Class: Oso::Polar::Host

Inherits:
Object
  • Object
show all
Defined in:
lib/oso/polar/host.rb

Overview

Translate between Polar and the host language (Ruby).

Constant Summary collapse

DEFAULT_COMBINE_QUERY = 
proc { raise 'implement combine_query to use data filtering' }
DEFAULT_BUILD_QUERY = 
proc { raise 'implement build_query to use data filtering' }
DEFAULT_EXEC_QUERY = 
proc { raise 'implement exec_query to use data filtering' }
OPS = 
{
  'Lt' => :<,
  'Gt' => :>,
  'Eq' => :==,
  'Geq' => :>=,
  'Leq' => :<=,
  'Neq' => :!=
}.freeze

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(ffi_polar) ⇒ Host

Returns a new instance of Host.



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# File 'lib/oso/polar/host.rb', line 78

def initialize(ffi_polar)
  @ffi_polar = ffi_polar
  @types = {}
  @instances = {}
  @accept_expression = false
  @combine_query = DEFAULT_COMBINE_QUERY
  @build_query = DEFAULT_BUILD_QUERY
  @exec_query = DEFAULT_EXEC_QUERY
end

Instance Attribute Details

#accept_expression=(value) ⇒ Object

Sets the attribute accept_expression

Parameters:

  • value —

    the value to set the attribute accept_expression to.



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# File 'lib/oso/polar/host.rb', line 71

def accept_expression=(value)
  @accept_expression = value
end

#adapter ⇒ Object

Returns the value of attribute adapter.



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# File 'lib/oso/polar/host.rb', line 72

def adapter
  @adapter
end

#build_query ⇒ Object

Returns the value of attribute build_query.



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# File 'lib/oso/polar/host.rb', line 72

def build_query
  @build_query
end

#combine_query ⇒ Object

Returns the value of attribute combine_query.



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# File 'lib/oso/polar/host.rb', line 72

def combine_query
  @combine_query
end

#exec_query ⇒ Object

Returns the value of attribute exec_query.



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# File 'lib/oso/polar/host.rb', line 72

def exec_query
  @exec_query
end

#types ⇒ Hash<String, UserType> (readonly)

Returns:



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# File 'lib/oso/polar/host.rb', line 58

def types
  @types
end

Instance Method Details

#cache_class(cls, name:, fields:, build_query:, combine_query:, exec_query:) ⇒ String

Store a Ruby class in the #types cache.

under a previously-registered name.

Parameters:

  • cls (Class) —

    the class to cache.

  • name (String) —

    the name to cache the class as.

Returns:

  • (String) —

    the name the class is cached as.

Raises:



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# File 'lib/oso/polar/host.rb', line 113

def cache_class(cls, name:, fields:, build_query:, combine_query:, exec_query:) # rubocop:disable Metrics/ParameterLists, Metrics/MethodLength
  raise DuplicateClassAliasError.new name: name, old: get_class(name), new: cls if types.key? name

  types[name] = types[cls] = UserType.new(
    name: name,
    klass: PolarClass.new(cls),
    id: cache_instance(cls),
    fields: fields || {},
    combine_query: combine_query || self.combine_query,
    exec_query: exec_query || self.exec_query,
    build_query: build_query || self.build_query
  )
  name
end

#cache_instance(instance, id: nil) ⇒ Integer

Cache a Ruby instance in the #instances cache, fetching a new id if one isn’t provided.

Parameters:

  • instance (Object)
  • id (Integer) (defaults to: nil) —

    the instance ID. Generated via FFI if not provided.

Returns:

  • (Integer) —

    the instance ID.



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# File 'lib/oso/polar/host.rb', line 171

def cache_instance(instance, id: nil)
  id = ffi_polar.new_id if id.nil?
  # Save the instance as a PolarClass if it is a non-anonymous class
  instance = PolarClass.new(instance) if instance.is_a?(Class)
  instances[id] = instance
  id
end

#enrich_message(msg) ⇒ Object 



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# File 'lib/oso/polar/host.rb', line 412

def enrich_message(msg)
  msg.gsub(/\^\{id: ([0-9]+)\}/) do
    get_instance(Regexp.last_match[1].to_i).to_s
  end
end

#get_class(name) ⇒ Class

Fetch a Ruby class from the #types cache.

Parameters:

  • name (String)

Returns:

  • (Class)

Raises:



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# File 'lib/oso/polar/host.rb', line 99

def get_class(name)
  typ = types[name]
  raise UnregisteredClassError, name if typ.nil?

  typ.klass.get
end

#get_instance(id) ⇒ Object

Fetch a Ruby instance from the #instances cache.

