src/mango_selector_text.erl - couchdb-mango - Git at Google

 % Licensed under the Apache License, Version 2.0 (the "License"); you may not
 % use this file except in compliance with the License. You may obtain a copy of
 % the License at
 %
 % http://www.apache.org/licenses/LICENSE-2.0
 %
 % Unless required by applicable law or agreed to in writing, software
 % distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 % WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 % License for the specific language governing permissions and limitations under
 % the License.

 -module(mango_selector_text).


 -export([
     convert/1,
     convert/2,

     append_sort_type/2
 ]).


 -include_lib("couch/include/couch_db.hrl").
 -include("mango.hrl").


 %% Regex for <<"\\.">>
 -define(PERIOD, "\\.").


 convert(Object) ->
     TupleTree = convert([], Object),
     iolist_to_binary(to_query(TupleTree)).


 convert(Path, {[{<<"$and">>, Args}]}) ->
     Parts = [convert(Path, Arg) || Arg <- Args],
     {op_and, Parts};
 convert(Path, {[{<<"$or">>, Args}]}) ->
     Parts = [convert(Path, Arg) || Arg <- Args],
     {op_or, Parts};
 convert(Path, {[{<<"$not">>, Arg}]}) ->
     {op_not, {field_exists_query(Path), convert(Path, Arg)}};
 convert(Path, {[{<<"$default">>, Arg}]}) ->
     {op_field, {_, Query}} = convert(Path, Arg),
     {op_default, Query};

 % The $text operator specifies a Lucene syntax query
 % so we just pull it in directly.
 convert(Path, {[{<<"$text">>, Query}]}) when is_binary(Query) ->
     {op_field, {make_field(Path, Query), value_str(Query)}};

 % The MongoDB docs for $all are super confusing and read more
 % like they screwed up the implementation of this operator
 % and then just documented it as a feature.
 %
 % This implementation will match the behavior as closely as
 % possible based on the available docs but we'll need to have
 % the testing team validate how MongoDB handles edge conditions
 convert(Path, {[{<<"$all">>, Args}]}) ->
     case Args of
         [Values] when is_list(Values) ->
             % If Args is a single element array then we have to
             % either match if Path is that array or if it contains
             % the array as an element of an array (which isn't at all
             % confusing). For Lucene to return us all possible matches
             % that means we just need to search for each value in
             % Path.[] and Path.[].[] and rely on our filtering to limit
             % the results properly.
             Fields1 = convert(Path, {[{<<"$eq">> , Values}]}),
             Fields2 = convert([<<"[]">>| Path], {[{<<"$eq">> , Values}]}),
             {op_or, [Fields1, Fields2]};
         _ ->
             % Otherwise the $all operator is equivalent to an $and
             % operator so we treat it as such.
             convert([<<"[]">> | Path], {[{<<"$and">>, Args}]})
     end;

 % The $elemMatch Lucene query is not an exact translation
 % as we can't enforce that the matches are all for the same
 % item in an array. We just rely on the final selector match
 % to filter out anything that doesn't match. The only trick
 % is that we have to add the `[]` path element since the docs
 % say this has to match against an array.
 convert(Path, {[{<<"$elemMatch">>, Arg}]}) ->
     convert([<<"[]">> | Path], Arg);

