[ruby-talk:11806] Re: Array bugs?

> -----Original Message-----
> From: ts [mailto:[e-mail]]
> Sent: Wednesday, February 28, 2001 02:44 AM
> To: ruby-talk ML
> Cc: [e-mail]
> Subject: [ruby-talk:11760] Re: Array bugs?
> 
> 
> >>>>> "C" == Christoph Rippel <[e-mail]> writes:
> 
> C> for hashes (you should use a recursion limited hash-value - this effects
> C> the hash value of non-recursive Arrays too (and hash-value of Hashes 
> C> them-selves) but its simpler than an ``untangled hash value'' and more 
> C> efficient (even for non-recursive Arrays).
> 
>  I've not understood, how do you define the hash value of
> 
>   a = []
>   a << a
> 
>  actually it give an error.


Not tested ...


class Fixnum
#  unsigned long int  " self << 1 "
def  wrap_by_1;  
	self[31] + (self << 1) - (self[31]<< 32)
end
end



class Object
def protected_hash(level);   hash end
end

class Array
def protected_hash (level)
	return length if level < 1
	hsh =  length	
	each do |i| 
		# in array.c this is  h = (h<<1) | (h<0 ? 1 : 0);
		hsh = (hsh.wrap_by_1) | (hsh<0 ? 1 : 0);
		hsh ^= i.protected_hash (level- 1) 
  	end
	return hsh
end
def hash
	untangled_hash 5
end
end


## Nicer variation IMO

class Object
def  is_recursive?; false end
end


class Array
def  is_recursive?; true end

def protected_hash (level)
	return length if level < 1
	hsh =  length	
	each do |i| 
		hsh = (hsh.wrap_by_1) | (hsh<0 ? 1 : 0);
		if i.is_recursive?
			hsh ^= i.protected_hash (level- 1) 
		else	
			hsh ^= i.hash
		end
  	end
	return hsh
end
def hash
	untangled_hash 5
end
end


Christoph