diff -r 000000000000 -r 6474c204b198 storage/src/variantToSQLiteT_impl.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/storage/src/variantToSQLiteT_impl.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,127 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * vim: sw=2 ts=2 et lcs=trail\:.,tab\:>~ :
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// Note: we are already in the namepace mozilla::storage
+
+// Note 2: whoever #includes this file must provide implementations of
+// sqlite3_T_* prior.
+
+////////////////////////////////////////////////////////////////////////////////
+//// variantToSQLiteT Implementation
+
+template <typename T>
+int
+variantToSQLiteT(T aObj,
+                 nsIVariant *aValue)
+{
+  // Allow to return nullptr not wrapped to nsIVariant for speed.
+  if (!aValue)
+    return sqlite3_T_null(aObj);
+
+  uint16_t type;
+  (void)aValue->GetDataType(&type);
+  switch (type) {
+    case nsIDataType::VTYPE_INT8:
+    case nsIDataType::VTYPE_INT16:
+    case nsIDataType::VTYPE_INT32:
+    case nsIDataType::VTYPE_UINT8:
+    case nsIDataType::VTYPE_UINT16:
+    {
+      int32_t value;
+      nsresult rv = aValue->GetAsInt32(&value);
+      NS_ENSURE_SUCCESS(rv, SQLITE_MISMATCH);
+      return sqlite3_T_int(aObj, value);
+    }
+    case nsIDataType::VTYPE_UINT32: // Try to preserve full range
+    case nsIDataType::VTYPE_INT64:
+    // Data loss possible, but there is no unsigned types in SQLite
+    case nsIDataType::VTYPE_UINT64:
+    {
+      int64_t value;
+      nsresult rv = aValue->GetAsInt64(&value);
+      NS_ENSURE_SUCCESS(rv, SQLITE_MISMATCH);
+      return sqlite3_T_int64(aObj, value);
+    }
+    case nsIDataType::VTYPE_FLOAT:
+    case nsIDataType::VTYPE_DOUBLE:
+    {
+      double value;
+      nsresult rv = aValue->GetAsDouble(&value);
+      NS_ENSURE_SUCCESS(rv, SQLITE_MISMATCH);
+      return sqlite3_T_double(aObj, value);
+    }
+    case nsIDataType::VTYPE_BOOL:
+    {
+      bool value;
+      nsresult rv = aValue->GetAsBool(&value);
+      NS_ENSURE_SUCCESS(rv, SQLITE_MISMATCH);
+      return sqlite3_T_int(aObj, value ? 1 : 0);
+    }
+    case nsIDataType::VTYPE_CHAR:
+    case nsIDataType::VTYPE_CHAR_STR:
+    case nsIDataType::VTYPE_STRING_SIZE_IS:
+    case nsIDataType::VTYPE_UTF8STRING:
+    case nsIDataType::VTYPE_CSTRING:
+    {
+      nsAutoCString value;
+      // GetAsAUTF8String should never perform conversion when coming from
+      // 8-bit string types, and thus can accept strings with arbitrary encoding
+      // (including UTF8 and ASCII).
+      nsresult rv = aValue->GetAsAUTF8String(value);
+      NS_ENSURE_SUCCESS(rv, SQLITE_MISMATCH);
+      return sqlite3_T_text(aObj, value);
+    }
+    case nsIDataType::VTYPE_WCHAR:
+    case nsIDataType::VTYPE_DOMSTRING:
+    case nsIDataType::VTYPE_WCHAR_STR:
+    case nsIDataType::VTYPE_WSTRING_SIZE_IS:
+    case nsIDataType::VTYPE_ASTRING:
+    {
+      nsAutoString value;
+      // GetAsAString does proper conversion to UCS2 from all string-like types.
+      // It can be used universally without problems (unless someone implements
+      // their own variant, but that's their problem).
+      nsresult rv = aValue->GetAsAString(value);
+      NS_ENSURE_SUCCESS(rv, SQLITE_MISMATCH);
+      return sqlite3_T_text16(aObj, value);
+    }
+    case nsIDataType::VTYPE_VOID:
+    case nsIDataType::VTYPE_EMPTY:
+    case nsIDataType::VTYPE_EMPTY_ARRAY:
+      return sqlite3_T_null(aObj);
+    case nsIDataType::VTYPE_ARRAY:
+    {
+      uint16_t type;
+      nsIID iid;
+      uint32_t count;
+      void *data;
+      nsresult rv = aValue->GetAsArray(&type, &iid, &count, &data);
+      NS_ENSURE_SUCCESS(rv, SQLITE_MISMATCH);
+
+      // Check to make sure it's a supported type.
+      NS_ASSERTION(type == nsIDataType::VTYPE_UINT8,
+                   "Invalid type passed!  You may leak!");
+      if (type != nsIDataType::VTYPE_UINT8) {
+        // Technically this could leak with certain data types, but somebody was
+        // being stupid passing us this anyway.
+        NS_Free(data);
+        return SQLITE_MISMATCH;
+      }
+
+      // Finally do our thing.  The function should free the array accordingly!
+      int rc = sqlite3_T_blob(aObj, data, count);
+      return rc;
+    }
+    // Maybe, it'll be possible to convert these
+    // in future too.
+    case nsIDataType::VTYPE_ID:
+    case nsIDataType::VTYPE_INTERFACE:
+    case nsIDataType::VTYPE_INTERFACE_IS:
+    default:
+      return SQLITE_MISMATCH;
+  }
+  return SQLITE_OK;
+}