cosnotification_filter.erl

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%%--------------------------------------------------------------------
%% ``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 via the world wide web 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 Utvecklings AB.
%% Portions created by Ericsson are Copyright 1999, Ericsson Utvecklings
%% AB. All Rights Reserved.''
%% 
%%     $Id$
%%
%%----------------------------------------------------------------------
%% File    : cosNotification_Filter.erl
%% Purpose : 
%% Created : 28 Dec 1999
%%----------------------------------------------------------------------

-module(cosNotification_Filter).


%%--------------- INCLUDES -----------------------------------
-include_lib("orber/include/corba.hrl").
-include_lib("orber/include/ifr_types.hrl").
%% Application files
-include("CosNotification.hrl").
-include("CosNotifyChannelAdmin.hrl").
-include("CosNotifyComm.hrl").
-include("CosNotifyFilter.hrl").

-include("CosNotification_Definitions.hrl").

%%--------------- EXPORTS ------------------------------------
%% Internal Filter Functions
-export([eval/1, 
	 eval/2,
	 create_filter/1,
	 check_types/1,
	 match_types/3,
	 validate_types/1]).

%%--------------- DEFINES ------------------------------------
-define(EVENT_PATH,         [{dotid,"header"}, {dotid,"fixed_header"},
			     {dotid,"event_name"}]).
-define(DOMAIN_PATH,        [{dotid,"header"}, {dotid,"fixed_header"},
			     {dotid,"event_type"}, {dotid,"domain_name"}]).
-define(TYPE_PATH,          [{dotid,"header"}, {dotid,"fixed_header"},
			     {dotid,"event_type"}, {dotid,"type_name"}]).
-define(VARIABLE_PATH(I),   [{dotid,"header"}, {dotid,"variable_header"}, {dotid,I}]).
-define(FILTERABLE_PATH(I), [{dotid,"filterable_data"}, {dotid,I}]).


%%------------------------------------------------------------
%%--------------- FILTER FUNCTIONS ---------------------------
%%------------------------------------------------------------
%%------------------------------------------------------------
%% function : create_filter/1
%% Arguments: String - Filter grammar
%% Returns  : 
%% Effect   : 
%%------------------------------------------------------------
create_filter(Str) ->
    {ok, Tokens} = cosNotification_Scanner:scan(Str),
    case cosNotification_Grammar:parse(Tokens) of
	{ok, Filter} ->
	    {ok, Filter};
	_->
	    corba:raise(#'CosNotifyFilter_InvalidConstraint'{constr = Str})
    end.

%%------------------------------------------------------------
%% function : eval
%% Arguments: 
%% Returns  : 
%% Effect   : 
%%------------------------------------------------------------

eval('$empty') -> true;
eval(Tree)     -> eval(Tree, []).


%% Leaf expressions (literals and idents).
eval('$empty', _)               -> true;
eval(Lit, _Env) when number(Lit) -> Lit;
eval(Lit, _Env) when list(Lit)   -> Lit; %list == string
eval(Lit, _Env) when atom(Lit)   -> Lit;   %atom == bool
eval({component, V}, []) ->
    %% Cannot evaluate variables at this stage.
    throw({error, {unbound_variable, V}});
eval({component, V}, Env) ->
    case catch lookup(V, Env, undefined) of
	{ok, Val} -> 
	    Val;
	_X -> 
	    {error, {unbound_variable, V}}
    end;

