commit 84d50446b59ea7b4255d0358681f1cf372423aae
Author: Ari Lazier <alazier@gmail.com>
Date:   Thu May 28 16:53:35 2015 -0700

    refactor out schema version code to c++

diff --git a/object_store.cpp b/object_store.cpp
new file mode 100644
index 00000000..517085f2
--- /dev/null
+++ b/object_store.cpp
@@ -0,0 +1,104 @@
+////////////////////////////////////////////////////////////////////////////
+//
+// Copyright 2014 Realm Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+////////////////////////////////////////////////////////////////////////////
+
+#include "object_store.hpp"
+
+using namespace realm;
+
+const char * const c_metadataTableName = "metadata";
+const char * const c_versionColumnName = "version";
+const size_t c_versionColumnIndex = 0;
+
+const char * const c_primaryKeyTableName = "pk";
+const char * const c_primaryKeyObjectClassColumnName = "pk_table";
+const size_t c_primaryKeyObjectClassColumnIndex =  0;
+const char * const c_primaryKeyPropertyNameColumnName = "pk_property";
+const size_t c_primaryKeyPropertyNameColumnIndex =  1;
+
+const uint64_t ObjectStore::NotVersioned = std::numeric_limits<uint64_t>::max();
+
+bool ObjectStore::has_metadata_tables(realm::Group *group) {
+    return group->get_table(c_primaryKeyTableName) && group->get_table(c_metadataTableName);
+}
+
+bool ObjectStore::create_metadata_tables(realm::Group *group) {
+    bool changed = false;
+    realm::TableRef table = group->get_or_add_table(c_primaryKeyTableName);
+    if (table->get_column_count() == 0) {
+        table->add_column(realm::type_String, c_primaryKeyObjectClassColumnName);
+        table->add_column(realm::type_String, c_primaryKeyPropertyNameColumnName);
+        changed = true;
+    }
+
+    table = group->get_or_add_table(c_metadataTableName);
+    if (table->get_column_count() == 0) {
+        table->add_column(realm::type_Int, c_versionColumnName);
+
+        // set initial version
+        table->add_empty_row();
+        table->set_int(c_versionColumnIndex, 0, realm::ObjectStore::NotVersioned);
+        changed = true;
+    }
+
+    return changed;
+}
+
+uint64_t ObjectStore::get_schema_version(realm::Group *group) {
+    realm::TableRef table = group->get_table(c_metadataTableName);
+    if (!table || table->get_column_count() == 0) {
+        return realm::ObjectStore::NotVersioned;
+    }
+    return table->get_int(c_versionColumnIndex, 0);
+}
+
+void ObjectStore::set_schema_version(realm::Group *group, uint64_t version) {
+    realm::TableRef table = group->get_or_add_table(c_metadataTableName);
+    table->set_int(c_versionColumnIndex, 0, version);
+}
+
+std::string ObjectStore::get_primary_key_for_object(realm::Group *group, std::string object_type) {
+    realm::TableRef table = group->get_table(c_primaryKeyTableName);
+    if (!table) {
+        return "";
+    }
+    size_t row = table->find_first_string(c_primaryKeyObjectClassColumnIndex, object_type);
+    if (row == realm::not_found) {
+        return "";
+    }
+    return table->get_string(c_primaryKeyPropertyNameColumnIndex, row);
+}
+
+void ObjectStore::set_primary_key_for_object(realm::Group *group, std::string object_type, std::string primary_key) {
+    realm::TableRef table = group->get_table(c_primaryKeyTableName);
+
+    // get row or create if new object and populate
+    size_t row = table->find_first_string(c_primaryKeyObjectClassColumnIndex, object_type);
+    if (row == realm::not_found && primary_key.length()) {
+        row = table->add_empty_row();
+        table->set_string(c_primaryKeyObjectClassColumnIndex, row, object_type);
+    }
+
+    // set if changing, or remove if setting to nil
+    if (primary_key.length() == 0 && row != realm::not_found) {
+        table->remove(row);
+    }
+    else {
+        table->set_string(c_primaryKeyPropertyNameColumnIndex, row, primary_key);
+    }
+}
+
diff --git a/object_store.hpp b/object_store.hpp
new file mode 100644
index 00000000..483fb0aa
--- /dev/null
+++ b/object_store.hpp
@@ -0,0 +1,54 @@
+////////////////////////////////////////////////////////////////////////////
+//
+// Copyright 2014 Realm Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+////////////////////////////////////////////////////////////////////////////
+
+#ifndef __Realm__object_store__
+#define __Realm__object_store__
+
+#include <realm/group.hpp>
+
+namespace realm {
+    class ObjectStore {
+    public:
+        // Schema version used for uninitialized Realms
+        static const uint64_t NotVersioned;
+
+        // check if the realm already has all metadata tables
+        static bool has_metadata_tables(realm::Group *group);
+
+        // create any metadata tables that don't already exist
+        // must be in write transaction to set
+        // returns true if it actually did anything
+        static bool create_metadata_tables(realm::Group *group);
+
+        // get the last set schema version
+        static uint64_t get_schema_version(realm::Group *group);
+
+        // set a new schema version
+        static void set_schema_version(realm::Group *group, uint64_t version);
+
+        // get primary key property name for object type
+        static std::string get_primary_key_for_object(realm::Group *group, std::string object_type);
+        
+        // sets primary key property for object type
+        // must be in write transaction to set
+        static void set_primary_key_for_object(realm::Group *group, std::string object_type, std::string primary_key);
+    };
+}
+
+#endif /* defined(__Realm__object_store__) */
+