davisp commented on a change in pull request #1376: Add fields to sort based on
selector
URL: https://github.com/apache/couchdb/pull/1376#discussion_r193521699
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File path: src/mango/src/mango_selector.erl
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@@ -638,11 +639,110 @@ has_required_fields_int([{[{Field, Cond}]} | Rest],
RequiredFields) ->
end.
+% Returns true if a field in the selector is a constant value e.g. {a: {$eq:
1}}
+is_constant_field(Selector, Field) ->
+ is_constant_field_int(Selector, Field).
+
+
+is_constant_field_int({[]}, _Field) ->
+ false;
+
+is_constant_field_int(Selector, Field) when not is_list(Selector) ->
+ is_constant_field_int([Selector], Field);
+
+is_constant_field_int([], _Field) ->
+ false;
+
+is_constant_field_int([{[{<<"$and">>, Args}]}], Field) when is_list(Args) ->
+ lists:any(fun(Arg) -> is_constant_field_int(Arg, Field) end, Args);
+
+is_constant_field_int([{[{<<"$and">>, Args}]}], Field) ->
+ is_constant_field_int(Args, Field);
+
+is_constant_field_int([{[{SelectorField, {[{Cond, _Val}]}}]} | _Rest], Field)
when SelectorField =:= Field ->
+ Cond =:= <<"$eq">>;
+
+is_constant_field_int([{[{SelectorField, _}]} | Rest], Field) when
SelectorField =/= Field ->
Review comment:
No need to use the guard here as you capture all equality cases in the
previous clause.
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