Class: Steep::Subtyping::Check

Inherits:
Object
  • Object
show all
Defined in:
lib/steep/subtyping/check.rb

Defined Under Namespace

Classes: CannotResolveError

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(builder:) ⇒ Check

Returns a new instance of Check.



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# File 'lib/steep/subtyping/check.rb', line 7

def initialize(builder:)
  @builder = builder
  @cache = {}
end

Instance Attribute Details

#builder ⇒ Object (readonly)

Returns the value of attribute builder.



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# File 'lib/steep/subtyping/check.rb', line 4

def builder
  @builder
end

#cache ⇒ Object (readonly)

Returns the value of attribute cache.



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# File 'lib/steep/subtyping/check.rb', line 5

def cache
  @cache
end

Instance Method Details

#cacheable?(relation) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/steep/subtyping/check.rb', line 42

def cacheable?(relation)
  relation.sub_type.free_variables.empty? && relation.super_type.free_variables.empty?
end

#check(relation, constraints:, assumption: Set.new, trace: Trace.new) ⇒ Object 



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# File 'lib/steep/subtyping/check.rb', line 12

def check(relation, constraints:, assumption: Set.new, trace: Trace.new)
  Steep.logger.tagged "#{relation.sub_type} <: #{relation.super_type}" do
    prefix = trace.size
    cached = cache[relation]
    if cached && constraints.empty?
      if cached.success?
        cached
      else
        cached.merge_trace(trace)
      end
    else
      if assumption.member?(relation)
        success(constraints: constraints)
      else
        trace.add(relation.sub_type, relation.super_type) do
          assumption = assumption + Set.new([relation])
          check0(relation, assumption: assumption, trace: trace, constraints: constraints).tap do |result|
            result = result.else do |failure|
              failure.drop(prefix)
            end

            Steep.logger.debug "result=#{result.class}"
            cache[relation] = result if cacheable?(relation)
          end
        end
      end
    end
  end
end

#check0(relation, assumption:, trace:, constraints:) ⇒ Object 



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# File 'lib/steep/subtyping/check.rb', line 54

def check0(relation, assumption:, trace:, constraints:)
  case
  when same_type?(relation, assumption: assumption)
    success(constraints: constraints)

  when relation.sub_type.is_a?(AST::Types::Any) || relation.super_type.is_a?(AST::Types::Any)
    success(constraints: constraints)

  when relation.super_type.is_a?(AST::Types::Top)
    success(constraints: constraints)

  when relation.sub_type.is_a?(AST::Types::Bot)
    success(constraints: constraints)

  when relation.super_type.is_a?(AST::Types::Var)
    if constraints.unknown?(relation.super_type.name)
      constraints.add(relation.super_type.name, sub_type: relation.sub_type)
      success(constraints: constraints)
    else
      failure(error: Result::Failure::UnknownPairError.new(relation: relation),
              trace: trace)
    end

  when relation.sub_type.is_a?(AST::Types::Var)
    if constraints.unknown?(relation.sub_type.name)
      constraints.add(relation.sub_type.name, super_type: relation.super_type)
      success(constraints: constraints)
    else
      failure(error: Result::Failure::UnknownPairError.new(relation: relation),
              trace: trace)
    end

  when relation.sub_type.is_a?(AST::Types::Union)
    results = relation.sub_type.types.map do |sub_type|
      check0(Relation.new(sub_type: sub_type, super_type: relation.super_type),
             assumption: assumption,
             trace: trace,
             constraints: constraints)
    end

    if results.all?(&:success?)
      results.first
    else
      results.find(&:failure?)
    end

  when relation.super_type.is_a?(AST::Types::Union)
    results = relation.super_type.types.map do |super_type|
      check0(Relation.new(sub_type: relation.sub_type, super_type: super_type),
             assumption: assumption,
             trace: trace,
             constraints: constraints)
    end

    results.find(&:success?) || results.first

  when relation.sub_type.is_a?(AST::Types::Intersection)
    results = relation.sub_type.types.map do |sub_type|
      check0(Relation.new(sub_type: sub_type, super_type: relation.super_type),
             assumption: assumption,
             trace: trace,
             constraints: constraints)
    end

    results.find(&:success?) || results.first

  when relation.super_type.is_a?(AST::Types::Intersection)
    results = relation.super_type.types.map do |super_type|
      check0(Relation.new(sub_type: relation.sub_type, super_type: super_type),
             assumption: assumption,
             trace: trace,
             constraints: constraints)
    end

