recursive memory operations now possible

Conflicts:

	lib/arel/algebra/relations/relation.rb

10 files changed, 46 insertions, 17 deletions

diff --git a/lib/arel/algebra/extensions/hash.rb b/lib/arel/algebra/extensions/hash.rb
index bc97785e62..7472b5aa73 100644
--- a/lib/arel/algebra/extensions/hash.rb
+++ b/lib/arel/algebra/extensions/hash.rb
@@ -4,11 +4,4 @@ class Hash
       bound.merge(key.bind(relation) => value.bind(relation))
     end
   end
-  
-  def slice(*attributes)
-    inject({}) do |cheese, (key, value)|
-      cheese[key] = value if attributes.include?(key)
-      cheese
-    end
-  end
 end
\ No newline at end of file
diff --git a/lib/arel/algebra/relations.rb b/lib/arel/algebra/relations.rb
index b75a31e5e3..94df5938fe 100644
--- a/lib/arel/algebra/relations.rb
+++ b/lib/arel/algebra/relations.rb
@@ -2,6 +2,7 @@ require 'arel/algebra/relations/relation'
 require 'arel/algebra/relations/utilities/compound'
 require 'arel/algebra/relations/utilities/nil'
 require 'arel/algebra/relations/utilities/externalization'
+require 'arel/algebra/relations/row'
 require 'arel/algebra/relations/writes'
 require 'arel/algebra/relations/operations/alias'
 require 'arel/algebra/relations/operations/group'
diff --git a/lib/arel/algebra/relations/relation.rb b/lib/arel/algebra/relations/relation.rb
index 6d76e66638..fe8cab4b02 100644
--- a/lib/arel/algebra/relations/relation.rb
+++ b/lib/arel/algebra/relations/relation.rb
@@ -14,10 +14,6 @@ module Arel
       self
     end
 
-    def root
-      self
-    end
-
     module Enumerable
       include ::Enumerable
 
diff --git a/lib/arel/algebra/relations/row.rb b/lib/arel/algebra/relations/row.rb
new file mode 100644
index 0000000000..2d63498452
--- /dev/null
+++ b/lib/arel/algebra/relations/row.rb
@@ -0,0 +1,21 @@
+module Arel
+  class Row
+    attributes :relation, :tuple
+    deriving :==, :initialize
+    
+    def [](attribute)
+      tuple[relation.position_of(attribute)]
+    end
+    
+    def slice(*attributes)
+      Row.new(relation, attributes.inject([]) do |cheese, attribute|
+        cheese << self[attribute]
+        cheese
+      end)
+    end
+    
+    def bind(relation)
+      Row.new(relation, tuple)
+    end
+  end
+end
\ No newline at end of file
diff --git a/lib/arel/engines/memory/predicates.rb b/lib/arel/engines/memory/predicates.rb
index bbf39ba794..e233f3ba39 100644
--- a/lib/arel/engines/memory/predicates.rb
+++ b/lib/arel/engines/memory/predicates.rb
@@ -21,15 +21,19 @@ module Arel
   end
 
   class Equality < Binary
+    def operator; :== end
   end
 
   class GreaterThanOrEqualTo < Binary
+    def operator; :>= end
   end
 
   class GreaterThan < Binary
+    def operator; :> end
   end
 
   class LessThanOrEqualTo < Binary
+    def operator; :<= end
   end
 
   class LessThan < Binary
@@ -37,8 +41,10 @@ module Arel
   end
 
   class Match < Binary
+    def operator; :=~ end
   end
 
   class In < Binary
+    def operator; :include? end
   end
 end
diff --git a/lib/arel/engines/memory/relations.rb b/lib/arel/engines/memory/relations.rb
index 1b009537b9..820b0af4b2 100644
--- a/lib/arel/engines/memory/relations.rb
+++ b/lib/arel/engines/memory/relations.rb
@@ -1,3 +1,4 @@
+require 'arel/engines/memory/relations/relation'
 require 'arel/engines/memory/relations/array'
 require 'arel/engines/memory/relations/operations'
 require 'arel/engines/memory/relations/compound'
diff --git a/lib/arel/engines/memory/relations/array.rb b/lib/arel/engines/memory/relations/array.rb
index c02c62891b..ea0b5af5ba 100644
--- a/lib/arel/engines/memory/relations/array.rb
+++ b/lib/arel/engines/memory/relations/array.rb
@@ -15,7 +15,7 @@ module Arel
     end
 
     def eval
-      @array.collect { |row| attributes.zip(row).to_hash }
+      @array.collect { |r| Row.new(self, r) }
     end
   end
 end
\ No newline at end of file
diff --git a/lib/arel/engines/memory/relations/compound.rb b/lib/arel/engines/memory/relations/compound.rb
index b029082d57..3791fa4622 100644
--- a/lib/arel/engines/memory/relations/compound.rb
+++ b/lib/arel/engines/memory/relations/compound.rb
@@ -1,5 +1,9 @@
 module Arel
   class Compound < Relation
     delegate :array, :to => :relation
+    
+    def unoperated_rows
+      relation.eval.collect { |row| row.bind(self) }
+    end
   end
 end
diff --git a/lib/arel/engines/memory/relations/operations.rb b/lib/arel/engines/memory/relations/operations.rb
index 115df054df..8e03aca7b1 100644
--- a/lib/arel/engines/memory/relations/operations.rb
+++ b/lib/arel/engines/memory/relations/operations.rb
@@ -1,13 +1,13 @@
 module Arel
   class Where < Compound
     def eval
-      relation.eval.select { |row| predicate.eval(row) }
+      unoperated_rows.select { |row| predicate.eval(row) }
     end
   end
   
   class Order < Compound
     def eval
-      relation.eval.sort do |row1, row2|
+      unoperated_rows.sort do |row1, row2|
         ordering = orderings.detect { |o| o.eval(row1, row2) != 0 } || orderings.last
         ordering.eval(row1, row2)
       end
@@ -16,19 +16,19 @@ module Arel
   
   class Project < Compound
     def eval
-      relation.eval.collect { |r| r.slice(*projections) }
+      unoperated_rows.collect { |r| r.slice(*projections) }
     end
   end
   
   class Take < Compound
     def eval
-      relation.eval[0, taken]
+      unoperated_rows[0, taken]
     end
   end
   
   class Skip < Compound
     def eval
-      relation.eval[skipped..-1]
+      unoperated_rows[skipped..-1]
     end
   end
   
diff --git a/lib/arel/engines/memory/relations/relation.rb b/lib/arel/engines/memory/relations/relation.rb
new file mode 100644
index 0000000000..abfb8bb37f
--- /dev/null
+++ b/lib/arel/engines/memory/relations/relation.rb
@@ -0,0 +1,7 @@
+module Arel
+  class Relation
+    def position_of(attribute)
+      attributes.index(self[attribute])
+    end
+  end
+end
\ No newline at end of file