 % Our comparison operators are fairly straight forward
 convert(Path, {[{<<"$lt">>, Arg}]}) when is_list(Arg); is_tuple(Arg);
         Arg =:= null ->
     field_exists_query(Path);
 convert(Path, {[{<<"$lt">>, Arg}]}) ->
     {op_field, {make_field(Path, Arg), range(lt, Arg)}};
 convert(Path, {[{<<"$lte">>, Arg}]}) when is_list(Arg); is_tuple(Arg);
         Arg =:= null->
     field_exists_query(Path);
 convert(Path, {[{<<"$lte">>, Arg}]}) ->
     {op_field, {make_field(Path, Arg), range(lte, Arg)}};
 %% This is for indexable_fields
 convert(Path, {[{<<"$eq">>, Arg}]}) when Arg =:= null ->
     {op_null, {make_field(Path, Arg), value_str(Arg)}};
 convert(Path, {[{<<"$eq">>, Args}]}) when is_list(Args) ->
     Path0 = [<<"[]">> | Path],
     LPart = {op_field, {make_field(Path0, length), value_str(length(Args))}},
     Parts0 = [convert(Path0, {[{<<"$eq">>, Arg}]}) || Arg <- Args],
     Parts = [LPart | Parts0],
     {op_and, Parts};
 convert(Path, {[{<<"$eq">>, {_} = Arg}]}) ->
     convert(Path, Arg);
 convert(Path, {[{<<"$eq">>, Arg}]}) ->
     {op_field, {make_field(Path, Arg), value_str(Arg)}};
 convert(Path, {[{<<"$ne">>, Arg}]}) ->
     {op_not, {field_exists_query(Path), convert(Path, {[{<<"$eq">>, Arg}]})}};
 convert(Path, {[{<<"$gte">>, Arg}]}) when is_list(Arg); is_tuple(Arg);
         Arg =:= null ->
     field_exists_query(Path);
 convert(Path, {[{<<"$gte">>, Arg}]}) ->
     {op_field, {make_field(Path, Arg), range(gte, Arg)}};
 convert(Path, {[{<<"$gt">>, Arg}]}) when is_list(Arg); is_tuple(Arg);
         Arg =:= null->
     field_exists_query(Path);
 convert(Path, {[{<<"$gt">>, Arg}]}) ->
     {op_field, {make_field(Path, Arg), range(gt, Arg)}};

 convert(Path, {[{<<"$in">>, Args}]}) ->
     {op_or, convert_in(Path, Args)};

 convert(Path, {[{<<"$nin">>, Args}]}) ->
     {op_not, {field_exists_query(Path), convert(Path, {[{<<"$in">>, Args}]})}};

 convert(Path, {[{<<"$exists">>, ShouldExist}]}) ->
     FieldExists = field_exists_query(Path),
     case ShouldExist of
         true -> FieldExists;
         false -> {op_not, {FieldExists, false}}
     end;

 % We're not checking the actual type here, just looking for
 % anything that has a possibility of matching by checking
 % for the field name. We use the same logic for $exists on
 % the actual query.
 convert(Path, {[{<<"$type">>, _}]}) ->
     field_exists_query(Path);

 convert(Path, {[{<<"$mod">>, _}]}) ->
     field_exists_query(Path, "number");

 % The lucene regular expression engine does not use java's regex engine but
 % instead a custom implementation. The syntax is therefore different, so we do
 % would get different behavior than our view indexes. To be consistent, we will
 % simply return docs for fields that exist and then run our match filter.
 convert(Path, {[{<<"$regex">>, _}]}) ->
     field_exists_query(Path, "string");

 convert(Path, {[{<<"$size">>, Arg}]}) ->
     {op_field, {make_field([<<"[]">> | Path], length), value_str(Arg)}};

 % All other operators are internal assertion errors for
 % matching because we either should've removed them during
 % normalization or something else broke.
 convert(_Path, {[{<<"$", _/binary>>=Op, _}]}) ->
     ?MANGO_ERROR({invalid_operator, Op});

 % We've hit a field name specifier. Check if the field name is accessing
 % arrays. Convert occurrences of element position references to .[]. Then we
 % need to break the name into path parts and continue our conversion.
 convert(Path, {[{Field0, Cond}]}) ->
     {ok, PP0} = case Field0 of
         <<>> ->
             {ok, []};
         _ ->
             mango_util:parse_field(Field0)
     end,
     % Later on, we perform a lucene_escape_user call on the
     % final Path, which calls parse_field again. Calling the function
     % twice converts <<"a\\.b">> to [<<"a">>,<<"b">>]. This leads to
     % an incorrect query since we need [<<"a.b">>]. Without breaking
     % our escaping mechanism, we simply revert this first parse_field
     % effect and replace instances of "." to "\\.".
     MP = mango_util:cached_re(mango_period, ?PERIOD),
     PP1 = [re:replace(P, MP, <<"\\\\.">>,
         [global,{return,binary}]) || P <- PP0],
     {PP2, HasInteger} = replace_array_indexes(PP1, [], false),
     NewPath = PP2 ++ Path,
     case HasInteger of
         true ->
             OldPath = lists:reverse(PP1, Path),
             OldParts = convert(OldPath, Cond),
             NewParts = convert(NewPath, Cond),
             {op_or, [OldParts, NewParts]};
         false ->
             convert(NewPath, Cond)
     end;

