Patch 8.1.2342

[Bram Moolenaar]

Patch 8.1.2342
Problem: Random number generator in Vim script is slow.
Solution: Add rand() and srand(). (Yasuhiro Matsumoto, closes #1277)
Files: runtime/doc/eval.txt, src/evalfunc.c, src/testdir/Make_all.mak,
src/testdir/test_random.vim


*** ../vim-8.1.2341/runtime/doc/eval.txt 2019-11-25 00:04:34.263239656 +0100
--- runtime/doc/eval.txt 2019-11-25 15:27:58.105100025 +0100
***************
*** 2648,2653 ****
--- 2648,2654 ----
pyeval({expr}) any evaluate |Python| expression
py3eval({expr}) any evaluate |python3| expression
pyxeval({expr}) any evaluate |python_x| expression
+ rand([{expr}]) Number get pseudo-random number
range({expr} [, {max} [, {stride}]])
List items from {expr} to {max}
readdir({dir} [, {expr}]) List file names in {dir} selected by {expr}
***************
*** 2761,2766 ****
--- 2762,2768 ----
split({expr} [, {pat} [, {keepempty}]])
List make |List| from {pat} separated {expr}
sqrt({expr}) Float square root of {expr}
+ srand([{expr}]) List get seed for |rand()|
state([{what}]) String current state of Vim
str2float({expr}) Float convert String to Float
str2list({expr} [, {utf8}]) List convert each character of {expr} to
***************
*** 7631,7636 ****
--- 7639,7658 ----
Can also be used as a |method|: >
GetExpr()->range()
<
+
+ rand([{expr}]) *rand()*
+ Return a pseudo-random Number generated with an xorshift
+ algorithm using seed {expr}. {expr} can be initialized by
+ |srand()| and will be updated by rand().
+ If {expr} is omitted, an internal seed value is used and
+ updated.
+
+ Examples: >
+ :echo rand()
+ :let seed = srand()
+ :echo rand(seed)
+ :echo rand(seed)
+ <
*readdir()*
readdir({directory} [, {expr}])
Return a list with file and directory names in {directory}.
***************
*** 9106,9111 ****
--- 9146,9164 ----
{only available when compiled with the |+float| feature}


+ srand([{expr}]) *srand()*
+ Initialize seed used by |rand()|:
+ - If {expr} is not given, seed values are initialized by
+ time(NULL) a.k.a. epoch time.
+ - If {expr} is given, return seed values which x element is
+ {expr}. This is useful for testing or when a predictable
+ sequence is expected.
+
+ Examples: >
+ :let seed = srand()
+ :let seed = srand(userinput)
+ :echo rand(seed)
+
state([{what}]) *state()*
Return a string which contains characters indicating the
current state. Mostly useful in callbacks that want to do
*** ../vim-8.1.2341/src/evalfunc.c 2019-11-25 00:04:34.263239656 +0100
--- src/evalfunc.c 2019-11-25 15:36:11.670868004 +0100
***************
*** 169,174 ****
--- 169,175 ----
#if defined(FEAT_PYTHON) || defined(FEAT_PYTHON3)
static void f_pyxeval(typval_T *argvars, typval_T *rettv);
#endif
+ static void f_rand(typval_T *argvars, typval_T *rettv);
static void f_range(typval_T *argvars, typval_T *rettv);
static void f_reg_executing(typval_T *argvars, typval_T *rettv);
static void f_reg_recording(typval_T *argvars, typval_T *rettv);
***************
*** 225,230 ****
--- 226,232 ----
static void f_split(typval_T *argvars, typval_T *rettv);
#ifdef FEAT_FLOAT
static void f_sqrt(typval_T *argvars, typval_T *rettv);
+ static void f_srand(typval_T *argvars, typval_T *rettv);
static void f_str2float(typval_T *argvars, typval_T *rettv);
#endif
static void f_str2list(typval_T *argvars, typval_T *rettv);
***************
*** 634,639 ****
--- 636,642 ----
#if defined(FEAT_PYTHON) || defined(FEAT_PYTHON3)
{"pyxeval", 1, 1, FEARG_1, f_pyxeval},
#endif
+ {"rand", 0, 1, FEARG_1, f_rand},
{"range", 1, 3, FEARG_1, f_range},
{"readdir", 1, 2, FEARG_1, f_readdir},
{"readfile", 1, 3, FEARG_1, f_readfile},
***************
*** 725,730 ****
--- 728,734 ----
{"split", 1, 3, FEARG_1, f_split},
#ifdef FEAT_FLOAT
{"sqrt", 1, 1, FEARG_1, f_sqrt},
+ {"srand", 0, 1, FEARG_1, f_srand},
#endif
{"state", 0, 1, FEARG_1, f_state},
#ifdef FEAT_FLOAT
***************
*** 5129,5134 ****
--- 5133,5211 ----
#endif

