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/**
* Copyright (C) 2013 10gen 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/>.
*/
#include "mongo/db/ops/path_support.h"
#include "mongo/base/string_data.h"
#include "mongo/bson/mutable/algorithm.h"
#include "mongo/bson/mutable/document.h"
#include "mongo/bson/mutable/element.h"
#include "mongo/util/assert_util.h"
#include "mongo/util/mongoutils/str.h"
namespace mongo {
namespace pathsupport {
namespace {
bool isNumeric(const StringData& str, size_t* num) {
size_t res = 0;
for (size_t i = 0; i < str.size(); ++i) {
if (str[i] < '0' || str[i] > '9') {
return false;
}
else {
res = res * 10 + (str[i] - '0');
}
}
*num = res;
return true;
}
Status maybePadTo(mutablebson::Element* elemArray,
size_t sizeRequired) {
dassert(elemArray->getType() == Array);
if (sizeRequired > kMaxPaddingAllowed) {
return Status(ErrorCodes::CannotBackfillArray,
mongoutils::str::stream() << "can't backfill array to larger than "
<< kMaxPaddingAllowed << " elements");
}
size_t currSize = mutablebson::countChildren(*elemArray);
if (sizeRequired > currSize) {
size_t toPad = sizeRequired - currSize;
for (size_t i = 0; i < toPad; i++) {
Status status = elemArray->appendNull("");
if (!status.isOK()) {
return status;
}
}
}
return Status::OK();
}
} // unnamed namespace
Status findLongestPrefix(const FieldRef& prefix,
mutablebson::Element root,
size_t* idxFound,
mutablebson::Element* elemFound) {
// If root is empty or the prefix is so, there's no point in looking for a prefix.
const size_t prefixSize = prefix.numParts();
if (!root.hasChildren() || prefixSize == 0) {
return Status(ErrorCodes::NonExistentPath,
"either the document or the path are empty");
}
// Loop through prefix's parts. At each iteration, check that the part ('curr') exists
// in 'root' and that the type of the previous part ('prev') allows for children.
mutablebson::Element curr = root;
mutablebson::Element prev = root;
size_t i = 0;
size_t numericPart = 0;
bool viable = true;
for (;i < prefixSize; i++) {
// If prefix wants to reach 'curr' by applying a non-numeric index to an array
// 'prev', or if 'curr' wants to traverse a leaf 'prev', then we'd be in a
// non-viable path (see definition on the header file).
StringData prefixPart = prefix.getPart(i);
prev = curr;
switch (curr.getType()) {
case Object:
curr = prev[prefixPart];
break;
case Array:
if (!isNumeric(prefixPart, &numericPart)) {
viable = false;
} else {
curr = prev[numericPart];
}
break;
default:
viable = false;
}
// If we couldn't find the next field part of the prefix in the document or if the
// field part we're in constitutes a non-viable path, we can stop looking.
if (!curr.ok() || !viable) {
break;
}
}
// We broke out of the loop because one of four things happened. (a) 'prefix' and
// 'root' have nothing in common, (b) 'prefix' is not viable in 'root', (c) not all the
// parts in 'prefix' exist in 'root', or (d) all parts do. In each case, we need to
// figure out what index and Element pointer to return.
if (i == 0) {
return Status(ErrorCodes::NonExistentPath,
"cannot find path in the document");
}
else if (!viable) {
*idxFound = i - 1;
*elemFound = prev;
return Status(ErrorCodes::PathNotViable,
"cannot use the part to traverse the document");
}
else if (curr.ok()) {
*idxFound = i - 1;
*elemFound = curr;
return Status::OK();
}
else {
*idxFound = i - 1;
*elemFound = prev;
return Status::OK();
}
}
Status createPathAt(const FieldRef& prefix,
size_t idxFound,
mutablebson::Element elemFound,
mutablebson::Element newElem) {
Status status = Status::OK();
// Sanity check that 'idxField' is an actual part.
const size_t size = prefix.numParts();
if (idxFound >= size) {
return Status(ErrorCodes::BadValue, "index larger than path size");
}
mutablebson::Document& doc = elemFound.getDocument();
// If we are creating children under an array and a numeric index is next, then perhaps
// we need padding.
size_t i = idxFound;
bool inArray = false;
if (elemFound.getType() == mongo::Array) {
size_t newIdx = 0;
if (!isNumeric(prefix.getPart(idxFound), &newIdx)) {
return Status(ErrorCodes::InvalidPath, "Array require numeric fields");
}
status = maybePadTo(&elemFound, newIdx);
if (!status.isOK()) {
return status;
}
// If there is a next field, that would be an array element. We'd like to mark that
// field because we create array elements differently than we do regular objects.
if (++i < size) {
inArray = true;
}
}
// Create all the remaining parts but the last one.
for (; i < size - 1 ; i++) {
mutablebson::Element elem = doc.makeElementObject(prefix.getPart(i));
if (!elem.ok()) {
return Status(ErrorCodes::InternalError, "cannot create path");
}
// If this field is an array element, we wrap it in an object (because array
// elements are wraped in { "N": <element> } objects.
if (inArray) {
// TODO pass empty StringData to makeElementObject, when that's supported.
mutablebson::Element arrayObj = doc.makeElementObject("" /* it's an array */);
if (!arrayObj.ok()) {
return Status(ErrorCodes::InternalError, "cannot create item on array");
}
status = arrayObj.pushBack(elem);
if (!status.isOK()) {
return status;
}
status = elemFound.pushBack(arrayObj);
if (!status.isOK()) {
return status;
}
inArray = false;
}
else {
status = elemFound.pushBack(elem);
if (!status.isOK()) {
return status;
}
}
elemFound = elem;
}
// Attach the last element. Here again, if we're in a field that is an array element,
// we wrap it in an object first.
if (inArray) {
// TODO pass empty StringData to makeElementObject, when that's supported.
mutablebson::Element arrayObj = doc.makeElementObject("" /* it's an array */);
if (!arrayObj.ok()) {
return Status(ErrorCodes::InternalError, "cannot create item on array");
}
status = arrayObj.pushBack(newElem);
if (!status.isOK()) {
return status;
}
status = elemFound.pushBack(arrayObj);
if (!status.isOK()) {
return status;
}
}
else {
status = elemFound.pushBack(newElem);
if (!status.isOK()) {
return status;
}
}
return Status::OK();
}
} // namespace pathsupport
} // namespace mongo
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