Add case sensitive regexp

Explicitly declare if this is case sensitive or not

currently postgres assumes case insensitive regexp
no other databases support regexps

lib/arel/nodes.rb

@@ -30,6 +30,7 @@ require 'arel/nodes/table_alias'
 require 'arel/nodes/infix_operation'
 require 'arel/nodes/over'
 require 'arel/nodes/matches'
+require 'arel/nodes/regexp'
 
 # nary
 require 'arel/nodes/and'

lib/arel/nodes/binary.rb

@@ -38,9 +38,7 @@ module Arel
       LessThanOrEqual
       NotEqual
       NotIn
-      NotRegexp
       Or
-      Regexp
       Union
       UnionAll
       Intersect

lib/arel/nodes/regexp.rb

@@ -0,0 +1,14 @@
+module Arel
+  module Nodes
+    class Regexp < Binary
+      attr_accessor :case_sensitive
+
+      def initialize(left, right, case_sensitive = true)
+        super(left, right)
+        @case_sensitive = case_sensitive
+      end
+    end
+
+    class NotRegexp < Regexp; end
+  end
+end

lib/arel/visitors/postgresql.rb

@@ -26,11 +26,13 @@ module Arel
       end
 
       def visit_Arel_Nodes_Regexp o, collector
-        infix_value o, collector, ' ~ '
+        op = o.case_sensitive ? ' ~ ' : ' ~* '
+        infix_value o, collector, op
       end
 
       def visit_Arel_Nodes_NotRegexp o, collector
-        infix_value o, collector, ' !~ '
+        op = o.case_sensitive ? ' !~ ' : ' !~* '
+        infix_value o, collector, op
       end
 
       def visit_Arel_Nodes_DistinctOn o, collector

test/visitors/test_postgres.rb

@@ -120,6 +120,13 @@ module Arel
           }
         end
 
+        it "can handle case insensitive" do
+          node = Arel::Nodes::Regexp.new(@table[:name], Nodes.build_quoted('foo%'), false)
+          compile(node).must_be_like %{
+            "users"."name" ~* 'foo%'
+          }
+        end
+
         it 'can handle subqueries' do
           subquery = @table.project(:id).where(Arel::Nodes::Regexp.new(@table[:name], Nodes.build_quoted('foo%')))
           node = @attr.in subquery
@@ -137,6 +144,13 @@ module Arel
           }
         end
 
+        it "can handle case insensitive" do
+          node = Arel::Nodes::NotRegexp.new(@table[:name], Nodes.build_quoted('foo%'), false)
+          compile(node).must_be_like %{
+            "users"."name" !~* 'foo%'
+          }
+        end
+
         it 'can handle subqueries' do
           subquery = @table.project(:id).where(Arel::Nodes::NotRegexp.new(@table[:name], Nodes.build_quoted('foo%')))
           node = @attr.in subquery