/* * call-seq: * array[index] -> obj or nil * array[start, length] -> an_array or nil * array[range] -> an_array or nil * array.slice(index) -> obj or nil * array.slice(start, length) -> an_array or nil * array.slice(range) -> an_array or nil * * Element Reference---Returns the element at _index_, * or returns a subarray starting at _start_ and * continuing for _length_ elements, or returns a subarray * specified by _range_. * Negative indices count backward from the end of the * array (-1 is the last element). Returns nil if the index * (or starting index) are out of range. * * a = [ "a", "b", "c", "d", "e" ] * a[2] + a[0] + a[1] #=> "cab" * a[6] #=> nil * a[1, 2] #=> [ "b", "c" ] * a[1..3] #=> [ "b", "c", "d" ] * a[4..7] #=> [ "e" ] * a[6..10] #=> nil * a[-3, 3] #=> [ "c", "d", "e" ] * # special cases * a[5] #=> nil * a[5, 1] #=> [] * a[5..10] #=> [] * */ VALUE rb_ary_aref(argc, argv, ary) int argc; VALUE *argv; VALUE ary; { VALUE arg; long beg, len; if (argc == 2) { if (SYMBOL_P(argv[0])) { rb_raise(rb_eTypeError, "Symbol as array index"); } beg = NUM2LONG(argv[0]); len = NUM2LONG(argv[1]); if (beg < 0) { beg += RARRAY(ary)->len; } return rb_ary_subseq(ary, beg, len); } if (argc != 1) { rb_scan_args(argc, argv, "11", 0, 0); } arg = argv[0]; /* special case - speeding up */ if (FIXNUM_P(arg)) { return rb_ary_entry(ary, FIX2LONG(arg)); } if (SYMBOL_P(arg)) { rb_raise(rb_eTypeError, "Symbol as array index"); } /* check if idx is Range */ switch (rb_range_beg_len(arg, &beg, &len, RARRAY(ary)->len, 0)) { case Qfalse: break; case Qnil: return Qnil; default: return rb_ary_subseq(ary, beg, len); } return rb_ary_entry(ary, NUM2LONG(arg)); }