Initial data commit

Task/Soundex/Erlang/soundex.erl

@@ -0,0 +1,45 @@
+-module(soundex).
+-export([soundex/1]).
+
+soundex([]) ->
+    [];
+soundex(Str) ->
+    [Head|Tail] = string:to_upper(Str),
+    [Head | isoundex(Tail, [], todigit(Head))].
+
+isoundex([], Acc, _) ->
+    case length(Acc) of
+	N when N == 3 ->
+	    lists:reverse(Acc);
+	N when N < 3 ->
+	    isoundex([], [$0 | Acc], ignore);
+	N when N > 3 ->
+	    isoundex([], lists:sublist(Acc, N-2, N), ignore)
+    end;
+isoundex([Head|Tail], Acc, Lastn) ->
+    Dig = todigit(Head),
+    case Dig of
+	Dig when Dig /= $0, Dig /= Lastn ->
+	    isoundex(Tail, [Dig | Acc], Dig);
+	_ ->
+	    case Head of
+		$H ->
+		    isoundex(Tail, Acc, Lastn);
+		$W ->
+		    isoundex(Tail, Acc, Lastn);
+		N when N >= $A, N =< $Z ->
+		    isoundex(Tail, Acc, Dig);
+		_ ->
+		    isoundex(Tail, Acc, Lastn)	% This clause handles non alpha characters
+	    end
+    end.
+
+todigit(Chr) ->	
+    Digits = "01230120022455012623010202",
+    HeadOff = Chr - $A + 1,
+    case HeadOff of
+	N when N > 0, N < 27 ->
+	    lists:nth(HeadOff, Digits);
+	_ ->					% Treat non alpha characters as a vowel
+	    $0
+    end.