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/**
* Copyright (C) 2019-present MongoDB, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the Server Side Public License, version 1,
* as published by MongoDB, Inc.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* Server Side Public License for more details.
*
* You should have received a copy of the Server Side Public License
* along with this program. If not, see
* <http://www.mongodb.com/licensing/server-side-public-license>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the Server Side Public License in all respects for
* all of the code used other than as permitted herein. If you modify file(s)
* with this exception, you may extend this exception to your version of the
* file(s), but you are not obligated to do so. If you do not wish to do so,
* delete this exception statement from your version. If you delete this
* exception statement from all source files in the program, then also delete
* it in the license file.
*/
#pragma once
namespace mongo {
struct ProjectionPolicies {
// Allows the caller to indicate whether the projection should default to including or
// excluding the _id field in the event that the projection spec does not specify the
// desired behavior. For instance, given a projection {a: 1}, specifying 'kExcludeId' is
// equivalent to projecting {a: 1, _id: 0} while 'kIncludeId' is equivalent to the
// projection {a: 1, _id: 1}. If the user explicitly specifies a projection on _id, then
// this will override the default policy; for instance, {a: 1, _id: 0} will exclude _id for
// both 'kExcludeId' and 'kIncludeId'.
enum class DefaultIdPolicy { kIncludeId, kExcludeId };
// Allows the caller to specify how the projection should handle nested arrays; that is, an
// array whose immediate parent is itself an array. For example, in the case of sample
// document {a: [1, 2, [3, 4], {b: [5, 6]}]} the array [3, 4] is a nested array. The array
// [5, 6] is not, because there is an intervening object between it and its closest array
// ancestor.
enum class ArrayRecursionPolicy { kRecurseNestedArrays, kDoNotRecurseNestedArrays };
// Allows the caller to specify whether computed fields should be allowed within inclusion
// projections. Computed fields are implicitly prohibited by exclusion projections.
enum class ComputedFieldsPolicy { kBanComputedFields, kAllowComputedFields };
// Whether $elemMatch, find() $slice and positional projection are allowed.
enum class FindOnlyFeaturesPolicy { kBanFindOnlyFeatures, kAllowFindOnlyFeatures };
// Whether the empty projection, {}, is permitted.
enum class EmptyProjectionPolicy { kBanEmptyProjection, kAllowEmptyProjection };
static const DefaultIdPolicy kDefaultIdPolicyDefault = DefaultIdPolicy::kIncludeId;
static const ArrayRecursionPolicy kArrayRecursionPolicyDefault =
ArrayRecursionPolicy::kRecurseNestedArrays;
static const ComputedFieldsPolicy kComputedFieldsPolicyDefault =
ComputedFieldsPolicy::kAllowComputedFields;
static const FindOnlyFeaturesPolicy kFindOnlyFeaturesPolicyDefault =
FindOnlyFeaturesPolicy::kBanFindOnlyFeatures;
static const EmptyProjectionPolicy kEmptyProjectionPolicyDefault =
EmptyProjectionPolicy::kBanEmptyProjection;
static ProjectionPolicies findProjectionPolicies() {
return ProjectionPolicies{kDefaultIdPolicyDefault,
kArrayRecursionPolicyDefault,
kComputedFieldsPolicyDefault,
FindOnlyFeaturesPolicy::kAllowFindOnlyFeatures,
EmptyProjectionPolicy::kAllowEmptyProjection};
}
static ProjectionPolicies aggregateProjectionPolicies() {
return ProjectionPolicies{kDefaultIdPolicyDefault,
kArrayRecursionPolicyDefault,
kComputedFieldsPolicyDefault,
FindOnlyFeaturesPolicy::kBanFindOnlyFeatures,
kEmptyProjectionPolicyDefault};
}
static ProjectionPolicies wildcardIndexSpecProjectionPolicies() {
return ProjectionPolicies{DefaultIdPolicy::kExcludeId,
ArrayRecursionPolicy::kDoNotRecurseNestedArrays,
ComputedFieldsPolicy::kBanComputedFields,
FindOnlyFeaturesPolicy::kBanFindOnlyFeatures,
kEmptyProjectionPolicyDefault};
}
static ProjectionPolicies columnStoreIndexSpecProjectionPolicies() {
return ProjectionPolicies{kDefaultIdPolicyDefault,
ArrayRecursionPolicy::kDoNotRecurseNestedArrays,
ComputedFieldsPolicy::kBanComputedFields,
FindOnlyFeaturesPolicy::kBanFindOnlyFeatures,
EmptyProjectionPolicy::kAllowEmptyProjection};
}
ProjectionPolicies(
DefaultIdPolicy idPolicy = kDefaultIdPolicyDefault,
ArrayRecursionPolicy arrayRecursionPolicy = kArrayRecursionPolicyDefault,
ComputedFieldsPolicy computedFieldsPolicy = kComputedFieldsPolicyDefault,
FindOnlyFeaturesPolicy findOnlyFeaturesPolicy = kFindOnlyFeaturesPolicyDefault,
EmptyProjectionPolicy emptyProjectionPolicy = kEmptyProjectionPolicyDefault)
: idPolicy(idPolicy),
arrayRecursionPolicy(arrayRecursionPolicy),
computedFieldsPolicy(computedFieldsPolicy),
findOnlyFeaturesPolicy(findOnlyFeaturesPolicy),
emptyProjectionPolicy(emptyProjectionPolicy) {}
const DefaultIdPolicy idPolicy;
const ArrayRecursionPolicy arrayRecursionPolicy;
const ComputedFieldsPolicy computedFieldsPolicy;
const FindOnlyFeaturesPolicy findOnlyFeaturesPolicy;
const EmptyProjectionPolicy emptyProjectionPolicy;
bool findOnlyFeaturesAllowed() const {
return findOnlyFeaturesPolicy == FindOnlyFeaturesPolicy::kAllowFindOnlyFeatures;
}
bool emptyProjectionAllowed() const {
return emptyProjectionPolicy == EmptyProjectionPolicy::kAllowEmptyProjection;
}
};
} // namespace mongo
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