reorganized file structures

Conflicts:

	lib/arel.rb
	lib/arel/arel.rb
	lib/arel/engines/memory/predicates.rb
	lib/arel/engines/memory/relations/array.rb
	lib/arel/engines/sql/relations/table.rb

27 files changed, 675 insertions, 0 deletions

diff --git a/lib/arel/algebra/extensions.rb b/lib/arel/algebra/extensions.rb
new file mode 100644
index 0000000000..5338fee989
--- /dev/null
+++ b/lib/arel/algebra/extensions.rb
@@ -0,0 +1,4 @@
+require 'arel/algebra/extensions/object'
+require 'arel/algebra/extensions/class'
+require 'arel/algebra/extensions/array'
+require 'arel/algebra/extensions/hash'
diff --git a/lib/arel/algebra/extensions/array.rb b/lib/arel/algebra/extensions/array.rb
new file mode 100644
index 0000000000..5b6d6d6abd
--- /dev/null
+++ b/lib/arel/algebra/extensions/array.rb
@@ -0,0 +1,5 @@
+class Array
+  def to_hash
+    Hash[*flatten]
+  end
+end
\ No newline at end of file
diff --git a/lib/arel/algebra/extensions/class.rb b/lib/arel/algebra/extensions/class.rb
new file mode 100644
index 0000000000..f37898e7d7
--- /dev/null
+++ b/lib/arel/algebra/extensions/class.rb
@@ -0,0 +1,37 @@
+class Class
+  def attributes(*attrs)
+    @attributes = attrs
+    attr_reader *attrs
+  end
+  
+  def deriving(*methods)
+    methods.each { |m| derive m }
+  end
+  
+  def derive(method_name)
+    methods = {
+      :initialize => "
+        def #{method_name}(#{@attributes.join(',')})
+          #{@attributes.collect { |a| "@#{a} = #{a}" }.join("\n")}
+        end
+      ",
+      :== => "
+        def ==(other)
+          #{name} === other &&
+          #{@attributes.collect { |a| "@#{a} == other.#{a}" }.join(" &&\n")}
+        end
+      "
+    }
+    class_eval methods[method_name], __FILE__, __LINE__
+  end
+  
+  def hash_on(delegatee)
+    define_method :eql? do |other|
+      self == other
+    end
+    
+    define_method :hash do
+      @hash ||= delegatee.hash
+    end
+  end
+end
\ No newline at end of file
diff --git a/lib/arel/algebra/extensions/hash.rb b/lib/arel/algebra/extensions/hash.rb
new file mode 100644
index 0000000000..7472b5aa73
--- /dev/null
+++ b/lib/arel/algebra/extensions/hash.rb
@@ -0,0 +1,7 @@
+class Hash
+  def bind(relation)
+    inject({}) do |bound, (key, value)|
+      bound.merge(key.bind(relation) => value.bind(relation))
+    end
+  end
+end
\ No newline at end of file
diff --git a/lib/arel/algebra/extensions/object.rb b/lib/arel/algebra/extensions/object.rb
new file mode 100644
index 0000000000..d626407dcb
--- /dev/null
+++ b/lib/arel/algebra/extensions/object.rb
@@ -0,0 +1,15 @@
+class Object
+  def bind(relation)
+    Arel::Value.new(self, relation)
+  end
+
+  def find_correlate_in(relation)
+    bind(relation)
+  end
+
+  def metaclass
+    class << self
+      self
+    end
+  end
+end
diff --git a/lib/arel/algebra/extensions/pathname.rb b/lib/arel/algebra/extensions/pathname.rb
new file mode 100644
index 0000000000..2f7e2733e7
--- /dev/null
+++ b/lib/arel/algebra/extensions/pathname.rb