/*
+ * "rand()" function
+ */
+ static void
+ f_rand(typval_T *argvars, typval_T *rettv)
+ {
+ list_T *l = NULL;
+ UINT32_T x, y, z, w, t;
+ static int rand_seed_initialized = FALSE;
+ static UINT32_T xyzw[4] = {123456789, 362436069, 521288629, 88675123};
+
+ #define SHUFFLE_XORSHIFT128 \
+ t = x ^ (x << 11); \
+ x = y; y = z; z = w; \
+ w = (w ^ (w >> 19)) ^ (t ^ (t >> 8));
+
+ if (argvars[0].v_type == VAR_UNKNOWN)
+ {
+ // When argument is not given, return random number initialized
+ // statically.
+ if (!rand_seed_initialized)
+ {
+ xyzw[0] = (varnumber_T)time(NULL);
+ rand_seed_initialized = TRUE;
+ }
+
+ x = xyzw[0];
+ y = xyzw[1];
+ z = xyzw[2];
+ w = xyzw[3];
+ SHUFFLE_XORSHIFT128;
+ xyzw[0] = x;
+ xyzw[1] = y;
+ xyzw[2] = z;
+ xyzw[3] = w;
+ }
+ else if (argvars[0].v_type == VAR_LIST)
+ {
+ listitem_T *lx, *ly, *lz, *lw;
+
+ l = argvars[0].vval.v_list;
+ if (list_len(l) != 4)
+ goto theend;
+
+ lx = list_find(l, 0L);
+ ly = list_find(l, 1L);
+ lz = list_find(l, 2L);
+ lw = list_find(l, 3L);
+ if (lx->li_tv.v_type != VAR_NUMBER) goto theend;
+ if (ly->li_tv.v_type != VAR_NUMBER) goto theend;
+ if (lz->li_tv.v_type != VAR_NUMBER) goto theend;
+ if (lw->li_tv.v_type != VAR_NUMBER) goto theend;
+ x = (UINT32_T)lx->li_tv.vval.v_number;
+ y = (UINT32_T)ly->li_tv.vval.v_number;
+ z = (UINT32_T)lz->li_tv.vval.v_number;
+ w = (UINT32_T)lw->li_tv.vval.v_number;
+ SHUFFLE_XORSHIFT128;
+ lx->li_tv.vval.v_number = (varnumber_T)x;
+ ly->li_tv.vval.v_number = (varnumber_T)y;
+ lz->li_tv.vval.v_number = (varnumber_T)z;
+ lw->li_tv.vval.v_number = (varnumber_T)w;
+ }
+ else
+ goto theend;
+
+ rettv->v_type = VAR_NUMBER;
+ rettv->vval.v_number = (varnumber_T)w;
+ return;
+
+ theend:
+ semsg(_(e_invarg2), tv_get_string(&argvars[0]));
+ }
+
+ /*
* "range()" function
*/
static void
***************
*** 7013,7018 ****
--- 7090,7120 ----
}

