6 files changed, 70 insertions, 0 deletions
diff --git a/lib/arel/extensions/array.rb b/lib/arel/extensions/array.rb
new file mode 100644
index 0000000000..793c06aad8
--- /dev/null
+++ b/lib/arel/extensions/array.rb
@@ -0,0 +1,13 @@
+class Array
+  def to_hash
+    Hash[*flatten]
+  end
+  
+  def to_sql(formatter = nil)
+    "(" + collect { |e| e.to_sql(formatter) }.join(', ') + ")"
+  end
+  
+  def inclusion_predicate_sql
+    "IN"
+  end
+end
+\ No newline at end of file
diff --git a/lib/arel/extensions/class.rb b/lib/arel/extensions/class.rb
new file mode 100644
index 0000000000..0e5b728c26
--- /dev/null
+++ b/lib/arel/extensions/class.rb
@@ -0,0 +1,17 @@
+class Class
+  def abstract(*methods)
+    methods.each do |method|
+      define_method method do
+        raise NotImplementedError
+      end
+    end
+  end
+  
+  def hash_on(delegatee)
+    define_method :eql? do |other|
+      self == other
+    end
+    
+    delegate :hash, :to => delegatee
+  end
+end
+\ No newline at end of file
diff --git a/lib/arel/extensions/hash.rb b/lib/arel/extensions/hash.rb
new file mode 100644
index 0000000000..7472b5aa73
--- /dev/null
+++ b/lib/arel/extensions/hash.rb
@@ -0,0 +1,7 @@
+class Hash
+  def bind(relation)
+    inject({}) do |bound, (key, value)|
+      bound.merge(key.bind(relation) => value.bind(relation))
+    end
+  end
+end
+\ No newline at end of file
diff --git a/lib/arel/extensions/nil_class.rb b/lib/arel/extensions/nil_class.rb
new file mode 100644
index 0000000000..729c4cada7
--- /dev/null
+++ b/lib/arel/extensions/nil_class.rb
@@ -0,0 +1,5 @@
+class NilClass
+  def equality_predicate_sql
+    'IS'
+  end
+end
+\ No newline at end of file
diff --git a/lib/arel/extensions/object.rb b/lib/arel/extensions/object.rb
new file mode 100644
index 0000000000..779098f7ea
--- /dev/null
+++ b/lib/arel/extensions/object.rb
@@ -0,0 +1,19 @@
+class Object  
+  def bind(relation)
+    Arel::Value.new(self, relation)
+  end
+  
+  def to_sql(formatter = nil)
+    formatter.scalar self
+  end
+  
+  def equality_predicate_sql
+    '='
+  end
+  
+  def metaclass
+    class << self
+      self
+    end
+  end
+end
+\ No newline at end of file
diff --git a/lib/arel/extensions/range.rb b/lib/arel/extensions/range.rb
new file mode 100644
index 0000000000..d7329efe34
--- /dev/null
+++ b/lib/arel/extensions/range.rb
@@ -0,0 +1,9 @@
+class Range
+  def to_sql(formatter = nil)
+    formatter.range self.begin, self.end
+  end
+  
+  def inclusion_predicate_sql
+    "BETWEEN"
+  end
+end
+\ No newline at end of file