Class: Spitewaste::SpitewasteParser

Inherits:
Object
  • Object
show all
Defined in:
lib/spitewaste/parsers/spitewaste.rb

Constant Summary collapse

NameError = 
Class.new Exception
INSTRUCTIONS = 
/(\S+):|(\b(#{OPERATORS_M2T.keys * ?|})\s+(-?\d\S*)?)/
SPECIAL_INSN = 
/(call|jump|jz|jn)\s+(\S+)/

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(program, **options) ⇒ SpitewasteParser

Returns a new instance of SpitewasteParser.



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# File 'lib/spitewaste/parsers/spitewaste.rb', line 16

def initialize program, **options
  @src = program.dup
  @macros = {}
  @symbol_file = options['symbol_file']

  preprocess!
  eliminate_dead_code! unless options[:keep_dead_code]
end

Instance Attribute Details

#error ⇒ Object (readonly)

Returns the value of attribute error.



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# File 'lib/spitewaste/parsers/spitewaste.rb', line 14

def error
  @error
end

#instructions ⇒ Object (readonly)

Returns the value of attribute instructions.



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# File 'lib/spitewaste/parsers/spitewaste.rb', line 14

def instructions
  @instructions
end

#src ⇒ Object (readonly)

Returns the value of attribute src.



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# File 'lib/spitewaste/parsers/spitewaste.rb', line 14

def src
  @src
end

#symbol_table ⇒ Object (readonly)

Returns the value of attribute symbol_table.



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# File 'lib/spitewaste/parsers/spitewaste.rb', line 14

def symbol_table
  @symbol_table
end

Instance Method Details

#parse ⇒ Object 



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# File 'lib/spitewaste/parsers/spitewaste.rb', line 25

def parse
  @instructions = []

  # first-come, first-served mapping from label names to auto-incrementing
  # indices starting from 0; it would be nice if names could round-trip,
  # but even encoding short ones would result in unpleasantly wide code.
  @symbol_table = Hash.new { |h, k| h[k] = h.size }
  @src.scan(/(\S+):/) { @symbol_table[$1] } # populate label indices
  File.write @symbol_file, @symbol_table.to_json if @symbol_file

  special = @src.scan SPECIAL_INSN
  @src.scan INSTRUCTIONS do |label, _, operator, arg|
    next @instructions << [:label, @symbol_table[label]] if label

    if %i[call jump jz jn].include? operator = operator.to_sym
      arg = @symbol_table[special.shift[1]]
    else
      if OPERATORS_M2T.keys.index(operator) < 8 && !arg
        raise "missing arg for #{operator}"
      elsif arg
        begin
          arg = Integer arg
        rescue ArgumentError
          raise "invalid argument '#{arg}' for #{operator}"
        end
      end
    end

    @instructions << [operator, arg]
  end
end