Annotation of /sml/trunk/src/compiler/Semant/pickle/rehash.sml

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Revision 1137 - (view) (download)

1 :	blume	879	(* rehash.sml
2 :			*
3 :			* (C) 2001 Lucent Technologies, Bell Labs
4 :			*
5 :			* Compute hash for a library that is the product of filtering
6 :			* a larger environment. Since every environment (after unpickling)
7 :			* contains references to its own hash id, re-hashing requires
8 :			* the original hash id (to be able to recognize it). The result
9 :			* of re-hashing will then be the same value that would have been
10 :			* produced had the smaller environment been pickled (and hashed) in
11 :			* the first place. *)
12 :	blume	1058	structure Rehash : sig
13 :	blume	1137	val addGUID : { hash: PersStamps.persstamp, guid: string }
14 :	blume	1058	-> PersStamps.persstamp
15 :			val rehash : { env: StaticEnv.staticEnv,
16 :			orig_pid: PersStamps.persstamp,
17 :	blume	1137	guid: string }
18 :	blume	1058	-> PersStamps.persstamp
19 :			end = struct
20 :	blume	1137	fun addGUID { hash, guid } = let
21 :	blume	1058	val crc = CRC.fromString (Byte.bytesToString (PersStamps.toBytes hash))
22 :			fun append (c, x) = CRC.append (x, c)
23 :	blume	1137	val crc' = CharVector.foldl append crc guid
24 :	blume	1058	in
25 :			PersStamps.fromBytes (Byte.stringToBytes (CRC.toString crc'))
26 :			end
27 :
28 :	blume	1137	fun rehash { env, orig_pid, guid } =
29 :			addGUID { hash = #hash (PickMod.pickleEnv
30 :			(PickMod.REHASH orig_pid) env),
31 :			guid = guid }
32 :	blume	879	end

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