 %% For $in
 convert(Path, Val) when is_binary(Val); is_number(Val); is_boolean(Val) ->
     {op_field, {make_field(Path, Val), value_str(Val)}};

 % Anything else is a bad selector.
 convert(_Path, {Props} = Sel) when length(Props) > 1 ->
     erlang:error({unnormalized_selector, Sel}).


 to_query({op_and, Args}) when is_list(Args) ->
     QueryArgs = lists:map(fun to_query/1, Args),
     ["(", mango_util:join(<<" AND ">>, QueryArgs), ")"];

 to_query({op_or, Args}) when is_list(Args) ->
     ["(", mango_util:join(" OR ", lists:map(fun to_query/1, Args)), ")"];

 to_query({op_not, {ExistsQuery, Arg}}) when is_tuple(Arg) ->
     ["(", to_query(ExistsQuery), " AND NOT (", to_query(Arg), "))"];

 %% For $exists:false
 to_query({op_not, {ExistsQuery, false}}) ->
     ["($fieldnames:/.*/ ", " AND NOT (", to_query(ExistsQuery), "))"];

 to_query({op_insert, Arg}) when is_binary(Arg) ->
     ["(", Arg, ")"];

 %% We escape : and / for now for values and all lucene chars for fieldnames
 %% This needs to be resolved.
 to_query({op_field, {Name, Value}}) ->
     NameBin = iolist_to_binary(Name),
     ["(", mango_util:lucene_escape_user(NameBin), ":", Value, ")"];

 %% This is for indexable_fields
 to_query({op_null, {Name, Value}}) ->
     NameBin = iolist_to_binary(Name),
     ["(", mango_util:lucene_escape_user(NameBin), ":", Value, ")"];

 to_query({op_fieldname, {Name, Wildcard}}) ->
     NameBin = iolist_to_binary(Name),
     ["($fieldnames:", mango_util:lucene_escape_user(NameBin), Wildcard, ")"];

 to_query({op_default, Value}) ->
     ["($default:", Value, ")"].


 %% We match on fieldname and fieldname.[]
 convert_in(Path, Args) ->
     Path0 = [<<"[]">> | Path],
     lists:map(fun(Arg) ->
         case Arg of
             {Object} ->
                 Parts = lists:map(fun (SubObject) ->
                     Fields1 = convert(Path, {[SubObject]}),
                     Fields2 = convert(Path0, {[SubObject]}),
                     {op_or, [Fields1, Fields2]}
                 end, Object),
                 {op_or, Parts};
             SingleVal ->
                 Fields1 = {op_field, {make_field(Path, SingleVal),
                 value_str(SingleVal)}},
                 Fields2 = {op_field, {make_field(Path0, SingleVal),
                 value_str(SingleVal)}},
                 {op_or, [Fields1, Fields2]}
         end
     end, Args).


 make_field(Path, length) ->
     [path_str(Path), <<":length">>];
 make_field(Path, Arg) ->
     [path_str(Path), <<":">>, type_str(Arg)].


 range(lt, Arg) ->
     Min = get_range(min, Arg),
     [<<"[", Min/binary, " TO ">>, value_str(Arg), <<"}">>];
 range(lte, Arg) ->
     Min = get_range(min, Arg),
     [<<"[", Min/binary, " TO ">>, value_str(Arg), <<"]">>];
 range(gte, Arg) ->
     Max = get_range(max, Arg),
     [<<"[">>, value_str(Arg), <<" TO ", Max/binary, "]">>];
 range(gt, Arg) ->
     Max = get_range(max, Arg),
     [<<"{">>, value_str(Arg), <<" TO ", Max/binary, "]">>].

 get_range(min, Arg) when is_number(Arg) ->
     <<"-Infinity">>;
 get_range(min, _Arg) ->
     <<"\"\"">>;
 get_range(max, Arg) when is_number(Arg) ->
     <<"Infinity">>;
 get_range(max, _Arg) ->
     <<"\u0x10FFFF">>.