%% CORBA2.3-15/26 states:
%% "The name parameters in tk_objref, tk_struct, tk_union, tk_enum, tk_alias, 
%% tk_value, tk_value_box, tk_abstract_interface, tk_native and tk_except TypeCodes
%% and the member name parameters in tk_struct, tk_union, tk_enum, tk_value and
%% tk_except TypeCodes are not specified by (or significant in) GIOP. Agents should
%% not make assumptions about type equivalence based on these name values; only the
%% structural information (including RepositoryId values, if provided) is
%% significant. If provided, the strings should be the simple, unscoped names
%% supplied in the OMG IDL definition text. If omitted, they are encoded as empty
%% strings."
%% Makes it rather hard to follow the grammar 100 %.
eval({default_component, V}, Env) ->
    case catch lookup(V, Env, default_component) of
	{ok, false} -> 
	    false;
	{ok, true} -> 
	    true;
	_X -> 
	    {error, {unbound_variable, V}}
    end;
eval({exist_component, V}, Env) ->
    case catch lookup(V, Env, exist_component) of
	{ok, false} -> 
	    false;
	{ok, _} -> 
	    true;
	{error, _} -> 
	    false;
	_X -> 
	    {error, {unbound_variable, V}}
    end;
%% Arithmetic expressions.
eval({'*', X, Y}, Env) ->
    eval_arith({fun(_X, _Y) -> _X*_Y end, X, Y}, Env);
eval({'/', X, Y}, Env) ->
    eval_arith({fun(_X, _Y) -> _X/_Y end, X, Y}, Env);
eval({'+', X, Y}, Env) ->
    eval_arith({fun(_X, _Y) -> _X+_Y end, X, Y}, Env);
eval({'-', X, Y}, Env) ->
    eval_arith({fun(_X, _Y) -> _X-_Y end, X, Y}, Env);
eval({'u-', X}, Env) ->
    eval_arith({fun(_X) -> -_X end, X}, Env);
%% Relational expressions.
eval({'==', X, Y}, Env) ->
    eval_rel({fun(_X, _Y) -> _X == _Y end, X, Y}, Env);
eval({'!=', X, Y}, Env) ->
    eval_rel({fun(_X, _Y) -> _X /= _Y end, X, Y}, Env);
eval({'<', X, Y}, Env) ->
    eval_rel({fun(_X, _Y) -> _X < _Y end, X, Y}, Env);
eval({'<=', X, Y}, Env) ->
    eval_rel({fun(_X, _Y) -> _X =< _Y end, X, Y}, Env);
eval({'>', X, Y}, Env) ->
    eval_rel({fun(_X, _Y) -> _X > _Y end, X, Y}, Env);
eval({'>=', X, Y}, Env) ->
    eval_rel({fun(_X, _Y) -> _X >= _Y end, X, Y}, Env);
eval({'~', Needle, Haystack}, Env) ->		%substring match
    N = eval(Needle, Env),
    H = eval(Haystack, Env),
    if
	list(N), list(H) ->
	    string:str(H, N) /= 0;
	true ->
	    throw({error, {bad_type, Needle, Haystack}})
    end;
eval({'in', Needle, Haystack}, Env) ->		%set membership
    N = eval(Needle, Env),
    H = eval(Haystack, Env),
    if
	list(H) ->
	    lists:member(N, H);
	true ->
	    throw({error, {bad_type, Needle, Haystack}})
    end;
%% Boolean expressions.
eval({'and', false, _Y}, _Env) ->
    false;
eval({'and', _X, false}, _Env) ->
    false;
eval({'and', X, Y}, Env) ->
    eval_and_bool({fun(_X, _Y) -> _X and _Y end, X, Y}, Env);

eval({'or', true, _Y}, _Env) ->
    true;
eval({'or', _X, true}, _Env) ->
    true;
eval({'or', X, Y}, Env) ->
    eval_or_bool({fun(_X, _Y) -> _X or _Y end, X, Y}, Env);
eval({'not', X}, Env) ->
    eval_bool({fun(_X) -> not _X end, X}, Env);
%% Catch-all
eval(_T, _Env) ->
    throw({error, internal}).

eval_bool({Fun, X}, Env) ->
    Xe = eval(X, Env),
    if 
	atom(Xe) ->
	    Fun(Xe);
	true ->
	    throw({error, {bad_type, X}})
    end.
eval_and_bool({Fun, X, Y}, Env) ->
    case eval(X, Env) of
	false ->
	    %% No need for evaluating the other expression.
	    false;
	Xe ->
	    Ye = eval(Y, Env),
	    if 
		atom(Xe), atom(Ye) ->
		    Fun(Xe, Ye);
		true ->
		    throw({error, {bad_type, X, Y}})
	    end
    end.
eval_or_bool({Fun, X, Y}, Env) ->
    case eval(X, Env) of
	true ->
	    %% No need for evaluating the other expression.
	    true;
	Xe ->
	    Ye = eval(Y, Env),
	    if 
		atom(Xe), atom(Ye) ->
		    Fun(Xe, Ye);
		true ->
		    throw({error, {bad_type, X, Y}})
	    end
    end.


