Class: Akaza::VM

Inherits:
Object
  • Object
show all
Defined in:
lib/akaza/vm.rb

Instance Method Summary collapse

Constructor Details

#initialize(commands, input, output) ⇒ VM

Returns a new instance of VM.



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# File 'lib/akaza/vm.rb', line 3

def initialize(commands, input, output)
  @commands = commands
  @input = input
  @output = output
  @stack = []
  @heap = {}
  @call_stack = []
  @index = 0
  @labels = {}

  prepare_label
end

Instance Method Details

#eval ⇒ Object 



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# File 'lib/akaza/vm.rb', line 16

def eval
  while true
    # p @stack
    # p @heap
    # puts '-' * 100
    # p @commands[@index]
    case @commands[@index]
    in [:stack_push, number]
      @stack.push number
    in [:stack_dup]
      @stack.push @stack.last
    in [:stack_swap]
      @stack[-1], @stack[-2] = @stack[-2], @stack[-1]
    in [:stack_pop]
      @stack.pop
    in [:calc_add]
      @stack[-2] = @stack[-2] + @stack[-1]
      @stack.pop
    in [:calc_sub]
      @stack[-2] = @stack[-2] - @stack[-1]
      @stack.pop
    in [:calc_multi]
      @stack[-2] = @stack[-2] * @stack[-1]
      @stack.pop
    in [:calc_div]
      @stack[-2] = @stack[-2] / @stack[-1]
      @stack.pop
    in [:calc_mod]
      @stack[-2] = @stack[-2] % @stack[-1]
      @stack.pop
    in [:heap_save]
      val = @stack.pop
      addr = @stack.pop
      @heap[addr] = val
    in [:heap_load]
      val = @heap[@stack[-1]]
      raise "Heap #{addr} is not initialized" unless val
      @stack[-1] = val
    in [:flow_def, label]
      # skip
    in [:flow_call, label]
      raise "unknwon label:#{label.inspect}" unless @labels.key?(label)
      @call_stack.push @index
      @index = @labels[label]
    in [:flow_jump, label]
      raise "unknwon label:#{label.inspect}" unless @labels.key?(label)
      @index = @labels[label]
    in [:flow_jump_if_zero, label]
      @index = @labels[label] if @stack.pop == 0
    in [:flow_jump_if_neg, label]
      @index = @labels[label] if @stack.pop < 0
    in [:flow_end]
      @index = @call_stack.pop
    in [:flow_exit]
      return
    in [:io_write_char]
      @output.write @stack.pop.chr
    in [:io_write_num]
      @output.write @stack.pop.to_s
    in [:io_read_char]
      addr = @stack.pop
      @heap[addr] = @input.read(1).ord
    in [:io_read_num]
      addr = @stack.pop
      @heap[addr] = @input.readline.to_i
    end
    @index += 1
  end
end

#prepare_label ⇒ Object 



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# File 'lib/akaza/vm.rb', line 86

def prepare_label
  @commands.each.with_index do |command, index|
    case command
    in [:flow_def, label]
      @labels[label] = index
    else
      # skip
    end
  end
end