moved sql related code to its own engine area

Conflicts:

	lib/arel/engine.rb
	lib/arel/extensions/object.rb
	lib/arel/predicates.rb
	lib/arel/primitives/attribute.rb
	lib/arel/primitives/expression.rb
	lib/arel/primitives/value.rb
	lib/arel/relations/operations/join.rb
	lib/arel/relations/relation.rb
	lib/arel/relations/utilities/externalization.rb
	lib/arel/relations/utilities/nil.rb
	lib/arel/relations/writes/delete.rb
	lib/arel/relations/writes/insert.rb
	lib/arel/relations/writes/update.rb
	spec/arel/unit/relations/skip_spec.rb
	spec/arel/unit/relations/take_spec.rb
	spec/spec_helper.rb

30 files changed, 485 insertions, 0 deletions

diff --git a/lib/arel/engines/array/array.rb b/lib/arel/engines/array/array.rb
new file mode 100644
index 0000000000..3a3a47308a
--- /dev/null
+++ b/lib/arel/engines/array/array.rb
@@ -0,0 +1 @@
+require 'arel/engines/array/relations/array'
\ No newline at end of file
diff --git a/lib/arel/engines/array/relations/array.rb b/lib/arel/engines/array/relations/array.rb
new file mode 100644
index 0000000000..dac65abbc2
--- /dev/null
+++ b/lib/arel/engines/array/relations/array.rb
@@ -0,0 +1,19 @@
+module Arel
+  class Array < Relation
+    include Recursion::BaseCase
+
+    def initialize(array, attribute_names)
+      @array, @attribute_names = array, attribute_names
+    end
+
+    def attributes
+      @attributes ||= @attribute_names.collect do |name|
+        Attribute.new(self, name.to_sym)
+      end
+    end
+
+    def call(connection = nil)
+      @array.collect { |row| attributes.zip(row).to_hash }
+    end
+  end
+end
\ No newline at end of file
diff --git a/lib/arel/engines/sql/christener.rb b/lib/arel/engines/sql/christener.rb
new file mode 100644
index 0000000000..5883a75f41
--- /dev/null
+++ b/lib/arel/engines/sql/christener.rb
@@ -0,0 +1,13 @@
+module Arel
+  module Sql
+    class Christener
+      def name_for(relation)
+        @used_names ||= Hash.new(0)
+        (@relation_names ||= Hash.new do |hash, relation|
+          @used_names[name = relation.name] += 1
+          hash[relation] = name + (@used_names[name] > 1 ? "_#{@used_names[name]}" : '')
+        end)[relation.table]
+      end
+    end
+  end
+end
\ No newline at end of file
diff --git a/lib/arel/engines/sql/engine.rb b/lib/arel/engines/sql/engine.rb
new file mode 100644
index 0000000000..e5d1a8b0ca
--- /dev/null
+++ b/lib/arel/engines/sql/engine.rb
@@ -0,0 +1,41 @@
+module Arel
+  module Sql
+    class Engine
+      def initialize(ar = nil)
+        @ar = ar
+      end
+
+      def connection
+        @ar.connection
+      end
+
+      def method_missing(method, *args, &block)
+        @ar.connection.send(method, *args, &block)
+      end
+
+      module CRUD
+        def create(relation)
+          connection.insert(relation.to_sql)
+        end
+
+        def read(relation)
+          results = connection.execute(relation.to_sql)
+          rows = []
+          results.each do |row|
+            rows << attributes.zip(row).to_hash
+          end
+          rows
+        end
+
+        def update(relation)
+          connection.update(relation.to_sql)
+        end
+
+        def delete(relation)
+          connection.delete(relation.to_sql)
+        end
+      end
+      include CRUD
+    end
+  end
+end
\ No newline at end of file
diff --git a/lib/arel/engines/sql/extensions.rb b/lib/arel/engines/sql/extensions.rb
new file mode 100644
index 0000000000..6f4ad32148
--- /dev/null
+++ b/lib/arel/engines/sql/extensions.rb
@@ -0,0 +1,4 @@
+require 'arel/engines/sql/extensions/object'
