project works with strings

lib/arel.rb

@@ -3,8 +3,10 @@ require 'arel/table'
 require 'arel/attributes'
 require 'arel/tree_manager'
 require 'arel/nodes'
-require 'arel/visitors/to_sql'
 
-# below is deprecated
+#### these are deprecated
 require 'arel/sql/engine'
 require 'arel/sql_literal'
+####
+
+require 'arel/visitors/to_sql'

lib/arel/nodes/sql_literal.rb

@@ -1,11 +1,6 @@
 module Arel
   module Nodes
-    class SqlLiteral
-      attr_accessor :string
-
-      def initialize string
-        @string = string
-      end
+    class SqlLiteral < String
     end
   end
 end

lib/arel/sql_literal.rb

@@ -1,8 +1,4 @@
 module Arel
   class SqlLiteral < Nodes::SqlLiteral
-    def initialize string
-      warn "#{caller.first} should use Nodes::SqlLiteral"
-      super
-    end
   end
 end

lib/arel/table.rb

@@ -10,8 +10,8 @@ module Arel
       @engine = engine
     end
 
-    def where expression
-      TreeManager.new(@engine).from(self).where expression
+    def tm
+      TreeManager.new(@engine).from(self)
     end
 
     def columns

lib/arel/visitors/to_sql.rb

@@ -22,8 +22,8 @@ module Arel
       def visit_Arel_Nodes_SelectCore o
         [
           "SELECT #{o.projections.map { |x| visit x }.join ', '}",
-          "FROM #{o.froms.map { |x| visit x }.join ', ' }",
-          ("WHERE #{o.wheres.map { |x| visit x }.join ' AND ' }" unless o.wheres.blank?)
+          ("FROM #{o.froms.map { |x| visit x }.join ', ' }" unless o.froms.empty?),
+          ("WHERE #{o.wheres.map { |x| visit x }.join ' AND ' }" unless o.wheres.empty?)
         ].compact.join ' '
       end
 
@@ -40,9 +40,20 @@ module Arel
       end
 
       def visit_Fixnum o; o end
+      alias :visit_String :visit_Fixnum
+      alias :visit_Arel_Nodes_SqlLiteral :visit_Fixnum
+      alias :visit_Arel_SqlLiteral :visit_Fixnum # This is deprecated
 
+      DISPATCH = {}
       def visit object
-        send :"visit_#{object.class.name.gsub('::', '_')}", object
+        send DISPATCH[object.class], object
+      end
+
+      private_instance_methods(false).each do |method|
+        method = method.to_s
+        next unless method =~ /^visit_(.*)$/
+        const = $1.split('_').inject(Object) { |m,s| m.const_get s }
+        DISPATCH[const] = method
       end
 
       def quote_table_name name

spec/arel/tree_manager.rb

@@ -2,6 +2,26 @@ require 'spec_helper'
 
 module Arel
   describe 'tree manager' do
+    describe 'project' do
+      it 'takes strings' do
+        table   = Table.new :users
+        manager = Arel::TreeManager.new Table.engine
+        manager.project '*'
+        manager.to_sql.should == %{
+          SELECT *
+        }.gsub("\n", '').gsub(/(^\s*|\s*$)/, '').squeeze(' ')
+      end
+
+      it "takes sql literals" do
+        table   = Table.new :users
+        manager = Arel::TreeManager.new Table.engine
+        manager.project Nodes::SqlLiteral.new '*'
+        manager.to_sql.should == %{
+          SELECT *
+        }.gsub("\n", '').gsub(/(^\s*|\s*$)/, '').squeeze(' ')
+      end
+    end
+
     describe 'take' do
       it "knows take" do
         table   = Table.new :users