%% According to issue 2203, OMG stated that arithmetic operations involving booleans
%% is allowed. TRUE equals 1 and FALSE 0. They refer to:

%% "We at NEC like this feature, and feel it is both required and
%% standard with the way CORBA treats boolean values. We feel it's
%% required because it allows the constraint grammar to handle
%% expressions that combine the results of boolean comparisons, 
%% which we feel is typically expected of a constraint grammar
%% (e.g., ($.fruit == apples) + ($.color == red) + ($.kind == macintosh) > 2)
%% Furthermore, while we have no fundamental opposition to explicitly
%% stating that TRUE=1 and FALSE=0, we don't necessarily feel it's
%% necessary because section 12.3.1 of CORBA alread states that 
%% "Boolean values are encoded as single octets, where TRUE is the
%% value 1, and FALSE is 0." Essentially, we feel CORBA already 
%% defines TRUE to be 1 and FALSE to be 0, however we are not 
%% opposed to adding such a statement into Notification if folks 
%% feel it's necessary."
%% If still valid, see: ftp://ftp.omg.org/pub/docs/telecom/99-07-06.txt

%% The section they refer to (CORBA-2.0) merely states that TRUE and FALSE are
%% encoded as 1 and 0 in GIOP. Does not imply that booleans may be used as numeric.
%% But, they have stated that this should be the case so..... 

remap_bool(Num) when number(Num) -> Num;
remap_bool(true) -> 1;
remap_bool(false) -> 0;
remap_bool(X) -> throw({error, {bad_type, X}}).

eval_arith({Fun, X}, Env) ->
    Xe = remap_bool(eval(X, Env)),
    Fun(Xe);
eval_arith({Fun, X, Y}, Env) ->
    Xe = remap_bool(eval(X, Env)),
    Ye = remap_bool(eval(Y, Env)),
    Fun(Xe, Ye).

eval_rel({Fun, X, Y}, Env) ->
    Xe = eval(X, Env),
    Ye = eval(Y, Env),
    if 
	number(Xe), number(Ye) ->
	    Fun(Xe, Ye);
	list(Xe), list(Ye) ->
	    Fun(Xe, Ye);
	atom(Xe), atom(Ye) ->
	    Fun(Xe, Ye);
	true ->
	    throw({error, {bad_type, X, Y}})
    end.

%%------------------------------------------------------------
%% function : get_variable
%% Arguments: A sequence of CosNotification::Property{}, i.e., 
%%            name-value pairs.
%%            ID - name in the Property
%%            Any - remainder of body
%% Returns  : Value in the Property | false
%% Comment  : When searching for a variable we must start with
%%            'variable_header' followed by 'filterable_body'.
%%            If not found we will then look in the 'remainder_of_body'
%%------------------------------------------------------------

get_variable([], ID, Any) when record(Any, any) ->
    case {any:get_value(Any), any:get_typecode(Any)} of
	{#'CosNotification_Property'{name=ID, value=A}, _} ->
	    any:get_value(A);
	{_, TC} when atom(TC) ->
	    %% Since TC atom it must be a simple type, which don't have members.
	    throw({error, {bad_id, ID}});
	{Value, {tk_alias,_,ID,_}} when record(Value, any) ->
	    %% {tk_alias, IFRId, ID, TypeCode}
	    any:get_value(Value);
	{Value, {tk_alias,_,ID,_}} ->
	    %% {tk_alias, IFRId, ID, TypeCode}
	    Value;
	{Value, _TC} ->
	    get_variable([],ID, Value)
    end;
get_variable([], ID, #'CosNotification_Property'{name=ID, value=Any}) ->
    any:get_value(Any);
get_variable([], ID, [#'CosNotification_Property'{name=ID, value=Any}|_]) ->
    any:get_value(Any);
get_variable([], ID, [H|T]) when record(H, 'CosNotification_Property') ->
    get_variable([], ID, T);
get_variable([], ID, false) ->
    throw({error, {bad_id, ID}});
get_variable([], ID, Value) ->
    M = element(1, Value),