joins can be created

3 files changed, 44 insertions, 0 deletions

diff --git a/lib/arel/nodes/inner_join.rb b/lib/arel/nodes/inner_join.rb
new file mode 100644
index 0000000000..a39ded9f1c
--- /dev/null
+++ b/lib/arel/nodes/inner_join.rb
@@ -0,0 +1,13 @@
+module Arel
+  module Nodes
+    class InnerJoin
+      attr_accessor :left, :right, :constraint
+
+      def initialize left, right, constraint
+        @left       = left
+        @right      = right
+        @constraint = constraint
+      end
+    end
+  end
+end
diff --git a/lib/arel/nodes/on.rb b/lib/arel/nodes/on.rb
new file mode 100644
index 0000000000..4cc76b70db
--- /dev/null
+++ b/lib/arel/nodes/on.rb
@@ -0,0 +1,11 @@
+module Arel
+  module Nodes
+    class On
+      attr_accessor :expr
+
+      def initialize expr
+        @expr = expr
+      end
+    end
+  end
+end
diff --git a/lib/arel/nodes/table_alias.rb b/lib/arel/nodes/table_alias.rb
new file mode 100644
index 0000000000..4f1d70ee54
--- /dev/null
+++ b/lib/arel/nodes/table_alias.rb
@@ -0,0 +1,20 @@
+module Arel
+  module Nodes
+    class TableAlias
+      attr_reader :name, :relation, :columns
+
+      def initialize name, relation
+        @name     = name
+        @relation = relation
+        @columns  = relation.columns.map { |column|
+          column.dup.tap { |col| col.relation = self }
+        }
+      end
+
+      def [] name
+        name = name.to_s
+        columns.find { |column| column.name == name }
+      end
+    end
+  end
+end