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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
#include <fmt/format.h>
#include "mongo/db/exec/projection_executor_utils.h"
#include "mongo/db/matcher/copyable_match_expression.h"
#include "mongo/db/pipeline/expression.h"
namespace mongo {
/**
* An internal expression to apply a find positional projection to the projection post image
* document. This expression is never parsed or serialized.
*
* See projection_executor::applyPositionalProjection() for more details.
*/
class ExpressionInternalFindPositional final : public Expression {
public:
ExpressionInternalFindPositional(const boost::intrusive_ptr<ExpressionContext>& expCtx,
boost::intrusive_ptr<Expression> preImageExpr,
boost::intrusive_ptr<Expression> postImageExpr,
FieldPath path,
CopyableMatchExpression matchExpr)
: Expression{expCtx, {preImageExpr, postImageExpr}},
_path{std::move(path)},
_matchExpr{std::move(matchExpr)} {}
Value evaluate(const Document& root, Variables* variables) const final {
using namespace fmt::literals;
auto preImage = _children[0]->evaluate(root, variables);
auto postImage = _children[1]->evaluate(root, variables);
uassert(51255,
"Positional operator pre-image can only be an object, but got {}"_format(
typeName(preImage.getType())),
preImage.getType() == BSONType::Object);
uassert(51258,
"Positional operator post-image can only be an object, but got {}"_format(
typeName(postImage.getType())),
postImage.getType() == BSONType::Object);
return Value{projection_executor_utils::applyFindPositionalProjection(
preImage.getDocument(), postImage.getDocument(), *_matchExpr, _path)};
}
void acceptVisitor(ExpressionVisitor* visitor) final {
return visitor->visit(this);
}
Value serialize(bool explain) const final {
MONGO_UNREACHABLE;
}
ComputedPaths getComputedPaths(const std::string& exprFieldPath,
Variables::Id renamingVar = Variables::kRootId) const final {
// The positional projection can change any field within the path it's applied to, so we'll
// treat the first component in '_positionalInfo.path' as the computed path.
return {{_path.front().toString()}, {}};
}
boost::intrusive_ptr<Expression> optimize() final {
for (const auto& child : _children) {
child->optimize();
}
// SERVER-43740: ideally we'd want to optimize '_matchExpr' here as well. However, given
// that the match expression is stored as a shared copyable expression in this class, and
// 'MatchExpression::optimize()' takes and returns a unique pointer on a match expression,
// there is no easy way to replace a copyable match expression with its optimized
// equivalent. So, for now we will assume that the copyable match expression is passed to
// this expression already optimized. Once we have MatchExpression and Expression combined,
// we should revisit this code and make sure that 'optimized()' method is called on
// _matchExpr.
return this;
}
protected:
void _doAddDependencies(DepsTracker* deps) const final {
for (const auto& child : _children) {
child->addDependencies(deps);
}
_matchExpr->addDependencies(deps);
deps->needWholeDocument = true;
}
private:
const FieldPath _path;
const CopyableMatchExpression _matchExpr;
};
/**
* An internal expression to apply a find $slice projection to the projection post image document.
* This expression is never parsed or serialized.
*
* See projection_executor::applySliceProjection() for more details.
*/
class ExpressionInternalFindSlice final : public Expression {
public:
ExpressionInternalFindSlice(const boost::intrusive_ptr<ExpressionContext>& expCtx,
boost::intrusive_ptr<Expression> postImageExpr,
FieldPath path,
boost::optional<int> skip,
int limit)
: Expression{expCtx, {postImageExpr}}, _path{std::move(path)}, _skip{skip}, _limit{limit} {}
Value evaluate(const Document& root, Variables* variables) const final {
using namespace fmt::literals;
auto postImage = _children[0]->evaluate(root, variables);
uassert(51256,
"$slice operator can only be applied to an object, but got {}"_format(
typeName(postImage.getType())),
postImage.getType() == BSONType::Object);
return Value{projection_executor_utils::applyFindSliceProjection(
postImage.getDocument(), _path, _skip, _limit)};
}
void acceptVisitor(ExpressionVisitor* visitor) final {
return visitor->visit(this);
}
Value serialize(bool explain) const final {
MONGO_UNREACHABLE;
}
ComputedPaths getComputedPaths(const std::string& exprFieldPath,
Variables::Id renamingVar = Variables::kRootId) const final {
// The $slice projection can change any field within the path it's applied to, so we'll
// treat the first component in '_sliceInfo.path' as the computed path.
return {{_path.front().toString()}, {}};
}
boost::intrusive_ptr<Expression> optimize() final {
invariant(_children.size() == 1ul);
_children[0]->optimize();
return this;
}
protected:
void _doAddDependencies(DepsTracker* deps) const final {
invariant(_children.size() == 1ul);
_children[0]->addDependencies(deps);
deps->needWholeDocument = true;
}
private:
const FieldPath _path;
const boost::optional<int> _skip;
const int _limit;
};
/**
* An internal expression to apply a find $elemMatch projection to the document root.
* See projection_executor::applyElemMatchProjection() for details.
*/
class ExpressionInternalFindElemMatch final : public Expression {
public:
ExpressionInternalFindElemMatch(const boost::intrusive_ptr<ExpressionContext>& expCtx,
boost::intrusive_ptr<Expression> child,
FieldPath path,
CopyableMatchExpression matchExpr)
: Expression{expCtx, {child}}, _path{std::move(path)}, _matchExpr{std::move(matchExpr)} {}
Value evaluate(const Document& root, Variables* variables) const final {
using namespace fmt::literals;
auto input = _children[0]->evaluate(root, variables);
uassert(51253,
"$elemMatch operator can only be applied to an object, but got {}"_format(
typeName(input.getType())),
input.getType() == BSONType::Object);
return projection_executor_utils::applyFindElemMatchProjection(
input.getDocument(), *_matchExpr, _path);
}
void acceptVisitor(ExpressionVisitor* visitor) final {
return visitor->visit(this);
}
Value serialize(bool explain) const final {
MONGO_UNREACHABLE;
}
boost::intrusive_ptr<Expression> optimize() final {
invariant(_children.size() == 1ul);
_children[0]->optimize();
// SERVER-43740: ideally we'd want to optimize '_matchExpr' here as well. However, given
// that the match expression is stored as a shared copyable expression in this class, and
// 'MatchExpression::optimize()' takes and returns a unique pointer on a match expression,
// there is no easy way to replace a copyable match expression with its optimized
// equivalent. So, for now we will assume that the copyable match expression is passed to
// this expression already optimized. Once we have MatchExpression and Expression combined,
// we should revisit this code and make sure that 'optimized()' method is called on
// _matchExpr.
return this;
}
protected:
void _doAddDependencies(DepsTracker* deps) const final {
invariant(_children.size() == 1ul);
_children[0]->addDependencies(deps);
_matchExpr->addDependencies(deps);
deps->needWholeDocument = true;
}
private:
const FieldPath _path;
const CopyableMatchExpression _matchExpr;
};
} // namespace mongo
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