From 84adefa331c4159d432d22840663c38f155cd4c1 Mon Sep 17 00:00:00 2001
From: Erlang/OTP <otp@erlang.org>
Date: Fri, 20 Nov 2009 14:54:40 +0000
Subject: The R13B03 release.

---
 lib/tv/src/tv_db_sort.erl | 141 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 141 insertions(+)
 create mode 100644 lib/tv/src/tv_db_sort.erl

(limited to 'lib/tv/src/tv_db_sort.erl')

diff --git a/lib/tv/src/tv_db_sort.erl b/lib/tv/src/tv_db_sort.erl
new file mode 100644
index 0000000000..3675c7b413
--- /dev/null
+++ b/lib/tv/src/tv_db_sort.erl
@@ -0,0 +1,141 @@
+%%
+%% %CopyrightBegin%
+%% 
+%% Copyright Ericsson AB 1997-2009. All Rights Reserved.
+%% 
+%% The contents of this file are subject to the Erlang Public License,
+%% Version 1.1, (the "License"); you may not use this file except in
+%% compliance with the License. You should have received a copy of the
+%% Erlang Public License along with this software. If not, it can be
+%% retrieved online at http://www.erlang.org/.
+%% 
+%% Software distributed under the License is distributed on an "AS IS"
+%% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
+%% the License for the specific language governing rights and limitations
+%% under the License.
+%% 
+%% %CopyrightEnd%
+-module(tv_db_sort).
+
+
+
+-export([mergesort/3, merge/4, get_compare_value/2]).
+
+
+
+
+
+%%%*********************************************************************
+%%% EXTERNAL FUNCTIONS
+%%%*********************************************************************
+
+
+
+
+
+mergesort(_KeyNo, [X], _ReverseOrder) -> 
+    [X];
+mergesort(_KeyNo, [], _ReverseOrder) -> 
+    [];
+mergesort(KeyNo, X, ReverseOrder) -> 
+    split(KeyNo, X, [], [], ReverseOrder).
+
+
+
+
+
+
+
+
+   %% If we want reverse order when just merging two lists,
+   %% each of them has to be in reverse order first!
+
+merge(KeyNo, [{E1, C1} | T1], [{E2, C2} | T2], Reverse) when not Reverse ->
+    K1 = get_compare_value(KeyNo, E1),
+    K2 = get_compare_value(KeyNo, E2),
+    case get_correct_order(K1, E1, K2, E2) of
+	{1, 2} ->
+	    [{E1, C1} | merge(KeyNo, T1, [{E2, C2} | T2], Reverse)]; 
+	{2, 1} ->
+	    [{E2, C2} | merge(KeyNo, [{E1, C1} | T1], T2, Reverse)]
+    end;
+merge(KeyNo, [{E1, C1} | T1], [{E2, C2} | T2], Reverse) ->
+    K1 = get_compare_value(KeyNo, E1),
+    K2 = get_compare_value(KeyNo, E2),
+    case get_correct_order(K1, E1, K2, E2) of
+	{1, 2} ->
+	    [{E2, C2} | merge(KeyNo, [{E1, C1} | T1], T2, Reverse)];
+	{2, 1} ->
+	    [{E1, C1} | merge(KeyNo, T1, [{E2, C2} | T2], Reverse)] 
+    end;
+merge(_KeyNo, [], L2, _Reverse) ->       % L2 may be the empty list also!
+    L2;
+merge(_KeyNo, L1, [], _Reverse) ->       % L1 may be the empty list also!
+    L1.
+
+    
+
+
+
+
+get_compare_value(KeyNo, E) when is_tuple(E) ->
+    case catch element(KeyNo, E) of
+	{'EXIT', {badarg, {?MODULE, get_compare_value, [KeyNo, E]}}} ->
+	    short_tuple;
+	V ->
+	    {tuple, V}
+    end;
+get_compare_value(_KeyNo, _E) ->
+    no_tuple.
+
+
+
+
+
+
+
+
+
+
+%%%********************************************************************
+%%% INTERNAL FUNCTIONS
+%%%********************************************************************
+
+
+
+
+split(KeyNo, [A,B|T], X, Y, Reverse) ->
+    split(KeyNo, T, [A|X], [B|Y], Reverse);
+split(KeyNo, [H], X, Y, Reverse) ->
+    split(KeyNo, [], [H|X], Y, Reverse);
+split(KeyNo, [], X, Y, Reverse) ->
+    merge(KeyNo, 
+	  mergesort(KeyNo, X, Reverse), 
+	  mergesort(KeyNo, Y, Reverse), 
+	  Reverse).
+
+
+
+
+
+
+get_correct_order({tuple, V1}, _E1, {tuple, V2}, _E2) when V1 < V2 ->
+    {1, 2};
+get_correct_order({tuple, _V1}, _E1, {tuple, _V2}, _E2) ->
+    {2, 1};
+get_correct_order(short_tuple, _E1, {tuple, _V2}, _E2) ->
+    {1, 2};
+get_correct_order({tuple, _V1}, _E1, short_tuple, _E2) ->
+    {2, 1};
+get_correct_order(short_tuple, E1, short_tuple, E2) when E1 < E2 ->
+    {1, 2};
+get_correct_order(short_tuple, _E1, short_tuple, _E2) ->
+    {2, 1};
+get_correct_order(no_tuple, E1, no_tuple, E2) when E1 < E2 ->
+    {1, 2};
+get_correct_order(no_tuple, _E1, no_tuple, _E2) ->
+    {2, 1};
+get_correct_order(_Anything, _E1, no_tuple, _E2) ->     % Tuples first, then other 
+    {1, 2};                                           % terms in correct order!
+get_correct_order(no_tuple, _E1, _Anything, _E2) ->
+    {2, 1}.
-- 
cgit v1.2.3