Tidy up removing old files

src/rice.erl

@@ -1,155 +0,0 @@
--module(rice).
--export([encode/1, 
-	encode/2, 
-	checkforhash/2, 
-	converttohash/1]).
--include_lib("eunit/include/eunit.hrl").
-
-%% Factor is the power of 2 representing the expected normal gap size between
-%% members of the hash, and therefore the size of the bitstring to represent the
-%% remainder for the gap
-%%
-%% The encoded output should contain a single byte which is the Factor, followed
-%% by a series of exponents and remainders.
-%%
-%% The exponent is n 1's followed by a 0, where n * (2 ^ Factor) + remainder 
-%% represents the gap to the next hash 
-%%
-%% The size passed in should be the maximum possible value of the hash.
-%% If this isn't provided - assumes 2^32 - the default for phash2 
-
-encode(HashList) ->
-	encode(HashList, 4 * 1024 * 1024 * 1024).
-
-encode(HashList, Size) ->
-	SortedHashList = lists:usort(HashList),
-	ExpectedGapSize = Size div length(SortedHashList),
-	Factor = findpowerundergap(ExpectedGapSize),
-	riceencode(SortedHashList, Factor).
-
-%% Outcome may be suboptimal if lists have not been de-duplicated
-%% Will fail on an unsorted list
-
-riceencode(HashList, Factor) when Factor<256 ->
-	Divisor = powtwo(Factor),
-	riceencode(HashList, Factor, Divisor, <<>>, 0).
-
-riceencode([], Factor, _, BitStrAcc, _) ->
-	Prefix  = binary:encode_unsigned(Factor),
-	<<Prefix/bytes, BitStrAcc/bitstring>>;
-riceencode([HeadHash|TailList], Factor, Divisor, BitStrAcc, LastHash) ->
-	HashGap = HeadHash - LastHash,
-	case HashGap of 
-		0 -> 
-			riceencode(TailList, Factor, Divisor, BitStrAcc, HeadHash);
-		N when N > 0 ->
-			Exponent = buildexponent(HashGap div Divisor),
-			Remainder = HashGap rem Divisor,
-			ExpandedBitStrAcc = <<BitStrAcc/bitstring, Exponent/bitstring, Remainder:Factor>>,
-			riceencode(TailList, Factor, Divisor, ExpandedBitStrAcc, HeadHash)
-		end.
-
-
-%% Checking for a hash needs to roll through the compressed bloom, decoding until
-%% the member is found (match!), passed (not matched) or the end of the encoded
-%% bitstring has been reached (not matched)
-
-checkforhash(HashToCheck, BitStr) ->
-	<<Factor:8/integer, RiceEncodedBitStr/bitstring>> = BitStr,
-	Divisor = powtwo(Factor),
-	checkforhash(HashToCheck, RiceEncodedBitStr, Factor, Divisor, 0).
-
-checkforhash(_, <<>>, _, _, _) ->
-	false;
-checkforhash(HashToCheck, BitStr, Factor, Divisor, Acc) ->
-	[Exponent, BitStrTail] = findexponent(BitStr),
-	[Remainder, BitStrTail2] = findremainder(BitStrTail, Factor),
-	NextHash = Acc + Divisor * Exponent + Remainder,
-	case NextHash of 
-		HashToCheck -> true;
-		N when N>HashToCheck -> false;
-		_ -> checkforhash(HashToCheck, BitStrTail2, Factor, Divisor, NextHash)
-	end.
-
-
-%% Exported functions - currently used only in testing
-
-converttohash(ItemList) -> 
-	converttohash(ItemList, []).
-
-converttohash([], HashList) ->
-	HashList;
-converttohash([H|T], HashList) ->
-	converttohash(T, [erlang:phash2(H)|HashList]).
-
-
-
-%% Helper functions
-
-buildexponent(Exponent) ->
-	buildexponent(Exponent, <<0:1>>).
-
-buildexponent(0, OutputBits) ->
-	OutputBits;
-buildexponent(Exponent, OutputBits) ->
-	buildexponent(Exponent - 1, <<1:1, OutputBits/bitstring>>).
-
-
-findexponent(BitStr) ->
-	findexponent(BitStr, 0).
-
-findexponent(BitStr, Acc) ->
-	<<H:1/bitstring, T/bitstring>> = BitStr,
-	case H of
-		<<1:1>> -> findexponent(T, Acc + 1);
-		<<0:1>> -> [Acc, T]
-	end.
-
-
-findremainder(BitStr, Factor) ->
-	<<Remainder:Factor/integer, BitStrTail/bitstring>> = BitStr,
-	[Remainder, BitStrTail].
-
-
-powtwo(N) -> powtwo(N, 1).
-
-powtwo(0, Acc) ->
-	Acc;
-powtwo(N, Acc) ->
-	powtwo(N-1, Acc * 2).
-
-%% Helper method for finding the factor of two which provides the most 
-%% efficient compression given an average gap size
-
-findpowerundergap(GapSize) -> findpowerundergap(GapSize, 1, 0).
-
-findpowerundergap(GapSize, Acc, Counter) ->
-	case Acc of
-		N when N > GapSize -> Counter - 1;
-		_ -> findpowerundergap(GapSize, Acc * 2, Counter + 1)
-	end.
-
-
-%% Unit tests
-
-findpowerundergap_test_() -> 
-	[
-	?_assertEqual(9, findpowerundergap(700)), 
-	?_assertEqual(9, findpowerundergap(512)), 
-	?_assertEqual(8, findpowerundergap(511))].
-
-encode_test_() ->
-	[
-	?_assertEqual(<<9, 6, 44, 4:5>>, encode([24,924], 1024)),
-	?_assertEqual(<<9, 6, 44, 4:5>>, encode([24,24,924], 1024)),
-	?_assertEqual(<<9, 6, 44, 4:5>>, encode([24,924,924], 1024))
-	].
-
-check_test_() ->
-	[
-	?_assertEqual(true, checkforhash(924, <<9, 6, 44, 4:5>>)),
-	?_assertEqual(true, checkforhash(24, <<9, 6, 44, 4:5>>)),
-	?_assertEqual(false, checkforhash(23, <<9, 6, 44, 4:5>>)),
-	?_assertEqual(false, checkforhash(923, <<9, 6, 44, 4:5>>)),
-	?_assertEqual(false, checkforhash(925, <<9, 6, 44, 4:5>>))
-	].