Rc-lang开发周记1 中间代码表示

.github # CI 尽管代码不多，但是依然要依靠单元测试和CI保证每次修改的正确性
analysis # 代码分析的内容，目前并没有做过多的内容
interface # 编译器、解释器和REPL的入口
compiler # compiler的实现
interpreter # 解释执行的实现
ir # 多级ir的实现，ast, tac, vm指令
lib # 编译器相关的一些简单的库，比如env, log或者错误处理之类
parser
spec # 专门用于测试

a2 = (b + c) * 4
需要被翻译为
a1 = b + c
a2 = a1 * 4

class Quad
  attr_accessor :op, :result, :lhs, :rhs

  def initialize(op, result, lhs, rhs)
    @op, @result, @lhs, @rhs = op, result, lhs, rhs
  end

  def to_s
    "#{@result} = #{@lhs} #{@op} #{@rhs}"
  end

  def ==(other)
    @op == other.op && @result == other.result && @lhs == other.lhs && @rhs == other.rhs
  end
end

class Assign < Quad
  def initialize(result, lhs)
    @op = 'assign'
    @result = result
    @lhs = lhs
    @rhs = EmptyValue.new
  end
end

class Call < Quad
  def initialize(result, target, args)
    @op = 'call'
    @result = result
    @lhs = target
    @rhs = args
  end

  def target
    @lhs
  end

  def args
    @rhs
  end
end

class Assign # Rc::AST::Assign
  attr_reader :var_obj, :expr
  def initialize(var_obj, expr)
    @var_obj, @expr = var_obj, expr
  end
end

def on_assign(node)
  name = visit(node.var_obj)
  expr = visit(node.expr)
  Assign.new(name, expr).tap { |assign| @tac_list.push assign }
end

class Expr # Rc::AST::Expr
	attr_reader :expr
end
# Rc::AST::Expr -> Operand
def on_expr(node)
  expr = visit(node.expr)
  if expr.is_a? Operand
    expr
  elsif expr.is_a? Quad
    expr.result
  else
    raise 'unknown expr type'
  end
end

context 'assign' do
  it 'succeed' do
    s = <<SRC
def f1
	a = 1
	b = 2
	c = a * b
end
SRC
    tac = get_tac(s)
    list = tac.first_fun_tac_list
    expect(list[1]).to eq Assign.new(Name.new('a'), Number.new(1))
    expect(list[2]).to eq Assign.new(Name.new('b'), Number.new(2))
    expect(list[3]).to eq Quad.new('*', TempName.new('0'), Name.new('a'), Name.new('b'))
    expect(list[4]).to eq Assign.new(Name.new('c'), TempName.new('0'))
  end
end

class Operand
end

class Name < Operand
  attr_accessor :name

  def initialize(name)
    @name = name
  end

  def to_s
    @name.gsub(/:/, '')
  end

  def ==(other)
    @name == other.name
  end
end


class TempName < Name
end

class Number < Operand  
    attr_accessor :num  
    def initialize(num)    
        @num = num  
    end  
    def to_s    
        @num.to_s  
    end  
    def ==(other)    
        @num == other.num  
   end
end

class Memory < Operand
  attr_reader :addr

  def initialize(addr)
    @addr = addr
  end

  def ==(other)
    @addr == other.addr
  end
end

def on_bool_constant(node)
  Number.new(node.val.to_i)
end

def on_number_constant(node)
  Number.new(node.val.to_i)
end

def on_string_constant(node)
  Memory.new(@const_table.add(node.val))
end

class Memory < Operand
  attr_reader :addr

  def initialize(addr)
    @addr = addr
  end

  def ==(other)
    @addr == other.addr
  end
end

class ConstTable
  attr_reader :list

  def initialize
    @list = []
  end

  def add(constant)
    i = @list.index(constant)
		i.or_else do
      @list.push constant
      @list.size - 1
    end
  end

  private def method_missing(symbol, *args)
    @list.method(symbol).try { |x| x.call(*args) }
  end

  def ==(other)
	list == @other.list
  end
end