/*
+ * "srand()" function
+ */
+ static void
+ f_srand(typval_T *argvars, typval_T *rettv)
+ {
+ if (rettv_list_alloc(rettv) == FAIL)
+ return;
+ if (argvars[0].v_type == VAR_UNKNOWN)
+ list_append_number(rettv->vval.v_list, (varnumber_T)vim_time());
+ else
+ {
+ int error = FALSE;
+ UINT32_T x = (UINT32_T)tv_get_number_chk(&argvars[0], &error);
+
+ if (error)
+ return;
+
+ list_append_number(rettv->vval.v_list, x);
+ }
+ list_append_number(rettv->vval.v_list, 362436069);
+ list_append_number(rettv->vval.v_list, 521288629);
+ list_append_number(rettv->vval.v_list, 88675123);
+ }
+
+ /*
* "str2float()" function
*/
static void
*** ../vim-8.1.2341/src/testdir/Make_all.mak 2019-11-25 00:04:34.263239656 +0100
--- src/testdir/Make_all.mak 2019-11-25 15:17:52.075876012 +0100
***************
*** 211,216 ****
--- 211,217 ----
test_pyx3 \
test_quickfix \
test_quotestar \
+ test_random \
test_recover \
test_regex_char_classes \
test_regexp_latin \
***************
*** 403,408 ****
--- 404,410 ----
test_pyx3.res \
test_quickfix.res \
test_quotestar.res \
+ test_random.res \
test_regex_char_classes.res \
test_registers.res \
test_restricted.res \
*** ../vim-8.1.2341/src/testdir/test_random.vim 2019-11-25 15:39:15.965972075 +0100
--- src/testdir/test_random.vim 2019-11-25 15:35:04.435188636 +0100
***************
*** 0 ****
--- 1,28 ----
+ " Tests for srand() and rand()
+
+ func Test_Rand()
+ let r = srand(123456789)
+ call assert_equal([123456789, 362436069, 521288629, 88675123], r)
+ call assert_equal(3701687786, rand(r))
+ call assert_equal(458299110, rand(r))
+ call assert_equal(2500872618, rand(r))
+ call assert_equal(3633119408, rand(r))
+ call assert_equal(516391518, rand(r))
+
+ call test_settime(12341234)
+ let s = srand()
+ call assert_equal(s, srand())
+ call test_settime(12341235)
+ call assert_notequal(s, srand())
+
+ call srand()
+ let v = rand()
+ call assert_notequal(v, rand())
+
+ call assert_fails('echo srand([1])', 'E745:')
+ call assert_fails('echo rand([1, 2, 3])', 'E475:')
+ call assert_fails('echo rand([[1], 2, 3, 4])', 'E475:')
+ call assert_fails('echo rand([1, [2], 3, 4])', 'E475:')
+ call assert_fails('echo rand([1, 2, [3], 4])', 'E475:')
+ call assert_fails('echo rand([1, 2, 3, [4]])', 'E475:')
+ endfunc
*** ../vim-8.1.2341/src/version.c 2019-11-25 00:04:34.263239656 +0100
--- src/version.c 2019-11-25 15:36:29.354783057 +0100
***************
*** 739,740 ****
--- 739,742 ----
{ /* Add new patch number below this line */
+ /**/
+ 2342,
/**/

--
"A clear conscience is usually the sign of a bad memory."
-- Steven Wright

/// Bram Moolenaar -- Br...@Moolenaar.net -- http://www.Moolenaar.net \\\
/// sponsor Vim, vote for features -- http://www.Vim.org/sponsor/ \\\
\\\ an exciting new programming language -- http://www.Zimbu.org ///
\\\ help me help AIDS victims -- http://ICCF-Holland.org ///

[Bram Moolenaar]

I wrote:

> Patch 8.1.2342
> Problem: Random number generator in Vim script is slow.
> Solution: Add rand() and srand(). (Yasuhiro Matsumoto, closes #1277)
> Files: runtime/doc/eval.txt, src/evalfunc.c, src/testdir/Make_all.mak,
> src/testdir/test_random.vim

I would appreciate it if someone with knowledge of statistics would give
this a try and check that it's sufficiently random.

I also wonder if there is something better to seed with than time().

--
hundred-and-one symptoms of being an internet addict:
119. You are reading a book and look for the scroll bar to get to
the next page.

[Dominique Pellé]

Bram Moolenaar wrote:

> I wrote:
>
> > Patch 8.1.2342
> > Problem: Random number generator in Vim script is slow.
> > Solution: Add rand() and srand(). (Yasuhiro Matsumoto, closes #1277)
> > Files: runtime/doc/eval.txt, src/evalfunc.c, src/testdir/Make_all.mak,
> > src/testdir/test_random.vim
>
> I would appreciate it if someone with knowledge of statistics would give
> this a try and check that it's sufficiently random.
>
> I also wonder if there is something better to seed with than time().

srand() we could read from /dev/urandom, on platforms that
support it. According to https://en.wikipedia.org/wiki/dev/random,
it's available on at least Linux, macOs, OpenBSD, FreeBSD.

Dominique