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+%%<copyright>
+%% <year>1996-2007</year>
+%% <holder>Ericsson AB, All Rights Reserved</holder>
+%%</copyright>
+%%<legalnotice>
+%% 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.
+%%
+%% The Initial Developer of the Original Code is Ericsson AB.
+%%</legalnotice>
+%%
+-module(ex1).
+
+%% External exports
+-export([start/0, my_name/1, my_name/2, friends_table/3]).
+
+%% Internal exports
+-export([init/0]).
+
+-define(status_col, 4).
+
+-define(active, 1).
+-define(notInService, 2).
+-define(notReady, 3).
+-define(createAndGo, 4). % Action; written, not read
+-define(createAndWait, 5). % Action; written, not read
+-define(destroy, 6). % Action; written, not read
+
+start() ->
+ spawn(ex1, init, []).
+
+
+%%----------------------------------------------------------------
+%% Instrumentation function for variable myName.
+%% Returns: (get) {value, Name}
+%% (set) noError
+%%----------------------------------------------------------------
+my_name(get) ->
+ ex1_server ! {self(), get_my_name},
+ Name = wait_answer(),
+ {value, Name}.
+
+my_name(set, NewName) ->
+ ex1_server ! {self(), {set_my_name, NewName}},
+ noError.
+
+%%----------------------------------------------------------------
+%% Instrumentation function for table friendsTable.
+%%----------------------------------------------------------------
+friends_table(get, RowIndex, Cols) ->
+ case get_row(RowIndex) of
+ {ok, Row} ->
+ get_cols(Cols, Row);
+ _ ->
+ {noValue, noSuchInstance}
+ end;
+
+friends_table(get_next, RowIndex, Cols) ->
+ case get_next_row(RowIndex) of
+ {ok, Row} ->
+ get_next_cols(Cols, Row);
+ _ ->
+ case get_next_row([]) of
+ {ok, Row} ->
+ % Get next cols from first row.
+ NewCols = add_one_to_cols(Cols),
+ get_next_cols(NewCols, Row);
+ _ ->
+ end_of_table(Cols)
+ end
+ end;
+
+%%----------------------------------------------------------------
+%% If RowStatus is set, then:
+%% *) If set to destroy, check that row does exist
+%% *) If set to createAndGo, check that row doesn't exist AND
+%% that all columns are given values.
+%% *) Otherwise, error (for simplicity).
+%% Otherwise, row is modified; check that row exists.
+%%----------------------------------------------------------------
+friends_table(is_set_ok, RowIndex, Cols) ->
+ RowExists =
+ case get_row(RowIndex) of
+ {ok, _Row} -> true;
+ _ -> false
+ end,
+ case is_row_status_col_changed(Cols) of
+ {true, ?destroy} when RowExists == true ->
+ {noError, 0};
+ {true, ?createAndGo} when RowExists == false,
+ length(Cols) == 3 ->
+ {noError, 0};
+ {true, _} ->
+ {inconsistentValue, ?status_col};
+ false when RowExists == true ->
+ {noError, 0};
+ _ ->
+ [{Col, _NewVal} | _Cols] = Cols,
+ {inconsistentName, Col}
+ end;
+
+friends_table(set, RowIndex, Cols) ->
+ case is_row_status_col_changed(Cols) of
+ {true, ?destroy} ->
+ ex1_server ! {self(), {delete_row, RowIndex}};
+ {true, ?createAndGo} ->
+ NewRow = make_row(RowIndex, Cols),
+ ex1_server ! {self(), {add_row, NewRow}};
+ false ->
+ {ok, Row} = get_row(RowIndex),
+ NewRow = merge_rows(Row, Cols),
+ ex1_server ! {self(), {delete_row, RowIndex}},
+ ex1_server ! {self(), {add_row, NewRow}}
+ end,
+ {noError, 0}.
+
+%%----------------------------------------------------------------
+%% Make a list of {value, Val} of the Row and Cols list.
+%%----------------------------------------------------------------
+get_cols([Col | Cols], Row) ->
+ [{value, element(Col, Row)} | get_cols(Cols, Row)];
+get_cols([], _Row) ->
+ [].
+
+%%----------------------------------------------------------------
+%% As get_cols, but the Cols list may contain invalid column
+%% numbers. If it does, we must find the next valid column,
+%% or return endOfTable.
