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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/>.
*/
#pragma once
#include "mongo/db/matcher/expression.h"
#include "mongo/db/query/stage_types.h"
namespace mongo {
/**
* This is an abstract representation of a query plan. It can be transcribed into a tree of
* PlanStages, which can then be handed to a PlanRunner for execution.
*/
struct QuerySolutionNode {
QuerySolutionNode() { }
virtual ~QuerySolutionNode() { }
/**
* What stage should this be transcribed to? See stage_types.h.
*/
virtual StageType getType() const = 0;
/**
* Internal function called by toString()
*/
virtual void appendToString(stringstream* ss) const = 0;
private:
MONGO_DISALLOW_COPYING(QuerySolutionNode);
};
/**
* A QuerySolution must be entirely self-contained and own everything inside of it.
*
* A tree of stages may be built from a QuerySolution. The QuerySolution must outlive the tree
* of stages.
*/
struct QuerySolution {
QuerySolution() { }
// Owned here.
scoped_ptr<QuerySolutionNode> root;
// Owned here.
scoped_ptr<MatchExpression> filter;
// Any filters in root or below point into this. Must be owned.
BSONObj filterData;
/**
* Output a human-readable string representing the plan.
*/
string toString() {
if (NULL == root) {
return "empty query solution";
}
stringstream ss;
root->appendToString(&ss);
return ss.str();
}
private:
MONGO_DISALLOW_COPYING(QuerySolution);
};
struct CollectionScanNode : public QuerySolutionNode {
CollectionScanNode() : filter(NULL) { }
virtual StageType getType() const { return STAGE_COLLSCAN; }
virtual void appendToString(stringstream* ss) const {
*ss << "COLLSCAN ns=" << name << " filter= " << filter->toString() << endl;
}
string name;
// Not owned.
// This is a sub-tree of the filter in the QuerySolution that owns us.
MatchExpression* filter;
};
} // namespace mongo
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