patch 8.2.0935: flattening a list with existing code is slow
Problem: Flattening a list with existing code is slow.
Solution: Add flatten(). (Mopp, closes #3676)
diff --git a/runtime/doc/eval.txt b/runtime/doc/eval.txt
index 3340d59..f3e240a 100644
--- a/runtime/doc/eval.txt
+++ b/runtime/doc/eval.txt
@@ -2451,6 +2451,7 @@
String find directory {name} in {path}
findfile({name} [, {path} [, {count}]])
String find file {name} in {path}
+flatten({list} [, {maxdepth}]) List flatten {list} up to {maxdepth} levels
float2nr({expr}) Number convert Float {expr} to a Number
floor({expr}) Float round {expr} down
fmod({expr1}, {expr2}) Float remainder of {expr1} / {expr2}
@@ -4514,6 +4515,25 @@
Can also be used as a |method|: >
GetName()->findfile()
+flatten({list} [, {maxdepth}]) *flatten()*
+ Flatten {list} up to {maxdepth} levels. Without {maxdepth}
+ the result is a |List| without nesting, as if {maxdepth} is
+ a very large number.
+ The {list} is changed in place, make a copy first if you do
+ not want that.
+ *E964*
+ {maxdepth} means how deep in nested lists changes are made.
+ {list} is not modified when {maxdepth} is 0.
+ {maxdepth} must be positive number.
+
+ If there is an error the number zero is returned.
+
+ Example: >
+ :echo flatten([1, [2, [3, 4]], 5])
+< [1, 2, 3, 4, 5] >
+ :echo flatten([1, [2, [3, 4]], 5], 1)
+< [1, 2, [3, 4], 5]
+
float2nr({expr}) *float2nr()*
Convert {expr} to a Number by omitting the part after the
decimal point.
diff --git a/runtime/doc/usr_41.txt b/runtime/doc/usr_41.txt
index 1d896f9..e39f1fe 100644
--- a/runtime/doc/usr_41.txt
+++ b/runtime/doc/usr_41.txt
@@ -650,6 +650,7 @@
min() minimum value in a List
count() count number of times a value appears in a List
repeat() repeat a List multiple times
+ flatten() flatten a List
Dictionary manipulation: *dict-functions*
get() get an entry without an error for a wrong key
diff --git a/src/evalfunc.c b/src/evalfunc.c
index 4414509..e67aa58 100644
--- a/src/evalfunc.c
+++ b/src/evalfunc.c
@@ -541,6 +541,7 @@
{"filter", 2, 2, FEARG_1, ret_any, f_filter},
{"finddir", 1, 3, FEARG_1, ret_string, f_finddir},
{"findfile", 1, 3, FEARG_1, ret_string, f_findfile},
+ {"flatten", 1, 2, FEARG_1, ret_list_any, f_flatten},
{"float2nr", 1, 1, FEARG_1, ret_number, FLOAT_FUNC(f_float2nr)},
{"floor", 1, 1, FEARG_1, ret_float, FLOAT_FUNC(f_floor)},
{"fmod", 2, 2, FEARG_1, ret_float, FLOAT_FUNC(f_fmod)},
diff --git a/src/list.c b/src/list.c
index baff654..de802e6 100644
--- a/src/list.c
+++ b/src/list.c
@@ -731,6 +731,95 @@
}
/*
+ * Flatten "list" to depth "maxdepth".
+ * It does nothing if "maxdepth" is 0.
+ * Returns FAIL when out of memory.