 field_exists_query(Path) ->
     % We specify two here for :* and .* so that we don't incorrectly
     % match a path foo.name against foo.name_first (if were to just
     % appened * isntead).
     Parts = [
         % We need to remove the period from the path list to indicate that it is
         % a path separator. We escape the colon because it is not used as a
         % separator and we escape colons in field names.
         {op_fieldname, {[path_str(Path), ":"], "*"}},
         {op_fieldname, {[path_str(Path)], ".*"}}
     ],
     {op_or, Parts}.


 field_exists_query(Path, Type) ->
     {op_fieldname, {[path_str(Path), ":"], Type}}.


 path_str(Path) ->
     path_str(Path, []).


 path_str([], Acc) ->
     Acc;
 path_str([Part], Acc) ->
     % No reverse because Path is backwards
     % during recursion of convert.
     [Part | Acc];
 path_str([Part | Rest], Acc) ->
     case Part of
         % do not append a period if Part is blank
         <<>> ->
             path_str(Rest, [Acc]);
         _ ->
             path_str(Rest, [<<".">>, Part | Acc])
     end.


 type_str(Value) when is_number(Value) ->
     <<"number">>;
 type_str(Value) when is_boolean(Value) ->
     <<"boolean">>;
 type_str(Value) when is_binary(Value) ->
     <<"string">>;
 type_str(null) ->
     <<"null">>.


 value_str(Value) when is_binary(Value) ->
     case mango_util:is_number_string(Value) of
         true ->
             <<"\"", Value/binary, "\"">>;
         false ->
             mango_util:lucene_escape_query_value(Value)
     end;
 value_str(Value) when is_integer(Value) ->
     list_to_binary(integer_to_list(Value));
 value_str(Value) when is_float(Value) ->
     list_to_binary(float_to_list(Value));
 value_str(true) ->
     <<"true">>;
 value_str(false) ->
     <<"false">>;
 value_str(null) ->
     <<"true">>.


 append_sort_type(RawSortField, Selector) ->
     EncodeField = mango_util:lucene_escape_user(RawSortField),
     String = mango_util:has_suffix(EncodeField, <<"_3astring">>),
     Number = mango_util:has_suffix(EncodeField, <<"_3anumber">>),
     case {String, Number} of
         {true, _} ->
             <<EncodeField/binary, "<string>">>;
         {_, true} ->
             <<EncodeField/binary, "<number>">>;
         _ ->
             Type = get_sort_type(RawSortField, Selector),
             <<EncodeField/binary, Type/binary>>
     end.


 get_sort_type(Field, Selector) ->
     Types = get_sort_types(Field, Selector, []),
     case lists:usort(Types) of
         [str] -> <<"_3astring<string>">>;
         [num] -> <<"_3anumber<number>">>;
         _ -> ?MANGO_ERROR({text_sort_error, Field})
     end.


 get_sort_types(Field, {[{Field, {[{<<"$", _/binary>>, Cond}]}}]}, Acc)
         when is_binary(Cond) ->
     [str | Acc];

 get_sort_types(Field, {[{Field, {[{<<"$", _/binary>>, Cond}]}}]}, Acc)
         when is_number(Cond) ->
     [num | Acc];

 get_sort_types(Field, {[{_, Cond}]}, Acc) when is_list(Cond) ->
     lists:foldl(fun(Arg, InnerAcc) ->
         get_sort_types(Field, Arg, InnerAcc)
     end, Acc, Cond);

 get_sort_types(Field, {[{_, Cond}]}, Acc)  when is_tuple(Cond)->
     get_sort_types(Field, Cond, Acc);

 get_sort_types(_Field, _, Acc)  ->
     Acc.


 replace_array_indexes([], NewPartsAcc, HasIntAcc) ->
     {NewPartsAcc, HasIntAcc};
 replace_array_indexes([Part | Rest], NewPartsAcc, HasIntAcc) ->
     {NewPart, HasInt} = try
         _ = list_to_integer(binary_to_list(Part)),
         {<<"[]">>, true}
     catch _:_ ->
         {Part, false}
     end,
     replace_array_indexes(Rest, [NewPart | NewPartsAcc],
          HasInt or HasIntAcc).
	% Licensed under the Apache License, Version 2.0 (the "License"); you may not
	% use this file except in compliance with the License. You may obtain a copy of
	% the License at
	%
	% http://www.apache.org/licenses/LICENSE-2.0
	%
	% Unless required by applicable law or agreed to in writing, software
	% distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
	% WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
	% License for the specific language governing permissions and limitations under
	% the License.

