factor/library/arrays.factor

! Copyright (C) 2005 Slava Pestov.
! See http://factor.sf.net/license.txt for BSD license.
IN: kernel-internals
USING: generic kernel lists math-internals sequences vectors ;

! An array is a range of memory storing pointers to other
! objects. Arrays are not used directly, and their access words
! are not bounds checked. Examples of abstractions built on
! arrays include vectors, hashtables, and tuples.

! These words are unsafe. I'd say "do not call them", but that
! Java-esque. By all means, do use arrays if you need something
! low-level... but be aware that vectors are usually a better
! choice.

BUILTIN: array 8 [ 1 length f ] ;

: array-nth ( n array -- obj )
    #! Unsafe.
    swap 2 fixnum+ slot ; inline

: set-array-nth ( obj n array -- )
    #! Unsafe.
    swap 2 fixnum+ set-slot ; inline

M: array nth array-nth ;
M: array set-nth set-array-nth ;

: dispatch ( n vtable -- )
    #! This word is unsafe since n is not bounds-checked. Do not
    #! call it directly.
    2 slot array-nth call ;