SERVER-7174 Implement $inc on new update framework

1 files changed, 73 insertions, 0 deletions

diff --git a/src/mongo/db/ops/modifier_inc.h b/src/mongo/db/ops/modifier_inc.h
new file mode 100644
index 00000000000..5dc9f8fae95
--- /dev/null
+++ b/src/mongo/db/ops/modifier_inc.h
@@ -0,0 +1,73 @@
+/**
+ *    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/>.
+ */
+
+#pragma once
+
+#include <boost/scoped_ptr.hpp>
+#include <string>
+
+#include "mongo/base/disallow_copying.h"
+#include "mongo/bson/mutable/element.h"
+#include "mongo/db/field_ref.h"
+#include "mongo/db/ops/modifier_interface.h"
+
+namespace mongo {
+
+    class ModifierInc : public ModifierInterface {
+        MONGO_DISALLOW_COPYING(ModifierInc);
+
+    public:
+
+        ModifierInc();
+        virtual ~ModifierInc();
+
+        /**
+         * A 'modExpr' is a BSONElement {<fieldname>: <value>} coming from a $inc mod such as
+         * {$inc: {<fieldname: <value>}}. init() extracts the field name and the value to be
+         * assigned to it from 'modExpr'. It returns OK if successful or a status describing
+         * the error.
+         */
+        virtual Status init(const BSONElement& modExpr);
+
+        /** Evaluates the validity of applying $inc to the identified node, and computes
+         *  effects, handling upcasting and overflow as necessary.
+         */
+        virtual Status prepare(mutablebson::Element root,
+                               const StringData& matchedField,
+                               ExecInfo* execInfo);
+
+        /** Updates the node passed in prepare with the results of the $inc */
+        virtual Status apply() const;
+
+        /** Converts the result of the $inc into an equivalent $set under logRoot */
+        virtual Status log(mutablebson::Element logRoot) const;
+
+    private:
+
+        // Access to each component of fieldName that's the target of this mod.
+        FieldRef _fieldRef;
+
+        // 0 or index for $-positional in _fieldRef.
+        size_t _posDollar;
+
+        // Element of the $set expression.
+        SafeNum _val;
+
+        struct PreparedState;
+        scoped_ptr<PreparedState> _preparedState;
+    };
+
+} // namespace mongo