Class: ActiveFacts::CQL::Compiler::Operation

Inherits:
Object
  • Object
show all
Defined in:
lib/activefacts/cql/compiler/expression.rb

Overview

An Operation is a binary or ternary fact type involving an operator, a result, and one or two operands. Viewed as a result, it behaves like a Reference with a nested Clause. Viewed as a fact type, it behaves like a Clause.

The only exception here is an equality comparison, where it may turn out that the equality is merely a projection. In this case the Operation is dropped from the clauses and is replaced by the projected operand.

Each operand may be a Literal, a Reference, or another Operation, so we need to recurse down the tree to build the query.

Direct Known Subclasses

Comparison, Product, Reciprocal, Sum

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize ⇒ Operation

Returns a new instance of Operation.



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# File 'lib/activefacts/cql/compiler/expression.rb', line 51

def initialize
  @certainty = true	  # Assume it's definite
end

Instance Attribute Details

#binding ⇒ Object

What Binding for that ObjectType



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# File 'lib/activefacts/cql/compiler/expression.rb', line 33

def binding
  @binding
end

#certainty ⇒ Object

nil, true, false -> maybe, definitely, not



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# File 'lib/activefacts/cql/compiler/expression.rb', line 37

def certainty
  @certainty
end

#clause ⇒ Object

What clause does the result participate in?



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# File 'lib/activefacts/cql/compiler/expression.rb', line 34

def clause
  @clause
end

#fact_type ⇒ Object (readonly)

Returns the value of attribute fact_type.



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# File 'lib/activefacts/cql/compiler/expression.rb', line 48

def fact_type
  @fact_type
end

#player ⇒ Object

What ObjectType does the Binding denote



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# File 'lib/activefacts/cql/compiler/expression.rb', line 32

def player
  @player
end

#role ⇒ Object

Which Role of this ObjectType



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# File 'lib/activefacts/cql/compiler/expression.rb', line 35

def role
  @role
end

#role_ref ⇒ Object

Which RoleRef to that Role



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# File 'lib/activefacts/cql/compiler/expression.rb', line 36

def role_ref
  @role_ref
end

Instance Method Details

#bind(context) ⇒ Object 



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# File 'lib/activefacts/cql/compiler/expression.rb', line 76

def bind context
  refs.each do |o|
    o.bind context
  end
  name = result_type_name(context)
  @player = result_value_type(context, name)
  key = "#{name} #{object_id}"  # Every Operation result is a unique Binding
  @binding = (context.bindings[key] ||= Binding.new(@player))
  @binding.refs << self
  @binding
end

#conjunction ⇒ Object 



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# File 'lib/activefacts/cql/compiler/expression.rb', line 47

def conjunction; nil; end

#identify_other_players(context) ⇒ Object 



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# File 'lib/activefacts/cql/compiler/expression.rb', line 68

def identify_other_players context
  # Just recurse, there's no way (yet: REVISIT?) to add a role name to the result of an expression
  refs.each { |o|
    o.identify_other_players(context)
  }
  identify_player context
end

#identify_players_with_role_name(context) ⇒ Object 



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# File 'lib/activefacts/cql/compiler/expression.rb', line 59

def identify_players_with_role_name context
  # Just recurse, there's no way (yet: REVISIT?) to add a role name to the result of an expression
  refs.each { |o|
    o.identify_players_with_role_name(context)
  }
  # As yet, an operation cannot have a role name:
  # identify_player context if role_name
end

