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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.
*/
#pragma once
#include "mongo/db/field_ref.h"
#include "mongo/db/matcher/expression.h"
namespace mongo {
/**
* A PathMatchExpression is an expression that acts on a field path with syntax
* like "path.to.something": {$operator: ...}. Many such expressions are leaves in
* the AST, such as $gt, $mod, $exists, and so on. But expressions that are not
* leaves, such as $_internalSchemaObjectMatch, may also match against a field
* path.
*/
class PathMatchExpression : public MatchExpression {
public:
PathMatchExpression(MatchType matchType,
boost::optional<StringData> path,
ElementPath::LeafArrayBehavior leafArrBehavior,
ElementPath::NonLeafArrayBehavior nonLeafArrayBehavior,
clonable_ptr<ErrorAnnotation> annotation = nullptr)
: MatchExpression(matchType, std::move(annotation)),
_elementPath(path ? boost::optional<ElementPath>(
ElementPath(*path, leafArrBehavior, nonLeafArrayBehavior))
: boost::none) {}
bool matches(const MatchableDocument* doc, MatchDetails* details = nullptr) const final {
invariant(_elementPath);
MatchableDocument::IteratorHolder cursor(doc, &*_elementPath);
while (cursor->more()) {
ElementIterator::Context e = cursor->next();
if (!matchesSingleElement(e.element(), details)) {
continue;
}
if (details && details->needRecord() && !e.arrayOffset().eoo()) {
details->setElemMatchKey(e.arrayOffset().fieldName());
}
return true;
}
return false;
}
/**
* Gets the path that the expression applies to. Note that this returns an empty string for
* empty path as well as no path cases. optPath() should be preferred in order to
* distinguish between the two.
*/
StringData path() const override final {
return _elementPath ? _elementPath->fieldRef().dottedField() : "";
}
const FieldRef* fieldRef() const override final {
return _elementPath ? &(_elementPath->fieldRef()) : nullptr;
}
/**
* Gets the path that the expression applies to. If the expression does not apply to a specific
* path, returns boost::none.
*/
boost::optional<StringData> optPath() const {
return _elementPath ? boost::optional<StringData>(path()) : boost::none;
}
/**
* Resets the path for this expression. Note that this method will make a copy of 'path' such
* that there's no lifetime requirements for the string which 'path' points into.
*/
void setPath(StringData path) {
invariant(_elementPath);
_elementPath->reset(path);
}
/**
* Finds an applicable rename from 'renameList' (if one exists) and applies it to the expression
* path. Each pair in 'renameList' specifies a path prefix that should be renamed (as the first
* element) and the path components that should replace the renamed prefix (as the second
* element).
*/
void applyRename(const StringMap<std::string>& renameList) {
if (!_elementPath) {
return;
}
size_t renamesFound = 0u;
std::string rewrittenPath;
for (const auto& rename : renameList) {
if (rename.first == path()) {
rewrittenPath = rename.second;
++renamesFound;
}
FieldRef prefixToRename(rename.first);
const auto& pathFieldRef = _elementPath->fieldRef();
if (prefixToRename.isPrefixOf(pathFieldRef)) {
// Get the 'pathTail' by chopping off the 'prefixToRename' path components from the
// beginning of the 'pathFieldRef' path.
auto pathTail = pathFieldRef.dottedSubstring(prefixToRename.numParts(),
pathFieldRef.numParts());
// Replace the chopped off components with the component names resulting from the
// rename.
rewrittenPath = str::stream() << rename.second << "." << pathTail.toString();
++renamesFound;
}
}
// There should never be multiple applicable renames.
invariant(renamesFound <= 1u);
if (renamesFound == 1u) {
// There is an applicable rename. Modify the path of this expression to use the new
// name.
setPath(rewrittenPath);
}
}
void serialize(BSONObjBuilder* out, bool includePath) const override {
if (includePath) {
out->append(path(), getSerializedRightHandSide());
} else {
out->appendElements(getSerializedRightHandSide());
}
}
/**
* Returns a BSONObj that represents the right-hand-side of a PathMatchExpression. Used for
* serialization of PathMatchExpression in cases where we do not want to serialize the path in
* line with the expression. For example {x: {$not: {$eq: 1}}}, where $eq is the
* PathMatchExpression.
*/
virtual BSONObj getSerializedRightHandSide() const = 0;
private:
// ElementPath holds a FieldRef, which owns the underlying path string.
// May be boost::none if this MatchExpression does not apply to a specific path.
boost::optional<ElementPath> _elementPath;
};
} // namespace mongo
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