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module Arel
class Table
include Arel::Crud
include Arel::FactoryMethods
@engine = nil
class << self; attr_accessor :engine; end
attr_accessor :name, :engine, :aliases, :table_alias
# TableAlias and Table both have a #table_name which is the name of the underlying table
alias :table_name :name
def initialize name, options = {}
@name = name.to_s
@columns = nil
@aliases = []
@engine = Table.engine
# Sometime AR sends an :as parameter to table, to let the table know
# that it is an Alias. We may want to override new, and return a
# TableAlias node?
@table_alias = options[:as]
if @table_alias.to_s == @name
@table_alias = nil
end
end
def alias name = "#{self.name}_2"
Nodes::TableAlias.new(self, name).tap do |node|
@aliases << node
end
end
def from engine = Table.engine
SelectManager.new(engine, self)
end
def join relation, klass = Nodes::InnerJoin
return from unless relation
case relation
when String, Nodes::SqlLiteral
raise if relation.empty?
klass = Nodes::StringJoin
end
from.join(relation, klass)
end
def outer_join relation
join(relation, Nodes::OuterJoin)
end
def group *columns
from.group(*columns)
end
def order *expr
from.order(*expr)
end
def where condition
from.where condition
end
def project *things
from.project(*things)
end
def take amount
from.take amount
end
def skip amount
from.skip amount
end
def having expr
from.having expr
end
def [] name
::Arel::Attribute.new self, name
end
def hash
# Perf note: aliases and table alias is excluded from the hash
# aliases can have a loop back to this table breaking hashes in parent
# relations, for the vast majority of cases @name is unique to a query
@name.hash
end
def eql? other
self.class == other.class &&
self.name == other.name &&
self.aliases == other.aliases &&
self.table_alias == other.table_alias
end
alias :== :eql?
private
def attributes_for columns
return nil unless columns
columns.map do |column|
Attributes.for(column).new self, column.name.to_sym
end
end
end
end
|
