From 38b10d5ea1411e4adcbb190cc6a38c9529b8998c Mon Sep 17 00:00:00 2001
From: Aaron Patterson <aaron.patterson@gmail.com>
Date: Fri, 13 Aug 2010 08:11:08 -0700
Subject: project works with strings

---
 lib/arel.rb                   |  6 ++++--
 lib/arel/nodes/sql_literal.rb |  7 +------
 lib/arel/sql_literal.rb       |  4 ----
 lib/arel/table.rb             |  4 ++--
 lib/arel/visitors/to_sql.rb   | 17 ++++++++++++++---
 spec/arel/tree_manager.rb     | 20 ++++++++++++++++++++
 6 files changed, 41 insertions(+), 17 deletions(-)

diff --git a/lib/arel.rb b/lib/arel.rb
index e1d34d4561..aeb5161b1d 100644
--- a/lib/arel.rb
+++ b/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'
diff --git a/lib/arel/nodes/sql_literal.rb b/lib/arel/nodes/sql_literal.rb
index 45866adfa8..53ff376071 100644
--- a/lib/arel/nodes/sql_literal.rb
+++ b/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
diff --git a/lib/arel/sql_literal.rb b/lib/arel/sql_literal.rb
index f844ea62ce..5cb4973117 100644
--- a/lib/arel/sql_literal.rb
+++ b/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
diff --git a/lib/arel/table.rb b/lib/arel/table.rb
index 7933c8c1a4..3d0fae07b4 100644
--- a/lib/arel/table.rb
+++ b/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
diff --git a/lib/arel/visitors/to_sql.rb b/lib/arel/visitors/to_sql.rb
index 44a585698f..53ae6e0860 100644
--- a/lib/arel/visitors/to_sql.rb
+++ b/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
diff --git a/spec/arel/tree_manager.rb b/spec/arel/tree_manager.rb
index 44dbb9f727..92af2f3dcd 100644
--- a/spec/arel/tree_manager.rb
+++ b/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
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