SERVER-23654 Add $facet aggregation stage

1 files changed, 81 insertions, 0 deletions

diff --git a/src/mongo/db/pipeline/document_source_tee_consumer.cpp b/src/mongo/db/pipeline/document_source_tee_consumer.cpp
new file mode 100644
index 00000000000..321d228b7cc
--- /dev/null
+++ b/src/mongo/db/pipeline/document_source_tee_consumer.cpp
@@ -0,0 +1,81 @@
+/**
+ *    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 "mongo/db/pipeline/document_source_tee_consumer.h"
+
+#include <boost/intrusive_ptr.hpp>
+#include <boost/optional.hpp>
+#include <vector>
+
+#include "mongo/db/pipeline/document.h"
+#include "mongo/db/pipeline/expression_context.h"
+
+namespace mongo {
+
+using boost::intrusive_ptr;
+
+DocumentSourceTeeConsumer::DocumentSourceTeeConsumer(const intrusive_ptr<ExpressionContext>& expCtx,
+                                                     const intrusive_ptr<TeeBuffer>& bufferSource)
+    : DocumentSource(expCtx), _bufferSource(bufferSource), _iterator() {}
+
+boost::intrusive_ptr<DocumentSourceTeeConsumer> DocumentSourceTeeConsumer::create(
+    const boost::intrusive_ptr<ExpressionContext>& expCtx,
+    const boost::intrusive_ptr<TeeBuffer>& bufferSource) {
+    return new DocumentSourceTeeConsumer(expCtx, bufferSource);
+}
+
+boost::optional<Document> DocumentSourceTeeConsumer::getNext() {
+    pExpCtx->checkForInterrupt();
+
+    if (!_initialized) {
+        _bufferSource->populate();
+        _initialized = true;
+        _iterator = _bufferSource->begin();
+    }
+
+    if (_iterator == _bufferSource->end()) {
+        return boost::none;
+    }
+
+    return {*_iterator++};
+}
+
+void DocumentSourceTeeConsumer::dispose() {
+    // Release our reference to the buffer. We shouldn't call dispose() on the buffer, since there
+    // might be other consumers that need to use it.
+    _bufferSource.reset();
+}
+
+Value DocumentSourceTeeConsumer::serialize(bool explain) const {
+    // This stage will be inserted into the beginning of a pipeline, but should not show up in the
+    // explain output.
+    return Value();
+}
+}  // namespace mongo