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/**
* Copyright (C) 2013 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 "mongo/db/hasher.h"
#include "mongo/db/jsobj.h"
#include "mongo/db/matcher/expression_parser.h"
#include "mongo/db/query/index_bounds.h"
#include "mongo/db/query/index_entry.h"
namespace mongo {
class CollatorInterface;
/**
* Translates expressions over fields into bounds on an index.
*/
class IndexBoundsBuilder {
public:
/**
* Describes various degrees of precision with which predicates can be evaluated based
* on the index bounds.
*
* The integer values of the enum are significant, and are assigned in order of
* increasing tightness. These values are used when we need to do comparison between two
* BoundsTightness values. Such comparisons can answer questions such as "Does predicate
* X have tighter or looser bounds than predicate Y?".
*/
enum BoundsTightness {
// Index bounds are inexact, and a fetch is required.
INEXACT_FETCH = 0,
// Index bounds are inexact, but no fetch is required
INEXACT_COVERED = 1,
// Index bounds are exact.
EXACT = 2
};
/**
* Populate the provided O.I.L. with one interval goes from MinKey to MaxKey (or vice-versa
* depending on the index direction).
*/
static void allValuesForField(const BSONElement& elt, OrderedIntervalList* out);
/**
* Turn the MatchExpression in 'expr' into a set of index bounds. The field that 'expr' is
* concerned with is indexed according to the keypattern element 'elt' from index 'index'.
*
* If 'expr' is elemMatch, the index tag is affixed to a child.
*
* The expression must be a predicate over one field. That is, expr->isLeaf() or
* expr->isArray() must be true, and expr->isLogical() must be false.
*/
static void translate(const MatchExpression* expr,
const BSONElement& elt,
const IndexEntry& index,
OrderedIntervalList* oilOut,
BoundsTightness* tightnessOut);
/**
* Creates bounds for 'expr' (indexed according to 'elt'). Intersects those bounds
* with the bounds in oilOut, which is an in/out parameter.
*/
static void translateAndIntersect(const MatchExpression* expr,
const BSONElement& elt,
const IndexEntry& index,
OrderedIntervalList* oilOut,
BoundsTightness* tightnessOut);
/**
* Creates bounds for 'expr' (indexed according to 'elt'). Unions those bounds
* with the bounds in oilOut, which is an in/out parameter.
*/
static void translateAndUnion(const MatchExpression* expr,
const BSONElement& elt,
const IndexEntry& index,
OrderedIntervalList* oilOut,
BoundsTightness* tightnessOut);
/**
* Make a range interval from the provided object.
* The object must have exactly two fields. The first field is the start, the second the
* end.
* The two inclusive flags indicate whether or not the start/end fields are included in the
* interval (closed interval if included, open if not).
*/
static Interval makeRangeInterval(const BSONObj& obj, bool startInclusive, bool endInclusive);
static Interval makeRangeInterval(const std::string& start,
const std::string& end,
bool startInclusive,
bool endInclusive);
/**
* Make a point interval from the provided object.
* The object must have exactly one field which is the value of the point interval.
*/
static Interval makePointInterval(const BSONObj& obj);
static Interval makePointInterval(const std::string& str);
static Interval makePointInterval(double d);
/**
* Wraps 'elt' in a BSONObj with an empty field name and returns the result. If 'elt' is a
* string, and 'collator' is non-null, the result contains the collator-generated comparison key
* rather than the original string.
*/
static BSONObj objFromElement(const BSONElement& elt, const CollatorInterface* collator);
/**
* Swap start/end in the provided interval.
*/
static void reverseInterval(Interval* ival);
/**
* Returns a std::string that when used as a matcher, would match a superset of regex. Used to
* optimize queries in some simple regex cases that start with '^'.
*
* Returns "" for complex regular expressions that cannot use tight index bounds.
*/
static std::string simpleRegex(const char* regex,
const char* flags,
const IndexEntry& index,
BoundsTightness* tightnessOut);
/**
* Returns an Interval from minKey to maxKey
*/
static Interval allValues();
static void translateRegex(const RegexMatchExpression* rme,
const IndexEntry& index,
OrderedIntervalList* oil,
BoundsTightness* tightnessOut);
static void translateEquality(const BSONElement& data,
const IndexEntry& index,
bool isHashed,
OrderedIntervalList* oil,
BoundsTightness* tightnessOut);
static void unionize(OrderedIntervalList* oilOut);
static void intersectize(const OrderedIntervalList& arg, OrderedIntervalList* oilOut);
/**
* Fills out 'bounds' with the bounds for an index scan over all values of the
* index described by 'keyPattern' in the default forward direction.
*/
static void allValuesBounds(const BSONObj& keyPattern, IndexBounds* bounds);
/**
* Assumes each OIL in 'bounds' is increasing.
*
* Aligns OILs (and bounds) according to the 'kp' direction * the scanDir.
*/
static void alignBounds(IndexBounds* bounds, const BSONObj& kp, int scanDir = 1);
/**
* Returns 'true' if the bounds 'bounds' can be represented as one interval between
* 'startKey' and 'endKey'. Inclusivity of each bound is set through the relevant
* (name)KeyInclusive parameter. Returns 'false' if otherwise.
*/
static bool isSingleInterval(const IndexBounds& bounds,
BSONObj* startKey,
bool* startKeyInclusive,
BSONObj* endKey,
bool* endKeyInclusive);
};
} // namespace mongo
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