introduced engine dependency for sql strategies

  - hacked in default engine for scalars -- BAD

12 files changed, 43 insertions, 33 deletions

diff --git a/lib/active_relation.rb b/lib/active_relation.rb
index 23a80a9c38..f04825ad4c 100644
--- a/lib/active_relation.rb
+++ b/lib/active_relation.rb
@@ -8,4 +8,5 @@ require 'active_relation/sql'
 require 'active_relation/extensions'
 require 'active_relation/predicates'
 require 'active_relation/relations'
+require 'active_relation/engines'
 require 'active_relation/primitives'
\ No newline at end of file
diff --git a/lib/active_relation/engines.rb b/lib/active_relation/engines.rb
new file mode 100644
index 0000000000..55eb817b88
--- /dev/null
+++ b/lib/active_relation/engines.rb
@@ -0,0 +1 @@
+require 'active_relation/engines/engine'
\ No newline at end of file
diff --git a/lib/active_relation/engines/engine.rb b/lib/active_relation/engines/engine.rb
new file mode 100644
index 0000000000..36b77b886e
--- /dev/null
+++ b/lib/active_relation/engines/engine.rb
@@ -0,0 +1,4 @@
+module ActiveRelation
+  class Engine
+  end
+end
\ No newline at end of file
diff --git a/lib/active_relation/extensions/class.rb b/lib/active_relation/extensions/class.rb
new file mode 100644
index 0000000000..72b3bf0c15
--- /dev/null
+++ b/lib/active_relation/extensions/class.rb
@@ -0,0 +1,7 @@
+class Class
+  def memoize(method)
+    define_method "#{method}_with_memoization" do |*args|
+    end
+    alias_method_chain method, :memoization
+  end
+end
\ No newline at end of file
diff --git a/lib/active_relation/extensions/object.rb b/lib/active_relation/extensions/object.rb
index c8a0ff49e5..b0c7ada999 100644
--- a/lib/active_relation/extensions/object.rb
+++ b/lib/active_relation/extensions/object.rb
@@ -12,7 +12,7 @@ class Object
   end
   
   def strategy
-    ActiveRelation::Sql::Scalar.new
+    ActiveRelation::Sql::Scalar.new(ActiveRelation::Table.engine)
   end
   
   def metaclass
diff --git a/lib/active_relation/primitives/attribute.rb b/lib/active_relation/primitives/attribute.rb
index a72acb0c34..baaae1973c 100644
--- a/lib/active_relation/primitives/attribute.rb
+++ b/lib/active_relation/primitives/attribute.rb
@@ -1,6 +1,7 @@
 module ActiveRelation
   class Attribute
     attr_reader :relation, :name, :alias, :ancestor
+    delegate :engine, :to => :relation
 
     def initialize(relation, name, options = {})
       @relation, @name, @alias, @ancestor, @column = relation, name, options[:alias], options[:ancestor]
diff --git a/lib/active_relation/relations/compound.rb b/lib/active_relation/relations/compound.rb
index 4e583e61e8..a10b7588e7 100644
--- a/lib/active_relation/relations/compound.rb
+++ b/lib/active_relation/relations/compound.rb
@@ -3,7 +3,7 @@ module ActiveRelation
     attr_reader :relation
     delegate :joins, :selects, :orders, :groupings, :table_sql, :inserts, :limit,
              :offset, :name, :alias, :aggregation?, :alias?, :prefix_for, :column_for,
-             :hash,
+             :hash, :engine,
              :to => :relation
     
     def attributes
diff --git a/lib/active_relation/relations/join.rb b/lib/active_relation/relations/join.rb
index 8e0dcb2a4b..043b237de7 100644
--- a/lib/active_relation/relations/join.rb
+++ b/lib/active_relation/relations/join.rb
@@ -1,6 +1,7 @@
 module ActiveRelation
   class Join < Relation
     attr_reader :join_sql, :relation1, :relation2, :predicates
+    delegate :engine, :to => :relation1
 
     def initialize(join_sql, relation1, relation2, *predicates)
       @join_sql, @relation1, @relation2, @predicates = join_sql, relation1, relation2, predicates
@@ -57,8 +58,10 @@ module ActiveRelation
     end
     
     Externalizer = Struct.new(:relation) do
+      delegate :engine, :to => :relation
+      
       def table_sql
-        relation.aggregation?? relation.to_sql(Sql::Aggregation.new) : relation.send(:table_sql)
+        relation.aggregation?? relation.to_sql(Sql::Aggregation.new(engine)) : relation.send(:table_sql)
       end
       
       def selects
diff --git a/lib/active_relation/relations/relation.rb b/lib/active_relation/relations/relation.rb
index 889cf59d3a..3d4ff6613c 100644
--- a/lib/active_relation/relations/relation.rb
+++ b/lib/active_relation/relations/relation.rb
@@ -1,7 +1,5 @@
 module ActiveRelation
   class Relation
-    include Sql::Quoting
-
     def session
       Session.new
     end
@@ -108,12 +106,12 @@ module ActiveRelation
       self == other
     end
 
