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/**
* Copyright (C) 2017 MongoDB Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License, version 3,
* as published by the Free Software Foundation.
*
* 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
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* 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 GNU Affero General 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/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,
StringData path,
ElementPath::LeafArrayBehavior leafArrBehavior,
ElementPath::NonLeafArrayBehavior nonLeafArrayBehavior)
: MatchExpression(matchType), _path(path) {
_elementPath.init(_path);
_elementPath.setLeafArrayBehavior(leafArrBehavior);
_elementPath.setNonLeafArrayBehavior(nonLeafArrayBehavior);
}
virtual ~PathMatchExpression() {}
bool matches(const MatchableDocument* doc, MatchDetails* details = nullptr) const final {
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;
}
const StringData path() const final {
return _path;
}
void setPath(StringData path) {
_path = path;
_elementPath.init(_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) {
FieldRef pathFieldRef(_path);
size_t renamesFound = 0u;
for (auto rename : renameList) {
if (rename.first == _path) {
_rewrittenPath = rename.second;
++renamesFound;
}
FieldRef prefixToRename(rename.first);
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);
}
}
protected:
void _doAddDependencies(DepsTracker* deps) const final {
if (!_path.empty()) {
deps->fields.insert(_path.toString());
}
}
private:
StringData _path;
ElementPath _elementPath;
// We use this when we rewrite the value in '_path' and we need a backing store for the
// rewritten string.
std::string _rewrittenPath;
};
} // namespace mongo
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