regex: stop butchering them

MariaDB, MySQL and PostgreSQL support PRCE.

NEWS.md

@@ -2,6 +2,15 @@
 
 ## Current Release
 
+### Changes
+
+- `regexp` and `not_regexp` no longer try to change the regexes.
+  MariaDB, MySQL and PostgreSQL perfectly support PRCE, hence we
+  no longer try to rewrite the regexes.
+  Note that `regexp_replace` did not perform any of these rewritings.
+
+## Release v2.1.7/v1.3.7
+
 ### New Features
 
 - `o.format_date` as an alternative to `o.format`

lib/arel_extensions/comparators.rb

@@ -19,40 +19,13 @@ def <=(other)
     # REGEXP function
     # Pattern matching using regular expressions
     def =~(other)
-        #      arg = self.relation.engine.connection.schema_cache.columns_hash(self.relation.table_name)[self.name.to_s].type
-        #      if arg == :string || arg == :text
-      Arel::Nodes::Regexp.new self, convert_regexp(other)
-      #      end
+      Arel::Nodes::Regexp.new self, Arel.quoted(other, self)
     end
 
     # NOT_REGEXP function
     # Negation of Regexp
     def !~(other)
-        #      arg = self.relation.engine.connection.schema_cache.columns_hash(self.relation.table_name)[self.name.to_s].type
-        #      if arg == :string || arg == :text
-      Arel::Nodes::NotRegexp.new self, convert_regexp(other)
-      #      end
-    end
-
-    private
-
-    # Function used for not_regexp.
-    def convert_regexp(other)
-      case other
-      when String
-        # Do nothing.
-      when Regexp
-        other = other.source.gsub('\A', '^')
-        other.gsub!('\z', '$')
-        other.gsub!('\Z', '$')
-        other.gsub!('\d', '[0-9]')
-        other.gsub!('\D', '[^0-9]')
-        other.gsub!('\w', '[0-9A-Za-z]')
-        other.gsub!('\W', '[^A-Za-z0-9_]')
-      else
-        raise(ArgumentError)
-      end
-      Arel.quoted(other, self)
+      Arel::Nodes::NotRegexp.new self, Arel.quoted(other, self)
     end
   end
 end