Add initial processing functions as glc_lib

src/glc.erl

@@ -78,6 +78,10 @@
     with/2
 ]).
 
+-export([
+    union/1
+]).
+
 -record(module, {
     'query' :: term(),
     tables :: [{atom(), ets:tid()}],
@@ -107,28 +111,50 @@ eq(Key, Term) when is_atom(Key) -> {Key, '=', Term}.
 gt(Key, Term) when is_atom(Key) -> {Key, '>', Term}.
 
 
-%% @doc Apply multiple conditions to the input.
-%% For an event to be considered valid output the condition of all filters
-%% specified in the input must hold for the input event.
+%% @doc Filter the input using multiple filters.
+%%
+%% For an input to be considered valid output the all filters specified
+%% in the list must hold for the input event. The list is expected to
+%% be a non-empty list. If the list of filters is an empty list a `badarg'
+%% error will be thrown.
 -spec all([q()]) -> q().
-all(Conds) when is_list(Conds) ->
-    {all, Conds}.
+all([_|_]=Conds) ->
+    {all, Conds};
+all(Other) ->
+    erlang:error(badarg, [Other]).
 
-%% @doc Apply one of multiple conditions to the input.
+%% @doc Filter the input using one of multiple filters.
+%%
+%% For an input to be considered valid output on of the filters specified
+%% in the list must hold for the input event. The list is expected to be
+%% a non-empty list. If the list of filters is an empty list a `badarg'
+%% error will be thrown.
 -spec any([q()]) -> q().
-any(Conds) when is_list(Conds) ->
-    {any, Conds}.
+any([_|_]=Conds) ->
+    {any, Conds};
+any(Other) ->
+    erlang:error(badarg, [Other]).
+
 
 %% @doc Always return `true' or `false'.
 -spec null(boolean()) -> q().
 null(Result) when is_boolean(Result) ->
     {null, Result}.
 
-%% @doc Apply a function to each output.
+%% @doc Apply a function to each output of a query.
+%%
+%% Updating the output action of a query finalizes it. Attempting
+%% to use a finalized query to construct a new query will result
+%% in a `badarg' error.
 -spec with(q(), fun((gre:event()) -> term())) -> q().
 with(Query, Fun) when is_function(Fun, 1) ->
     {with, Query, Fun}.
 
+%% @doc Return a union of multiple queries.
+-spec union([q()]) -> q().
+union(Queries) ->
+    {union, Queries}.
+
 
 %% @doc Compile a query to a module.
 %%
@@ -176,8 +202,8 @@ module_data(Query) ->
     %% tables are referred to by name in the generated code. the table/1
     %% function maps names to tids.
     Tables = [{params,Params}, {counters,Counters}],
-    Tree = query_tree(Query),
-    {ok, #module{'query'=Query, tables=Tables, qtree=Tree}}.
+    Query2 = glc_lib:reduce(Query),
+    {ok, #module{'query'=Query, tables=Tables, qtree=Query2}}.
 
 
 %% @private Map a query to a simplified query tree term.
@@ -208,11 +234,7 @@ module_data(Query) ->
     {atom(), '>', term()} |
     {any, [qcond()]} |
     {all, [qcond()]}.
--type qbody() :: tuple().
--type qtree() :: [{qcond(), qbody()}].
--spec query_tree(term()) -> qtree().
-query_tree(Query) ->
-    Query.
+
 
