class Sequel::SQL::Expression

Base class for all SQL expression objects.

Attributes

comparison_attrs[R]

All attributes used for equality and hash methods.

Public Class Methods

attr_reader(*args) click to toggle source

Expression objects are assumed to be value objects, where their attribute values can't change after assignment. In order to make it easy to define equality and hash methods, subclass instances assume that the only values that affect the results of such methods are the values of the object's attributes.

Calls superclass method
# File lib/sequel/sql.rb, line 87
def attr_reader(*args)
  super
  comparison_attrs.concat(args)
end
inherited(subclass) click to toggle source

Copy the ::comparison_attrs into the subclass.

Calls superclass method
# File lib/sequel/sql.rb, line 93
def inherited(subclass)
  super
  subclass.instance_variable_set(:@comparison_attrs, comparison_attrs.dup)
end

Public Instance Methods

==(other) click to toggle source

Alias of eql?

# File lib/sequel/sql.rb, line 112
def ==(other)
  eql?(other)
end
eql?(other) click to toggle source

Returns true if the receiver is the same expression as the the other expression.

# File lib/sequel/sql.rb, line 118
def eql?(other)
  other.is_a?(self.class) && !self.class.comparison_attrs.find{|a| send(a) != other.send(a)}
end
hash() click to toggle source

Make sure that the hash value is the same if the attributes are the same.

# File lib/sequel/sql.rb, line 123
def hash
  ([self.class] + self.class.comparison_attrs.map{|x| send(x)}).hash
end
inspect() click to toggle source

Attempt to produce a string suitable for eval, such that:

eval(obj.inspect) == obj
# File lib/sequel/extensions/eval_inspect.rb, line 64
def inspect
  # Assume by default that the object can be recreated by calling
  # self.class.new with any attr_reader values defined on the class,
  # in the order they were defined.
  klass = self.class
  args = inspect_args.map do |arg|
    if arg.is_a?(String) && arg =~ /\A\*/
      # Special case string arguments starting with *, indicating that
      # they should return an array to be splatted as the remaining arguments
      send(arg.sub('*', '')).map{|a| Sequel.eval_inspect(a)}.join(', ')
    else
      Sequel.eval_inspect(send(arg))
    end
  end
  "#{klass}.#{inspect_new_method}(#{args.join(', ')})"
end
lit() click to toggle source

Returns self, because SQL::Expression already acts like LiteralString.

# File lib/sequel/sql.rb, line 134
def lit
  self
end
sql_literal(ds) click to toggle source

Alias of to_s

# File lib/sequel/sql.rb, line 139
def sql_literal(ds)
  s = ''
  to_s_append(ds, s)
  s
end

Private Instance Methods

inspect_args() click to toggle source

Which attribute values to use in the inspect string.

# File lib/sequel/extensions/eval_inspect.rb, line 84
def inspect_args
  self.class.comparison_attrs
end
inspect_new_method() click to toggle source

Use the new method by default for creating new objects.

# File lib/sequel/extensions/eval_inspect.rb, line 89
def inspect_new_method
  :new
end