# encoding: utf-8

module Mutant

  symbolset = ->(strings) { strings.map(&:to_sym).to_set.freeze }

  # Set of nodes that cannot be on the LHS of an assignment
  NOT_ASSIGNABLE = symbolset.(%w(int float str dstr class module self))

  # Set of op-assign types
  OP_ASSIGN              = symbolset.call(%w(or_asgn and_asgn op_asgn))
  # Set of node types that are not valid when emitted standalone
  NOT_STANDALONE         = symbolset.(%w( splat restarg block_pass))
  INDEX_OPERATORS        = symbolset.(%w([] []=))
  UNARY_METHOD_OPERATORS = symbolset.(%w(~@ +@ -@ !))

  # Operators ruby implementeds as methods
  METHOD_OPERATORS = symbolset.(%w(
    <=> === []= [] <= >= == !~ != =~ <<
    >> ** * % / | ^ & < > + - ~@ +@ -@ !
  ))

  BINARY_METHOD_OPERATORS = (
    METHOD_OPERATORS - (INDEX_OPERATORS + UNARY_METHOD_OPERATORS)
  ).to_set.freeze

  OPERATOR_METHODS = (
    METHOD_OPERATORS + INDEX_OPERATORS + UNARY_METHOD_OPERATORS
  ).to_set.freeze

  # Nodes that are NOT handled by mutant.
  #
  # not - 1.8 only, mutant does not support 1.8
  #
  NODE_BLACKLIST = symbolset.(%w(not))

  # Nodes that are NOT generated by parser but used by mutant / unparser.
  NODE_EXTRA = symbolset.(%w(empty))

  NODE_TYPES = ((Parser::Meta::NODE_TYPES + NODE_EXTRA) - NODE_BLACKLIST).to_set.freeze

end # Mutant