+require 'arel/engines/sql/extensions/array'
+require 'arel/engines/sql/extensions/range'
+require 'arel/engines/sql/extensions/nil_class'
\ No newline at end of file
diff --git a/lib/arel/engines/sql/extensions/array.rb b/lib/arel/engines/sql/extensions/array.rb
new file mode 100644
index 0000000000..1daa5abca7
--- /dev/null
+++ b/lib/arel/engines/sql/extensions/array.rb
@@ -0,0 +1,9 @@
+class Array
+  def to_sql(formatter = nil)
+    "(" + collect { |e| e.to_sql(formatter) }.join(', ') + ")"
+  end
+
+  def inclusion_predicate_sql
+    "IN"
+  end
+end
\ No newline at end of file
diff --git a/lib/arel/engines/sql/extensions/nil_class.rb b/lib/arel/engines/sql/extensions/nil_class.rb
new file mode 100644
index 0000000000..729c4cada7
--- /dev/null
+++ b/lib/arel/engines/sql/extensions/nil_class.rb
@@ -0,0 +1,5 @@
+class NilClass
+  def equality_predicate_sql
+    'IS'
+  end
+end
\ No newline at end of file
diff --git a/lib/arel/engines/sql/extensions/object.rb b/lib/arel/engines/sql/extensions/object.rb
new file mode 100644
index 0000000000..ef990eee2f
--- /dev/null
+++ b/lib/arel/engines/sql/extensions/object.rb
@@ -0,0 +1,9 @@
+class Object
+  def to_sql(formatter)
+    formatter.scalar self
+  end
+
+  def equality_predicate_sql
+    '='
+  end
+end
\ No newline at end of file
diff --git a/lib/arel/engines/sql/extensions/range.rb b/lib/arel/engines/sql/extensions/range.rb
new file mode 100644
index 0000000000..d7329efe34
--- /dev/null
+++ b/lib/arel/engines/sql/extensions/range.rb
@@ -0,0 +1,9 @@
+class Range
+  def to_sql(formatter = nil)
+    formatter.range self.begin, self.end
+  end
+  
+  def inclusion_predicate_sql
+    "BETWEEN"
+  end
+end
\ No newline at end of file
diff --git a/lib/arel/engines/sql/formatters.rb b/lib/arel/engines/sql/formatters.rb
new file mode 100644
index 0000000000..f82ddf631f
--- /dev/null
+++ b/lib/arel/engines/sql/formatters.rb
@@ -0,0 +1,121 @@
+module Arel
+  module Sql
+    class Formatter
+      attr_reader :environment
+      delegate :christener, :engine, :to => :environment
+      delegate :name_for, :to => :christener
+      delegate :quote_table_name, :quote_column_name, :quote, :to => :engine
+
+      def initialize(environment)
+        @environment = environment
+      end
+    end
+
+    class SelectClause < Formatter
+      def attribute(attribute)
+        # FIXME this should check that the column exists
+        if attribute.name.to_s =~ /^\w*$/
+          "#{quote_table_name(name_for(attribute.original_relation))}.#{quote_column_name(attribute.name)}" + (attribute.alias ? " AS #{quote(attribute.alias.to_s)}" : "")
+        else
+          attribute.name.to_s + (attribute.alias ? " AS #{quote(attribute.alias.to_s)}" : "")
+        end
+      end
+
+      def expression(expression)
+        if expression.function_sql == "DISTINCT"
+          "#{expression.function_sql} #{expression.attribute.to_sql(self)}" + (expression.alias ? " AS #{quote_column_name(expression.alias)}" : '')
+        else
+          "#{expression.function_sql}(#{expression.attribute.to_sql(self)})" + (expression.alias ? " AS #{quote_column_name(expression.alias)}" : " AS #{expression.function_sql.to_s.downcase}_id")
+        end
+      end
+
+      def select(select_sql, table)
+        "(#{select_sql}) AS #{quote_table_name(name_for(table))}"
+      end
+
+      def value(value)
+        value
+      end
+    end
+
+    class PassThrough < Formatter
+      def value(value)
+        value
+      end
+    end
+
+    class WhereClause < PassThrough
+    end
+
+    class OrderClause < PassThrough
