Method: Range#step

Defined in:
range.c

#step(n = 1) {|obj| ... } ⇒ Object #step(n = 1) ⇒ Object

Iterates over the range, passing each nth element to the block. If begin and end are numeric, n is added for each iteration. Otherwise step invokes succ to iterate through range elements.

If no block is given, an enumerator is returned instead.

range = Xs.new(1)..Xs.new(10)
range.step(2) {|x| puts x}
puts
range.step(3) {|x| puts x}

produces:

 1 x
 3 xxx
 5 xxxxx
 7 xxxxxxx
 9 xxxxxxxxx

 1 x
 4 xxxx
 7 xxxxxxx
10 xxxxxxxxxx

See Range for the definition of class Xs.

Overloads:

  • #step(n = 1) {|obj| ... } ⇒ Object

    Yields:

    • (obj) 


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# File 'range.c', line 390

static VALUE
range_step(int argc, VALUE *argv, VALUE range)
{
    VALUE b, e, step, tmp;

    RETURN_SIZED_ENUMERATOR(range, argc, argv, range_step_size);

    b = RANGE_BEG(range);
    e = RANGE_END(range);
    if (argc == 0) {
	step = INT2FIX(1);
    }
    else {
	rb_scan_args(argc, argv, "01", &step);
	if (!rb_obj_is_kind_of(step, rb_cNumeric)) {
	    step = rb_to_int(step);
	}
	if (rb_funcall(step, '<', 1, INT2FIX(0))) {
	    rb_raise(rb_eArgError, "step can't be negative");
	}
	else if (!rb_funcall(step, '>', 1, INT2FIX(0))) {
	    rb_raise(rb_eArgError, "step can't be 0");
	}
    }

    if (FIXNUM_P(b) && FIXNUM_P(e) && FIXNUM_P(step)) { /* fixnums are special */
	long end = FIX2LONG(e);
	long i, unit = FIX2LONG(step);

	if (!EXCL(range))
	    end += 1;
	i = FIX2LONG(b);
	while (i < end) {
	    rb_yield(LONG2NUM(i));
	    if (i + unit < i) break;
	    i += unit;
	}

    }
    else if (SYMBOL_P(b) && SYMBOL_P(e)) { /* symbols are special */
	VALUE args[2], iter[2];

	args[0] = rb_sym_to_s(e);
	args[1] = EXCL(range) ? Qtrue : Qfalse;
	iter[0] = INT2FIX(1);
	iter[1] = step;
	rb_block_call(rb_sym_to_s(b), rb_intern("upto"), 2, args, sym_step_i, (VALUE)iter);
    }
    else if (ruby_float_step(b, e, step, EXCL(range))) {
	/* done */
    }
    else if (rb_obj_is_kind_of(b, rb_cNumeric) ||
	     !NIL_P(rb_check_to_integer(b, "to_int")) ||
	     !NIL_P(rb_check_to_integer(e, "to_int"))) {
	ID op = EXCL(range) ? '<' : idLE;
	VALUE v = b;
	int i = 0;

	while (RTEST(rb_funcall(v, op, 1, e))) {
	    rb_yield(v);
	    i++;
	    v = rb_funcall(b, '+', 1, rb_funcall(INT2NUM(i), '*', 1, step));
	}
    }
    else {
	tmp = rb_check_string_type(b);

	if (!NIL_P(tmp)) {
	    VALUE args[2], iter[2];

	    b = tmp;
	    args[0] = e;
	    args[1] = EXCL(range) ? Qtrue : Qfalse;
	    iter[0] = INT2FIX(1);
	    iter[1] = step;
	    rb_block_call(b, rb_intern("upto"), 2, args, step_i, (VALUE)iter);
	}
	else {
	    VALUE args[2];

	    if (!discrete_object_p(b)) {
		rb_raise(rb_eTypeError, "can't iterate from %s",
			 rb_obj_classname(b));
	    }
	    args[0] = INT2FIX(1);
	    args[1] = step;
	    range_each_func(range, step_i, (VALUE)args);
	}
    }
    return range;
}