src/mango/src/mango_eval.erl

% 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_eval).
-behavior(couch_eval).


-export([
    acquire_map_context/1,
    release_map_context/1,
    map_docs/2
]).


-export([
    index_doc/2
]).


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


acquire_map_context(Opts) ->
    #{
        db_name := DbName,
        ddoc_id := DDocId,
        map_funs := MapFuns
    } = Opts,
    Indexes = lists:map(fun (Def) ->
        #idx{
            type = <<"json">>,
            dbname = DbName,
            ddoc = DDocId,
            def = Def
        }
    end, MapFuns),
    {ok, Indexes}.


release_map_context(_) ->
    ok.


map_docs(Indexes, Docs) ->
    {ok, lists:map(fun(Doc) ->
        Json = couch_doc:to_json_obj(Doc, []),
        Results = index_doc(Indexes, Json),
        {Doc#doc.id, Results}
    end, Docs)}.


index_doc(Indexes, Doc) ->
    lists:map(fun(Idx) ->
        {IdxDef} = mango_idx:def(Idx),
        Results = get_index_entries(IdxDef, Doc),
        case lists:member(not_found, Results) of
            true ->
                [];
            false ->
                [{Results, null}]
        end
    end, Indexes).


get_index_entries(IdxDef, Doc) ->
    {Fields} = couch_util:get_value(<<"fields">>, IdxDef),
    Selector = get_index_partial_filter_selector(IdxDef),
    case should_index(Selector, Doc) of
        false ->
            [not_found];
        true ->
            get_index_values(Fields, Doc)
    end.


get_index_values(Fields, Doc) ->
    lists:map(fun({Field, _Dir}) ->
        case mango_doc:get_field(Doc, Field) of
            not_found -> not_found;
            bad_path -> not_found;
            Value -> Value
        end
    end, Fields).


get_index_partial_filter_selector(IdxDef) ->
    case couch_util:get_value(<<"partial_filter_selector">>, IdxDef, {[]}) of
        {[]} ->
            % this is to support legacy text indexes that had the
            % partial_filter_selector set as selector
            couch_util:get_value(<<"selector">>, IdxDef, {[]});
        Else ->
            Else
    end.


should_index(Selector, Doc) ->
    NormSelector = mango_selector:normalize(Selector),
    Matches = mango_selector:match(NormSelector, Doc),
    IsDesign = case mango_doc:get_field(Doc, <<"_id">>) of
        <<"_design/", _/binary>> -> true;
        _ -> false
    end,
    Matches and not IsDesign.