+%%----------------------------------------------------------------
+get_next_cols([Col | Cols], Row) when Col < 2 ->
+ [{[2, element(1, Row)], element(2, Row)} |
+ get_next_cols(Cols, Row)];
+get_next_cols([Col | Cols], Row) when Col > 4 ->
+ [endOfTable |
+ get_next_cols(Cols, Row)];
+get_next_cols([Col | Cols], Row) ->
+ [{[Col, element(1, Row)], element(Col, Row)} |
+ get_next_cols(Cols, Row)];
+get_next_cols([], _Row) ->
+ [].
+
+%%----------------------------------------------------------------
+%% Make a list of endOfTable with as many elems as Cols list.
+%%----------------------------------------------------------------
+end_of_table([_Col | Cols]) ->
+ [endOfTable | end_of_table(Cols)];
+end_of_table([]) ->
+ [].
+
+add_one_to_cols([Col | Cols]) ->
+ [Col + 1 | add_one_to_cols(Cols)];
+add_one_to_cols([]) ->
+ [].
+
+is_row_status_col_changed(Cols) ->
+ case lists:keysearch(?status_col, 1, Cols) of
+ {value, {?status_col, StatusVal}} ->
+ {true, StatusVal};
+ _ -> false
+ end.
+
+get_row(RowIndex) ->
+ ex1_server ! {self(), {get_row, RowIndex}},
+ wait_answer().
+
+get_next_row(RowIndex) ->
+ ex1_server ! {self(), {get_next_row, RowIndex}},
+ wait_answer().
+
+wait_answer() ->
+ receive
+ {ex1_server, Answer} ->
+ Answer
+ end.
+
+%%%----------------------------------------------------------------
+%%% Server code follows
+%%%----------------------------------------------------------------
+init() ->
+ register(ex1_server, self()),
+ loop("", []).
+
+loop(MyName, Table) ->
+ receive
+ {From, get_my_name} ->
+ From ! {ex1_server, MyName},
+ loop(MyName, Table);
+ {_From, {set_my_name, NewName}} ->
+ loop(NewName, Table);
+ {From, {get_row, RowIndex}} ->
+ Res = table_get_row(Table, RowIndex),
+ From ! {ex1_server, Res},
+ loop(MyName, Table);
+ {From, {get_next_row, RowIndex}} ->
+ Res = table_get_next_row(Table, RowIndex),
+ From ! {ex1_server, Res},
+ loop(MyName, Table);
+ {_From, {delete_row, RowIndex}} ->
+ NewTable = table_delete_row(Table, RowIndex),
+ loop(MyName, NewTable);
+ {_From, {add_row, NewRow}} ->
+ NewTable = table_add_row(Table, NewRow),
+ loop(MyName, NewTable)
+ end.
+
+
+%%-----------------------------------------------------------------
+%% Implementation of the table.
+%%-----------------------------------------------------------------
+table_get_row([{Index, Name, Address, Status} | _], [Index]) ->
+ {ok, {Index, Name, Address, Status}};
+table_get_row([_H | T], RowIndex) ->
+ table_get_row(T, RowIndex);
+table_get_row([], _RowIndex) ->
+ no_such_row.
+
+table_get_next_row([Row | _T], []) ->
+ {ok, Row};
+table_get_next_row([Row | _T], [Index | _]) when element(1, Row) > Index ->
+ {ok, Row};
+table_get_next_row([_Row | T], RowIndex) ->
+ table_get_next_row(T, RowIndex);
+table_get_next_row([], _RowIndex) ->
+ endOfTable.
+
+table_delete_row([{Index, _, _, _} | T], [Index]) ->
+ T;
+table_delete_row([H | T], RowIndex) ->
+ [H | table_delete_row(T, RowIndex)];
+table_delete_row([], _RowIndex) ->
+ [].
+
+table_add_row([Row | T], NewRow) when element(1, Row) > element(1, NewRow) ->
+ [NewRow, Row | T];
+table_add_row([H | T], NewRow) ->
+ [H | table_add_row(T, NewRow)];
+table_add_row([], NewRow) ->
+ [NewRow].
+
+make_row([Index], [{2, Name}, {3, Address} | _]) ->
+ {Index, Name, Address, ?active}.
+
+merge_rows(Row, [{Col, NewVal} | T]) ->
+ merge_rows(setelement(Col, Row, NewVal), T);
+merge_rows(Row, []) ->
+ Row.
+
+
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