    if results.all?(&:success?)
      results.first
    else
      results.find(&:failure?)
    end

  when relation.sub_type.is_a?(AST::Types::Name) && relation.super_type.is_a?(AST::Types::Name)
    if relation.sub_type.name == relation.super_type.name && relation.sub_type.args.size == relation.super_type.args.size
      results = relation.sub_type.args.zip(relation.super_type.args).flat_map do |(sub, sup)|
        Relation.new(sub_type: sub, super_type: sup).yield_self do |rel|
          [rel, rel.flip]
        end
      end.map do |relation|
        check0(relation,
               assumption: assumption,
               trace: trace,
               constraints: constraints)
      end

      if results.all?(&:success?)
        results.first
      else
        results.find(&:failure?)
      end
    else
      sub_interface = resolve(relation.sub_type, with_initialize: false)
      super_interface = resolve(relation.super_type, with_initialize: false)

      check_interface(sub_interface, super_interface, assumption: assumption, trace: trace, constraints: constraints)
    end

  else
    failure(error: Result::Failure::UnknownPairError.new(relation: relation),
            trace: trace)
  end
end

#check_block_given(name, sub_block, super_block, trace:, constraints:) ⇒ Object 



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# File 'lib/steep/subtyping/check.rb', line 304

def check_block_given(name, sub_block, super_block, trace:, constraints:)
  case
  when !super_block && !sub_block
    success(constraints: constraints)
  when super_block && sub_block
    success(constraints: constraints)
  else
    failure(
      error: Result::Failure::BlockMismatchError.new(name: name),
      trace: trace
    )
  end
end

#check_block_params(name, sub_block, super_block, assumption:, trace:, constraints:) ⇒ Object 



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# File 'lib/steep/subtyping/check.rb', line 454

def check_block_params(name, sub_block, super_block, assumption:, trace:, constraints:)
  if sub_block
    check_method_params(name,
                        super_block.params,
                        sub_block.params,
                        assumption: assumption,
                        trace: trace,
                        constraints: constraints)
  else
    success(constraints: constraints)
  end
end

#check_block_return(sub_block, super_block, assumption:, trace:, constraints:) ⇒ Object 



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# File 'lib/steep/subtyping/check.rb', line 467

def check_block_return(sub_block, super_block, assumption:, trace:, constraints:)
  if sub_block
    relation = Relation.new(sub_type: super_block.return_type,
                                super_type: sub_block.return_type)
    check(relation, assumption: assumption, trace: trace, constraints: constraints)
  else
    success(constraints: constraints)
  end
end

#check_interface(sub_type, super_type, assumption:, trace:, constraints:) ⇒ Object 



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# File 'lib/steep/subtyping/check.rb', line 184

def check_interface(sub_type, super_type, assumption:, trace:, constraints:)
  method_pairs = []

  super_type.methods.each do |name, sup_method|
    sub_method = sub_type.methods[name]

    if sub_method
      method_pairs << [sub_method, sup_method]
    else
      return failure(error: Result::Failure::MethodMissingError.new(name: name),
                     trace: trace)
    end
  end

  method_pairs.each do |(sub_method, sup_method)|
    result = check_method(sub_method.name, sub_method, sup_method, assumption: assumption, trace: trace, constraints: constraints)
    return result if result.failure?
  end

  success(constraints: constraints)
end

#check_method(name, sub_method, super_method, assumption:, trace:, constraints:) ⇒ Object 



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# File 'lib/steep/subtyping/check.rb', line 206

def check_method(name, sub_method, super_method, assumption:, trace:, constraints:)
  trace.add(sub_method, super_method) do
    all_results = super_method.types.map do |super_type|
      sub_method.types.map do |sub_type|
        trace.add(sub_type, super_type) do
          case
          when super_type.type_params.empty? && sub_type.type_params.empty?
            check_method_type(name,
                              sub_type,
                              super_type,
                              assumption: assumption,
                              trace: trace,
                              constraints: constraints)

          when super_type.type_params.empty?
            yield_self do
              sub_args = sub_type.type_params.map {|x| AST::Types::Var.fresh(x) }
              sub_type = sub_type.instantiate(Interface::Substitution.build(sub_type.type_params,
                                                                            sub_args))

