Class: Sequel::SQL::Expression
- Defined in:
- lib/sequel/sql.rb,
lib/sequel/extensions/eval_inspect.rb
Overview
Base class for all SQL expression objects.
Direct Known Subclasses
AliasedExpression, ColumnAll, ComplexExpression, GenericExpression, JoinClause, OrderedExpression, Window
Class Attribute Summary collapse
-
.comparison_attrs ⇒ Object
readonly
All attributes used for equality and hash methods.
Class Method Summary collapse
-
.attr_reader(*args) ⇒ Object
Expression objects are assumed to be value objects, where their attribute values can’t change after assignment.
-
.inherited(subclass) ⇒ Object
Copy the comparison_attrs into the subclass.
Instance Method Summary collapse
-
#==(other) ⇒ Object
Alias of
eql?
. -
#eql?(other) ⇒ Boolean
Returns true if the receiver is the same expression as the the
other
expression. -
#hash ⇒ Object
Make sure that the hash value is the same if the attributes are the same.
-
#inspect ⇒ Object
Attempt to produce a string suitable for eval, such that:.
-
#lit ⇒ Object
Returns
self
, becauseSQL::Expression
already acts likeLiteralString
. -
#sql_literal(ds) ⇒ Object
Alias of
to_s
.
Class Attribute Details
.comparison_attrs ⇒ Object (readonly)
All attributes used for equality and hash methods.
69 70 71 |
# File 'lib/sequel/sql.rb', line 69 def comparison_attrs @comparison_attrs end |
Class Method Details
.attr_reader(*args) ⇒ Object
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.
76 77 78 79 |
# File 'lib/sequel/sql.rb', line 76 def attr_reader(*args) super comparison_attrs.concat(args) end |
.inherited(subclass) ⇒ Object
Copy the comparison_attrs into the subclass.
82 83 84 85 |
# File 'lib/sequel/sql.rb', line 82 def inherited(subclass) super subclass.instance_variable_set(:@comparison_attrs, comparison_attrs.dup) end |
Instance Method Details
#==(other) ⇒ Object
Alias of eql?
101 102 103 |
# File 'lib/sequel/sql.rb', line 101 def ==(other) eql?(other) end |
#eql?(other) ⇒ Boolean
Returns true if the receiver is the same expression as the the other
expression.
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# File 'lib/sequel/sql.rb', line 107 def eql?(other) other.is_a?(self.class) && !self.class.comparison_attrs.find{|a| send(a) != other.send(a)} end |
#hash ⇒ Object
Make sure that the hash value is the same if the attributes are the same.
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# File 'lib/sequel/sql.rb', line 112 def hash ([self.class] + self.class.comparison_attrs.map{|x| send(x)}).hash end |
#inspect ⇒ Object
Attempt to produce a string suitable for eval, such that:
eval(obj.inspect) == obj
118 119 120 |
# File 'lib/sequel/sql.rb', line 118 def inspect "#<#{self.class} #{instance_variables.map{|iv| "#{iv}=>#{instance_variable_get(iv).inspect}"}.join(', ')}>" end |
#lit ⇒ Object
Returns self
, because SQL::Expression
already acts like LiteralString
.
123 124 125 |
# File 'lib/sequel/sql.rb', line 123 def lit self end |
#sql_literal(ds) ⇒ Object
Alias of to_s
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# File 'lib/sequel/sql.rb', line 128 def sql_literal(ds) s = '' to_s_append(ds, s) s end |