Allow users to register their own adapter

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'

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

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