Re: fastest data structure for a hash-like lookup

[Kevin Rodgers]

Florian von Savigny wrote:

> I need a data structure that can be accessed via a key (the keys are
> unique), which points to a value that is a list (in the general sense,
> not in the elisp sense) of three elements. [In Perl, I would implement
> this as a hash where the values are references to lists.]. It may also
> be thought of as a structure with keys that point to "a set of three
> values" each. The structure would be quite large and not be
> manipulated by the elisp program, but merely serve as a lookup table.
>
> I think I've read something that sounded like a vector would be the
> right thing to use (is not changed, is fast), but I haven't found any
> advice on that. Or is it an obarray? A property list? An alist? An
> array? A combination of two? And how would that look like?

You definitly want to use an obarray.  From each key string, generate a symbol
in the obarray whose value is the list you want to look up.

(defvar my-hash (make-vector some-large-prime-number 0))

(defun my-hash-set (key value)
  (set (intern key my-hash) value))

(defun my-hash-get (key)
  (symbol-value (intern-soft key my-hash)))

--
<a href="mailto:&lt;kevin.rodgers&#64;ihs.com&gt;";>Kevin Rodgers</a>