-    def to_sql(strategy = Sql::Relation.new)
+    def to_sql(strategy = Sql::Relation.new(engine))
       strategy.select [
-        "SELECT #{attributes.collect{ |a| a.to_sql(Sql::Projection.new) }.join(', ')}",
+        "SELECT #{attributes.collect{ |a| a.to_sql(Sql::Projection.new(engine)) }.join(', ')}",
         "FROM #{table_sql}",
         (joins unless joins.blank?),
-        ("WHERE #{selects.collect{|s| s.to_sql(Sql::Selection.new)}.join("\n\tAND ")}" unless selects.blank?),
+        ("WHERE #{selects.collect{|s| s.to_sql(Sql::Selection.new(engine))}.join("\n\tAND ")}" unless selects.blank?),
         ("ORDER BY #{orders.collect(&:to_sql)}" unless orders.blank?),
         ("GROUP BY #{groupings.collect(&:to_sql)}" unless groupings.blank?),
         ("LIMIT #{limit.to_sql}" unless limit.blank?),
@@ -121,11 +119,7 @@ module ActiveRelation
       ].compact.join("\n"), self.alias
     end
     alias_method :to_s, :to_sql
-    
-    def connection
-      ActiveRecord::Base.connection
-    end
-    
+        
     def attribute_for_name(name)
       attributes.detect { |a| a.alias_or_name.to_s == name.to_s }
     end
diff --git a/lib/active_relation/relations/table.rb b/lib/active_relation/relations/table.rb
index 271e76f362..84eb1213ee 100644
--- a/lib/active_relation/relations/table.rb
+++ b/lib/active_relation/relations/table.rb
@@ -1,10 +1,12 @@
 module ActiveRelation
   class Table < Relation
-    attr_reader :name
+    cattr_accessor :engine
+    attr_reader :name, :engine
+    
     delegate :hash, :to => :name
     
-    def initialize(name)
-      @name = name.to_s
+    def initialize(name, engine = Table.engine)
+      @name, @engine = name.to_s, engine
     end
 
     def attributes
@@ -31,7 +33,7 @@ module ActiveRelation
     end
     
     def columns
-      @columns ||= connection.columns(name, "#{name} Columns")
+      @columns ||= engine.columns(name, "#{name} Columns")
     end
     
     def descend
@@ -44,7 +46,7 @@ module ActiveRelation
 
     protected    
     def table_sql
-      "#{quote_table_name(name)}"
+      "#{engine.quote_table_name(name)}"
     end
     
     private
diff --git a/lib/active_relation/sessions/session.rb b/lib/active_relation/sessions/session.rb
index 7eb66a1395..0724abc5a7 100644
--- a/lib/active_relation/sessions/session.rb
+++ b/lib/active_relation/sessions/session.rb
@@ -26,25 +26,21 @@ module ActiveRelation
     end
     
     module CRUD
-      def connection
-        ActiveRecord::Base.connection
-      end
-      
       def create(insert)
-        connection.insert(insert.to_sql)
+        insert.engine.insert(insert.to_sql)
       end
       
       def read(select)
         @read ||= {}
-        @read.has_key?(select) ? @read[select] : (@read[select] = connection.select_all(select.to_sql))
+        @read.has_key?(select) ? @read[select] : (@read[select] = select.engine.select_all(select.to_sql))
       end
       
       def update(update)
-        connection.update(update.to_sql)
+        update.engine.update(update.to_sql)
       end
       
       def delete(delete)
-        connection.delete(delete.to_sql)
+        delete.engine.delete(delete.to_sql)
       end
     end
     include CRUD
diff --git a/lib/active_relation/sql.rb b/lib/active_relation/sql.rb
index 0fc8b3e1be..a5701ca8cd 100644
--- a/lib/active_relation/sql.rb
+++ b/lib/active_relation/sql.rb
@@ -1,16 +1,17 @@
 module ActiveRelation
   module Sql
     module Quoting
-      def connection
-        Session.new.connection
-      end
-  
-      delegate :quote_table_name, :quote_column_name, :quote, :to => :connection
+      delegate :quote_table_name, :quote_column_name, :quote, :to => :engine
     end
     
     # module Formatting Context / Strategy # unit test me!!!
     class Strategy
+      attr_reader :engine
       include Quoting
+      
+      def initialize(engine)
+        @engine = engine
+      end
     end
     
     class Projection < Strategy
@@ -51,13 +52,13 @@ module ActiveRelation
     
     class Aggregation < Strategy
       def select(select_sql, aliaz)
-        "(#{select_sql}) AS #{quote_table_name(aliaz)}"
+        "(#{select_sql}) AS #{engine.quote_table_name(aliaz)}"
       end
     end
     
     class Attribute < Predicate
       def initialize(attribute)
-        @attribute = attribute
+        @attribute, @engine = attribute, attribute.engine
       end
       
       def scalar(scalar)