              constraints.add_var(*sub_args)

              match_method_type(name, sub_type, super_type, trace: trace).yield_self do |pairs|
                case pairs
                when Array
                  subst = pairs.each.with_object(Interface::Substitution.empty) do |(sub, sup), subst|
                    case
                    when sub.is_a?(AST::Types::Var) && sub_args.include?(sub)
                      subst.add!(sub.name, sup)
                    when sup.is_a?(AST::Types::Var) && sub_args.include?(sup)
                      subst.add!(sup.name, sub)
                    end
                  end

                  check_method_type(name,
                                    sub_type.subst(subst),
                                    super_type,
                                    assumption: assumption,
                                    trace: trace,
                                    constraints: constraints)
                else
                  pairs
                end
              end
            end

          when super_type.type_params.size == sub_type.type_params.size
            yield_self do
              args = sub_type.type_params.map {|x| AST::Types::Var.fresh(x) }

              sub_type_ = sub_type.instantiate(Interface::Substitution.build(sub_type.type_params, args))
              super_type_ = super_type.instantiate(Interface::Substitution.build(super_type.type_params, args))

              constraints.add_var(*args)

              check_method_type(name,
                                sub_type_,
                                super_type_,
                                assumption: assumption,
                                trace: trace,
                                constraints: constraints)
            end
          else
            failure(error: Result::Failure::PolyMethodSubtyping.new(name: name),
                    trace: trace)
          end
        end
      end
    end

    all_results.each do |results|
      if results.any?(&:success?)
        #ok
      else
        return results.find(&:failure?)
      end
    end

    success(constraints: constraints)
  end
end

#check_method_params(name, sub_params, super_params, assumption:, trace:, constraints:) ⇒ Object 



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# File 'lib/steep/subtyping/check.rb', line 318

def check_method_params(name, sub_params, super_params, assumption:, trace:, constraints:)
  match_params(name, sub_params, super_params, trace: trace).yield_self do |pairs|
    case pairs
    when Array
      pairs.each do |(sub_type, super_type)|
        relation = Relation.new(super_type: sub_type, sub_type: super_type)

        result = check(relation, assumption: assumption, trace: trace, constraints: constraints)
        return result if result.failure?
      end

      success(constraints: constraints)
    else
      pairs
    end
  end
end

#check_method_type(name, sub_type, super_type, assumption:, trace:, constraints:) ⇒ Object 



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# File 'lib/steep/subtyping/check.rb', line 288

def check_method_type(name, sub_type, super_type, assumption:, trace:, constraints:)
  Steep.logger.tagged("#{name}: #{sub_type} <: #{super_type}") do
    check_method_params(name, sub_type.params, super_type.params, assumption: assumption, trace: trace, constraints: constraints).then do
      check_block_given(name, sub_type.block, super_type.block, trace: trace, constraints: constraints).then do
        check_block_params(name, sub_type.block, super_type.block, assumption: assumption, trace: trace, constraints: constraints).then do
          check_block_return(sub_type.block, super_type.block, assumption: assumption, trace: trace, constraints:constraints).then do
            relation = Relation.new(super_type: super_type.return_type,
                                    sub_type: sub_type.return_type)
            check(relation, assumption: assumption, trace: trace, constraints: constraints)
          end
        end
      end
    end
  end
end

#compact(types) ⇒ Object 



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# File 'lib/steep/subtyping/check.rb', line 486

def compact(types)
  types = types.reject {|type| type.is_a?(AST::Types::Any) }

  if types.empty?
    [AST::Types::Any.new]
  else
    compact0(types)
  end
end

#compact0(types) ⇒ Object 



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# File 'lib/steep/subtyping/check.rb', line 496

def compact0(types)
  if types.size == 1
    types
  else
    type, *types_ = types
    compacted = compact0(types_)
    compacted.flat_map do |type_|
      case
      when type == type_
        [type]
      when check(Relation.new(sub_type: type_, super_type: type), constraints: Constraints.empty).success?
        [type]
      when check(Relation.new(sub_type: type, super_type: type_), constraints: Constraints.empty).success?
        [type_]
      else
        [type, type_]
      end
    end.uniq
  end
end

#failure(error:, trace:) ⇒ Object 



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# File 'lib/steep/subtyping/check.rb', line 50

def failure(error:, trace:)
  Result::Failure.new(error: error, trace: trace)
end

