rubyx/lib/soml/compiler/if_statement.rb

module Soml
  Compiler.class_eval do

    # an if evaluates the condition and jumps to the true block if true
    # so the else block is automatically after that.
    # But then the else needs to jump over the true block unconditionally.
    def on_if_statement statement
      branch_type , condition , if_true , if_false = *statement
      condition = condition.first

      reset_regs
      process(condition)

      branch_class = Object.const_get "Register::Is#{branch_type.capitalize}"
      true_block = Register::Label.new(if_true, "if_true")
      add_code branch_class.new( condition , true_block )

      # compile the false block
      reset_regs
      process_all(if_false) if if_false
      merge = Register::Label.new(statement , "if_merge")
      add_code Register::Branch.new(if_false, merge )

      # compile the true block
      add_code true_block
      reset_regs
      process_all(if_true)

      #puts "compiled if: end"
      add_code merge

      nil # statements don't return anything
    end
  end
end