 %% abstract code geneation functions
 
@@ -256,20 +278,14 @@ abstract_module_(Module, #module{tables=Tables, qtree=Tree}=Data) ->
         abstract_info(Data) ++
         [erl_syntax:clause(
             [erl_syntax:underscore()], none,
-                [erl_syntax:application(
-                 erl_syntax:atom(erlang),
-                 erl_syntax:atom(error),
-                 [erl_syntax:atom(badarg)])])]),
+                [abstract_apply(erlang, error, [erl_syntax:atom(badarg)])])]),
      %% table(Name) -> ets:tid().
      erl_syntax:function(
         erl_syntax:atom(table),
         abstract_tables(Tables) ++
         [erl_syntax:clause(
          [erl_syntax:underscore()], none,
-            [erl_syntax:application(
-             erl_syntax:atom(erlang),
-             erl_syntax:atom(error),
-             [erl_syntax:atom(badarg)])])]),
+            [abstract_apply(erlang, error, [erl_syntax:atom(badarg)])])]),
      %% handle(Event) - entry function
      erl_syntax:function(
        erl_syntax:atom(handle),
@@ -417,9 +433,7 @@ abstract_getkey(Key, OnMatch, OnNomatch, #state{fields=Fields}=State) ->
 abstract_getkey_(Key, OnMatch, OnNomatch, #state{
         event=Event, fields=Fields}=State) ->
     [erl_syntax:case_expr(
-        erl_syntax:application(
-            erl_syntax:atom(gre), erl_syntax:atom(find),
-            [erl_syntax:atom(Key), Event]),
+        abstract_apply(gre, find, [erl_syntax:atom(Key), Event]),
         [erl_syntax:clause([
             erl_syntax:tuple([
                 erl_syntax:atom(true),
@@ -457,12 +471,8 @@ abstract_getparam_(Term, OnBound, #state{paramstab=Table,
     end,
     [erl_syntax:match_expr(
         param_variable(Key),
-        erl_syntax:application(
-            erl_syntax:atom(ets),
-            erl_syntax:atom(lookup_element),
-            [erl_syntax:application(
-                erl_syntax:atom(table),
-                [erl_syntax:atom(params)]),
+        abstract_apply(ets, lookup_element,
+            [abstract_apply(table, [erl_syntax:atom(params)]),
              erl_syntax:abstract(Key),
              erl_syntax:abstract(2)]))
     ] ++ OnBound(State#state{paramvars=[{Term, param_variable(Key)}|Params]}).
@@ -483,12 +493,8 @@ param_variable(Key) ->
 %% @todo Pass state record. Only Generate code if `statistics' is enabled.
 -spec abstract_count(atom()) -> syntaxTree().
 abstract_count(Counter) ->
-    erl_syntax:application(
-        erl_syntax:atom(ets),
-        erl_syntax:atom(update_counter),
-        [erl_syntax:application(
-            erl_syntax:atom(table),
-            [erl_syntax:atom(counters)]),
+    abstract_apply(ets, update_counter,
+        [abstract_apply(table, [erl_syntax:atom(counters)]),
          erl_syntax:abstract(Counter),
          erl_syntax:abstract({2,1})]).
 
@@ -497,12 +503,8 @@ abstract_count(Counter) ->
 %% @todo Pass state record. Only Generate code if `statistics' is enabled.
 -spec abstract_getcount(atom()) -> [syntaxTree()].
 abstract_getcount(Counter) ->
-    [erl_syntax:application(
-        erl_syntax:atom(ets),
-        erl_syntax:atom(lookup_element),
-        [erl_syntax:application(
-            erl_syntax:atom(table),
-            [erl_syntax:atom(counters)]),
+    [abstract_apply(ets, lookup_element,
+        [abstract_apply(table, [erl_syntax:atom(counters)]),
          erl_syntax:abstract(Counter),
          erl_syntax:abstract(2)])].
 
@@ -530,6 +532,21 @@ load_binary(Module, Binary) ->
         {error, Reason} -> exit({error_loading_module, Module, Reason})
     end.
 