@@ -0,0 +1,5 @@
+class Pathname
+  def /(path)
+    (self + path).expand_path
+  end
+end
\ No newline at end of file
diff --git a/lib/arel/algebra/predicates.rb b/lib/arel/algebra/predicates.rb
new file mode 100644
index 0000000000..f83101306e
--- /dev/null
+++ b/lib/arel/algebra/predicates.rb
@@ -0,0 +1,45 @@
+module Arel
+  class Predicate
+  end
+
+  class Binary < Predicate
+    attributes :operand1, :operand2
+    deriving :initialize
+
+    def ==(other)
+      self.class === other          and
+      @operand1  ==  other.operand1 and
+      @operand2  ==  other.operand2
+    end
+
+    def bind(relation)
+      self.class.new(operand1.find_correlate_in(relation), operand2.find_correlate_in(relation))
+    end
+  end
+
+  class Equality < Binary
+    def ==(other)
+      Equality === other and
+        ((operand1 == other.operand1 and operand2 == other.operand2) or
+         (operand1 == other.operand2 and operand2 == other.operand1))
+    end
+  end
+
+  class GreaterThanOrEqualTo < Binary
+  end
+
+  class GreaterThan < Binary
+  end
+
+  class LessThanOrEqualTo < Binary
+  end
+
+  class LessThan < Binary
+  end
+
+  class Match < Binary
+  end
+
+  class In < Binary
+  end
+end
\ No newline at end of file
diff --git a/lib/arel/algebra/primitives.rb b/lib/arel/algebra/primitives.rb
new file mode 100644
index 0000000000..a4c3169e0b
--- /dev/null
+++ b/lib/arel/algebra/primitives.rb
@@ -0,0 +1,4 @@
+require 'arel/algebra/primitives/attribute'
+require 'arel/algebra/primitives/value'
+require 'arel/algebra/primitives/expression'
+
diff --git a/lib/arel/algebra/primitives/attribute.rb b/lib/arel/algebra/primitives/attribute.rb
new file mode 100644
index 0000000000..5e216770e4
--- /dev/null
+++ b/lib/arel/algebra/primitives/attribute.rb
@@ -0,0 +1,133 @@
+require 'set'
+
+module Arel
+  class Attribute
+    attributes :relation, :name, :alias, :ancestor
+    deriving :==
+    delegate :engine, :christener, :to => :relation
+
+    def initialize(relation, name, options = {})
+      @relation, @name, @alias, @ancestor = relation, name, options[:alias], options[:ancestor]
+    end
+
+    def named?(hypothetical_name)
+      (@alias || name).to_s == hypothetical_name.to_s
+    end
+
+    def aggregation?
+      false
+    end
+
+    module Transformations
+      def self.included(klass)
+        klass.send :alias_method, :eql?, :==
+      end
+
+      def hash
+        @hash ||= history.size + name.hash + relation.hash
+      end
+
+      def as(aliaz = nil)
+        Attribute.new(relation, name, :alias => aliaz, :ancestor => self)
+      end
+
+      def bind(new_relation)
+        relation == new_relation ? self : Attribute.new(new_relation, name, :alias => @alias, :ancestor => self)
+      end
+
+      def to_attribute
+        self
+      end
+    end
+    include Transformations
+
+    module Congruence
+      def history
+        @history ||= [self] + (ancestor ? ancestor.history : [])
+      end
+
+      def join?
+        relation.join?
