From 6fb972f757c8b9ce59c414bd82c13b93975d677b Mon Sep 17 00:00:00 2001
From: Kevin Deisz <kevin.deisz@gmail.com>
Date: Thu, 19 Jan 2017 11:41:57 -0500
Subject: [PATCH] Allow users to register their own adapter

---
 .../connection_adapters/odbc_adapter.rb       |  1 +
 lib/odbc_adapter.rb                           | 15 +++++++++++++
 lib/odbc_adapter/dbms.rb                      | 22 ++++++++++---------
 3 files changed, 28 insertions(+), 10 deletions(-)

diff --git a/lib/active_record/connection_adapters/odbc_adapter.rb b/lib/active_record/connection_adapters/odbc_adapter.rb
index 8b588c56..10881dde 100644
--- a/lib/active_record/connection_adapters/odbc_adapter.rb
+++ b/lib/active_record/connection_adapters/odbc_adapter.rb
@@ -2,6 +2,7 @@
 require 'arel/visitors/bind_visitor'
 require 'odbc'
 
+require 'odbc_adapter'
 require 'odbc_adapter/database_limits'
 require 'odbc_adapter/database_statements'
 require 'odbc_adapter/quoting'
diff --git a/lib/odbc_adapter.rb b/lib/odbc_adapter.rb
index 194fb562..16e08551 100644
--- a/lib/odbc_adapter.rb
+++ b/lib/odbc_adapter.rb
@@ -1,2 +1,17 @@
 # Requiring with this pattern to mirror ActiveRecord
 require 'active_record/connection_adapters/odbc_adapter'
+
+module ODBCAdapter
+  class << self
+    def dbms_registry
+      @dbms_registry ||= {
+        /my.*sql/i => :MySQL,
+        /postgres/i => :PostgreSQL
+      }
+    end
+
+    def register(pattern, superclass, &block)
+      dbms_registry[pattern] = Class.new(superclass, &block)
+    end
+  end
+end
diff --git a/lib/odbc_adapter/dbms.rb b/lib/odbc_adapter/dbms.rb
index fd40876e..12a92775 100644
--- a/lib/odbc_adapter/dbms.rb
+++ b/lib/odbc_adapter/dbms.rb
@@ -20,8 +20,9 @@ def initialize(connection)
     end
 
     def adapter_class
-      require "odbc_adapter/adapters/#{name.downcase}_odbc_adapter"
-      Adapters.const_get(:"#{name}ODBCAdapter")
+      return adapter unless adapter.is_a?(Symbol)
+      require "odbc_adapter/adapters/#{adapter.downcase}_odbc_adapter"
+      Adapters.const_get(:"#{adapter}ODBCAdapter")
     end
 
     def field_for(field)
@@ -32,16 +33,17 @@ def field_for(field)
 
     # Maps a DBMS name to a symbol
     # Different ODBC drivers might return different names for the same DBMS
-    def name
-      @name ||=
+    def adapter
+      @adapter ||=
         begin
           reported = field_for(ODBC::SQL_DBMS_NAME).downcase.gsub(/\s/, '')
-          case reported
-          when /my.*sql/i               then :MySQL
-          when /postgres/i, 'snowflake' then :PostgreSQL
-          else
-            raise ArgumentError, "ODBCAdapter: Unsupported database (#{reported})"
-          end
+          found =
+            ODBCAdapter.dbms_registry.detect do |pattern, adapter|
+              adapter if reported =~ pattern
+            end
+
+          raise ArgumentError, "ODBCAdapter: Unsupported database (#{reported})" if found.nil?
+          found.last
         end
     end
   end