n65/lib/n65/directives/enter_scope.rb

# frozen_string_literal: true

require_relative '../instruction_base'

module N65
  # This directive to include bytes
  class EnterScope < InstructionBase
    def self.parse(line)
      # Anonymous scope
      match_data = line.match(/^\.scope$/)
      return EnterScope.new unless match_data.nil?

      # Named scope
      match_data = line.match(/^\.scope\s+([a-zA-Z][a-zA-Z0-9_]+)$/)
      return nil if match_data.nil?

      EnterScope.new(match_data[1])
    end

    # Initialize with filename
    def initialize(name = nil)
      @name = name
    end

    # Execute on the assembler, also create a symbol referring to
    # the current pc which contains a hyphen, and is impossible for
    # the user to create.  This makes a scope simultaneously act as
    # a label to the current PC.  If someone tries to use a scope
    # name as a label, it can return the address when the scope opened.
    def exec(assembler)
      assembler.symbol_table.enter_scope(@name)
      assembler.symbol_table.define_symbol("-#{@name}", assembler.program_counter) unless @name.nil?
    end

    def to_s
      ".scope #{@name}"
    end
  end
end