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/**
* Copyright (C) 2016 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.
*/
#include "mongo/platform/basic.h"
#include <boost/optional.hpp>
#include <cctype>
#include <vector>
#include "mongo/db/pipeline/document_path_support.h"
#include "mongo/base/parse_number.h"
#include "mongo/base/string_data.h"
#include "mongo/db/pipeline/document.h"
#include "mongo/db/pipeline/field_path.h"
#include "mongo/db/pipeline/value.h"
namespace mongo {
namespace document_path_support {
namespace {
/**
* Returns the array index that should be used if 'fieldName' represents a positional path
* specification (as '0' does in 'a.0'), or boost::none if 'fieldName' does not represent a
* positional path specification.
*/
boost::optional<size_t> getPositionalPathSpecification(StringData fieldName) {
// Do not accept positions like '-4' or '+4'
if (!std::isdigit(fieldName[0])) {
return boost::none;
}
unsigned int index;
auto status = parseNumberFromStringWithBase<unsigned int>(fieldName, 10, &index);
if (status.isOK()) {
return static_cast<size_t>(index);
}
return boost::none;
}
/**
* If 'value' is an array, invokes 'callback' once on each element of 'value'. Otherwise, if 'value'
* is not missing, invokes 'callback' on 'value' itself.
*/
void invokeCallbackOnTrailingValue(const Value& value,
stdx::function<void(const Value&)> callback) {
if (value.isArray()) {
for (auto&& finalValue : value.getArray()) {
if (!finalValue.missing()) {
callback(finalValue);
}
}
} else if (!value.missing()) {
callback(value);
}
}
void visitAllValuesAtPathHelper(Document doc,
const FieldPath& path,
size_t fieldPathIndex,
stdx::function<void(const Value&)> callback) {
invariant(path.getPathLength() > 0 && fieldPathIndex < path.getPathLength());
// The first field in the path must be treated as a field name, even if it is numeric as in
// "0.a.1.b".
auto nextValue = doc.getField(path.getFieldName(fieldPathIndex));
++fieldPathIndex;
if (path.getPathLength() == fieldPathIndex) {
invokeCallbackOnTrailingValue(nextValue, callback);
return;
}
// Follow numeric field names as positions in array values. This loop consumes all consecutive
// positional specifications, if applicable. For example, it will consume "0" and "1" from the
// path "a.0.1.b" if the value at "a" is an array with arrays inside it.
while (fieldPathIndex < path.getPathLength() && nextValue.isArray()) {
if (auto index = getPositionalPathSpecification(path.getFieldName(fieldPathIndex))) {
nextValue = nextValue[*index];
++fieldPathIndex;
} else {
break;
}
}
if (fieldPathIndex == path.getPathLength()) {
// The path ended in a positional traversal of arrays (e.g. "a.0").
invokeCallbackOnTrailingValue(nextValue, callback);
return;
}
if (nextValue.isArray()) {
// The positional path specification ended at an array, or we did not have a positional
// specification. In either case, there is still more path to explore, so we should go
// through all elements and look for the rest of the path in any objects we encounter.
//
// Note we do not expand arrays within arrays this way. For example, {a: [[{b: 1}]]} has no
// values on the path "a.b", but {a: [{b: 1}]} does.
for (auto&& subValue : nextValue.getArray()) {
if (subValue.getType() == BSONType::Object) {
visitAllValuesAtPathHelper(subValue.getDocument(), path, fieldPathIndex, callback);
}
}
} else if (nextValue.getType() == BSONType::Object) {
visitAllValuesAtPathHelper(nextValue.getDocument(), path, fieldPathIndex, callback);
}
}
} // namespace
void visitAllValuesAtPath(const Document& doc,
const FieldPath& path,
stdx::function<void(const Value&)> callback) {
visitAllValuesAtPathHelper(doc, path, 0, callback);
}
} // namespace document_path_support
} // namespace mongo
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