#match_method_type(name, sub_type, super_type, trace:) ⇒ Object 



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# File 'lib/steep/subtyping/check.rb', line 336

def match_method_type(name, sub_type, super_type, trace:)
  [].tap do |pairs|
    match_params(name, sub_type.params, super_type.params, trace: trace).yield_self do |result|
      return result unless result.is_a?(Array)
      pairs.push(*result)
      pairs.push [sub_type.return_type, super_type.return_type]

      case
      when !super_type.block && !sub_type.block
        # No block required and given

      when super_type.block && sub_type.block
        match_params(name, super_type.block.params, sub_type.block.params, trace: trace).yield_self do |block_result|
          return block_result unless block_result.is_a?(Array)
          pairs.push(*block_result)
          pairs.push [super_type.block.return_type, sub_type.block.return_type]
        end

      else
        return failure(error: Result::Failure::BlockMismatchError.new(name: name),
                       trace: trace)
      end
    end
  end
end

#match_params(name, sub_params, super_params, trace:) ⇒ Object 



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# File 'lib/steep/subtyping/check.rb', line 362

def match_params(name, sub_params, super_params, trace:)
  pairs = []

  sub_flat = sub_params.flat_unnamed_params
  sup_flat = super_params.flat_unnamed_params

  failure = failure(error: Result::Failure::ParameterMismatchError.new(name: name),
                    trace: trace)

  case
  when super_params.rest
    return failure unless sub_params.rest

    while sub_flat.size > 0
      sub_type = sub_flat.shift
      sup_type = sup_flat.shift

      if sup_type
        pairs << [sub_type.last, sup_type.last]
      else
        pairs << [sub_type.last, super_params.rest]
      end
    end

    if sub_params.rest
      pairs << [sub_params.rest, super_params.rest]
    end

  when sub_params.rest
    while sub_flat.size > 0
      sub_type = sub_flat.shift
      sup_type = sup_flat.shift

      if sup_type
        pairs << [sub_type.last, sup_type.last]
      else
        break
      end
    end

    if sub_params.rest && !sup_flat.empty?
      sup_flat.each do |sup_type|
        pairs << [sub_params.rest, sup_type.last]
      end
    end
  when sub_params.required.size + sub_params.optional.size >= super_params.required.size + super_params.optional.size
    while sub_flat.size > 0
      sub_type = sub_flat.shift
      sup_type = sup_flat.shift

      if sup_type
        pairs << [sub_type.last, sup_type.last]
      else
        if sub_type.first == :required
          return failure
        else
          break
        end
      end
    end
  else
    return failure
  end

  sub_flat_kws = sub_params.flat_keywords
  sup_flat_kws = super_params.flat_keywords

  sup_flat_kws.each do |name, _|
    if sub_flat_kws.key?(name)
      pairs << [sub_flat_kws[name], sup_flat_kws[name]]
    else
      if sub_params.rest_keywords
        pairs << [sub_params.rest_keywords, sup_flat_kws[name]]
      else
        return failure
      end
    end
  end

  sub_params.required_keywords.each do |name, _|
    unless super_params.required_keywords.key?(name)
      return failure
    end
  end

  if sub_params.rest_keywords && super_params.rest_keywords
    pairs << [sub_params.rest_keywords, super_params.rest_keywords]
  end

  pairs
end

#module_type(type) ⇒ Object 



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# File 'lib/steep/subtyping/check.rb', line 477

def module_type(type)
  case
  when builder.signatures.class?(type.name)
    type.class_type(constructor: nil)
  when builder.signatures.module?(type.name)
    type.module_type
  end
end

#resolve(type, self_type: type, instance_type: nil, module_type: nil, with_initialize:) ⇒ Object 



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# File 'lib/steep/subtyping/check.rb', line 526

def resolve(type, self_type: type, instance_type: nil, module_type: nil, with_initialize:)
  Steep.logger.debug("Check#resolve: type=#{type}")
  case type
  when AST::Types::Any, AST::Types::Var, AST::Types::Class, AST::Types::Instance
    raise CannotResolveError.new(type: type)
  when AST::Types::Name
    builder.build(type.name, with_initialize: with_initialize).yield_self do |abstract|
      case type.name
      when TypeName::Instance, TypeName::Interface
        abstract.instantiate(
          type: self_type,
          args: type.args,
          instance_type: type,
          module_type: module_type || module_type(type)
        )
      when TypeName::Class, TypeName::Module
        signature = builder.signatures.find_class_or_module(type.name.name)
        args = signature.params&.variables&.map {|var| AST::Types::Var.new(name: var) } || []
        abstract.instantiate(
          type: self_type,
          args: [],
          instance_type: AST::Types::Name.new_instance(name: type.name.name, args: args),
          module_type: module_type || module_type(type)
        )
      end
    end
  when AST::Types::Union
    interfaces = type.types.map do |member_type|
      fresh = AST::Types::Var.fresh(:___)