+      def attribute(attribute)
+        "#{quote_table_name(name_for(attribute.original_relation))}.#{quote_column_name(attribute.name)}"
+      end
+    end
+
+    class GroupClause < PassThrough
+      def attribute(attribute)
+        "#{quote_table_name(name_for(attribute.original_relation))}.#{quote_column_name(attribute.name)}"
+      end
+    end
+
+    class WhereCondition < Formatter
+      def attribute(attribute)
+        "#{quote_table_name(name_for(attribute.original_relation))}.#{quote_column_name(attribute.name)}"
+      end
+
+      def expression(expression)
+        "#{expression.function_sql}(#{expression.attribute.to_sql(self)})"
+      end
+
+      def value(value)
+        value.to_sql(self)
+      end
+
+      def scalar(value, column = nil)
+        quote(value, column)
+      end
+
+      def select(select_sql, table)
+        "(#{select_sql})"
+      end
+    end
+
+    class SelectStatement < Formatter
+      def select(select_sql, table)
+        select_sql
+      end
+    end
+
+    class TableReference < Formatter
+      def select(select_sql, table)
+        "(#{select_sql}) AS #{quote_table_name(name_for(table))}"
+      end
+
+      def table(table)
+        if table.name =~ /^(\w|-)*$/
+          quote_table_name(table.name) + (table.name != name_for(table) ? " AS " + quote_table_name(name_for(table)) : '')
+        else
+          table.name + (table.name != name_for(table) ? " AS " + (name_for(table)) : '')
+        end
+      end
+    end
+
+    class Attribute < WhereCondition
+      def scalar(scalar)
+        quote(scalar, environment.column)
+      end
+
+      def array(array)
+        "(" + array.collect { |e| e.to_sql(self) }.join(', ') + ")"
+      end
+
+      def range(left, right)
+        "#{left} AND #{right}"
+      end
+    end
+
+    class Value < WhereCondition
+    end
+  end
+end
diff --git a/lib/arel/engines/sql/predicates.rb b/lib/arel/engines/sql/predicates.rb
new file mode 100644
index 0000000000..dfeddb2de1
--- /dev/null
+++ b/lib/arel/engines/sql/predicates.rb
@@ -0,0 +1,37 @@
+module Arel
+  class Binary < Predicate
+    def to_sql(formatter = nil)
+      "#{operand1.to_sql} #{predicate_sql} #{operand1.format(operand2)}"
+    end
+  end
+
+  class Equality < Binary
+    def predicate_sql
+      operand2.equality_predicate_sql
+    end
+  end
+
+  class GreaterThanOrEqualTo < Binary
+    def predicate_sql; '>=' end
+  end
+
+  class GreaterThan < Binary
+    def predicate_sql; '>' end
+  end
+
+  class LessThanOrEqualTo < Binary
+    def predicate_sql; '<=' end
+  end
+
+  class LessThan < Binary
+    def predicate_sql; '<' end
+  end
+
+  class Match < Binary
+    def predicate_sql; 'LIKE' end
+  end
+
+  class In < Binary
+    def predicate_sql; operand2.inclusion_predicate_sql end
+  end
+end
\ No newline at end of file
diff --git a/lib/arel/engines/sql/primitives.rb b/lib/arel/engines/sql/primitives.rb
new file mode 100644
index 0000000000..405b1ca803
--- /dev/null
+++ b/lib/arel/engines/sql/primitives.rb
@@ -0,0 +1,3 @@
+require 'arel/engines/sql/primitives/attribute'
+require 'arel/engines/sql/primitives/value'
+require 'arel/engines/sql/primitives/expression'
\ No newline at end of file
diff --git a/lib/arel/engines/sql/primitives/attribute.rb b/lib/arel/engines/sql/primitives/attribute.rb
new file mode 100644
index 0000000000..48de690b6f
--- /dev/null
+++ b/lib/arel/engines/sql/primitives/attribute.rb
@@ -0,0 +1,17 @@
+require 'set'
+
+module Arel
+  class Attribute
+    def column
+      original_relation.column_for(self)