	-module(mango_selector_text).


	-export([
	convert/1,
	convert/2,

	append_sort_type/2
	]).


	-include_lib("couch/include/couch_db.hrl").
	-include("mango.hrl").


	%% Regex for <<"\\.">>
	-define(PERIOD, "\\.").


	convert(Object) ->
	TupleTree = convert([], Object),
	iolist_to_binary(to_query(TupleTree)).


	convert(Path, {[{<<"$and">>, Args}]}) ->
	Parts = [convert(Path, Arg) \|\| Arg <- Args],
	{op_and, Parts};
	convert(Path, {[{<<"$or">>, Args}]}) ->
	Parts = [convert(Path, Arg) \|\| Arg <- Args],
	{op_or, Parts};
	convert(Path, {[{<<"$not">>, Arg}]}) ->
	{op_not, {field_exists_query(Path), convert(Path, Arg)}};
	convert(Path, {[{<<"$default">>, Arg}]}) ->
	{op_field, {_, Query}} = convert(Path, Arg),
	{op_default, Query};

	% The $text operator specifies a Lucene syntax query
	% so we just pull it in directly.
	convert(Path, {[{<<"$text">>, Query}]}) when is_binary(Query) ->
	{op_field, {make_field(Path, Query), value_str(Query)}};

	% The MongoDB docs for $all are super confusing and read more
	% like they screwed up the implementation of this operator
	% and then just documented it as a feature.
	%
	% This implementation will match the behavior as closely as
	% possible based on the available docs but we'll need to have
	% the testing team validate how MongoDB handles edge conditions
	convert(Path, {[{<<"$all">>, Args}]}) ->
	case Args of
	[Values] when is_list(Values) ->
	% If Args is a single element array then we have to
	% either match if Path is that array or if it contains
	% the array as an element of an array (which isn't at all
	% confusing). For Lucene to return us all possible matches
	% that means we just need to search for each value in
	% Path.[] and Path.[].[] and rely on our filtering to limit
	% the results properly.
	Fields1 = convert(Path, {[{<<"$eq">> , Values}]}),
	Fields2 = convert([<<"[]">>\| Path], {[{<<"$eq">> , Values}]}),
	{op_or, [Fields1, Fields2]};
	_ ->
	% Otherwise the $all operator is equivalent to an $and
	% operator so we treat it as such.
	convert([<<"[]">> \| Path], {[{<<"$and">>, Args}]})
	end;

	% The $elemMatch Lucene query is not an exact translation
	% as we can't enforce that the matches are all for the same
	% item in an array. We just rely on the final selector match
	% to filter out anything that doesn't match. The only trick
	% is that we have to add the `[]` path element since the docs
	% say this has to match against an array.
	convert(Path, {[{<<"$elemMatch">>, Arg}]}) ->
	convert([<<"[]">> \| Path], Arg);

