SERVER-29575: Add an $_internalSchemaXor MatchExpression

1 files changed, 64 insertions, 0 deletions

diff --git a/src/mongo/db/matcher/schema/expression_internal_schema_xor.h b/src/mongo/db/matcher/schema/expression_internal_schema_xor.h
new file mode 100644
index 00000000000..2c3c65f9147
--- /dev/null
+++ b/src/mongo/db/matcher/schema/expression_internal_schema_xor.h
@@ -0,0 +1,64 @@
+/**
+ *    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_tree.h"
+
+namespace mongo {
+
+/**
+ * MatchExpression for $_internalSchemaXor keyword. Returns true only if exactly
+ * one of its child nodes matches.
+ */
+class InternalSchemaXorMatchExpression final : public ListOfMatchExpression {
+public:
+    static constexpr StringData kInternalSchemaXor = "$_internalSchemaXor"_sd;
+
+    InternalSchemaXorMatchExpression() : ListOfMatchExpression(INTERNAL_SCHEMA_XOR) {}
+
+    bool matches(const MatchableDocument* doc, MatchDetails* details = nullptr) const final;
+
+    bool matchesSingleElement(const BSONElement& element) const final;
+
+    virtual std::unique_ptr<MatchExpression> shallowClone() const {
+        auto xorCopy = stdx::make_unique<InternalSchemaXorMatchExpression>();
+        for (size_t i = 0; i < numChildren(); ++i) {
+            xorCopy->add(getChild(i)->shallowClone().release());
+        }
+        if (getTag()) {
+            xorCopy->setTag(getTag()->clone());
+        }
+        return std::move(xorCopy);
+    }
+
+    void debugString(StringBuilder& debug, int level = 0) const final;
+
+    void serialize(BSONObjBuilder* out) const final;
+};
+}  // namespace mongo
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