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/**
* Copyright (C) 2022-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.
*/
#include "mongo/db/pipeline/abt/transformer_visitor.h"
#include "mongo/db/pipeline/abt/agg_expression_visitor.h"
#include "mongo/db/pipeline/abt/utils.h"
#include "mongo/db/pipeline/document_source_group.h"
#include "mongo/db/pipeline/document_source_replace_root.h"
#include "mongo/db/pipeline/visitors/transformer_interface_walker.h"
namespace mongo::optimizer {
void ABTTransformerVisitor::visit(
const projection_executor::AddFieldsProjectionExecutor* transformer) {
visitInclusionNode(transformer->getRoot(), true /*isAddingFields*/);
}
void ABTTransformerVisitor::visit(
const projection_executor::ExclusionProjectionExecutor* transformer) {
visitExclusionNode(*transformer->getRoot());
}
void ABTTransformerVisitor::visit(
const projection_executor::InclusionProjectionExecutor* transformer) {
visitInclusionNode(*transformer->getRoot(), false /*isAddingFields*/);
}
void ABTTransformerVisitor::visit(const GroupFromFirstDocumentTransformation* transformer) {
unsupportedTransformer(transformer);
}
void ABTTransformerVisitor::visit(const ReplaceRootTransformation* transformer) {
auto entry = _ctx.getNode();
const ProjectionName projName{_ctx.getNextId("newRoot")};
ABT expr = generateAggExpression(
transformer->getExpression().get(), entry._rootProjection, _ctx.getPrefixId());
_ctx.setNode<EvaluationNode>(projName, projName, std::move(expr), std::move(entry._node));
}
void ABTTransformerVisitor::generateCombinedProjection() const {
auto result = _builder.generateABT();
// ReplaceRootTransformer won't integrate any paths using the field map builder.
if (!result) {
return;
}
auto entry = _ctx.getNode();
const ProjectionName projName = _ctx.getNextId("combinedProjection");
_ctx.setNode<EvaluationNode>(projName, projName, std::move(*result), std::move(entry._node));
}
void ABTTransformerVisitor::unsupportedTransformer(const TransformerInterface* transformer) const {
uasserted(ErrorCodes::InternalErrorNotSupported,
str::stream() << "Transformer is not supported (code: "
<< static_cast<int>(transformer->getType()) << ")");
}
void ABTTransformerVisitor::assertSupportedPath(const std::string& path) {
uassert(ErrorCodes::InternalErrorNotSupported,
"Projection contains unsupported numeric path component",
!FieldRef(path).hasNumericPathComponents());
}
/**
* Handles simple inclusion projections.
*/
void ABTTransformerVisitor::processProjectedPaths(const projection_executor::InclusionNode& node) {
// For each preserved path, mark that each path element along the field path should be
// included.
OrderedPathSet preservedPaths;
node.reportProjectedPaths(&preservedPaths);
for (const std::string& preservedPathStr : preservedPaths) {
assertSupportedPath(preservedPathStr);
_builder.integrateFieldPath(FieldPath(preservedPathStr),
[](const bool isLastElement, FieldMapEntry& entry) {
entry._hasLeadingObj = true;
entry._hasKeep = true;
});
}
}
/**
* Handles renamed fields and computed projections.
*/
void ABTTransformerVisitor::processComputedPaths(const projection_executor::InclusionNode& node,
const ProjectionName& rootProjection,
const bool isAddingFields) {
OrderedPathSet computedPaths;
StringMap<std::string> renamedPaths;
node.reportComputedPaths(&computedPaths, &renamedPaths);
// Handle path renames: essentially single element FieldPath expression.
for (const auto& renamedPathEntry : renamedPaths) {
ABT path = translateFieldPath(
FieldPath(renamedPathEntry.second),
make<PathIdentity>(),
[](FieldNameType fieldName, const bool isLastElement, ABT input) {
return make<PathGet>(
std::move(fieldName),
isLastElement ? std::move(input)
: make<PathTraverse>(PathTraverse::kUnlimited, std::move(input)));
});
auto entry = _ctx.getNode();
const ProjectionName renamedProjName{_ctx.getNextId("projRenamedPath")};
_ctx.setNode<EvaluationNode>(
entry._rootProjection,
renamedProjName,
make<EvalPath>(std::move(path), make<Variable>(entry._rootProjection)),
std::move(entry._node));
_builder.integrateFieldPath(
FieldPath(renamedPathEntry.first),
[&renamedProjName, &isAddingFields](const bool isLastElement, FieldMapEntry& entry) {
if (!isAddingFields) {
entry._hasKeep = true;
}
if (isLastElement) {
entry._constVarName = renamedProjName;
entry._hasTrailingDefault = true;
}
});
}
// Handle general expression projection.
for (const std::string& computedPathStr : computedPaths) {
assertSupportedPath(computedPathStr);
const FieldPath computedPath(computedPathStr);
auto entry = _ctx.getNode();
const ProjectionName getProjName{_ctx.getNextId("projGetPath")};
ABT getExpr = generateAggExpression(
node.getExpressionForPath(computedPath).get(), rootProjection, _ctx.getPrefixId());
_ctx.setNode<EvaluationNode>(std::move(entry._rootProjection),
getProjName,
std::move(getExpr),
std::move(entry._node));
_builder.integrateFieldPath(
computedPath,
[&getProjName, &isAddingFields](const bool isLastElement, FieldMapEntry& entry) {
if (!isAddingFields) {
entry._hasKeep = true;
}
if (isLastElement) {
entry._constVarName = getProjName;
entry._hasTrailingDefault = true;
}
});
}
}
void ABTTransformerVisitor::visitInclusionNode(const projection_executor::InclusionNode& node,
const bool isAddingFields) {
auto entry = _ctx.getNode();
const ProjectionName rootProjection{entry._rootProjection};
processProjectedPaths(node);
processComputedPaths(node, rootProjection, isAddingFields);
}
void ABTTransformerVisitor::visitExclusionNode(const projection_executor::ExclusionNode& node) {
// Handle simple exclusion projections: for each excluded path, mark that the last field
// path element should be dropped.
OrderedPathSet excludedPaths;
node.reportProjectedPaths(&excludedPaths);
for (const std::string& excludedPathStr : excludedPaths) {
assertSupportedPath(excludedPathStr);
_builder.integrateFieldPath(FieldPath(excludedPathStr),
[](const bool isLastElement, FieldMapEntry& entry) {
if (isLastElement) {
entry._hasDrop = true;
}
});
}
}
void translateProjection(AlgebrizerContext& ctx,
ProjectionName scanProjName,
boost::intrusive_ptr<ExpressionContext> expCtx,
const projection_ast::Projection* proj) {
const auto projExecutor = projection_executor::buildProjectionExecutor(
expCtx,
proj,
ProjectionPolicies::findProjectionPolicies(),
projection_executor::BuilderParamsBitSet{projection_executor::kDefaultBuilderParams});
FieldMapBuilder builder(scanProjName, true);
ABTTransformerVisitor visitor(ctx, builder);
TransformerInterfaceWalker walker(&visitor);
walker.walk(projExecutor.get());
visitor.generateCombinedProjection();
}
} // namespace mongo::optimizer
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