Remove `engine` from `TreeManager` and subclasses

This constructor parameter was unused for everything except the
convenience methods `to_sql` and `where_sql`. We can pass the engine
into those methods directly.

8 files changed, 16 insertions, 26 deletions

diff --git a/lib/arel/crud.rb b/lib/arel/crud.rb
index 6f4962cbfe..2dfe27445c 100644
--- a/lib/arel/crud.rb
+++ b/lib/arel/crud.rb
@@ -3,7 +3,7 @@ module Arel
   # FIXME hopefully we can remove this
   module Crud
     def compile_update values, pk
-      um = UpdateManager.new @engine
+      um = UpdateManager.new
 
       if Nodes::SqlLiteral === values
         relation = @ctx.from
@@ -26,11 +26,11 @@ module Arel
     end
 
     def create_insert
-      InsertManager.new @engine
+      InsertManager.new
     end
 
     def compile_delete
-      dm = DeleteManager.new @engine
+      dm = DeleteManager.new
       dm.wheres = @ctx.wheres
       dm.from @ctx.froms
       dm
diff --git a/lib/arel/delete_manager.rb b/lib/arel/delete_manager.rb
index b4c61f708f..af33c60740 100644
--- a/lib/arel/delete_manager.rb
+++ b/lib/arel/delete_manager.rb
@@ -1,6 +1,6 @@
 module Arel
   class DeleteManager < Arel::TreeManager
-    def initialize engine
+    def initialize
       super
       @ast = Nodes::DeleteStatement.new
       @ctx = @ast
diff --git a/lib/arel/insert_manager.rb b/lib/arel/insert_manager.rb
index 8839dd8181..7829c3f4f9 100644
--- a/lib/arel/insert_manager.rb
+++ b/lib/arel/insert_manager.rb
@@ -1,6 +1,6 @@
 module Arel
   class InsertManager < Arel::TreeManager
-    def initialize engine
+    def initialize
       super
       @ast = Nodes::InsertStatement.new
     end
diff --git a/lib/arel/nodes/table_alias.rb b/lib/arel/nodes/table_alias.rb
index ebfcb58e64..b32f057117 100644
--- a/lib/arel/nodes/table_alias.rb
+++ b/lib/arel/nodes/table_alias.rb
@@ -12,10 +12,6 @@ module Arel
       def table_name
         relation.respond_to?(:name) ? relation.name : name
       end
-
-      def engine
-        relation.engine
-      end
     end
   end
 end
diff --git a/lib/arel/select_manager.rb b/lib/arel/select_manager.rb
index 5a05e7e181..dd1ae37b65 100644
--- a/lib/arel/select_manager.rb
+++ b/lib/arel/select_manager.rb
@@ -6,8 +6,8 @@ module Arel
 
     STRING_OR_SYMBOL_CLASS = [Symbol, String]
 
-    def initialize engine, table = nil
-      super(engine)
+    def initialize table = nil
+      super()
       @ast   = Nodes::SelectStatement.new
       @ctx    = @ast.cores.last
       from table
@@ -176,10 +176,10 @@ module Arel
       @ast.orders
     end
 
-    def where_sql
+    def where_sql engine = Table.engine
       return if @ctx.wheres.empty?
 
-      viz = Visitors::WhereSql.new @engine.connection
+      viz = Visitors::WhereSql.new engine.connection
       Nodes::SqlLiteral.new viz.accept(@ctx, Collectors::SQLString.new).value
     end
 
diff --git a/lib/arel/table.rb b/lib/arel/table.rb
index d534c44fa1..2c7a2b7f93 100644
--- a/lib/arel/table.rb
+++ b/lib/arel/table.rb
@@ -6,7 +6,7 @@ module Arel
     @engine = nil
     class << self; attr_accessor :engine; end
 
-    attr_accessor :name, :engine, :aliases, :table_alias
+    attr_accessor :name, :aliases, :table_alias
 
     # TableAlias and Table both have a #table_name which is the name of the underlying table
     alias :table_name :name
@@ -15,7 +15,6 @@ module Arel
       @name    = name.to_s
       @columns = nil
       @aliases = []
-      @engine = Table.engine
 
       # Sometime AR sends an :as parameter to table, to let the table know
       # that it is an Alias.  We may want to override new, and return a
@@ -32,8 +31,8 @@ module Arel
       end
     end
 
-    def from engine = Table.engine
-      SelectManager.new(engine, self)
+    def from
+      SelectManager.new(self)
     end
 
     def join relation, klass = Nodes::InnerJoin
diff --git a/lib/arel/tree_manager.rb b/lib/arel/tree_manager.rb
index 8bff97af78..5278ab06a1 100644
--- a/lib/arel/tree_manager.rb
+++ b/lib/arel/tree_manager.rb
@@ -8,8 +8,7 @@ module Arel
 
     attr_accessor :bind_values
 
-    def initialize engine
-      @engine = engine
+    def initialize
       @ctx    = nil
       @bind_values = []
     end
@@ -20,13 +19,9 @@ module Arel
       collector.value
     end
 
-    def visitor
-      engine.connection.visitor
-    end
-
-    def to_sql
+    def to_sql engine = Table.engine
       collector = Arel::Collectors::SQLString.new
-      collector = visitor.accept @ast, collector
+      collector = engine.connection.visitor.accept @ast, collector
       collector.value
     end
 
diff --git a/lib/arel/update_manager.rb b/lib/arel/update_manager.rb
index db8cf05f76..36fb74fe7c 100644
--- a/lib/arel/update_manager.rb
+++ b/lib/arel/update_manager.rb
@@ -1,6 +1,6 @@
 module Arel
   class UpdateManager < Arel::TreeManager
-    def initialize engine
+    def initialize
       super
       @ast = Nodes::UpdateStatement.new
       @ctx = @ast