Parameters:

  • id (Integer)

Returns:

  • (Object)

Raises:



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# File 'lib/oso/polar/host.rb', line 156

def get_instance(id)
  raise UnregisteredInstanceError, id unless instance? id

  instance = instances[id]
  return instance.get if instance.is_a? PolarClass

  instance
end

#initialize_copy(other) ⇒ Object 



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# File 'lib/oso/polar/host.rb', line 88

def initialize_copy(other)
  @ffi_polar = other.ffi_polar
  @types = other.types.dup
  @instances = other.instances.dup
end

#instance?(id) ⇒ Boolean

Check if an instance exists in the #instances cache.

Parameters:

  • id (Integer)

Returns:

  • (Boolean) 


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# File 'lib/oso/polar/host.rb', line 142

def instance?(id)
  case id
  when Integer
    instances.key? id
  else
    instances.value? id
  end
end

#isa?(instance, class_tag:) ⇒ Boolean

Check if instance is an instance of class.

Parameters:

  • instance (Hash<String, Object>)
  • class_tag (String)

Returns:

  • (Boolean) 


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# File 'lib/oso/polar/host.rb', line 248

def isa?(instance, class_tag:)
  instance = to_ruby(instance)
  cls = get_class(class_tag)
  instance.is_a? cls
end

#make_instance(cls_name, args:, kwargs:, id:) ⇒ Integer

Construct and cache a Ruby instance.

Parameters:

  • cls_name (String) —

    name of the instance’s class.

  • args (Array<Object>) —

    positional args to the constructor.

  • kwargs (Hash<String, Object>) —

    keyword args to the constructor.

  • id (Integer) —

    the instance ID.

Returns:

  • (Integer) —

    the instance ID.

Raises:



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# File 'lib/oso/polar/host.rb', line 187

def make_instance(cls_name, args:, kwargs:, id:)
  instance = if kwargs.empty? # This check is for Ruby < 2.7.
               get_class(cls_name).__send__(:new, *args)
             else
               get_class(cls_name).__send__(:new, *args, **kwargs)
             end
  cache_instance(instance, id: id)
rescue StandardError => e
  raise PolarRuntimeError, "Error constructing instance of #{cls_name}: #{e}"
end

#operator(operation, args) ⇒ Boolean

Compare two values

Parameters:

  • operation (String) —

    operation to perform.

  • args (Array<Object>) —

    left and right args to operation.

Returns:

  • (Boolean)

Raises:



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# File 'lib/oso/polar/host.rb', line 213

def operator(operation, args)
  left, right = args
  op = OPS[operation]
  raise PolarRuntimeError, "Unsupported external operation '#{left.class} #{operation} #{right.class}'" if op.nil?

  begin
    left.__send__ op, right
  rescue StandardError
    raise PolarRuntimeError, "External operation '#{left.class} #{operation} #{right.class}' failed."
  end
end

#register_mros ⇒ Object

rubocop:disable Metrics/AbcSize



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# File 'lib/oso/polar/host.rb', line 128

def register_mros # rubocop:disable Metrics/AbcSize
  types.values.uniq.each do |typ|
    mro = []
    typ.klass.get.ancestors.each do |a|
      mro.push(types[a].id) if types.key?(a)
    end
    ffi_polar.register_mro(typ.name, mro)
  end
end

#serialize_types ⇒ Object

rubocop:disable Metrics/AbcSize, Metrics/MethodLength



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# File 'lib/oso/polar/host.rb', line 254

def serialize_types # rubocop:disable Metrics/AbcSize, Metrics/MethodLength
  polar_types = {}
  types.values.uniq.each do |typ|
    tag = typ.name
    fields = typ.fields
    field_types = {}
    fields.each do |k, v|
      field_types[k] =
        if v.is_a? ::Oso::Polar::DataFiltering::Relation
          {
            'Relation' => {
              'kind' => v.kind,
              'other_class_tag' => v.other_type,
              'my_field' => v.my_field,
              'other_field' => v.other_field
            }
          }
        else
          { 'Base' => { 'class_tag' => types[v].name } }
        end
    end
    polar_types[tag] = field_types
  end
  polar_types
end

#subclass?(left_tag:, right_tag:) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/oso/polar/host.rb', line 239

def subclass?(left_tag:, right_tag:)
  get_class(left_tag) <= get_class(right_tag)
end

#subspecializer?(instance_id, left_tag:, right_tag:) ⇒ Boolean

Check if the left class is more specific than the right class with respect to the given instance.

Parameters:

  • instance_id (Integer)
  • left_tag (String)
  • right_tag (String)

Returns:

  • (Boolean) 


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# File 'lib/oso/polar/host.rb', line 232

def subspecializer?(instance_id, left_tag:, right_tag:)
  mro = get_instance(instance_id).class.ancestors
  left_index = mro.index(get_class(left_tag))
  right_index = mro.index(get_class(right_tag))
  left_index && right_index && left_index < right_index
end

#to_polar(value) ⇒ Hash<String, Object>

Turn a Ruby value into a Polar term that’s ready to be sent across the FFI boundary.

