class Parser::CurrentArgStack


@api private
Emulates ‘p->cur_arg` in MRI’s parse.y
stack is [:a, :b, :c]
^
def m1(a = (def m2(b = def m3(c = 1); end); end)); end
i.e. while parsing
Stack that holds names of current arguments,

def initialize 

def initialize
  @stack = []
  freeze
end

def pop 

def pop
  @stack.pop
end

def push(value) 

def push(value)
  @stack << value
end

def reset 

def reset
  @stack.clear
end

def set(value) 

def set(value)
  pop
  push(value)
end

def top 

def top
  @stack.last
end