Class: Wardite::Revisitor

Inherits:
Object
  • Object
show all
Defined in:
lib/wardite/revisitor.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(ops) ⇒ Revisitor

Returns a new instance of Revisitor.



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# File 'lib/wardite/revisitor.rb', line 8

def initialize(ops)
  @ops = ops
end

Instance Attribute Details

#ops ⇒ Object

: Array



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# File 'lib/wardite/revisitor.rb', line 4

def ops
  @ops
end

Instance Method Details

#fetch_ops_while_else_or_end(pc_start) ⇒ Object 



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# File 'lib/wardite/revisitor.rb', line 44

def fetch_ops_while_else_or_end(pc_start)
  cursor = pc_start
  depth = 0
  loop {
    cursor += 1
    inst = @ops[cursor]
    case inst&.code
    when nil
      raise EvalError, "end op not found"
    when :if, :block, :loop
      depth += 1
    when :else
      if depth == 0
        return cursor
      end
      # do not touch depth
    when :end
      if depth == 0
        return cursor
      else
        depth -= 1
      end
    else
      # nop
    end
  }
  raise "not found corresponding end"
end

#fetch_ops_while_end(pc_start) ⇒ Object 



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# File 'lib/wardite/revisitor.rb', line 76

def fetch_ops_while_end(pc_start)
  cursor = pc_start
  depth = 0
  loop {
    cursor += 1
    inst = @ops[cursor]
    case inst&.code
    when nil
      raise EvalError, "end op not found"
    when :if, :block, :loop
      depth += 1
    when :end
      if depth == 0
        return cursor
      else
        depth -= 1
      end
    else
      # nop
    end
  }
  raise "not found corresponding end"
end

#revisit! ⇒ Object 



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# File 'lib/wardite/revisitor.rb', line 13

def revisit!
  @ops.each_with_index do |op, idx|
    case op.code
    when :block
      next_pc = fetch_ops_while_end(idx)
      if op.meta[:end_pos] != next_pc
        raise "mismatched end_pos for block at #{op}: #{op.meta[:end_pos]} vs #{next_pc}"
      end
  
    when :loop
      next_pc = fetch_ops_while_end(idx)
      if op.meta[:end_pos] != next_pc
        raise "mismatched end_pos for loop at #{op}: #{op.meta[:end_pos]} vs #{next_pc}"
      end
  
    when :if
      next_pc = fetch_ops_while_end(idx)
      else_pc = fetch_ops_while_else_or_end(idx)
      if op.meta[:end_pos] != next_pc
        raise "mismatched end_pos for if at #{op}: #{op.meta[:end_pos]} vs #{next_pc}"
      end
      if op.meta[:else_pos] != else_pc
        raise "mismatched else_pos for if at #{op}: #{op.meta[:else_pos]} vs #{else_pc}"
      end
    end
  end
end