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/**
* Copyright (C) 2015 10gen Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License, version 3,
* as published by the Free Software Foundation.
*
* 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
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* 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 GNU Affero General 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
#include <vector>
#include "mongo/base/disallow_copying.h"
#include "mongo/stdx/functional.h"
#include "mongo/util/string_map.h"
namespace mongo {
class BSONObj;
class MatchExpression;
struct IndexEntry;
using IndexabilityDiscriminator = stdx::function<bool(const MatchExpression* me)>;
using IndexabilityDiscriminators = std::vector<IndexabilityDiscriminator>;
/**
* PlanCacheIndexabilityState holds a set of "indexability discriminators" for certain paths.
* An indexability discriminator is a binary predicate function, used to classify match
* expressions based on the data values in the expression.
*/
class PlanCacheIndexabilityState {
MONGO_DISALLOW_COPYING(PlanCacheIndexabilityState);
public:
PlanCacheIndexabilityState() = default;
/**
* Gets the set of discriminators associated with 'path'. Returns an empty set if no
* discriminators are registered for 'path'.
*
* The object returned by reference is valid until the next call to updateDiscriminators()
* or until destruction of 'this', whichever is first.
*/
const IndexabilityDiscriminators& getDiscriminators(StringData path) const;
/**
* Clears discriminators for all paths, and regenerate them from 'indexEntries'.
*/
void updateDiscriminators(const std::vector<IndexEntry>& indexEntries);
private:
/**
* Adds sparse index discriminators for the sparse index with the given key pattern to
* '_pathDiscriminatorsMap'.
*
* A sparse index discriminator distinguishes equality matches to null from other expression
* types. For example, this allows the predicate {a: 1} to be considered of a different
* shape from the predicate {a: null}, if there is a sparse index defined with "a" as an
* element of the key pattern. The former predicate is compatibile with this index, but the
* latter is not compatible.
*/
void processSparseIndex(const BSONObj& keyPattern);
/**
* Adds partial index discriminators for the partial index with the given filter expression
* to '_pathDiscriminatorsMap'.
*
* A partial index discriminator distinguishes expressions that match a given partial index
* predicate from expressions that don't match the partial index predicate. For example,
* this allows the predicate {a: {$gt: 5}} to be considered a different shape than the
* predicate {a: {$gt: -5}}, if there is a partial index defined with document filter {a:
* {$gt: 0}}. The former is compatible with this index, but the latter is not compatible.
*/
void processPartialIndex(const MatchExpression* filterExpr);
using PathDiscriminatorsMap = StringMap<IndexabilityDiscriminators>;
PathDiscriminatorsMap _pathDiscriminatorsMap;
};
} // namespace mongo
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