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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/matcher/expression_with_placeholder.h"
#include "mongo/db/matcher/expression_parser.h"
#include <regex>
namespace mongo {
namespace {
/**
* Finds the top-level field that 'expr' is over. Returns boost::none if the expression does not
* have a top-level field name, or a non-OK status if there are multiple top-level field names.
*/
StatusWith<boost::optional<StringData>> parseTopLevelFieldName(MatchExpression* expr) {
if (auto pathExpr = dynamic_cast<PathMatchExpression*>(expr)) {
auto firstDotPos = pathExpr->path().find('.');
if (firstDotPos == std::string::npos) {
return {pathExpr->path()};
}
return {pathExpr->path().substr(0, firstDotPos)};
} else if (expr->getCategory() == MatchExpression::MatchCategory::kLogical) {
boost::optional<StringData> placeholder;
for (size_t i = 0; i < expr->numChildren(); ++i) {
auto statusWithId = parseTopLevelFieldName(expr->getChild(i));
if (!statusWithId.isOK()) {
return statusWithId.getStatus();
}
if (!placeholder) {
placeholder = statusWithId.getValue();
continue;
}
if (statusWithId.getValue() && placeholder != statusWithId.getValue()) {
return Status(ErrorCodes::FailedToParse,
str::stream()
<< "Expected a single top-level field name, found '"
<< *placeholder << "' and '" << *statusWithId.getValue() << "'");
}
}
return placeholder;
}
return {boost::none};
}
} // namespace
bool ExpressionWithPlaceholder::equivalent(const ExpressionWithPlaceholder* other) const {
if (!other) {
return false;
}
return _placeholder == other->_placeholder && _filter->equivalent(other->_filter.get());
}
// The placeholder must begin with a lowercase letter and contain no special characters.
const std::regex ExpressionWithPlaceholder::placeholderRegex("^[a-z][a-zA-Z0-9]*$");
// static
StatusWith<std::unique_ptr<ExpressionWithPlaceholder>> ExpressionWithPlaceholder::make(
std::unique_ptr<MatchExpression> filter) {
auto statusWithId = parseTopLevelFieldName(filter.get());
if (!statusWithId.isOK()) {
return statusWithId.getStatus();
}
boost::optional<std::string> placeholder;
if (statusWithId.getValue()) {
placeholder = statusWithId.getValue()->toString();
if (!std::regex_match(*placeholder, placeholderRegex)) {
return Status(ErrorCodes::BadValue,
str::stream() << "The top-level field name must be an alphanumeric "
"string beginning with a lowercase letter, found '"
<< *placeholder << "'");
}
}
auto exprWithPlaceholder =
std::make_unique<ExpressionWithPlaceholder>(std::move(placeholder), std::move(filter));
return {std::move(exprWithPlaceholder)};
}
void ExpressionWithPlaceholder::optimizeFilter() {
_filter = MatchExpression::optimize(std::move(_filter));
auto newPlaceholder = parseTopLevelFieldName(_filter.get());
invariant(newPlaceholder.getStatus());
if (newPlaceholder.getValue()) {
_placeholder = newPlaceholder.getValue()->toString();
dassert(std::regex_match(*_placeholder, placeholderRegex));
} else {
_placeholder = boost::none;
}
}
} // namespace mongo
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