Moved all adapter specific code into adapters/ directory and updated all adapters to utilize the same "require_adapter" method of loading specific-database adapters.

* Adds back in SQLite3 and PostgreSQL support

issue-url: http://github.com/zdennis/activerecord-import/issues#issue/1 
[contributes #1]

lib/activerecord-import/active_record/adapters/mysql_adapter.rb

@@ -0,0 +1,47 @@
+require "active_record/connection_adapters/mysql_adapter"
+
+class ActiveRecord::ConnectionAdapters::MysqlAdapter
+  include ActiveRecord::Extensions::Import::ImportSupport  
+  include ActiveRecord::Extensions::Import::OnDuplicateKeyUpdateSupport
+    
+  # Returns a generated ON DUPLICATE KEY UPDATE statement given the passed
+  # in +args+. 
+  def sql_for_on_duplicate_key_update( table_name, *args ) # :nodoc:
+    sql = ' ON DUPLICATE KEY UPDATE '
+    arg = args.first
+    if arg.is_a?( Array )
+      sql << sql_for_on_duplicate_key_update_as_array( table_name, arg )
+    elsif arg.is_a?( Hash )
+      sql << sql_for_on_duplicate_key_update_as_hash( table_name, arg )
+    elsif arg.is_a?( String )
+      sql << arg
+    else
+      raise ArgumentError.new( "Expected Array or Hash" )
+    end
+    sql
+  end
+
+  def sql_for_on_duplicate_key_update_as_array( table_name, arr )  # :nodoc:
+    results = arr.map do |column|
+      qc = quote_column_name( column )
+      "#{table_name}.#{qc}=VALUES(#{qc})"        
+    end
+    results.join( ',' )
+  end
+  
+  def sql_for_on_duplicate_key_update_as_hash( table_name, hsh ) # :nodoc:
+    sql = ' ON DUPLICATE KEY UPDATE '
+    results = hsh.map do |column1, column2|
+      qc1 = quote_column_name( column1 )
+      qc2 = quote_column_name( column2 )
+      "#{table_name}.#{qc1}=VALUES( #{qc2} )"
+    end
+    results.join( ',')
+  end
+
+  #return true if the statement is a duplicate key record error
+  def duplicate_key_update_error?(exception)# :nodoc:
+    exception.is_a?(ActiveRecord::StatementInvalid) && exception.to_s.include?('Duplicate entry')
+  end
+
+end

lib/activerecord-import/active_record/adapters/sqlite3_adapter.rb

@@ -0,0 +1,11 @@
+require "active_record/connection_adapters/sqlite3_adapter"
+
+module ActiveRecord # :nodoc:
+  module ConnectionAdapters # :nodoc:
+    class Sqlite3Adapter # :nodoc:
+      def next_value_for_sequence(sequence_name)
+        %{nextval('#{sequence_name}')}
+      end
+    end
+  end
+end

lib/activerecord-import/base.rb

@@ -3,9 +3,10 @@ require "active_record"
 require "active_record/version"
 
 module ActiveRecord::Extensions
-  AdapterPath = File.join File.expand_path(File.dirname(__FILE__)), "/../active_record/adapters"
+  AdapterPath = File.join File.expand_path(File.dirname(__FILE__)), "/active_record/adapters"
   
   def self.require_adapter(adapter)
+    require File.join(AdapterPath,"/abstract_adapter")
     require File.join(AdapterPath,"/#{adapter}_adapter")
   end
 end

lib/activerecord-import/mysql.rb

@@ -1,53 +1,2 @@
-require "active_record/connection_adapters/mysql_adapter"
 require File.join File.dirname(__FILE__),  "base"
-
-module ActiveRecord::Extensions::ConnectionAdapters::MysqlAdapter # :nodoc:
-
-  include ActiveRecord::Extensions::Import::ImportSupport  
-  include ActiveRecord::Extensions::Import::OnDuplicateKeyUpdateSupport
-    
-  # Returns a generated ON DUPLICATE KEY UPDATE statement given the passed
-  # in +args+. 
-  def sql_for_on_duplicate_key_update( table_name, *args ) # :nodoc:
-    sql = ' ON DUPLICATE KEY UPDATE '
-    arg = args.first
-    if arg.is_a?( Array )
-      sql << sql_for_on_duplicate_key_update_as_array( table_name, arg )
-    elsif arg.is_a?( Hash )
-      sql << sql_for_on_duplicate_key_update_as_hash( table_name, arg )
-    elsif arg.is_a?( String )
-      sql << arg
-    else
-      raise ArgumentError.new( "Expected Array or Hash" )
-    end
-    sql
-  end
-
-  def sql_for_on_duplicate_key_update_as_array( table_name, arr )  # :nodoc:
-    results = arr.map do |column|
-      qc = quote_column_name( column )
-      "#{table_name}.#{qc}=VALUES(#{qc})"        
-    end
-    results.join( ',' )
-  end
-  
-  def sql_for_on_duplicate_key_update_as_hash( table_name, hsh ) # :nodoc:
-    sql = ' ON DUPLICATE KEY UPDATE '
-    results = hsh.map do |column1, column2|
-      qc1 = quote_column_name( column1 )
-      qc2 = quote_column_name( column2 )
-      "#{table_name}.#{qc1}=VALUES( #{qc2} )"
-    end
-    results.join( ',')
-  end
-
-  #return true if the statement is a duplicate key record error
-  def duplicate_key_update_error?(exception)# :nodoc:
-    exception.is_a?(ActiveRecord::StatementInvalid) && exception.to_s.include?('Duplicate entry')
-  end
-
-end
-
-ActiveRecord::ConnectionAdapters::MysqlAdapter.class_eval do
-  include ActiveRecord::Extensions::ConnectionAdapters::MysqlAdapter
-end
+ActiveRecord::Extensions.require_adapter "mysql"

lib/activerecord-import/sqlite3.rb

@@ -1,2 +1,2 @@
-require "active_record/connection_adapters/sqlite3_adapter"
 require File.join File.dirname(__FILE__),  "base"
+ActiveRecord::Extensions.require_adapter "sqlite3"

test/active_record/connection_adapter_test.rb

@@ -1,6 +1,6 @@
 require File.expand_path(File.dirname(__FILE__) + '/../test_helper')
 
-describe "ActiveRecord::ConnectionADapter::AbstractAdapter" do
+describe "ActiveRecord::ConnectionAdapter::AbstractAdapter" do
   context "#get_insert_value_sets - computing insert value sets" do
     let(:adapter){ ActiveRecord::ConnectionAdapters::AbstractAdapter }
     let(:base_sql){ "INSERT INTO atable (a,b,c)" }