Module: Loxxy::Ast::ASTVisitee

Included in:
LoxNode
Defined in:
lib/loxxy/ast/ast_visitee.rb

Overview

Mix-in module that relies on meta-programming to add a method called accept to the host class (an AST node). That method fulfills the expected behavior of the visitee in the Visitor design pattern.

Instance Method Summary collapse

Instance Method Details

#define_accept ⇒ Object

This method adds a method named accept that takes a visitor The visitor is expected to implement a method named: visit + class name (without the Lox prefix) in snake case Example: class name = LoxClassStmt => visit method = visit_class_stmt



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# File 'lib/loxxy/ast/ast_visitee.rb', line 36

def define_accept
  return if instance_methods(false).include?(:accept)

  base_name = name.split('::').last
  name_suffix = snake_case(base_name).sub(/^lox/, '')
  accept_body = <<-MTH_END
    # Part of the 'visitee' role in Visitor design pattern.
    # @param visitor [Ast::ASTVisitor] the visitor
    def accept(aVisitor)
      aVisitor.visit#{name_suffix}(self)
    end
  MTH_END

  class_eval(accept_body)
end

#snake_case(aName) ⇒ String

Convert the input string into a snake case string. Example: ClassExpr => class_expr

Parameters:

  • aName (String) —

    input name to convert

Returns:

  • (String) —

    the name converted into snake case



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# File 'lib/loxxy/ast/ast_visitee.rb', line 14

def snake_case(aName)
  converted = +''
  down = false
  aName.each_char do |ch|
    lower = ch.downcase
    if lower == ch
      converted << ch
      down = true
    else
      converted << '_' if down && converted[-1] != '_'
      converted << lower
      down = false
    end
  end

  converted
end