+%% @private Apply an exported function.
+-spec abstract_apply(atom(), atom(), [syntaxTree()]) -> syntaxTree().
+abstract_apply(Module, Function, Arguments) ->
+    erl_syntax:application(
+        erl_syntax:atom(Module),
+        erl_syntax:atom(Function),
+        Arguments).
+
+%% @private Apply a module local function.
+-spec abstract_apply(atom(), [syntaxTree()]) -> syntaxTree().
+abstract_apply(Function, Arguments) ->
+    erl_syntax:application(
+        erl_syntax:atom(Function),
+        Arguments).
+
 
 -ifdef(TEST).
 -include_lib("eunit/include/eunit.hrl").
@@ -654,4 +671,9 @@ with_function_test() ->
     ?assertEqual(1, receive Msg -> Msg after 0 -> notcalled end),
     done.
 
+union_single_test() ->
+    {compiled, _Mod} = setup_query(testmod13,
+        glc:union([glc:eq(a, 1)])),
+    done.
+
 -endif.

src/glc_lib.erl

@@ -0,0 +1,291 @@
+%% Copyright (c) 2012, Magnus Klaar <klaar@ninenines.eu>
+%%
+%% Permission to use, copy, modify, and/or distribute this software for any
+%% purpose with or without fee is hereby granted, provided that the above
+%% copyright notice and this permission notice appear in all copies.
+%%
+%% THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+%% WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+%% MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+%% ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+%% WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+%% ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+%% OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+
+%% @doc Query processing functions.
+-module(glc_lib).
+
+-export([
+    reduce/1
+]).
+
+%% @doc Return a reduced version of a query.
+%% 
+%% The purpose of this function is to ensure that a query filter
+%% is in the simplest possible form. The query filter returned
+%% from this function is functionally equivalent to the original.
+reduce(Query) ->
+    repeat(Query, fun(Q0) ->
+        Q1 = flatten(Q0),
+        Q2 = required(Q1),
+        Q3 = flatten(Q2),
+        Q4 = common(Q3),
+        Q4
+    end).
+
+%% @private Repeatedly apply a function to a query.
+%% This is used for query transformation functions 
+%% applied multiple times 
+repeat(Query, Fun) ->
+    case Fun(Query) of
+        Query -> Query;
+        Query2 -> repeat(Query2, Fun)
+    end.
+
+%% @private Flatten a condition tree.
+flatten({all, [Cond]}) ->
+    Cond;
+flatten({any, [Cond]}) ->
+    Cond;
+flatten({all, Conds}) ->
+    flatten_all([flatten(Cond) || Cond <- Conds]);
+flatten({any, [_|_]=Conds}) ->
+    flatten_any([flatten(Cond) || Cond <- Conds]);
+flatten({with, Cond, Action}) ->
+    {with, flatten(Cond), Action};
+flatten(Other) ->
+    return_valid(Other).
+
+
+%% @private Flatten and remove duplicate members of an "all" filter.
+flatten_all(Conds) ->
+    {all, lists:usort(flatten_all_(Conds))}.
+
+flatten_all_([{all, Conds}|T]) ->
+    Conds ++ flatten_all_(T);
+flatten_all_([H|T]) ->
+    [H|flatten_all_(T)];
+flatten_all_([]) ->
+    [].
+
+%% @private Flatten and remove duplicate members of an "any" filter.
+flatten_any(Conds) ->
+    {any, lists:usort(flatten_any_(Conds))}.
+
+flatten_any_([{any, Conds}|T]) ->
+    Conds ++ flatten_any_(T);
+flatten_any_([H|T]) ->