+ */
+ static int
+list_flatten(list_T *list, long maxdepth)
+{
+ listitem_T *item;
+ int n;
+
+ if (maxdepth == 0)
+ return OK;
+ CHECK_LIST_MATERIALIZE(list);
+
+ n = 0;
+ item = list->lv_first;
+ while (item != NULL)
+ {
+ fast_breakcheck();
+ if (got_int)
+ return FAIL;
+
+ if (item->li_tv.v_type == VAR_LIST)
+ {
+ listitem_T *next = item->li_next;
+
+ vimlist_remove(list, item, item);
+ if (list_extend(list, item->li_tv.vval.v_list, next) == FAIL)
+ return FAIL;
+
+ if (item->li_prev == NULL)
+ item = list->lv_first;
+ else
+ item = item->li_prev->li_next;
+
+ if (++n >= maxdepth)
+ {
+ n = 0;
+ item = next;
+ }
+ }
+ else
+ {
+ n = 0;
+ item = item->li_next;
+ }
+ }
+
+ return OK;
+}
+
+/*
+ * "flatten(list[, {maxdepth}])" function
+ */
+ void
+f_flatten(typval_T *argvars, typval_T *rettv)
+{
+ list_T *l;
+ long maxdepth;
+ int error = FALSE;
+
+ if (argvars[0].v_type != VAR_LIST)
+ {
+ semsg(_(e_listarg), "flatten()");
+ return;
+ }
+
+ if (argvars[1].v_type == VAR_UNKNOWN)
+ maxdepth = 999999;
+ else
+ {
+ maxdepth = (long)tv_get_number_chk(&argvars[1], &error);
+ if (error)
+ return;
+ if (maxdepth < 0)
+ {
+ emsg(_("E900: maxdepth must be non-negative number"));
+ return;
+ }
+ }
+
+ l = argvars[0].vval.v_list;
+ if (l != NULL && !var_check_lock(l->lv_lock,
+ (char_u *)N_("flatten() argument"), TRUE)
+ && list_flatten(l, maxdepth) == OK)
+ copy_tv(&argvars[0], rettv);
+}
+
+/*
* Extend "l1" with "l2".
* If "bef" is NULL append at the end, otherwise insert before this item.
* Returns FAIL when out of memory.
diff --git a/src/proto/list.pro b/src/proto/list.pro
index 77183af..bdbf7eb 100644
--- a/src/proto/list.pro
+++ b/src/proto/list.pro
@@ -30,6 +30,7 @@
int list_append_number(list_T *l, varnumber_T n);
int list_insert_tv(list_T *l, typval_T *tv, listitem_T *item);
void list_insert(list_T *l, listitem_T *ni, listitem_T *item);
+void f_flatten(typval_T *argvars, typval_T *rettv);
int list_extend(list_T *l1, list_T *l2, listitem_T *bef);
int list_concat(list_T *l1, list_T *l2, typval_T *tv);
list_T *list_copy(list_T *orig, int deep, int copyID);
@@ -37,7 +38,7 @@
char_u *list2string(typval_T *tv, int copyID, int restore_copyID);
int list_join(garray_T *gap, list_T *l, char_u *sep, int echo_style, int restore_copyID, int copyID);
void f_join(typval_T *argvars, typval_T *rettv);
-int get_list_tv(char_u **arg, typval_T *rettv, int evaluate, int do_error);
+int get_list_tv(char_u **arg, typval_T *rettv, int flags, int do_error);
int write_list(FILE *fd, list_T *list, int binary);
void init_static_list(staticList10_T *sl);
void f_list2str(typval_T *argvars, typval_T *rettv);
diff --git a/src/testdir/Make_all.mak b/src/testdir/Make_all.mak
index 7402067..2a133ef 100644
--- a/src/testdir/Make_all.mak
+++ b/src/testdir/Make_all.mak
@@ -135,6 +135,7 @@
test_find_complete \
test_findfile \
test_fixeol \
+ test_flatten \
test_float_func \
test_fnameescape \
test_fnamemodify \
@@ -373,6 +374,7 @@
test_find_complete.res \
test_findfile.res \
test_fixeol.res \
+ test_flatten.res \
test_float_func.res \
test_fnameescape.res \
test_fold.res \
diff --git a/src/testdir/test_flatten.vim b/src/testdir/test_flatten.vim
new file mode 100644
index 0000000..9908661
--- /dev/null
+++ b/src/testdir/test_flatten.vim
@@ -0,0 +1,81 @@
+" Test for flatting list.