+      end
+
+      def root
+        history.last
+      end
+
+      def original_relation
+        @original_relation ||= original_attribute.relation
+      end
+
+      def original_attribute
+        @original_attribute ||= history.detect { |a| !a.join? }
+      end
+
+      def find_correlate_in(relation)
+        relation[self] || self
+      end
+
+      def descends_from?(other)
+        history.include?(other)
+      end
+
+      def /(other)
+        other ? (history & other.history).size : 0
+      end
+    end
+    include Congruence
+
+    module Predications
+      def eq(other)
+        Equality.new(self, other)
+      end
+
+      def lt(other)
+        LessThan.new(self, other)
+      end
+
+      def lteq(other)
+        LessThanOrEqualTo.new(self, other)
+      end
+
+      def gt(other)
+        GreaterThan.new(self, other)
+      end
+
+      def gteq(other)
+        GreaterThanOrEqualTo.new(self, other)
+      end
+
+      def matches(regexp)
+        Match.new(self, regexp)
+      end
+
+      def in(array)
+        In.new(self, array)
+      end
+    end
+    include Predications
+
+    module Expressions
+      def count(distinct = false)
+        distinct ?  Expression.new(self, "DISTINCT").count :  Expression.new(self, "COUNT")
+      end
+
+      def sum
+        Expression.new(self, "SUM")
+      end
+
+      def maximum
+        Expression.new(self, "MAX")
+      end
+
+      def minimum
+        Expression.new(self, "MIN")
+      end
+
+      def average
+        Expression.new(self, "AVG")
+      end
+    end
+    include Expressions
+  end
+end
diff --git a/lib/arel/algebra/primitives/expression.rb b/lib/arel/algebra/primitives/expression.rb
new file mode 100644
index 0000000000..b67a5e1f8e
--- /dev/null
+++ b/lib/arel/algebra/primitives/expression.rb
@@ -0,0 +1,31 @@
+module Arel
+  class Expression < Attribute
+    attributes :attribute, :function_sql, :alias, :ancestor
+    deriving :==
+    delegate :relation, :to => :attribute
+    alias_method :name, :alias
+
+    def initialize(attribute, function_sql, aliaz = nil, ancestor = nil)
+      @attribute, @function_sql, @alias, @ancestor = attribute, function_sql, aliaz, ancestor
+    end
+
+    def aggregation?
+      true
+    end
+
+    module Transformations
+      def as(aliaz)
+        Expression.new(attribute, function_sql, aliaz, self)
+      end
+
+      def bind(new_relation)
+        new_relation == relation ? self : Expression.new(attribute.bind(new_relation), function_sql, @alias, self)
+      end
+
+      def to_attribute
+        Attribute.new(relation, @alias, :ancestor => self)
+      end
+    end
+    include Transformations
+  end
+end
diff --git a/lib/arel/algebra/primitives/value.rb b/lib/arel/algebra/primitives/value.rb
new file mode 100644
index 0000000000..91c4045507
--- /dev/null
+++ b/lib/arel/algebra/primitives/value.rb
@@ -0,0 +1,19 @@
+module Arel
+  class Value
+    attributes :value, :relation
+    deriving :initialize, :==
+    delegate :inclusion_predicate_sql, :equality_predicate_sql, :to => :value
+
+    def bind(relation)
+      Value.new(value, relation)
+    end
+
+    def aggregation?
+      false
+    end
+
+    def to_attribute
+      value
+    end
+  end
+end
diff --git a/lib/arel/algebra/relations.rb b/lib/arel/algebra/relations.rb
new file mode 100644
index 0000000000..03f04d2459
--- /dev/null
+++ b/lib/arel/algebra/relations.rb
@@ -0,0 +1,15 @@
+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/writes/delete'
+require 'arel/algebra/relations/writes/update'
+require 'arel/algebra/relations/writes/insert'
+require 'arel/algebra/relations/operations/alias'
+require 'arel/algebra/relations/operations/group'
+require 'arel/algebra/relations/operations/join'
+require 'arel/algebra/relations/operations/order'
+require 'arel/algebra/relations/operations/project'
+require 'arel/algebra/relations/operations/where'
+require 'arel/algebra/relations/operations/skip'
+require 'arel/algebra/relations/operations/take'
\ No newline at end of file
diff --git a/lib/arel/algebra/relations/operations/alias.rb b/lib/arel/algebra/relations/operations/alias.rb
new file mode 100644
index 0000000000..67837f6a75
--- /dev/null
+++ b/lib/arel/algebra/relations/operations/alias.rb
@@ -0,0 +1,7 @@
+module Arel
+  class Alias < Compound
+    attributes :relation
+    deriving :initialize
+    alias_method :==, :equal?
+  end
+end
\ No newline at end of file
diff --git a/lib/arel/algebra/relations/operations/group.rb b/lib/arel/algebra/relations/operations/group.rb
new file mode 100644
index 0000000000..04fd9fea62
--- /dev/null
+++ b/lib/arel/algebra/relations/operations/group.rb
@@ -0,0 +1,15 @@
+module Arel
+  class Group < Compound
+    attributes :relation, :groupings
+    deriving :==
+
+    def initialize(relation, *groupings, &block)
+      @relation = relation
+      @groupings = (groupings + (block_given?? [yield(relatoin)] : [])).collect { |g| g.bind(relation) }
+    end
+
+    def externalizable?
