build the association graph functionally

This lets us avoid the constant calls to Array#<<

3 files changed, 13 insertions, 20 deletions

diff --git a/activerecord/lib/active_record/associations/join_dependency.rb b/activerecord/lib/active_record/associations/join_dependency.rb
index 20457e9e57..4bcd69c69b 100644
--- a/activerecord/lib/active_record/associations/join_dependency.rb
+++ b/activerecord/lib/active_record/associations/join_dependency.rb
@@ -52,11 +52,10 @@ module ActiveRecord
       #    joins #=>  []
       #
       def initialize(base, associations, joins)
-        @join_root    = JoinBase.new(base)
         @alias_tracker = AliasTracker.new(base.connection, joins)
         @alias_tracker.aliased_name_for(base.table_name) # Updates the count for base.table_name to 1
         tree = self.class.make_tree associations
-        build tree, @join_root
+        @join_root = JoinBase.new base, build(tree, base)
         @join_root.children.each { |child| construct_tables! @join_root, child }
       end
 
@@ -212,23 +211,17 @@ module ActiveRecord
           raise ConfigurationError, "Association named '#{ name }' was not found on #{ klass.name }; perhaps you misspelled it?"
       end
 
-      def build(associations, parent)
-        associations.each do |name, right|
-          reflection = find_reflection parent.base_klass, name
-          join_association = build_join_association reflection
-          parent.children << join_association
-          build right, join_association
-        end
-      end
+      def build(associations, base_klass)
+        associations.map do |name, right|
+          reflection = find_reflection base_klass, name
+          reflection.check_validity!
 
-      def build_join_association(reflection)
-        reflection.check_validity!
+          if reflection.options[:polymorphic]
+            raise EagerLoadPolymorphicError.new(reflection)
+          end
 
-        if reflection.options[:polymorphic]
-          raise EagerLoadPolymorphicError.new(reflection)
+          JoinAssociation.new reflection, build(right, reflection.klass)
         end
-
-        JoinAssociation.new(reflection)
       end
 
       def construct(ar_parent, parent, row, rs, seen, model_cache, aliases)
diff --git a/activerecord/lib/active_record/associations/join_dependency/join_association.rb b/activerecord/lib/active_record/associations/join_dependency/join_association.rb
index d2c090ae56..191d430636 100644
--- a/activerecord/lib/active_record/associations/join_dependency/join_association.rb
+++ b/activerecord/lib/active_record/associations/join_dependency/join_association.rb
@@ -9,8 +9,8 @@ module ActiveRecord
 
         attr_accessor :tables
 
-        def initialize(reflection)
-          super(reflection.klass)
+        def initialize(reflection, children)
+          super(reflection.klass, children)
 
           @reflection      = reflection
           @tables          = nil
diff --git a/activerecord/lib/active_record/associations/join_dependency/join_part.rb b/activerecord/lib/active_record/associations/join_dependency/join_part.rb
index e22232168d..91e1c6a9d7 100644
--- a/activerecord/lib/active_record/associations/join_dependency/join_part.rb
+++ b/activerecord/lib/active_record/associations/join_dependency/join_part.rb
@@ -17,10 +17,10 @@ module ActiveRecord
 
         delegate :table_name, :column_names, :primary_key, :to => :base_klass
 
-        def initialize(base_klass)
+        def initialize(base_klass, children)
           @base_klass = base_klass
           @column_names_with_alias = nil
-          @children = []
+          @children = children
         end
 
         def name