Class: Locomotive::RelationalAlgebra::Select
- Inherits:
-
Unary
- Object
- RelAlgAstNode
- Operator
- Unary
- Locomotive::RelationalAlgebra::Select
- Defined in:
- lib/locomotive/relational_algebra/operators/filter/select.rb
Instance Attribute Summary collapse
-
#item ⇒ Object
Returns the value of attribute item.
Attributes inherited from Operator
Attributes included from AstHelpers::AstNode
#kind, #left_child, #owner, #right_child, #value
Instance Method Summary collapse
- #child=(op) ⇒ Object
- #clone ⇒ Object
-
#initialize(op, item) ⇒ Select
constructor
A new instance of Select.
- #set(var, plan) ⇒ Object
- #xml_content ⇒ Object
Methods inherited from Operator
#bound, #free, #to_xml, #xml_kind, #xml_schema
Methods included from XML
Methods included from AstHelpers::Annotations
Methods included from AstHelpers::AstNode
#has_left_child?, #has_right_child?, #is_leaf?, #traverse, #traverse_strategy=
Constructor Details
#initialize(op, item) ⇒ Select
Returns a new instance of Select.
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# File 'lib/locomotive/relational_algebra/operators/filter/select.rb', line 8 def initialize(op, item) self.item = item super(op) end |
Dynamic Method Handling
This class handles dynamic methods through the method_missing method in the class Locomotive::AstHelpers::Annotations
Instance Attribute Details
#item ⇒ Object
Returns the value of attribute item.
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# File 'lib/locomotive/relational_algebra/operators/filter/select.rb', line 6 def item @item end |
Instance Method Details
#child=(op) ⇒ Object
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# File 'lib/locomotive/relational_algebra/operators/filter/select.rb', line 13 def child=(op) unless op.schema.attributes?([item]) raise CorruptedSchema, "Schema #{op.schema.attributes} does not " \ "contain all attributes of #{item}." end unless op.schema[item].member? RBool.instance raise CorruptedSchema, "#{item}(#{op.schema[item]}) doesn have the type Boolean." end self.schema = op.schema.clone super(op) end |
#clone ⇒ Object
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# File 'lib/locomotive/relational_algebra/operators/filter/select.rb', line 35 def clone Select.new( self.child.clone, self.item.clone) end |
#set(var, plan) ⇒ Object
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# File 'lib/locomotive/relational_algebra/operators/filter/select.rb', line 41 def set(var,plan) Select.new( child.set(var,plan), item.clone) end |
#xml_content ⇒ Object
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# File 'lib/locomotive/relational_algebra/operators/filter/select.rb', line 29 def xml_content content do column :name => item.to_xml, :new => false end end |