+    end
+
+    def format(object)
+      object.to_sql(Sql::Attribute.new(self))
+    end
+
+    def to_sql(formatter = Sql::WhereCondition.new(relation))
+      formatter.attribute self
+    end
+  end
+end
\ No newline at end of file
diff --git a/lib/arel/engines/sql/primitives/expression.rb b/lib/arel/engines/sql/primitives/expression.rb
new file mode 100644
index 0000000000..24f6879848
--- /dev/null
+++ b/lib/arel/engines/sql/primitives/expression.rb
@@ -0,0 +1,7 @@
+module Arel
+  class Expression < Attribute
+    def to_sql(formatter = Sql::SelectClause.new(relation))
+      formatter.expression self
+    end
+  end
+end
\ No newline at end of file
diff --git a/lib/arel/engines/sql/primitives/value.rb b/lib/arel/engines/sql/primitives/value.rb
new file mode 100644
index 0000000000..a44acc26e0
--- /dev/null
+++ b/lib/arel/engines/sql/primitives/value.rb
@@ -0,0 +1,11 @@
+module Arel
+  class Value
+    def to_sql(formatter = Sql::WhereCondition.new(relation))
+      formatter.value value
+    end
+
+    def format(object)
+      object.to_sql(Sql::Value.new(relation))
+    end
+  end
+end
\ No newline at end of file
diff --git a/lib/arel/engines/sql/relations.rb b/lib/arel/engines/sql/relations.rb
new file mode 100644
index 0000000000..4de01b2691
--- /dev/null
+++ b/lib/arel/engines/sql/relations.rb
@@ -0,0 +1,5 @@
+require 'arel/engines/sql/relations/utilities'
+require 'arel/engines/sql/relations/relation'
+require 'arel/engines/sql/relations/operations'
+require 'arel/engines/sql/relations/writes'
+require 'arel/engines/sql/relations/table'
\ No newline at end of file
diff --git a/lib/arel/engines/sql/relations/operations.rb b/lib/arel/engines/sql/relations/operations.rb
new file mode 100644
index 0000000000..ff33fc6bc3
--- /dev/null
+++ b/lib/arel/engines/sql/relations/operations.rb
@@ -0,0 +1,2 @@
+require 'arel/engines/sql/relations/operations/alias'
+require 'arel/engines/sql/relations/operations/join'
diff --git a/lib/arel/engines/sql/relations/operations/alias.rb b/lib/arel/engines/sql/relations/operations/alias.rb
new file mode 100644
index 0000000000..32c9911a69
--- /dev/null
+++ b/lib/arel/engines/sql/relations/operations/alias.rb
@@ -0,0 +1,5 @@
+module Arel
+  class Alias < Compound
+    include Recursion::BaseCase
+  end
+end
\ No newline at end of file
diff --git a/lib/arel/engines/sql/relations/operations/join.rb b/lib/arel/engines/sql/relations/operations/join.rb
new file mode 100644
index 0000000000..be21119bc9
--- /dev/null
+++ b/lib/arel/engines/sql/relations/operations/join.rb
@@ -0,0 +1,19 @@
+module Arel
+  class Join < Relation
+    def table_sql(formatter = Sql::TableReference.new(self))
+      relation1.externalize.table_sql(formatter)
+    end
+
+    def joins(environment, formatter = Sql::TableReference.new(environment))
+      @joins ||= begin
+        this_join = [
+          join_sql,
+          relation2.externalize.table_sql(formatter),
+          ("ON" unless predicates.blank?),
+          (ons + relation2.externalize.wheres).collect { |p| p.bind(environment).to_sql(Sql::WhereClause.new(environment)) }.join(' AND ')
+        ].compact.join(" ")
+        [relation1.joins(environment), this_join, relation2.joins(environment)].compact.join(" ")
+      end
+    end
+  end
+end
\ No newline at end of file
diff --git a/lib/arel/engines/sql/relations/relation.rb b/lib/arel/engines/sql/relations/relation.rb
new file mode 100644
index 0000000000..5fd4121176
--- /dev/null
+++ b/lib/arel/engines/sql/relations/relation.rb
@@ -0,0 +1,28 @@
+module Arel
+  class Relation