+      true
+    end
+  end
+end
\ No newline at end of file
diff --git a/lib/arel/algebra/relations/operations/join.rb b/lib/arel/algebra/relations/operations/join.rb
new file mode 100644
index 0000000000..8e19254378
--- /dev/null
+++ b/lib/arel/algebra/relations/operations/join.rb
@@ -0,0 +1,41 @@
+module Arel
+  class Join < Relation
+    attributes :join_sql, :relation1, :relation2, :predicates
+    deriving :==
+    delegate :engine, :name, :to => :relation1
+    hash_on :relation1
+
+    def initialize(join_sql, relation1, relation2 = Nil.instance, *predicates)
+      @join_sql, @relation1, @relation2, @predicates = join_sql, relation1, relation2, predicates
+    end
+
+    def attributes
+      @attributes ||= (relation1.externalize.attributes +
+        relation2.externalize.attributes).collect { |a| a.bind(self) }
+    end
+
+    def wheres
+      # TESTME bind to self?
+      relation1.externalize.wheres
+    end
+
+    def ons
+      @ons ||= @predicates.collect { |p| p.bind(self) }
+    end
+
+    # TESTME
+    def externalizable?
+      relation1.externalizable? or relation2.externalizable?
+    end
+
+    def join?
+      true
+    end
+  end
+
+  class Relation
+    def join?
+      false
+    end
+  end
+end
diff --git a/lib/arel/algebra/relations/operations/order.rb b/lib/arel/algebra/relations/operations/order.rb
new file mode 100644
index 0000000000..05af3fde4d
--- /dev/null
+++ b/lib/arel/algebra/relations/operations/order.rb
@@ -0,0 +1,16 @@
+module Arel
+  class Order < Compound
+    attributes :relation, :orderings
+    deriving :==
+    
+    def initialize(relation, *orderings, &block)
+      @relation = relation
+      @orderings = (orderings + (block_given?? [yield(relation)] : [])).collect { |o| o.bind(relation) }
+    end
+
+    # TESTME
+    def orders
+      (orderings + relation.orders).collect { |o| o.bind(self) }
+    end
+  end
+end
\ No newline at end of file
diff --git a/lib/arel/algebra/relations/operations/project.rb b/lib/arel/algebra/relations/operations/project.rb
new file mode 100644
index 0000000000..5507ea3163
--- /dev/null
+++ b/lib/arel/algebra/relations/operations/project.rb
@@ -0,0 +1,19 @@
+module Arel
+  class Project < Compound
+    attributes :relation, :projections
+    deriving :==
+
+    def initialize(relation, *projections, &block)
+      @relation = relation
+      @projections = (projections + (block_given?? [yield(relation)] : [])).collect { |p| p.bind(relation) }
+    end
+
+    def attributes
+      @attributes ||= projections.collect { |p| p.bind(self) }
+    end
+
+    def externalizable?
+      attributes.any?(&:aggregation?) or relation.externalizable?
+    end
+  end
+end
diff --git a/lib/arel/algebra/relations/operations/skip.rb b/lib/arel/algebra/relations/operations/skip.rb
new file mode 100644
index 0000000000..930e4c94ea
--- /dev/null
+++ b/lib/arel/algebra/relations/operations/skip.rb
@@ -0,0 +1,10 @@
+module Arel
+  class Skip < Compound
+    attributes :relation, :skipped
+    deriving :initialize, :==
+    
+    def externalizable?
+      true
+    end
+  end
+end
\ No newline at end of file
diff --git a/lib/arel/algebra/relations/operations/take.rb b/lib/arel/algebra/relations/operations/take.rb
new file mode 100644
index 0000000000..2fd3fdf635
--- /dev/null
+++ b/lib/arel/algebra/relations/operations/take.rb
@@ -0,0 +1,10 @@
+module Arel
+  class Take < Compound
+    attributes :relation, :taken
+    deriving :initialize, :==
+    
+    def externalizable?