	% Our comparison operators are fairly straight forward
	convert(Path, {[{<<"$lt">>, Arg}]}) when is_list(Arg); is_tuple(Arg);
	Arg =:= null ->
	field_exists_query(Path);
	convert(Path, {[{<<"$lt">>, Arg}]}) ->
	{op_field, {make_field(Path, Arg), range(lt, Arg)}};
	convert(Path, {[{<<"$lte">>, Arg}]}) when is_list(Arg); is_tuple(Arg);
	Arg =:= null->
	field_exists_query(Path);
	convert(Path, {[{<<"$lte">>, Arg}]}) ->
	{op_field, {make_field(Path, Arg), range(lte, Arg)}};
	%% This is for indexable_fields
	convert(Path, {[{<<"$eq">>, Arg}]}) when Arg =:= null ->
	{op_null, {make_field(Path, Arg), value_str(Arg)}};
	convert(Path, {[{<<"$eq">>, Args}]}) when is_list(Args) ->
	Path0 = [<<"[]">> \| Path],
	LPart = {op_field, {make_field(Path0, length), value_str(length(Args))}},
	Parts0 = [convert(Path0, {[{<<"$eq">>, Arg}]}) \|\| Arg <- Args],
	Parts = [LPart \| Parts0],
	{op_and, Parts};
	convert(Path, {[{<<"$eq">>, {_} = Arg}]}) ->
	convert(Path, Arg);
	convert(Path, {[{<<"$eq">>, Arg}]}) ->
	{op_field, {make_field(Path, Arg), value_str(Arg)}};
	convert(Path, {[{<<"$ne">>, Arg}]}) ->
	{op_not, {field_exists_query(Path), convert(Path, {[{<<"$eq">>, Arg}]})}};
	convert(Path, {[{<<"$gte">>, Arg}]}) when is_list(Arg); is_tuple(Arg);
	Arg =:= null ->
	field_exists_query(Path);
	convert(Path, {[{<<"$gte">>, Arg}]}) ->
	{op_field, {make_field(Path, Arg), range(gte, Arg)}};
	convert(Path, {[{<<"$gt">>, Arg}]}) when is_list(Arg); is_tuple(Arg);
	Arg =:= null->
	field_exists_query(Path);
	convert(Path, {[{<<"$gt">>, Arg}]}) ->
	{op_field, {make_field(Path, Arg), range(gt, Arg)}};

	convert(Path, {[{<<"$in">>, Args}]}) ->
	{op_or, convert_in(Path, Args)};

	convert(Path, {[{<<"$nin">>, Args}]}) ->
	{op_not, {field_exists_query(Path), convert(Path, {[{<<"$in">>, Args}]})}};

	convert(Path, {[{<<"$exists">>, ShouldExist}]}) ->
	FieldExists = field_exists_query(Path),
	case ShouldExist of
	true -> FieldExists;
	false -> {op_not, {FieldExists, false}}
	end;

	% We're not checking the actual type here, just looking for
	% anything that has a possibility of matching by checking
	% for the field name. We use the same logic for $exists on
	% the actual query.
	convert(Path, {[{<<"$type">>, _}]}) ->
	field_exists_query(Path);

	convert(Path, {[{<<"$mod">>, _}]}) ->
	field_exists_query(Path, "number");

	% The lucene regular expression engine does not use java's regex engine but
	% instead a custom implementation. The syntax is therefore different, so we do
	% would get different behavior than our view indexes. To be consistent, we will
	% simply return docs for fields that exist and then run our match filter.
	convert(Path, {[{<<"$regex">>, _}]}) ->
	field_exists_query(Path, "string");

	convert(Path, {[{<<"$size">>, Arg}]}) ->
	{op_field, {make_field([<<"[]">> \| Path], length), value_str(Arg)}};

	% All other operators are internal assertion errors for
	% matching because we either should've removed them during
	% normalization or something else broke.
	convert(_Path, {[{<<"$", _/binary>>=Op, _}]}) ->
	?MANGO_ERROR({invalid_operator, Op});

	% We've hit a field name specifier. Check if the field name is accessing
	% arrays. Convert occurrences of element position references to .[]. Then we
	% need to break the name into path parts and continue our conversion.
	convert(Path, {[{Field0, Cond}]}) ->
	{ok, PP0} = case Field0 of
	<<>> ->
	{ok, []};
	_ ->
	mango_util:parse_field(Field0)
	end,
	% Later on, we perform a lucene_escape_user call on the
	% final Path, which calls parse_field again. Calling the function
	% twice converts <<"a\\.b">> to [<<"a">>,<<"b">>]. This leads to
	% an incorrect query since we need [<<"a.b">>]. Without breaking
	% our escaping mechanism, we simply revert this first parse_field
	% effect and replace instances of "." to "\\.".
	MP = mango_util:cached_re(mango_period, ?PERIOD),
	PP1 = [re:replace(P, MP, <<"\\\\.">>,
	[global,{return,binary}]) \|\| P <- PP0],
	{PP2, HasInteger} = replace_array_indexes(PP1, [], false),
	NewPath = PP2 ++ Path,
	case HasInteger of
	true ->
	OldPath = lists:reverse(PP1, Path),
	OldParts = convert(OldPath, Cond),
	NewParts = convert(NewPath, Cond),
	{op_or, [OldParts, NewParts]};
	false ->
	convert(NewPath, Cond)
	end;

