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module Arel
class Table
include Relation, Recursion::BaseCase
cattr_accessor :engine, :tables
attr_reader :name, :engine, :table_alias, :options
def initialize(name, options = {})
@name = name.to_s
@table_exists = nil
if options.is_a?(Hash)
@options = options
@engine = options[:engine] || Table.engine
@table_alias = options[:as].to_s if options[:as].present? && options[:as].to_s != @name
else
@engine = options # Table.new('foo', engine)
end
if @engine.connection
begin
require "arel/engines/sql/compilers/#{@engine.adapter_name.downcase}_compiler"
@@tables ||= engine.tables
rescue LoadError
raise "#{@engine.adapter_name} is not supported by Arel."
end
end
end
def as(table_alias)
Table.new(name, options.merge(:as => table_alias))
end
def table_exists?
if @table_exists
true
else
@table_exists = @@tables.include?(name) || engine.table_exists?(name)
end
end
def attributes
return @attributes if defined?(@attributes)
if table_exists?
@attributes = columns.collect do |column|
Sql::Attributes.for(column).new(column, self, column.name.to_sym)
end
else
[]
end
end
def eql?(other)
self == other
end
def hash
@hash ||= :name.hash
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 and
table_alias == other.table_alias
end
end
end
def Table(name, engine = Arel::Table.engine)
Arel::Table.new(name, engine)
end
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