+      true
+    end
+  end
+end
\ No newline at end of file
diff --git a/lib/arel/algebra/relations/operations/where.rb b/lib/arel/algebra/relations/operations/where.rb
new file mode 100644
index 0000000000..608aaeb4b7
--- /dev/null
+++ b/lib/arel/algebra/relations/operations/where.rb
@@ -0,0 +1,16 @@
+module Arel
+  class Where < Compound
+    attributes :relation, :predicate
+    deriving :==
+
+    def initialize(relation, *predicates, &block)
+      predicate = block_given?? yield(relation) : predicates.shift
+      @relation = predicates.empty?? relation : Where.new(relation, *predicates)
+      @predicate = predicate.bind(@relation)
+    end
+
+    def wheres
+      @wheres ||= (relation.wheres + [predicate]).collect { |p| p.bind(self) }
+    end
+  end
+end
diff --git a/lib/arel/algebra/relations/relation.rb b/lib/arel/algebra/relations/relation.rb
new file mode 100644
index 0000000000..20badaf165
--- /dev/null
+++ b/lib/arel/algebra/relations/relation.rb
@@ -0,0 +1,134 @@
+module Arel
+  class Relation
+    attr_reader :count
+
+    def session
+      Session.new
+    end
+
+    def call
+      engine.read(self)
+    end
+
+    def bind(relation)
+      self
+    end
+
+    def root
+      self
+    end
+
+    module Enumerable
+      include ::Enumerable
+
+      def each(&block)
+        session.read(self).each(&block)
+      end
+
+      def first
+        session.read(self).first
+      end
+    end
+    include Enumerable
+
+    module Operable
+      def join(other_relation = nil, join_type = "INNER JOIN")
+        case other_relation
+        when String
+          Join.new(other_relation, self)
+        when Relation
+          JoinOperation.new(join_type, self, other_relation)
+        else
+          self
+        end
+      end
+
+      def outer_join(other_relation = nil)
+        join(other_relation, "LEFT OUTER JOIN")
+      end
+
+      [:where, :project, :order, :take, :skip, :group].each do |operation_name|
+        operation = <<-OPERATION
+          def #{operation_name}(*arguments, &block)
+            arguments.all?(&:blank?) && !block_given?? self : #{operation_name.to_s.classify}.new(self, *arguments, &block)
+          end
+        OPERATION
+        class_eval operation, __FILE__, __LINE__
+      end
+
+      def alias
+        Alias.new(self)
+      end
+
+      module Writable
+        def insert(record)
+          session.create Insert.new(self, record); self
+        end
+
+        def update(assignments)
+          session.update Update.new(self, assignments)
+        end
+
+        def delete
+          session.delete Deletion.new(self)
+        end
+      end
+      include Writable
+
+      JoinOperation = Struct.new(:join_sql, :relation1, :relation2) do
+        def on(*predicates)
+          Join.new(join_sql, relation1, relation2, *predicates)
+        end
+      end
+    end
+    include Operable
+
+    module AttributeAccessable
+      def [](index)
+        case index
+        when Symbol, String
+          find_attribute_matching_name(index)
+        when Attribute, Expression
+          find_attribute_matching_attribute(index)
+        when Array
+          index.collect { |i| self[i] }
+        end
+      end
+
+      def find_attribute_matching_name(name)
+        attributes.detect { |a| a.named?(name) }
+      end
+
+      def find_attribute_matching_attribute(attribute)
+        matching_attributes(attribute).max do |a1, a2|
+          (a1.original_attribute / attribute) <=> (a2.original_attribute / attribute)
+        end
+      end
+
+      private
+      def matching_attributes(attribute)
+        (@matching_attributes ||= attributes.inject({}) do |hash, a|
+          (hash[a.root] ||= []) << a
+          hash
+        end)[attribute.root] || []
+      end
+
+      def has_attribute?(attribute)
+        !matching_attributes(attribute).empty?