+    def to_sql(formatter = Sql::SelectStatement.new(self))
+      formatter.select select_sql, self
+    end
+
+    def select_sql
+      [
+        "SELECT     #{attributes.collect { |a| a.to_sql(Sql::SelectClause.new(self)) }.join(', ')}",
+        "FROM       #{table_sql(Sql::TableReference.new(self))}",
+        (joins(self)                                                                                    unless joins(self).blank? ),
+        ("WHERE     #{wheres   .collect { |w| w.to_sql(Sql::WhereClause.new(self)) }.join("\n\tAND ")}" unless wheres.blank?      ),
+        ("GROUP BY  #{groupings.collect { |g| g.to_sql(Sql::GroupClause.new(self)) }.join(', ')}"       unless groupings.blank?   ),
+        ("ORDER BY  #{orders   .collect { |o| o.to_sql(Sql::OrderClause.new(self)) }.join(', ')}"       unless orders.blank?      ),
+        ("LIMIT     #{taken}"                                                                           unless taken.blank?       ),
+        ("OFFSET    #{skipped}"                                                                         unless skipped.blank?     )
+      ].compact.join("\n")
+    end
+
+    def inclusion_predicate_sql
+      "IN"
+    end
+
+    def christener
+      @christener ||= Sql::Christener.new
+    end
+  end
+end
\ No newline at end of file
diff --git a/lib/arel/engines/sql/relations/table.rb b/lib/arel/engines/sql/relations/table.rb
new file mode 100644
index 0000000000..0433abbbb2
--- /dev/null
+++ b/lib/arel/engines/sql/relations/table.rb
@@ -0,0 +1,36 @@
+module Arel
+  class Table < Relation
+    include Recursion::BaseCase
+
+    cattr_accessor :engine
+    attr_reader :name, :engine
+    hash_on :name
+
+    def initialize(name, engine = Table.engine)
+      @name, @engine = name.to_s, engine
+    end
+
+    def attributes
+      @attributes ||= columns.collect do |column|
+        Attribute.new(self, column.name.to_sym)
+      end
+    end
+
+    def column_for(attribute)
+      has_attribute?(attribute) and columns.detect { |c| c.name == attribute.name.to_s }
+    end
+
+    def columns
+      @columns ||= engine.columns(name, "#{name} Columns")
+    end
+
+    def reset
+      @attributes = @columns = nil
+    end
+
+    def ==(other)
+      Table      === other and
+      name       ==  other.name
+    end
+  end
+end
diff --git a/lib/arel/engines/sql/relations/utilities.rb b/lib/arel/engines/sql/relations/utilities.rb
new file mode 100644
index 0000000000..a1451ed448
--- /dev/null
+++ b/lib/arel/engines/sql/relations/utilities.rb
@@ -0,0 +1,3 @@
+require 'arel/engines/sql/relations/utilities/recursion'
+require 'arel/engines/sql/relations/utilities/externalization'
+require 'arel/engines/sql/relations/utilities/nil'
diff --git a/lib/arel/engines/sql/relations/utilities/externalization.rb b/lib/arel/engines/sql/relations/utilities/externalization.rb
new file mode 100644
index 0000000000..1ac6f2de8e
--- /dev/null
+++ b/lib/arel/engines/sql/relations/utilities/externalization.rb
@@ -0,0 +1,14 @@
+module Arel
+  class Externalization < Compound
+    include Recursion::BaseCase
+
+    def table_sql(formatter = Sql::TableReference.new(relation))
+      formatter.select relation.select_sql, self
+    end
+
+    # REMOVEME
+    def name
+      relation.name + '_external'
+    end
+  end
+end
\ No newline at end of file
diff --git a/lib/arel/engines/sql/relations/utilities/nil.rb b/lib/arel/engines/sql/relations/utilities/nil.rb
new file mode 100644
index 0000000000..77534b25ad
--- /dev/null
+++ b/lib/arel/engines/sql/relations/utilities/nil.rb