	%% For $in
	convert(Path, Val) when is_binary(Val); is_number(Val); is_boolean(Val) ->
	{op_field, {make_field(Path, Val), value_str(Val)}};

	% Anything else is a bad selector.
	convert(_Path, {Props} = Sel) when length(Props) > 1 ->
	erlang:error({unnormalized_selector, Sel}).


	to_query({op_and, Args}) when is_list(Args) ->
	QueryArgs = lists:map(fun to_query/1, Args),
	["(", mango_util:join(<<" AND ">>, QueryArgs), ")"];

	to_query({op_or, Args}) when is_list(Args) ->
	["(", mango_util:join(" OR ", lists:map(fun to_query/1, Args)), ")"];

	to_query({op_not, {ExistsQuery, Arg}}) when is_tuple(Arg) ->
	["(", to_query(ExistsQuery), " AND NOT (", to_query(Arg), "))"];

	%% For $exists:false
	to_query({op_not, {ExistsQuery, false}}) ->
	["($fieldnames:/.*/ ", " AND NOT (", to_query(ExistsQuery), "))"];

	to_query({op_insert, Arg}) when is_binary(Arg) ->
	["(", Arg, ")"];

	%% We escape : and / for now for values and all lucene chars for fieldnames
	%% This needs to be resolved.
	to_query({op_field, {Name, Value}}) ->
	NameBin = iolist_to_binary(Name),
	["(", mango_util:lucene_escape_user(NameBin), ":", Value, ")"];

	%% This is for indexable_fields
	to_query({op_null, {Name, Value}}) ->
	NameBin = iolist_to_binary(Name),
	["(", mango_util:lucene_escape_user(NameBin), ":", Value, ")"];

	to_query({op_fieldname, {Name, Wildcard}}) ->
	NameBin = iolist_to_binary(Name),
	["($fieldnames:", mango_util:lucene_escape_user(NameBin), Wildcard, ")"];

	to_query({op_default, Value}) ->
	["($default:", Value, ")"].


	%% We match on fieldname and fieldname.[]
	convert_in(Path, Args) ->
	Path0 = [<<"[]">> \| Path],
	lists:map(fun(Arg) ->
	case Arg of
	{Object} ->
	Parts = lists:map(fun (SubObject) ->
	Fields1 = convert(Path, {[SubObject]}),
	Fields2 = convert(Path0, {[SubObject]}),
	{op_or, [Fields1, Fields2]}
	end, Object),
	{op_or, Parts};
	SingleVal ->
	Fields1 = {op_field, {make_field(Path, SingleVal),
	value_str(SingleVal)}},
	Fields2 = {op_field, {make_field(Path0, SingleVal),
	value_str(SingleVal)}},
	{op_or, [Fields1, Fields2]}
	end
	end, Args).


	make_field(Path, length) ->
	[path_str(Path), <<":length">>];
	make_field(Path, Arg) ->
	[path_str(Path), <<":">>, type_str(Arg)].


	range(lt, Arg) ->
	Min = get_range(min, Arg),
	[<<"[", Min/binary, " TO ">>, value_str(Arg), <<"}">>];
	range(lte, Arg) ->
	Min = get_range(min, Arg),
	[<<"[", Min/binary, " TO ">>, value_str(Arg), <<"]">>];
	range(gte, Arg) ->
	Max = get_range(max, Arg),
	[<<"[">>, value_str(Arg), <<" TO ", Max/binary, "]">>];
	range(gt, Arg) ->
	Max = get_range(max, Arg),
	[<<"{">>, value_str(Arg), <<" TO ", Max/binary, "]">>].

	get_range(min, Arg) when is_number(Arg) ->
	<<"-Infinity">>;
	get_range(min, _Arg) ->
	<<"\"\"">>;
	get_range(max, Arg) when is_number(Arg) ->
	<<"Infinity">>;
	get_range(max, _Arg) ->
	<<"\u0x10FFFF">>.