+      end
+    end
+    include AttributeAccessable
+
+    module DefaultOperations
+      def attributes;             []  end
+      def wheres;                 []  end
+      def orders;                 []  end
+      def inserts;                []  end
+      def groupings;              []  end
+      def joins(formatter = nil); nil end # FIXME
+      def taken;                  nil end
+      def skipped;                nil end
+    end
+    include DefaultOperations
+  end
+end
diff --git a/lib/arel/algebra/relations/utilities/compound.rb b/lib/arel/algebra/relations/utilities/compound.rb
new file mode 100644
index 0000000000..e33b8dbf14
--- /dev/null
+++ b/lib/arel/algebra/relations/utilities/compound.rb
@@ -0,0 +1,18 @@
+module Arel
+  class Compound < Relation
+    attr_reader :relation
+    hash_on :relation
+    delegate :joins, :join?, :inserts, :taken, :skipped, :name, :externalizable?,
+             :column_for, :engine, :table, :table_sql, :array,
+             :to => :relation
+
+    [:attributes, :wheres, :groupings, :orders].each do |operation_name|
+      operation = <<-OPERATION
+        def #{operation_name}
+          @#{operation_name} ||= relation.#{operation_name}.collect { |o| o.bind(self) }
+        end
+      OPERATION
+      class_eval operation, __FILE__, __LINE__
+    end
+  end
+end
diff --git a/lib/arel/algebra/relations/utilities/externalization.rb b/lib/arel/algebra/relations/utilities/externalization.rb
new file mode 100644
index 0000000000..bd067f2304
--- /dev/null
+++ b/lib/arel/algebra/relations/utilities/externalization.rb
@@ -0,0 +1,24 @@
+module Arel
+  class Externalization < Compound
+    attributes :relation
+    deriving :initialize, :==
+
+    def wheres
+      []
+    end
+
+    def attributes
+      @attributes ||= relation.attributes.collect(&:to_attribute).collect { |a| a.bind(self) }
+    end
+  end
+
+  class Relation
+    def externalize
+      @externalized ||= externalizable?? Externalization.new(self) : self
+    end
+
+    def externalizable?
+      false
+    end
+  end
+end
diff --git a/lib/arel/algebra/relations/utilities/nil.rb b/lib/arel/algebra/relations/utilities/nil.rb
new file mode 100644
index 0000000000..6a9d678c45
--- /dev/null
+++ b/lib/arel/algebra/relations/utilities/nil.rb
@@ -0,0 +1,7 @@
+require 'singleton'
+
+module Arel
+  class Nil < Relation
+    include Singleton
+  end
+end
diff --git a/lib/arel/algebra/relations/writes/delete.rb b/lib/arel/algebra/relations/writes/delete.rb
new file mode 100644
index 0000000000..a94067c7fa
--- /dev/null
+++ b/lib/arel/algebra/relations/writes/delete.rb
@@ -0,0 +1,10 @@
+module Arel
+  class Deletion < Compound
+    attributes :relation
+    deriving :initialize, :==
+
+    def call
+      engine.delete(self)
+    end
+  end
+end
diff --git a/lib/arel/algebra/relations/writes/insert.rb b/lib/arel/algebra/relations/writes/insert.rb
new file mode 100644
index 0000000000..6d85e9769a
--- /dev/null
+++ b/lib/arel/algebra/relations/writes/insert.rb
@@ -0,0 +1,14 @@
+module Arel
+  class Insert < Compound
+    attributes :relation, :record
+    deriving :==
+
+    def initialize(relation, record)
+      @relation, @record = relation, record.bind(relation)
+    end
+
+    def call
+      engine.create(self)
+    end
+  end
+end
diff --git a/lib/arel/algebra/relations/writes/update.rb b/lib/arel/algebra/relations/writes/update.rb
new file mode 100644
index 0000000000..e647218a80
--- /dev/null
+++ b/lib/arel/algebra/relations/writes/update.rb
@@ -0,0 +1,14 @@
+module Arel
+  class Update < Compound
+    attributes :relation, :assignments
+    deriving :==
+
+    def initialize(relation, assignments)
+      @relation, @assignments = relation, assignments
+    end
+
+    def call
+      engine.update(self)
+    end
+  end
+end