#is_equality_comparison ⇒ Object 



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# File 'lib/activefacts/cql/compiler/expression.rb', line 144

def is_equality_comparison
  false
end

#is_existential_type ⇒ Object 



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# File 'lib/activefacts/cql/compiler/expression.rb', line 140

def is_existential_type
  false
end

#is_naked_object_type ⇒ Object 



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# File 'lib/activefacts/cql/compiler/expression.rb', line 99

def is_naked_object_type
  false # All Operations are non-naked
end

#leading_adjective ⇒ Object 



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# File 'lib/activefacts/cql/compiler/expression.rb', line 27

def leading_adjective; nil; end

#literal ⇒ Object 



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# File 'lib/activefacts/cql/compiler/expression.rb', line 30

def literal; nil; end

#match_existing_fact_type(context) ⇒ Object 



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# File 'lib/activefacts/cql/compiler/expression.rb', line 103

def match_existing_fact_type context
  opnds = refs
  result_ref = Reference.new(@binding.player.name)
  result_ref.player = @binding.player
  result_ref.binding = @binding
  @binding.refs << result_ref
  clause_ast = Clause.new(
    [result_ref, '='] +
      (opnds.size > 1 ? [opnds[0]] : []) +
      [operator, opnds[-1]]
  )

  # REVISIT: All operands must be value-types or simply-identified Entity Types.

  # REVISIT: We should auto-create steps from Entity Types to an identifying ValueType
  # REVISIT: We should traverse up the supertype of ValueTypes to find a DataType
  @fact_type = clause_ast.match_existing_fact_type(context, :exact_type => true)
	  if clause.certainty == false
	    raise "Negated fact types in expressions are not yet supported: #{clause.inspect}"
	  end
  return @fact_type if @fact_type

  @fact_type = clause_ast.make_fact_type context.vocabulary
  reading = clause_ast.make_reading context.vocabulary, @fact_type
  rrs = reading.role_sequence.all_role_ref_in_order
  opnds[0].role_ref = rrs[0]
  opnds[-1].role_ref = rrs[-1]
  opnds.each do |opnd|
    next unless opnd.is_a?(Operation)
    opnd.match_existing_fact_type context
	    if opnd.certainty == false
	      raise "Negated fact types in expressions are not yet supported: #{opnd.inspect}"
	    end
  end
  @fact_type
end

#nested_clauses ⇒ Object 



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# File 'lib/activefacts/cql/compiler/expression.rb', line 38

def nested_clauses; @nested_clauses ||= [self]; end

#objectification_of ⇒ Object 



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# File 'lib/activefacts/cql/compiler/expression.rb', line 40

def objectification_of; @fact_type; end

#objectified_as ⇒ Object

The Reference which objectified this fact type



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# File 'lib/activefacts/cql/compiler/expression.rb', line 49

def objectified_as; self; end

#operands(context = nil) ⇒ Object 



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# File 'lib/activefacts/cql/compiler/expression.rb', line 55

def operands context = nil
  raise "REVISIT: Implement operand enumeration in the operator subclass #{self.class.name}"
end

#operator ⇒ Object 



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# File 'lib/activefacts/cql/compiler/expression.rb', line 148

def operator
  raise "REVISIT: Implement operator access in the operator subclass #{self.class.name}"
end

#result_type_name(context) ⇒ Object 



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# File 'lib/activefacts/cql/compiler/expression.rb', line 88

def result_type_name(context)
  raise "REVISIT: Implement result_type_name in the #{self.class.name} subclass"
end

#result_value_type(context, name) ⇒ Object 



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# File 'lib/activefacts/cql/compiler/expression.rb', line 92

def result_value_type(context, name)
  vocabulary = context.vocabulary
  constellation = vocabulary.constellation
	  vocabulary.valid_value_type_name(name) ||
	    constellation.ValueType(vocabulary, name, :concept => :new)
end

#role_name ⇒ Object 



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# File 'lib/activefacts/cql/compiler/expression.rb', line 26

def role_name; nil; end

#side_effects ⇒ Object 



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# File 'lib/activefacts/cql/compiler/expression.rb', line 31

def side_effects; nil; end

#trailing_adjective ⇒ Object 



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# File 'lib/activefacts/cql/compiler/expression.rb', line 28

def trailing_adjective; nil; end

#value_constraint ⇒ Object 



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# File 'lib/activefacts/cql/compiler/expression.rb', line 29

def value_constraint; nil; end