src/compiler.rb

   1 class Compiler
   2   def initialize parser, code_generator, output
   3     @parser = parser
   4     @generator = code_generator
   5     @output = output
   6   end
   7
   8   def compile
   9     # Map for magic words whose code generator method has
  10     # a name different from the magic word
  11     names_map = {
  12       'else' => :ifelse,
  13       'if' => :ifnonzero,
  14       'return' => :ret,
  15       'tail-call' => :tail_call,
  16     }
  17
  18     while true
  19       words = @parser.parse_line
  20       break if words == nil
  21       next if words.empty?
  22
  23       # Process labels
  24       while words[0] =~ /^\w+:$/
  25         label = words[0][0..-2]
  26         @generator.label label
  27         words = words[1..-1]
  28       end
  29       next if words.empty?
  30
  31       # Process code
  32       action, args = words[0], words[1..-1]
  33       case action
  34       when 'else'
  35         if words.length == 1
  36           @generator.ifelse
  37         else
  38           if words[1] == 'if'
  39             @generator.ifelse
  40             @generator.ifnonzero words[2..-1]
  41           else
  42             raise "Invalid action: #{action} #{words[1]}"
  43           end
  44         end
  45       when 'end'
  46         case words[1]
  47         when 'function'
  48           @generator.end_function
  49         when 'if'
  50           @generator.end_if
  51         else
  52           raise "Unknown action: #{action} #{words[1]}"
  53         end
  54       else
  55         if names_map.has_key? action
  56           @generator.send names_map[action], *args
  57         else
  58           sym = nil
  59           begin
  60             sym = action.to_sym
  61           rescue ArgumentError
  62             # Not a valid symbol
  63           end
  64
  65           if sym != nil && @generator.respond_to?(action.to_sym)
  66             @generator.send action.to_sym, *args
  67           else
  68             raise "Unknown action: #{words[0]}"
  69           end
  70         end
  71       end
  72     end
  73
  74     @generator.write @output
  75   end
  76 end