@@ -0,0 +1,6 @@
+module Arel
+  class Nil < Relation
+    def table_sql(formatter = nil); '' end
+    def name; '' end
+  end
+end
\ No newline at end of file
diff --git a/lib/arel/engines/sql/relations/utilities/recursion.rb b/lib/arel/engines/sql/relations/utilities/recursion.rb
new file mode 100644
index 0000000000..848b059507
--- /dev/null
+++ b/lib/arel/engines/sql/relations/utilities/recursion.rb
@@ -0,0 +1,13 @@
+module Arel
+  module Recursion
+    module BaseCase
+      def table
+        self
+      end
+
+      def table_sql(formatter = Sql::TableReference.new(self))
+        formatter.table self
+      end
+    end
+  end
+end
\ No newline at end of file
diff --git a/lib/arel/engines/sql/relations/writes.rb b/lib/arel/engines/sql/relations/writes.rb
new file mode 100644
index 0000000000..dcadc326d9
--- /dev/null
+++ b/lib/arel/engines/sql/relations/writes.rb
@@ -0,0 +1,3 @@
+require 'arel/engines/sql/relations/writes/delete'
+require 'arel/engines/sql/relations/writes/insert'
+require 'arel/engines/sql/relations/writes/update'
diff --git a/lib/arel/engines/sql/relations/writes/delete.rb b/lib/arel/engines/sql/relations/writes/delete.rb
new file mode 100644
index 0000000000..b22ee51e24
--- /dev/null
+++ b/lib/arel/engines/sql/relations/writes/delete.rb
@@ -0,0 +1,12 @@
+module Arel
+  class Deletion < Compound
+    def to_sql(formatter = nil)
+      [
+        "DELETE",
+        "FROM #{table_sql}",
+        ("WHERE #{wheres.collect(&:to_sql).join('\n\tAND ')}" unless wheres.blank?  ),
+        ("LIMIT #{taken}"                                     unless taken.blank?    ),
+      ].compact.join("\n")
+    end
+  end
+end
\ No newline at end of file
diff --git a/lib/arel/engines/sql/relations/writes/insert.rb b/lib/arel/engines/sql/relations/writes/insert.rb
new file mode 100644
index 0000000000..aac9c87a5b
--- /dev/null
+++ b/lib/arel/engines/sql/relations/writes/insert.rb
@@ -0,0 +1,12 @@
+module Arel
+  class Insert < Compound
+    def to_sql(formatter = nil)
+      [
+        "INSERT",
+        "INTO #{table_sql}",
+        "(#{record.keys.collect { |key| engine.quote_column_name(key.name) }.join(', ')})",
+        "VALUES (#{record.collect { |key, value| key.format(value) }.join(', ')})"
+      ].join("\n")
+    end
+  end
+end
\ No newline at end of file
diff --git a/lib/arel/engines/sql/relations/writes/update.rb b/lib/arel/engines/sql/relations/writes/update.rb
new file mode 100644
index 0000000000..3e35a0d5cc
--- /dev/null
+++ b/lib/arel/engines/sql/relations/writes/update.rb
@@ -0,0 +1,14 @@
+module Arel
+  class Update < Compound
+    def to_sql(formatter = nil)
+      [
+        "UPDATE #{table_sql} SET",
+        assignments.collect do |attribute, value|
+          "#{engine.quote_column_name(attribute.name)} = #{attribute.format(value)}"
+        end.join(",\n"),
+        ("WHERE #{wheres.collect(&:to_sql).join('\n\tAND ')}"  unless wheres.blank?  ),
+        ("LIMIT #{taken}"                                      unless taken.blank?    )
+      ].join("\n")
+    end
+  end
+end
\ No newline at end of file
diff --git a/lib/arel/engines/sql/sql.rb b/lib/arel/engines/sql/sql.rb
new file mode 100644
index 0000000000..aed1fd861e
--- /dev/null
+++ b/lib/arel/engines/sql/sql.rb
@@ -0,0 +1,7 @@
+require 'arel/engines/sql/engine'
+require 'arel/engines/sql/relations'
+require 'arel/engines/sql/primitives'
+require 'arel/engines/sql/predicates'
+require 'arel/engines/sql/formatters'
+require 'arel/engines/sql/extensions'
+require 'arel/engines/sql/christener'
\ No newline at end of file