+    [H|flatten_any_(T)];
+flatten_any_([]) ->
+    [].
+
+%% @private Factor out required filters.
+%%
+%% Identical conditions may occur in all sub-filters of an "any" filter. These
+%% filters can be tested once before testing the conditions that are unique to
+%% each sub-filter.
+%%
+%% Assume that the input has been flattened first in order to eliminate all
+%% occurances of an "any" filters being "sub-filters" of "any" filters.
+required({any, [H|_]=Conds}) ->
+    Init = ordsets:from_list(case H of {all, Init2} -> Init2; H -> [H] end),
+    case required(Conds, Init) of
+        [] ->
+            Conds2 = [required(Cond) || Cond <- Conds],
+            {any, Conds2};
+        [_|_]=Req ->
+            Conds2 = [required(deleteall(Cond, Req)) || Cond <- Conds],
+            {all, [{all, Req}, {any, Conds2}]}
+    end;
+required({all, Conds}) ->
+    {all, [required(Cond) || Cond <- Conds]};
+required(Other) ->
+    Other.
+
+required([{all, Conds}|T], Acc) ->
+    required(T, ordsets:intersection(ordsets:from_list(Conds), Acc));
+required([{any, _}|_]=Cond, Acc) ->
+    erlang:error(badarg, [Cond, Acc]);
+required([H|T], Acc) ->
+    required(T, ordsets:intersection(ordsets:from_list([H]), Acc));
+required([], Acc) ->
+    Acc.
+
+%% @private Factor our common filters.
+%%
+%% Identical conditions may occur in some sub-filters of an "all" filter. These
+%% filters can be tested once before testing the conditions that are unique to
+%% each sub-filter. This is different from factoring out common sub-filters
+%% in an "any" filter where the only those sub-filters that exist in all
+%% members.
+%%
+%% Assume that the input has been flattened first in order to eliminate all
+%% occurances of an "any" filters being "sub-filters" of "any" filters.
+common({all, Conds}) ->
+    case common_(Conds, []) of
+        {found, Found} ->
+            {all, [Found|[delete(Cond, Found) || Cond <- Conds]]};
+        nonefound ->
+            {all, [common(Cond) || Cond <- Conds]}
+    end;
+common({any, Conds}) ->
+    {any, [common(Cond) || Cond <- Conds]};
+common(Other) ->
+    Other.
+    
+
+common_([{any, Conds}|T], Seen) ->
+    Set = ordsets:from_list(Conds),
+    case ordsets:intersection(Set, Seen) of
+        [] -> common_(T, ordsets:union(Set, Seen));
+        [H|_] -> {found, H}
+    end;
+common_([H|T], Seen) ->
+    case ordsets:is_element(H, Seen) of
+        false -> common_(T, ordsets:union(ordsets:from_list([H]), Seen));
+        true -> {found, H}
+    end;
+common_([], _Seen) ->
+    nonefound.
+    
+
+
+
+%% @private Delete all occurances of a filter.
+%%
+%% Assume that the function is called because a filter is tested
+%% by a parent filter. It is therefore safe to replace occurances
+%% with a null filter that always returns true.
+delete({all, Conds}, Filter) ->
+    {all, [delete(Cond, Filter) || Cond <- Conds, Cond =/= Filter]};
+delete({any, Conds}, Filter) ->
+    {any, [delete(Cond, Filter) || Cond <- Conds, Cond =/= Filter]};
+delete(Filter, Filter) ->
+    {null, true};
+delete(Cond, _Filter) ->
+    Cond.
+
+%% @private Delete all occurances of multiple filters.
+deleteall(Filter, [H|T]) ->
+    deleteall(delete(Filter, H), T);
+deleteall(Filter, []) ->
+    Filter.
+
+
+
