From 798cb370029712dc96e9ca5d1fbacc698c6d3649 Mon Sep 17 00:00:00 2001
From: bringert <unknown>
Date: Mon, 6 Dec 2004 16:02:08 +0000
Subject: Use HashTable to share strings in tokens when parsing GFC files.

---
 src/GF/Data/SharedString.hs | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)
 create mode 100644 src/GF/Data/SharedString.hs

(limited to 'src/GF/Data/SharedString.hs')

diff --git a/src/GF/Data/SharedString.hs b/src/GF/Data/SharedString.hs
new file mode 100644
index 000000000..f03f6f469
--- /dev/null
+++ b/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
-- 
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