added a primitive full-text search index in libsg. This can be use for finding an abstract tree whose linearization matches given keywords

src/runtime/haskell-bind/PGF2/FFI.hs

@@ -9,6 +9,9 @@ import Foreign.ForeignPtr
 import Control.Exception
 import GHC.Ptr
 
+data PGF = PGF {pgf :: Ptr PgfPGF, pgfMaster :: ForeignPtr GuPool}
+data Concr = Concr {concr :: Ptr PgfConcr, concrMaster :: PGF}
+
 ------------------------------------------------------------------
 -- libgu API