+%% @private Test if a term is a valid filter.
+is_valid({Field, '<', _Term}) when is_atom(Field) ->
+    true;
+is_valid({Field, '=', _Term}) when is_atom(Field) ->
+    true;
+is_valid({Field, '>', _Term}) when is_atom(Field) ->
+    true;
+is_valid({null, true}) ->
+    true;
+is_valid({null, false}) ->
+    true;
+is_valid(_Other) ->
+    false.
+
+%% @private Assert that a term is a valid filter.
+%% If the term is a valid filter. The original term will be returned.
+%% If the term is not a valid filter. A `badarg' error is thrown.
+return_valid(Term) ->
+    case is_valid(Term) of
+        true -> Term;
+        false ->
+            io:format(user, "~w~n", [Term]),
+            erlang:error(badarg, [Term])
+    end.
+
+
+-ifdef(TEST).
+-include_lib("eunit/include/eunit.hrl").
+
+all_one_test() ->
+    ?assertEqual(glc:eq(a, 1),
+        glc_lib:reduce(glc:all([glc:eq(a, 1)]))
+    ).
+
+all_sort_test() ->
+    ?assertEqual(glc:all([glc:eq(a, 1), glc:eq(b, 2)]),
+        glc_lib:reduce(glc:all([glc:eq(b, 2), glc:eq(a, 1)]))
+    ).
+
+any_one_test() ->
+    ?assertEqual(glc:eq(a, 1),
+        glc_lib:reduce(glc:any([glc:eq(a, 1)]))
+    ).
+
+any_sort_test() ->
+    ?assertEqual(glc:any([glc:eq(a, 1), glc:eq(b, 2)]),
+        glc_lib:reduce(glc:any([glc:eq(b, 2), glc:eq(a, 1)]))
+    ).
+
+all_nest_test() ->
+    ?assertEqual(glc:all([glc:eq(a, 1), glc:eq(b, 2)]),
+        glc_lib:reduce(glc:all([glc:eq(a, 1), glc:all([glc:eq(b, 2)])]))
+    ),
+    ?assertEqual(glc:all([glc:eq(a, 1), glc:eq(b, 2), glc:eq(c, 3)]),
+        glc_lib:reduce(glc:all([glc:eq(c, 3),
+            glc:all([glc:eq(a, 1),
+                glc:all([glc:eq(b, 2)])])]))
+    ).
+
+any_nest_test() ->
+    ?assertEqual(glc:any([glc:eq(a, 1), glc:eq(b, 2)]),
+        glc_lib:reduce(glc:any([glc:eq(a, 1), glc:any([glc:eq(b, 2)])]))
+    ),
+    ?assertEqual(glc:any([glc:eq(a, 1), glc:eq(b, 2), glc:eq(c, 3)]),
+        glc_lib:reduce(glc:any([glc:eq(c, 3),
+            glc:any([glc:eq(a, 1),
+                glc:any([glc:eq(b, 2)])])]))
+    ).
+
+all_equiv_test() ->
+    ?assertEqual(glc:eq(a, 1),
+        glc_lib:reduce(glc:all([glc:eq(a, 1), glc:eq(a, 1)]))
+    ).
+
+any_equiv_test() ->
+    ?assertEqual(glc:eq(a, 1),
+        glc_lib:reduce(glc:any([glc:eq(a, 1), glc:eq(a, 1)]))
+    ).
+
+any_required_test() ->
+    ?assertEqual(
+        glc:all([
+            glc:any([glc:eq(b, 2), glc:eq(c, 3)]),
+            glc:eq(a, 1)
+        ]),
+        glc_lib:reduce(
+            glc:any([
+                glc:all([glc:eq(a, 1), glc:eq(b, 2)]),
+                glc:all([glc:eq(a, 1), glc:eq(c, 3)])]))
+    ).
+        
+
+all_common_test() ->
+    ?assertEqual(
+        glc:all([glc:eq(a, 1), glc:eq(b, 2), glc:eq(c, 3)]),
+        glc_lib:reduce(
+            glc:all([
+                glc:any([glc:eq(a, 1), glc:eq(b, 2)]),
+                glc:any([glc:eq(a, 1), glc:eq(c, 3)])]))
+    ).
+
+delete_from_all_test() ->
+    ?assertEqual(
+        glc:all([glc:eq(b,2)]),
+        deleteall(
+            glc:all([glc:eq(a, 1),glc:eq(b,2)]), [glc:eq(a, 1)])
+    ).
+
+delete_from_any_test() ->
+    ?assertEqual(
+        glc:any([glc:eq(b,2)]),
+        deleteall(
+            glc:any([glc:eq(a, 1),glc:eq(b,2)]), [glc:eq(a, 1)])
+    ).
+
+-endif.