResIdent (TV . shareString) s)) } -- H
+\" ([$u # [\" \\ \n]] | (\\ (\" | \\ | \' | n | t)))* \"{ tok (\p s -> PT p (TL $ shareString $ unescapeInitTail s)) } -- H
+
+$d+      { tok (\p s -> PT p (TI s))    }
+
+
+{
+
+tok f p s = f p s
+
+data Tok =
+   TS !String     -- reserved words  -- H
+ | TL !String     -- string literals -- H
+ | TI String     -- integer literals
+ | TV !String     -- identifiers     -- H
+ | TD String     -- double precision float literals
+ | TC String     -- character literals
+
+ deriving (Eq,Show,Ord)
+
+data Token = 
+   PT  Posn Tok
+ | Err Posn
+  deriving (Eq,Show,Ord)
+
+tokenPos (PT (Pn _ l _) _ :_) = "line " ++ show l
+tokenPos (Err (Pn _ l _) :_) = "line " ++ show l
+tokenPos _ = "end of file"
+
+posLineCol (Pn _ l c) = (l,c)
+mkPosToken t@(PT p _) = (posLineCol p, prToken t)
+
+prToken t = case t of
+  PT _ (TS s) -> s
+  PT _ (TI s) -> s
+  PT _ (TV s) -> s
+  PT _ (TD s) -> s
+  PT _ (TC s) -> s
+
+  _ -> show t
+
+eitherResIdent :: (String -> Tok) -> String -> Tok
+eitherResIdent tv s = if isResWord s then (TS s) else (tv s) where
+  isResWord s = isInTree s $
+    B "lin" (B "concrete" (B "Type" (B "Str" (B "Ints" N N) N) (B "cat" (B "abstract" N N) N)) (B "fun" (B "flags" (B "data" N N) N) (B "in" (B "grammar" N N) N))) (B "pre" (B "open" (B "of" (B "lincat" N N) N) (B "param" (B "oper" N N) N)) (B "transfer" (B "table" (B "resource" N N) N) (B "variants" N N)))
+
+data BTree = N | B String BTree BTree deriving (Show)
+
+isInTree :: String -> BTree -> Bool
+isInTree x tree = case tree of
+  N -> False
+  B a left right
+   | x < a  -> isInTree x left
+   | x > a  -> isInTree x right
+   | x == a -> True
+
+unescapeInitTail :: String -> String
+unescapeInitTail = unesc . tail where
+  unesc s = case s of
+    '\\':c:cs | elem c ['\"', '\\', '\''] -> c : unesc cs
+    '\\':'n':cs  -> '\n' : unesc cs
+    '\\':'t':cs  -> '\t' : unesc cs
+    '"':[]    -> []
+    c:cs      -> c : unesc cs
+    _         -> []
+
+-------------------------------------------------------------------
+-- Alex wrapper code.
+-- A modified "posn" wrapper.
+-------------------------------------------------------------------
+
+data Posn = Pn !Int !Int !Int
+      deriving (Eq, Show,Ord)
+
+alexStartPos :: Posn
+alexStartPos = Pn 0 1 1
+
+alexMove :: Posn -> Char -> Posn
+alexMove (Pn a l c) '\t' = Pn (a+1)  l     (((c+7) `div` 8)*8+1)
+alexMove (Pn a l c) '\n' = Pn (a+1) (l+1)   1
+alexMove (Pn a l c) _    = Pn (a+1)  l     (c+1)
+
+type AlexInput = (Posn, -- current position,
+		  Char,	-- previous char
+		  String)	-- current input string
+
+tokens :: String -> [Token]
+tokens str = go (alexStartPos, '\n', str)
+    where
+      go :: (Posn, Char, String) -> [Token]
+      go inp@(pos, _, str) =
+    	  case alexScan inp 0 of
+    	    AlexEOF                -> []
+    	    AlexError (pos, _, _)  -> fail $ show pos ++ ": lexical error"
+    	    AlexSkip  inp' len     -> go inp'
+    	    AlexToken inp' len act -> act pos (take len str) : (go inp')
+
+alexGetChar :: AlexInput -> Maybe (Char,AlexInput)
+alexGetChar (p, c, [])    = Nothing
+alexGetChar (p, _, (c:s)) =
+    let p' = alexMove p c
+     in p' `seq` Just (c, (p', c, s))
+
+alexInputPrevChar :: AlexInput -> Char
+alexInputPrevChar (p, c, s) = c
+}

src/GF/Data/SharedString.hs

@@ -0,0 +1,18 @@
+module SharedString (shareString) where
+
+import Data.HashTable as H
+import System.IO.Unsafe (unsafePerformIO)
+
+{-# NOINLINE stringPool #-}
+stringPool :: HashTable String String
+stringPool = unsafePerformIO $ new (==) hashString
+
+{-# NOINLINE shareString #-}
+shareString :: String -> String
+shareString s = unsafePerformIO $ do
+    mv <- H.lookup stringPool s
+    case mv of
+	    Just s' -> return s'
+	    Nothing -> do
+		       H.insert stringPool s s
+		       return s