	field_exists_query(Path) ->
	% We specify two here for :* and .* so that we don't incorrectly
	% match a path foo.name against foo.name_first (if were to just
	% appened * isntead).
	Parts = [
	% We need to remove the period from the path list to indicate that it is
	% a path separator. We escape the colon because it is not used as a
	% separator and we escape colons in field names.
	{op_fieldname, {[path_str(Path), ":"], "*"}},
	{op_fieldname, {[path_str(Path)], ".*"}}
	],
	{op_or, Parts}.


	field_exists_query(Path, Type) ->
	{op_fieldname, {[path_str(Path), ":"], Type}}.


	path_str(Path) ->
	path_str(Path, []).


	path_str([], Acc) ->
	Acc;
	path_str([Part], Acc) ->
	% No reverse because Path is backwards
	% during recursion of convert.
	[Part \| Acc];
	path_str([Part \| Rest], Acc) ->
	case Part of
	% do not append a period if Part is blank
	<<>> ->
	path_str(Rest, [Acc]);
	_ ->
	path_str(Rest, [<<".">>, Part \| Acc])
	end.


	type_str(Value) when is_number(Value) ->
	<<"number">>;
	type_str(Value) when is_boolean(Value) ->
	<<"boolean">>;
	type_str(Value) when is_binary(Value) ->
	<<"string">>;
	type_str(null) ->
	<<"null">>.


	value_str(Value) when is_binary(Value) ->
	case mango_util:is_number_string(Value) of
	true ->
	<<"\"", Value/binary, "\"">>;
	false ->
	mango_util:lucene_escape_query_value(Value)
	end;
	value_str(Value) when is_integer(Value) ->
	list_to_binary(integer_to_list(Value));
	value_str(Value) when is_float(Value) ->
	list_to_binary(float_to_list(Value));
	value_str(true) ->
	<<"true">>;
	value_str(false) ->
	<<"false">>;
	value_str(null) ->
	<<"true">>.


	append_sort_type(RawSortField, Selector) ->
	EncodeField = mango_util:lucene_escape_user(RawSortField),
	String = mango_util:has_suffix(EncodeField, <<"_3astring">>),
	Number = mango_util:has_suffix(EncodeField, <<"_3anumber">>),
	case {String, Number} of
	{true, _} ->
	<<EncodeField/binary, "<string>">>;
	{_, true} ->
	<<EncodeField/binary, "<number>">>;
	_ ->
	Type = get_sort_type(RawSortField, Selector),
	<<EncodeField/binary, Type/binary>>
	end.


	get_sort_type(Field, Selector) ->
	Types = get_sort_types(Field, Selector, []),
	case lists:usort(Types) of
	[str] -> <<"_3astring<string>">>;
	[num] -> <<"_3anumber<number>">>;
	_ -> ?MANGO_ERROR({text_sort_error, Field})
	end.


	get_sort_types(Field, {[{Field, {[{<<"$", _/binary>>, Cond}]}}]}, Acc)
	when is_binary(Cond) ->
	[str \| Acc];

	get_sort_types(Field, {[{Field, {[{<<"$", _/binary>>, Cond}]}}]}, Acc)
	when is_number(Cond) ->
	[num \| Acc];

	get_sort_types(Field, {[{_, Cond}]}, Acc) when is_list(Cond) ->
	lists:foldl(fun(Arg, InnerAcc) ->
	get_sort_types(Field, Arg, InnerAcc)
	end, Acc, Cond);

	get_sort_types(Field, {[{_, Cond}]}, Acc) when is_tuple(Cond)->
	get_sort_types(Field, Cond, Acc);

	get_sort_types(_Field, _, Acc) ->
	Acc.


	replace_array_indexes([], NewPartsAcc, HasIntAcc) ->
	{NewPartsAcc, HasIntAcc};
	replace_array_indexes([Part \| Rest], NewPartsAcc, HasIntAcc) ->
	{NewPart, HasInt} = try
	_ = list_to_integer(binary_to_list(Part)),
	{<<"[]">>, true}
	catch _:_ ->
	{Part, false}
	end,
	replace_array_indexes(Rest, [NewPart \| NewPartsAcc],
	HasInt or HasIntAcc).