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% 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_sort).
-export([
new/1,
to_json/1,
fields/1,
directions/1
]).
-include("mango.hrl").
new(Fields) when is_list(Fields) ->
Sort = {[sort_field(Field) || Field <- Fields]},
validate(Sort),
{ok, Sort};
new(Else) ->
?MANGO_ERROR({invalid_sort_json, Else}).
to_json({Fields}) ->
to_json(Fields);
to_json([]) ->
[];
to_json([{Name, Dir} | Rest]) ->
[{[{Name, Dir}]} | to_json(Rest)].
fields({Props}) ->
[Name || {Name, _Dir} <- Props].
directions({Props}) ->
[Dir || {_Name, Dir} <- Props].
sort_field(<<"">>) ->
?MANGO_ERROR({invalid_sort_field, <<"">>});
sort_field(Field) when is_binary(Field) ->
{Field, <<"asc">>};
sort_field({[{Name, <<"asc">>}]}) when is_binary(Name) ->
{Name, <<"asc">>};
sort_field({[{Name, <<"desc">>}]}) when is_binary(Name) ->
{Name, <<"desc">>};
sort_field({Name, BadDir}) when is_binary(Name) ->
?MANGO_ERROR({invalid_sort_dir, BadDir});
sort_field(Else) ->
?MANGO_ERROR({invalid_sort_field, Else}).
validate({Props}) ->
% Assert each field is in the same direction
% until we support mixed direction sorts.
Dirs = [D || {_, D} <- Props],
case lists:usort(Dirs) of
[] ->
ok;
[_] ->
ok;
_ ->
?MANGO_ERROR({unsupported, mixed_sort})
end.
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