class Puppet::Pops::Evaluator::RelationshipOperator

The RelationshipOperator implements the semantics of the -> <- ~> <~ operators creating relationships or notification relationships between the left and right hand side’s references to resources.

This is separate class since a second level of evaluation is required that transforms string in left or right hand to type references. The task of “making a relationship” is delegated to the “runtime support” class that is included. This is done to separate the concerns of the new evaluator from the 3x runtime; messy logic goes into the runtime support module. Later when more is cleaned up this can be simplified further.

Constants

Issues
RELATIONSHIP_OPERATORS
RELATION_TYPE
REVERSE_OPERATORS

Public Instance Methods

assert_catalog_type(o, scope) click to toggle source

Asserts (and returns) the type if it is a PCatalogEntryType (A PCatalogEntryType is the base class of PHostClassType, and PResourceType).

# File lib/puppet/pops/evaluator/relationship_operator.rb, line 91
def assert_catalog_type(o, scope)
  unless @type_calculator.assignable?(@catalog_type, o)
    raise NotCatalogTypeError.new(o)
  end
  # TODO must check if this is an abstract PResourceType (i.e. without a type_name) - which should fail ?
  # e.g. File -> File (and other similar constructs) - maybe the catalog protects against this since references
  # may be to future objects...
  o
end

evaluate(left_right_evaluated, relationship_expression, scope) click to toggle source

Evaluate a relationship. TODO: The error reporting is not fine grained since evaluation has already taken place There is no references to the original source expressions at this point, only the overall relationship expression. (e.g.. the expression may be [‘string’, func_call(), etc.] -> func_call()) To implement this, the general evaluator needs to be able to track each evaluation result and associate it with a corresponding expression. This structure should then be passed to the relationship operator.

# File lib/puppet/pops/evaluator/relationship_operator.rb, line 117
def evaluate (left_right_evaluated, relationship_expression, scope)
  # assert operator (should have been validated, but this logic makes assumptions which would
  # screw things up royally). Better safe than sorry.
  unless RELATIONSHIP_OPERATORS.include?(relationship_expression.operator)
    fail(Issues::UNSUPPORTED_OPERATOR, relationship_expression, {:operator => relationship_expression.operator})
  end

  begin
    # Turn each side into an array of types (this also asserts their type)
    # (note wrap in array first if value is not already an array)
    #
    # TODO: Later when objects are Puppet Runtime Objects and know their type, it will be more efficient to check/infer
    # the type first since a chained operation then does not have to visit each element again. This is not meaningful now
    # since inference needs to visit each object each time, and this is what the transformation does anyway).
    #
    # real is [left, right], and both the left and right may be a single value or an array. In each case all content
    # should be flattened, and then transformed to a type. left or right may also be a value that is transformed
    # into an array, and thus the resulting left and right must be flattened individually
    # Once flattened, the operands should be sets (to remove duplicate entries)
    #
    real = left_right_evaluated.collect {|x| [x].flatten.collect {|x| transform(x, scope) }}
    real[0].flatten!
    real[1].flatten!
    real[0].uniq!
    real[1].uniq!

    # reverse order if operator is Right to Left
    source, target = reverse_operator?(relationship_expression) ? real.reverse : real

    # Add the relationships to the catalog
    source.each {|s| target.each {|t| add_relationship(s, t, RELATION_TYPE[relationship_expression.operator], scope) }}

    # Produce the transformed source RHS (if this is a chain, this does not need to be done again)
    real.slice(1)
  rescue NotCatalogTypeError => e
    fail(Issues::ILLEGAL_RELATIONSHIP_OPERAND_TYPE, relationship_expression, {:type => @type_calculator.string(e.type)})
  rescue IllegalRelationshipOperandError => e
    fail(Issues::ILLEGAL_RELATIONSHIP_OPERAND_TYPE, relationship_expression, {:operand => e.operand})
  end
end

reverse_operator?(o) click to toggle source

# File lib/puppet/pops/evaluator/relationship_operator.rb, line 158
def reverse_operator?(o)
  REVERSE_OPERATORS.include?(o.operator)
end

transform(o, scope) click to toggle source

# File lib/puppet/pops/evaluator/relationship_operator.rb, line 41
def transform(o, scope)
  @type_transformer_visitor.visit_this_1(self, o, scope)
end

transform_AbstractCollector(o, scope) click to toggle source

# File lib/puppet/pops/evaluator/relationship_operator.rb, line 79
def transform_AbstractCollector(o, scope)
  o
end

transform_Array(o, scope) click to toggle source

Array content needs to be transformed

# File lib/puppet/pops/evaluator/relationship_operator.rb, line 84
def transform_Array(o, scope)
  o.map{|x| transform(x, scope) }
end

transform_Collector(o, scope) click to toggle source

This transforms a 3x Collector (the result of evaluating a 3x AST::Collection). It is passed through verbatim since it is evaluated late by the compiler. At the point where the relationship is evaluated, it is simply recorded with the compiler for later evaluation. If one of the sides of the relationship is a Collector it is evaluated before the actual relationship is formed. (All of this happens at a later point in time.

# File lib/puppet/pops/evaluator/relationship_operator.rb, line 75
def transform_Collector(o, scope)
  o
end

transform_Object(o, scope) click to toggle source

Catch all non transformable objects @api private

# File lib/puppet/pops/evaluator/relationship_operator.rb, line 47
def transform_Object(o, scope)
  raise IllegalRelationshipOperandError.new(o)
end

transform_PAnyType(o, scope) click to toggle source

Types are what they are, just check the type @api private

# File lib/puppet/pops/evaluator/relationship_operator.rb, line 65
def transform_PAnyType(o, scope)
  assert_catalog_type(o, scope)
end

transform_QualifiedName(o, scope) click to toggle source

A qualified name is short hand for a class with this name @api private

# File lib/puppet/pops/evaluator/relationship_operator.rb, line 59
def transform_QualifiedName(o, scope)
  Puppet::Pops::Types::TypeFactory.host_class(o.value)
end

transform_String(o, scope) click to toggle source

A string must be a type reference in string format @api private

# File lib/puppet/pops/evaluator/relationship_operator.rb, line 53
def transform_String(o, scope)
  assert_catalog_type(@type_parser.parse(o), scope)
end

Public Class Methods

new() click to toggle source

# File lib/puppet/pops/evaluator/relationship_operator.rb, line 32
def initialize
  @type_transformer_visitor = Puppet::Pops::Visitor.new(self, "transform", 1, 1)
  @type_calculator = Puppet::Pops::Types::TypeCalculator.new()
  @type_parser = Puppet::Pops::Types::TypeParser.new()

  tf = Puppet::Pops::Types::TypeFactory
  @catalog_type = tf.variant(tf.catalog_entry, tf.type_type(tf.catalog_entry))
end