      resolve(member_type, self_type: type, instance_type: fresh, module_type: fresh, with_initialize: with_initialize).select_method_type do |method_type|
        !method_type.each_type.include?(fresh)
      end
    end

    methods = interfaces.inject(nil) do |methods, i|
      if methods
        intersection = {}
        i.methods.each do |name, new_method|
          existing_method = methods[name]

          if existing_method
            case
            when new_method == existing_method
              intersection[name] = new_method
            when check_method(name, new_method, existing_method,
                              assumption: Set.new,
                              trace: Trace.new,
                              constraints: Constraints.empty).success?
              intersection[name] = existing_method
            when check_method(name, existing_method, new_method,
                              assumption: Set.new,
                              trace: Trace.new,
                              constraints: Constraints.empty).success?
              intersection[name] = new_method
            else
              merged_method_types = []

              existing_method.types.each do |existing_method_type|
                new_method.types.each do |new_method_type|
                  if existing_method_type.params == new_method_type.params &&
                    existing_method_type.block == new_method_type.block &&
                    existing_method_type.type_params == new_method_type.type_params
                    merged_method_types << existing_method_type.with(
                      return_type: AST::Types::Union.build(
                        types: [
                          existing_method_type.return_type,
                          new_method_type.return_type
                        ]
                      ),
                      location: nil
                    )
                  end
                end
              end

              unless merged_method_types.empty?
                intersection[name] = Interface::Method.new(
                  type_name: nil,
                  name: name,
                  types: merged_method_types,
                  super_method: nil,
                  attributes: []
                )
              end
            end
          end
        end
        intersection
      else
        i.methods
      end
    end

    Interface::Instantiated.new(type: type,
                                methods: methods,
                                ivar_chains: {})

  when AST::Types::Intersection
    interfaces = type.types.map do |type| resolve(type, with_initialize: with_initialize) end

    methods = interfaces.inject(nil) do |methods, i|
      if methods
        i.methods.each do |name, method|
          if methods.key?(name)
            case
            when method == methods[name]
            when check_method(name, method, methods[name],
                              assumption: Set.new,
                              trace: Trace.new,
                              constraints: Constraints.empty).success?
              methods[name] = method
            when check_method(name, methods[name], method,
                              assumption: Set.new,
                              trace: Trace.new,
                              constraints: Constraints.empty).success?
              methods[name] = methods[name]
            else
              methods[name] = Interface::Method.new(
                type_name: nil,
                name: name,
                types: methods[name].types + method.types,
                super_method: nil,
                attributes: []
              )
            end
          else
            methods[name] = i.methods[name]
          end
        end
        methods
      else
        i.methods
      end
    end

    Interface::Instantiated.new(type: type,
                                methods: methods,
                                ivar_chains: {})
  when AST::Types::Void
    Interface::Instantiated.new(type: type,
                                methods: {},
                                ivar_chains: {})
  end
end

#same_type?(relation, assumption:) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/steep/subtyping/check.rb', line 165

def same_type?(relation, assumption:)
  if assumption.include?(relation) && assumption.include?(relation.flip)
    return true
  end

  case
  when relation.sub_type == relation.super_type
    true
  when relation.sub_type.is_a?(AST::Types::Name) && relation.super_type.is_a?(AST::Types::Name)
    return false unless relation.sub_type.name == relation.super_type.name
    return false unless relation.sub_type.args.size == relation.super_type.args.size
    relation.sub_type.args.zip(relation.super_type.args).all? do |(s, t)|
      same_type?(Relation.new(sub_type: s, super_type: t), assumption: assumption)
    end
  else
    false
  end
end

#success(constraints:) ⇒ Object 



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# File 'lib/steep/subtyping/check.rb', line 46

def success(constraints:)
  Result::Success.new(constraints: constraints)
end