initial implementation of cross-engine join

Conflicts:

	lib/arel/engines/memory/relations/array.rb
	lib/arel/engines/sql/primitives.rb

3 files changed, 7 insertions, 3 deletions

diff --git a/lib/arel/engines/memory/relations/array.rb b/lib/arel/engines/memory/relations/array.rb
index 15a3e95e1b..6e2dc29252 100644
--- a/lib/arel/engines/memory/relations/array.rb
+++ b/lib/arel/engines/memory/relations/array.rb
@@ -14,6 +14,10 @@ module Arel
       end
     end
 
+    def format(attribute, value)
+      value
+    end
+    
     def eval
       @array.collect { |r| Row.new(self, r) }
     end
diff --git a/lib/arel/engines/memory/relations/compound.rb b/lib/arel/engines/memory/relations/compound.rb
index 3791fa4622..9e7827dfb3 100644
--- a/lib/arel/engines/memory/relations/compound.rb
+++ b/lib/arel/engines/memory/relations/compound.rb
@@ -3,7 +3,7 @@ module Arel
     delegate :array, :to => :relation
     
     def unoperated_rows
-      relation.eval.collect { |row| row.bind(self) }
+      relation.call.collect { |row| row.bind(self) }
     end
   end
 end
diff --git a/lib/arel/engines/memory/relations/operations.rb b/lib/arel/engines/memory/relations/operations.rb
index e35fbe3234..e0fd2824b3 100644
--- a/lib/arel/engines/memory/relations/operations.rb
+++ b/lib/arel/engines/memory/relations/operations.rb
@@ -47,8 +47,8 @@ module Arel
   class Join < Relation
     def eval
       result = []
-      relation1.eval.each do |row1|
-        relation2.eval.each do |row2|
+      relation1.call.each do |row1|
+        relation2.call.each do |row2|
           combined_row = row1.combine(row2, self)
           if predicates.all? { |p| p.eval(combined_row) }
             result << combined_row