From e573a9ea468d748cf0ebd1a70521c1589efda23e Mon Sep 17 00:00:00 2001
From: Aaron Patterson <aaron.patterson@gmail.com>
Date: Thu, 12 Aug 2010 21:21:20 -0700
Subject: limits are added

---
 lib/arel/nodes.rb                  |  3 ++-
 lib/arel/nodes/select.rb           | 13 -------------
 lib/arel/nodes/select_core.rb      | 13 +++++++++++++
 lib/arel/nodes/select_statement.rb | 13 +++++++++++++
 lib/arel/table.rb                  |  4 ++++
 lib/arel/tree_manager.rb           | 21 ++++++++++++++-------
 lib/arel/visitors/to_sql.rb        |  9 ++++++++-
 7 files changed, 54 insertions(+), 22 deletions(-)
 delete mode 100644 lib/arel/nodes/select.rb
 create mode 100644 lib/arel/nodes/select_core.rb
 create mode 100644 lib/arel/nodes/select_statement.rb

(limited to 'lib/arel')

diff --git a/lib/arel/nodes.rb b/lib/arel/nodes.rb
index 53c17a8cca..5db177d53d 100644
--- a/lib/arel/nodes.rb
+++ b/lib/arel/nodes.rb
@@ -1,3 +1,4 @@
 require 'arel/nodes/equality'
 require 'arel/nodes/sql_literal'
-require 'arel/nodes/select'
+require 'arel/nodes/select_core'
+require 'arel/nodes/select_statement'
diff --git a/lib/arel/nodes/select.rb b/lib/arel/nodes/select.rb
deleted file mode 100644
index 8f68adbcd5..0000000000
--- a/lib/arel/nodes/select.rb
+++ /dev/null
@@ -1,13 +0,0 @@
-module Arel
-  module Nodes
-    class Select
-      attr_reader :froms, :projections, :wheres
-
-      def initialize
-        @froms       = []
-        @projections = []
-        @wheres      = []
-      end
-    end
-  end
-end
diff --git a/lib/arel/nodes/select_core.rb b/lib/arel/nodes/select_core.rb
new file mode 100644
index 0000000000..39145de697
--- /dev/null
+++ b/lib/arel/nodes/select_core.rb
@@ -0,0 +1,13 @@
+module Arel
+  module Nodes
+    class SelectCore
+      attr_reader :froms, :projections, :wheres
+
+      def initialize
+        @froms       = []
+        @projections = []
+        @wheres      = []
+      end
+    end
+  end
+end
diff --git a/lib/arel/nodes/select_statement.rb b/lib/arel/nodes/select_statement.rb
new file mode 100644
index 0000000000..122f6275fe
--- /dev/null
+++ b/lib/arel/nodes/select_statement.rb
@@ -0,0 +1,13 @@
+module Arel
+  module Nodes
+    class SelectStatement
+      attr_reader :cores
+      attr_accessor :limit
+
+      def initialize cores = [SelectCore.new]
+        @cores = cores
+        @limit = nil
+      end
+    end
+  end
+end
diff --git a/lib/arel/table.rb b/lib/arel/table.rb
index 0ab39f134d..7933c8c1a4 100644
--- a/lib/arel/table.rb
+++ b/lib/arel/table.rb
@@ -10,6 +10,10 @@ module Arel
       @engine = engine
     end
 
+    def where expression
+      TreeManager.new(@engine).from(self).where expression
+    end
+
     def columns
       @engine.connection.columns(@name, "#{@name} Columns").map do |column|
         Attributes.for(column).new self, column.name, column
diff --git a/lib/arel/tree_manager.rb b/lib/arel/tree_manager.rb
index b111ca9557..e92092d6e1 100644
--- a/lib/arel/tree_manager.rb
+++ b/lib/arel/tree_manager.rb
@@ -1,31 +1,38 @@
 module Arel
   class TreeManager
     def initialize engine
-      @engine         = engine
-      @statement_list = []
+      @engine  = engine
+      @selects = []
 
       # default to Select
-      @statement_list << Nodes::Select.new
+      @stmt = Nodes::SelectStatement.new
+      @core = @stmt.cores.last
+      @selects << @stmt
     end
 
     def from table
-      @statement_list.last.froms << table
+      @core.froms << table
       self
     end
 
     def project projection
-      @statement_list.last.projections << projection
+      @core.projections << projection
       self
     end
 
     def where expr
-      @statement_list.last.wheres << expr
+      @core.wheres << expr
+      self
+    end
+
+    def take limit
+      @stmt.limit = limit
       self
     end
 
     def to_sql
       viz = Visitors::ToSql.new @engine
-      viz.accept @statement_list.last
+      viz.accept @stmt
     end
   end
 end
diff --git a/lib/arel/visitors/to_sql.rb b/lib/arel/visitors/to_sql.rb
index bb2a4d07e8..44a585698f 100644
--- a/lib/arel/visitors/to_sql.rb
+++ b/lib/arel/visitors/to_sql.rb
@@ -12,7 +12,14 @@ module Arel
       end
 
       private
-      def visit_Arel_Nodes_Select o
+      def visit_Arel_Nodes_SelectStatement o
+        [
+          o.cores.map { |x| visit x }.join,
+          ("LIMIT #{o.limit}" if o.limit)
+        ].compact.join ' '
+      end
+
+      def visit_Arel_Nodes_SelectCore o
         [
           "SELECT #{o.projections.map { |x| visit x }.join ', '}",
           "FROM #{o.froms.map { |x| visit x }.join ', ' }",
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