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/**
* Copyright (C) 2011 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/pch.h"
#include "mongo/db/pipeline/document_source.h"
#include "mongo/db/pipeline/expression_context.h"
#include "mongo/db/pipeline/value.h"
namespace mongo {
DocumentSource::DocumentSource(
const intrusive_ptr<ExpressionContext> &pCtx):
pSource(NULL),
step(-1),
pExpCtx(pCtx),
nRowsOut(0) {
}
const char *DocumentSource::getSourceName() const {
static const char unknown[] = "[UNKNOWN]";
return unknown;
}
void DocumentSource::setSource(DocumentSource *pTheSource) {
verify(!pSource);
pSource = pTheSource;
}
bool DocumentSource::coalesce(
const intrusive_ptr<DocumentSource> &pNextSource) {
return false;
}
void DocumentSource::optimize() {
}
void DocumentSource::dispose() {
if ( pSource ) {
// This is required for the DocumentSourceCursor to release its read lock, see
// SERVER-6123.
pSource->dispose();
}
}
void DocumentSource::serializeToArray(vector<Value>& array, bool explain) const {
Value entry = serialize(explain);
if (!entry.missing()) {
array.push_back(entry);
}
}
BSONObj DocumentSource::depsToProjection(const set<string>& deps) {
BSONObjBuilder bb;
bool needId = false;
string last;
for (set<string>::const_iterator it(deps.begin()), end(deps.end()); it!=end; ++it) {
if (str::startsWith(*it, "_id") && (it->size() == 3 || (*it)[3] == '.')) {
// _id and subfields are handled specially due in part to SERVER-7502
needId = true;
continue;
}
if (!last.empty() && str::startsWith(*it, last)) {
// we are including a parent of *it so we don't need to include this field
// explicitly. In fact, due to SERVER-6527 if we included this field, the parent
// wouldn't be fully included. This logic relies on on set iterators going in
// lexicographic order so that a string is always directly before of all fields it
// prefixes.
continue;
}
last = *it + '.';
bb.append(*it, 1);
}
if (needId) // we are explicit either way
bb.append("_id", 1);
else
bb.append("_id", 0);
return bb.obj();
}
// Taken as a whole, these three functions should produce the same output document given the
// same deps set as mongo::Projection::transform would on the output of depsToProjection. The
// only exceptions are that we correctly handle the case where no fields are needed and we don't
// need to work around the above mentioned bug with subfields of _id (SERVER-7502). This is
// tested in a DEV block in DocumentSourceCursor::findNext().
//
// Output from this function is input for the next two
//
// ParsedDeps is a simple recursive look-up table. For each field in a ParsedDeps:
// If the value has type==Bool, the whole field is needed
// If the value has type==Object, the fields in the subobject are needed
// All other fields should be missing which means not needed
DocumentSource::ParsedDeps DocumentSource::parseDeps(const set<string>& deps) {
MutableDocument md;
string last;
for (set<string>::const_iterator it(deps.begin()), end(deps.end()); it!=end; ++it) {
if (!last.empty() && str::startsWith(*it, last)) {
// we are including a parent of *it so we don't need to include this field
// explicitly. In fact, if we included this field, the parent wouldn't be fully
// included. This logic relies on on set iterators going in lexicographic order so
// that a string is always directly before of all fields it prefixes.
continue;
}
last = *it + '.';
md.setNestedField(*it, Value(true));
}
return md.freeze();
}
// Helper for next function
static Value arrayHelper(const BSONObj& bson, const DocumentSource::ParsedDeps& neededFields) {
BSONObjIterator it(bson);
vector<Value> values;
while (it.more()) {
BSONElement bsonElement(it.next());
if (bsonElement.type() == Object) {
Document sub = DocumentSource::documentFromBsonWithDeps(
bsonElement.embeddedObject(),
neededFields);
values.push_back(Value(sub));
}
if (bsonElement.type() == Array) {
values.push_back(arrayHelper(bsonElement.embeddedObject(), neededFields));
}
}
return Value::consume(values);
}
Document DocumentSource::documentFromBsonWithDeps(const BSONObj& bson,
const ParsedDeps& neededFields) {
MutableDocument md(neededFields.size());
BSONObjIterator it(bson);
while (it.more()) {
BSONElement bsonElement (it.next());
StringData fieldName = bsonElement.fieldNameStringData();
Value isNeeded = neededFields[fieldName];
if (isNeeded.missing())
continue;
if (isNeeded.getType() == Bool) {
md.addField(fieldName, Value(bsonElement));
continue;
}
dassert(isNeeded.getType() == Object);
if (bsonElement.type() == Object) {
Document sub = documentFromBsonWithDeps(bsonElement.embeddedObject(),
isNeeded.getDocument());
md.addField(fieldName, Value(sub));
}
if (bsonElement.type() == Array) {
md.addField(fieldName, arrayHelper(bsonElement.embeddedObject(),
isNeeded.getDocument()));
}
}
return md.freeze();
}
}
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