Class: Steep::TypeInference::MultipleAssignment

Inherits:
Object
  • Object
show all
Defined in:
lib/steep/type_inference/multiple_assignment.rb

Constant Summary collapse

Assignments = 
_ = Struct.new(:rhs_type, :optional, :leading_assignments, :trailing_assignments, :splat_assignment, keyword_init: true) do
  # @implements Assignments

  def each(&block)
    if block
      leading_assignments.each(&block)
      if sp = splat_assignment
        yield sp
      end
      trailing_assignments.each(&block)
    else
      enum_for :each
    end
  end
end

Instance Method Summary collapse

Instance Method Details

#expand(mlhs, rhs_type, optional) ⇒ Object 



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# File 'lib/steep/type_inference/multiple_assignment.rb', line 20

def expand(mlhs, rhs_type, optional)
  lhss = mlhs.children

  case rhs_type
  when AST::Types::Tuple
    expand_tuple(lhss.dup, rhs_type, rhs_type.types.dup, optional)
  when AST::Types::Name::Instance
    if AST::Builtin::Array.instance_type?(rhs_type)
      expand_array(lhss.dup, rhs_type, optional)
    end
  when AST::Types::Any
    expand_any(lhss, rhs_type, AST::Builtin.any_type, optional)
  end
end

#expand_any(nodes, rhs_type, element_type, optional) ⇒ Object 



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# File 'lib/steep/type_inference/multiple_assignment.rb', line 142

def expand_any(nodes, rhs_type, element_type, optional)
  # @type var leading_assignments: Array[node_type_pair]
  leading_assignments = []
  # @type var trailing_assignments: Array[node_type_pair]
  trailing_assignments = []
  # @type var splat_assignment: node_type_pair?
  splat_assignment = nil

  array = leading_assignments

  nodes.each do |node|
    case node.type
    when :splat
      splat_assignment = [node, AST::Builtin::Array.instance_type(element_type)]
      array = trailing_assignments
    else
      array << [node, element_type]
    end
  end

  Assignments.new(
    rhs_type: rhs_type,
    optional: optional,
    leading_assignments: leading_assignments,
    trailing_assignments: trailing_assignments,
    splat_assignment: splat_assignment
  )
end

#expand_array(lhss, rhs_type, optional) ⇒ Object 



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# File 'lib/steep/type_inference/multiple_assignment.rb', line 87

def expand_array(lhss, rhs_type, optional)
  element_type = rhs_type.args[0] or raise

  # @type var leading_assignments: Array[node_type_pair]
  leading_assignments = []
  # @type var trailing_assignments: Array[node_type_pair]
  trailing_assignments = []
  # @type var splat_assignment: node_type_pair?
  splat_assignment = nil

  while !lhss.empty?
    first = lhss.first or raise

    case
    when first.type == :splat
      break
    else
      leading_assignments << [first, AST::Builtin.optional(element_type)]
      lhss.shift
    end
  end

  while !lhss.empty?
    last = lhss.last or raise

    case
    when last.type == :splat
      break
    else
      trailing_assignments << [last, AST::Builtin.optional(element_type)]
      lhss.pop
    end
  end

  case lhss.size
  when 0
    # nop
  when 1
    splat_assignment = [
      lhss.first || raise,
      AST::Builtin::Array.instance_type(element_type)
    ]
  else
    raise
  end

  Assignments.new(
    rhs_type: rhs_type,
    optional: optional,
    leading_assignments: leading_assignments,
    trailing_assignments: trailing_assignments,
    splat_assignment: splat_assignment
  )
end

#expand_tuple(lhss, rhs_type, tuples, optional) ⇒ Object 



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# File 'lib/steep/type_inference/multiple_assignment.rb', line 35

def expand_tuple(lhss, rhs_type, tuples, optional)
  # @type var leading_assignments: Array[node_type_pair]
  leading_assignments = []
  # @type var trailing_assignments: Array[node_type_pair]
  trailing_assignments = []
  # @type var splat_assignment: node_type_pair?
  splat_assignment = nil

  while !lhss.empty?
    first = lhss.first or raise

    case
    when first.type == :splat
      break
    else
      leading_assignments << [first, tuples.first || AST::Builtin.nil_type]
      lhss.shift
      tuples.shift
    end
  end

  while !lhss.empty?
    last = lhss.last or raise

    case
    when last.type == :splat
      break
    else
      trailing_assignments << [last, tuples.last || AST::Builtin.nil_type]
      lhss.pop
      tuples.pop
    end
  end

  case lhss.size
  when 0
    # nop
  when 1
    splat_assignment = [lhss.first || raise, AST::Types::Tuple.new(types: tuples)]
  else
    raise
  end

  Assignments.new(
    rhs_type: rhs_type,
    optional: optional,
    leading_assignments: leading_assignments,
    trailing_assignments: trailing_assignments,
    splat_assignment: splat_assignment
  )
end

#hint_for_mlhs(mlhs, env) ⇒ Object 



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# File 'lib/steep/type_inference/multiple_assignment.rb', line 171

def hint_for_mlhs(mlhs, env)
  case mlhs.type
  when :mlhs
    types = mlhs.children.map do |node|
      hint_for_mlhs(node, env) or return
    end
    AST::Types::Tuple.new(types: types)
  when :lvasgn, :ivasgn, :gvasgn
    name = mlhs.children[0]
    
    unless TypeConstruction::SPECIAL_LVAR_NAMES.include?(name)
      env[name] || AST::Builtin.any_type
    else
      AST::Builtin.any_type
    end
  when :splat
    return
  else
    return
  end
end