Parameters:

  • value (Object)

Returns:

  • (Hash<String, Object>) 


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# File 'lib/oso/polar/host.rb', line 285

def to_polar(value) # rubocop:disable Metrics/AbcSize, Metrics/CyclomaticComplexity, Metrics/MethodLength, Metrics/PerceivedComplexity
  value = case true # rubocop:disable Lint/LiteralAsCondition
          when value.instance_of?(TrueClass) || value.instance_of?(FalseClass)
            { 'Boolean' => value }
          when value.instance_of?(Integer)
            { 'Number' => { 'Integer' => value } }
          when value.instance_of?(Float)
            if value == Float::INFINITY
              value = 'Infinity'
            elsif value == -Float::INFINITY
              value = '-Infinity'
            elsif value.nan?
              value = 'NaN'
            end
            { 'Number' => { 'Float' => value } }
          when value.instance_of?(String)
            { 'String' => value }
          when value.instance_of?(Array)
            { 'List' => value.map { |el| to_polar(el) } }
          when value.instance_of?(Hash)
            { 'Dictionary' => { 'fields' => value.transform_values { |v| to_polar(v) } } }
          when value.instance_of?(Predicate)
            { 'Call' => { 'name' => value.name, 'args' => value.args.map { |el| to_polar(el) } } }
          when value.instance_of?(Variable)
            # This is supported so that we can query for unbound variables
            { 'Variable' => value.name }
          when value.instance_of?(Expression)
            { 'Expression' => { 'operator' => value.operator, 'args' => value.args.map { |el| to_polar(el) } } }
          when value.instance_of?(Pattern)
            dict = to_polar(value.fields)['value']
            if value.tag.nil?
              { 'Pattern' => dict }
            else
              { 'Pattern' => { 'Instance' => { 'tag' => value.tag, 'fields' => dict['Dictionary'] } } }
            end
          else
            instance_id = nil
            class_id = nil
            class_repr = nil
            # id=class_id,

            # pass `class_id` & `class_repr` for registered types
            if value.is_a?(Class) && types.key?(value)
              instance_id = class_id = types[value].id
            elsif types.key?(value.class)
              class_id = types[value.class].id
              class_repr = types[value.class].name
            end

            {
              'ExternalInstance' => {
                'instance_id' => cache_instance(value, id: instance_id),
                'repr' => nil,
                'class_repr' => class_repr,
                'class_id' => class_id
              }
            }
          end
  { 'value' => value }
end

#to_ruby(data) ⇒ Object

Turn a Polar term passed across the FFI boundary into a Ruby value.

Parameters:

  • data (Hash<String, Object>)

Options Hash (data):

  • :id (Integer)
  • :offset (Integer) —

    Character offset of the term in its source string.

  • :value (Hash<String, Object>)

Returns:

  • (Object)

Raises:



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# File 'lib/oso/polar/host.rb', line 354

def to_ruby(data) # rubocop:disable Metrics/AbcSize, Metrics/CyclomaticComplexity, Metrics/MethodLength, Metrics/PerceivedComplexity
  tag, value = data['value'].first
  case tag
  when 'String', 'Boolean'
    value
  when 'Number'
    num = value.values.first
    case value.keys.first
    when 'Float'
      case num
      when 'Infinity'
        Float::INFINITY
      when '-Infinity'
        -Float::INFINITY
      when 'NaN'
        Float::NAN
      else
        unless value['Float'].is_a? Float # rubocop:disable Metrics/BlockNesting
          raise PolarRuntimeError, "Expected a floating point number, got \"#{value['Float']}\""
        end

        num
      end
    else
      num
    end
  when 'List'
    value.map { |el| to_ruby(el) }
  when 'Dictionary'
    value['fields'].transform_values { |v| to_ruby(v) }
  when 'ExternalInstance'
    get_instance(value['instance_id'])
  when 'Call'
    Predicate.new(value['name'], args: value['args'].map { |a| to_ruby(a) })
  when 'Variable'
    Variable.new(value)
  when 'Expression'
    raise UnexpectedPolarTypeError, tag unless accept_expression

    args = value['args'].map { |a| to_ruby(a) }
    Expression.new(value['operator'], args)
  when 'Pattern'
    case value.keys.first
    when 'Instance'
      tag = value.values.first['tag']
      fields = value.values.first['fields']['fields'].transform_values { |v| to_ruby(v) }
      Pattern.new(tag, fields)
    when 'Dictionary'
      fields = value.values.first['fields'].transform_values { |v| to_ruby(v) }
      Pattern.new(nil, fields)
    else
      raise UnexpectedPolarTypeError, "#{value.keys.first} variant of Pattern"
    end
  else
    raise UnexpectedPolarTypeError, tag
  end
end