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// expression_parser.h
/**
* 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/base/status.h"
#include "mongo/base/status_with.h"
#include "mongo/db/matcher/expression.h"
#include "mongo/db/matcher/expression_leaf.h"
#include "mongo/db/matcher/expression_tree.h"
#include "mongo/stdx/functional.h"
namespace mongo {
class OperationContext;
typedef StatusWith<MatchExpression*> StatusWithMatchExpression;
class MatchExpressionParser {
public:
/**
* In general, expression parsing and matching should not require context, but the $where
* clause is an exception in that it needs to read the sys.js collection.
*
* The default behaviour is to return an error status that $where context is not present.
*
* Do not use this class to pass-in generic context as it should only be used for $where.
*/
class WhereCallback {
public:
virtual StatusWithMatchExpression parseWhere(const BSONElement& where) const;
virtual ~WhereCallback() { }
};
/**
* caller has to maintain ownership obj
* the tree has views (BSONElement) into obj
*/
static StatusWithMatchExpression parse(
const BSONObj& obj,
const WhereCallback& whereCallback = WhereCallback()) {
// The 0 initializes the match expression tree depth.
return MatchExpressionParser(&whereCallback)._parse(obj, 0);
}
private:
explicit MatchExpressionParser(const WhereCallback* whereCallback)
: _whereCallback(whereCallback) {
}
/**
* 5 = false
* { a : 5 } = false
* { $lt : 5 } = true
* { $ref: "s", $id: "x" } = false
* { $ref: "s", $id: "x", $db: "mydb" } = false
* { $ref : "s" } = false (if incomplete DBRef is allowed)
* { $id : "x" } = false (if incomplete DBRef is allowed)
* { $db : "mydb" } = false (if incomplete DBRef is allowed)
*/
bool _isExpressionDocument( const BSONElement& e, bool allowIncompleteDBRef );
/**
* { $ref: "s", $id: "x" } = true
* { $ref : "s" } = true (if incomplete DBRef is allowed)
* { $id : "x" } = true (if incomplete DBRef is allowed)
* { $db : "x" } = true (if incomplete DBRef is allowed)
*/
bool _isDBRefDocument( const BSONObj& obj, bool allowIncompleteDBRef );
/**
* Parse 'obj' and return either a MatchExpression or an error.
*
* 'level' tracks the current depth of the tree across recursive calls to this
* function. Used in order to apply special logic at the top-level and to return an
* error if the tree exceeds the maximum allowed depth.
*/
StatusWithMatchExpression _parse( const BSONObj& obj, int level );
/**
* parses a field in a sub expression
* if the query is { x : { $gt : 5, $lt : 8 } }
* e is { $gt : 5, $lt : 8 }
*/
Status _parseSub( const char* name,
const BSONObj& obj,
AndMatchExpression* root,
int level );
/**
* parses a single field in a sub expression
* if the query is { x : { $gt : 5, $lt : 8 } }
* e is $gt : 5
*/
StatusWithMatchExpression _parseSubField( const BSONObj& context,
const AndMatchExpression* andSoFar,
const char* name,
const BSONElement& e,
int level );
StatusWithMatchExpression _parseComparison( const char* name,
ComparisonMatchExpression* cmp,
const BSONElement& e );
StatusWithMatchExpression _parseMOD( const char* name,
const BSONElement& e );
StatusWithMatchExpression _parseRegexElement( const char* name,
const BSONElement& e );
StatusWithMatchExpression _parseRegexDocument( const char* name,
const BSONObj& doc );
Status _parseArrayFilterEntries( ArrayFilterEntries* entries,
const BSONObj& theArray );
// arrays
StatusWithMatchExpression _parseElemMatch( const char* name,
const BSONElement& e,
int level );
StatusWithMatchExpression _parseAll( const char* name,
const BSONElement& e,
int level );
// tree
Status _parseTreeList( const BSONObj& arr, ListOfMatchExpression* out, int level );
StatusWithMatchExpression _parseNot( const char* name,
const BSONElement& e,
int level );
// The maximum allowed depth of a query tree. Just to guard against stack overflow.
static const int kMaximumTreeDepth;
// Performs parsing for the $where clause. We do not own this pointer - it has to live
// as long as the parser is active.
const WhereCallback* _whereCallback;
};
/**
* This implementation is used for the server-side code.
*/
class WhereCallbackReal : public MatchExpressionParser::WhereCallback {
public:
/**
* The OperationContext passed here is not owned, but just referenced. It gets assigned to
* any $where parsers, which this callback generates. Therefore, the op context must only
* be destroyed after these parsers and their clones (shallowClone) have been destroyed.
*/
WhereCallbackReal(OperationContext* txn, const StringData& dbName);
virtual StatusWithMatchExpression parseWhere(const BSONElement& where) const;
private:
// Not owned here
OperationContext* const _txn;
const StringData _dbName;
};
/**
* This is just a pass-through implementation, used by sharding only.
*/
class WhereCallbackNoop : public MatchExpressionParser::WhereCallback {
public:
WhereCallbackNoop();
virtual StatusWithMatchExpression parseWhere(const BSONElement& where) const;
};
typedef stdx::function<StatusWithMatchExpression(const char* name, int type, const BSONObj& section)> MatchExpressionParserGeoCallback;
extern MatchExpressionParserGeoCallback expressionParserGeoCallback;
typedef stdx::function<StatusWithMatchExpression(const BSONObj& queryObj)> MatchExpressionParserTextCallback;
extern MatchExpressionParserTextCallback expressionParserTextCallback;
}
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