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/**
* Copyright (C) 2018-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/platform/basic.h"
#include "mongo/db/pipeline/parsed_inclusion_projection.h"
#include <algorithm>
namespace mongo {
namespace parsed_aggregation_projection {
//
// InclusionNode
//
InclusionNode::InclusionNode(ProjectionPolicies policies, std::string pathToNode)
: ProjectionNode(policies, std::move(pathToNode)) {}
InclusionNode* InclusionNode::addOrGetChild(const std::string& field) {
return static_cast<InclusionNode*>(ProjectionNode::addOrGetChild(field));
}
void InclusionNode::reportDependencies(DepsTracker* deps) const {
for (auto&& includedField : _projectedFields) {
deps->fields.insert(FieldPath::getFullyQualifiedPath(_pathToNode, includedField));
}
if (!_pathToNode.empty() && !_expressions.empty()) {
// The shape of any computed fields in the output will change depending on if the field is
// an array or not, so in addition to any dependencies of the expression itself, we need to
// add this field to our dependencies.
deps->fields.insert(_pathToNode);
}
for (auto&& expressionPair : _expressions) {
expressionPair.second->addDependencies(deps);
}
for (auto&& childPair : _children) {
childPair.second->reportDependencies(deps);
}
}
//
// ParsedInclusionProjection
//
void ParsedInclusionProjection::parse(const BSONObj& spec) {
// It is illegal to specify an inclusion with no output fields.
bool atLeastOneFieldInOutput = false;
// Tracks whether or not we should apply the default _id projection policy.
bool idSpecified = false;
for (auto elem : spec) {
auto fieldName = elem.fieldNameStringData();
idSpecified = idSpecified || fieldName == "_id"_sd || fieldName.startsWith("_id."_sd);
if (fieldName == "_id") {
const bool idIsExcluded = (!elem.trueValue() && (elem.isNumber() || elem.isBoolean()));
if (idIsExcluded) {
// Ignoring "_id" here will cause it to be excluded from result documents.
_idExcluded = true;
continue;
}
// At least part of "_id" is included or a computed field. Fall through to below to
// parse what exactly "_id" was specified as.
}
atLeastOneFieldInOutput = true;
switch (elem.type()) {
case BSONType::Bool:
case BSONType::NumberInt:
case BSONType::NumberLong:
case BSONType::NumberDouble:
case BSONType::NumberDecimal: {
// This is an inclusion specification.
invariant(elem.trueValue());
_root->addProjectionForPath(FieldPath(elem.fieldName()));
break;
}
case BSONType::Object: {
// This is either an expression, or a nested specification.
if (parseObjectAsExpression(fieldName, elem.Obj(), _expCtx->variablesParseState)) {
// It was an expression.
break;
}
// The field name might be a dotted path. If so, we need to keep adding children
// to our tree until we create a child that represents that path.
auto remainingPath = FieldPath(elem.fieldName());
auto* child = _root.get();
while (remainingPath.getPathLength() > 1) {
child = child->addOrGetChild(remainingPath.getFieldName(0).toString());
remainingPath = remainingPath.tail();
}
// It is illegal to construct an empty FieldPath, so the above loop ends one
// iteration too soon. Add the last path here.
child = child->addOrGetChild(remainingPath.fullPath());
parseSubObject(elem.Obj(), _expCtx->variablesParseState, child);
break;
}
default: {
// This is a literal value.
_root->addExpressionForPath(
FieldPath(elem.fieldName()),
Expression::parseOperand(_expCtx, elem, _expCtx->variablesParseState));
}
}
}
if (!idSpecified) {
// _id wasn't specified, so apply the default _id projection policy here.
if (_policies.idPolicy == ProjectionPolicies::DefaultIdPolicy::kExcludeId) {
_idExcluded = true;
} else {
atLeastOneFieldInOutput = true;
_root->addProjectionForPath(FieldPath("_id"));
}
}
uassert(16403,
str::stream() << "$project requires at least one output field: " << spec.toString(),
atLeastOneFieldInOutput);
}
Document ParsedInclusionProjection::applyProjection(const Document& inputDoc) const {
// All expressions will be evaluated in the context of the input document, before any
// transformations have been applied.
return _root->applyToDocument(inputDoc);
}
bool ParsedInclusionProjection::parseObjectAsExpression(
StringData pathToObject,
const BSONObj& objSpec,
const VariablesParseState& variablesParseState) {
if (objSpec.firstElementFieldName()[0] == '$') {
// This is an expression like {$add: [...]}. We have already verified that it has only one
// field.
invariant(objSpec.nFields() == 1);
_root->addExpressionForPath(
pathToObject, Expression::parseExpression(_expCtx, objSpec, variablesParseState));
return true;
}
return false;
}
void ParsedInclusionProjection::parseSubObject(const BSONObj& subObj,
const VariablesParseState& variablesParseState,
InclusionNode* node) {
for (auto elem : subObj) {
invariant(elem.fieldName()[0] != '$');
// Dotted paths in a sub-object have already been disallowed in
// ParsedAggregationProjection's parsing.
invariant(elem.fieldNameStringData().find('.') == std::string::npos);
switch (elem.type()) {
case BSONType::Bool:
case BSONType::NumberInt:
case BSONType::NumberLong:
case BSONType::NumberDouble:
case BSONType::NumberDecimal: {
// This is an inclusion specification.
invariant(elem.trueValue());
node->addProjectionForPath(FieldPath(elem.fieldName()));
break;
}
case BSONType::Object: {
// This is either an expression, or a nested specification.
auto fieldName = elem.fieldNameStringData().toString();
if (parseObjectAsExpression(
FieldPath::getFullyQualifiedPath(node->getPath(), fieldName),
elem.Obj(),
variablesParseState)) {
break;
}
auto* child = node->addOrGetChild(fieldName);
parseSubObject(elem.Obj(), variablesParseState, child);
break;
}
default: {
// This is a literal value.
node->addExpressionForPath(
FieldPath(elem.fieldName()),
Expression::parseOperand(_expCtx, elem, variablesParseState));
}
}
}
}
bool ParsedInclusionProjection::isSubsetOfProjection(const BSONObj& proj) const {
std::set<std::string> preservedPaths;
_root->reportProjectedPaths(&preservedPaths);
for (auto&& includedField : preservedPaths) {
if (!proj.hasField(includedField))
return false;
}
// If the inclusion has any computed fields or renamed fields, then it's not a subset.
std::set<std::string> computedPaths;
StringMap<std::string> renamedPaths;
_root->reportComputedPaths(&computedPaths, &renamedPaths);
return computedPaths.empty() && renamedPaths.empty();
}
} // namespace parsed_aggregation_projection
} // namespace mongo
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