+func Test_flatten()
+ call assert_fails('call flatten(1)', 'E686:')
+ call assert_fails('call flatten({})', 'E686:')
+ call assert_fails('call flatten("string")', 'E686:')
+ call assert_fails('call flatten([], [])', 'E745:')
+ call assert_fails('call flatten([], -1)', 'E900: maxdepth')
+
+ call assert_equal([], flatten([]))
+ call assert_equal([], flatten([[]]))
+ call assert_equal([], flatten([[[]]]))
+
+ call assert_equal([1, 2, 3], flatten([1, 2, 3]))
+ call assert_equal([1, 2, 3], flatten([[1], 2, 3]))
+ call assert_equal([1, 2, 3], flatten([1, [2], 3]))
+ call assert_equal([1, 2, 3], flatten([1, 2, [3]]))
+ call assert_equal([1, 2, 3], flatten([[1], [2], 3]))
+ call assert_equal([1, 2, 3], flatten([1, [2], [3]]))
+ call assert_equal([1, 2, 3], flatten([[1], 2, [3]]))
+ call assert_equal([1, 2, 3], flatten([[1], [2], [3]]))
+
+ call assert_equal([1, 2, 3], flatten([[1, 2, 3], []]))
+ call assert_equal([1, 2, 3], flatten([[], [1, 2, 3]]))
+ call assert_equal([1, 2, 3], flatten([[1, 2], [], [3]]))
+ call assert_equal([1, 2, 3], flatten([[], [1, 2, 3], []]))
+ call assert_equal([1, 2, 3, 4], flatten(range(1, 4)))
+
+ " example in the help
+ call assert_equal([1, 2, 3, 4, 5], flatten([1, [2, [3, 4]], 5]))
+ call assert_equal([1, 2, [3, 4], 5], flatten([1, [2, [3, 4]], 5], 1))
+
+ call assert_equal([0, [1], 2, [3], 4], flatten([[0, [1]], 2, [[3], 4]], 1))
+ call assert_equal([1, 2, 3], flatten([[[[1]]], [2], [3]], 3))
+ call assert_equal([[1], [2], [3]], flatten([[[1], [2], [3]]], 1))
+ call assert_equal([[1]], flatten([[1]], 0))
+
+ " Make it flatten if the given maxdepth is larger than actual depth.
+ call assert_equal([1, 2, 3], flatten([[1, 2, 3]], 1))
+ call assert_equal([1, 2, 3], flatten([[1, 2, 3]], 2))
+
+ let l:list = [[1], [2], [3]]
+ call assert_equal([1, 2, 3], flatten(l:list))
+ call assert_equal([1, 2, 3], l:list)
+
+ " Tests for checking reference counter works well.
+ let l:x = {'foo': 'bar'}
+ call assert_equal([1, 2, l:x, 3], flatten([1, [2, l:x], 3]))
+ call test_garbagecollect_now()
+ call assert_equal('bar', l:x.foo)
+
+ let l:list = [[1], [2], [3]]
+ call assert_equal([1, 2, 3], flatten(l:list))
+ call test_garbagecollect_now()
+ call assert_equal([1, 2, 3], l:list)
+
+ " Tests for checking circular reference list can be flatten.
+ let l:x = [1]
+ let l:y = [x]
+ let l:z = flatten(l:y)
+ call assert_equal([1], l:z)
+ call test_garbagecollect_now()
+ let l:x[0] = 2
+ call assert_equal([2], l:x)
+ call assert_equal([1], l:z) " NOTE: primitive types are copied.
+ call assert_equal([1], l:y)
+
+ let l:x = [2]
+ let l:y = [1, [l:x], 3] " [1, [[2]], 3]
+ let l:z = flatten(l:y, 1)
+ call assert_equal([1, [2], 3], l:z)
+ let l:x[0] = 9
+ call assert_equal([1, [9], 3], l:z) " Reference to l:x is kept.
+ call assert_equal([1, [9], 3], l:y)
+
+ let l:x = [1]
+ let l:y = [2]
+ call add(x, y) " l:x = [1, [2]]
+ call add(y, x) " l:y = [2, [1, [...]]]
+ call assert_equal([1, 2, 1, 2], flatten(l:x, 2))
+ call assert_equal([2, l:x], l:y)
+endfunc
diff --git a/src/version.c b/src/version.c
index 04f61c9..d992e9b 100644
--- a/src/version.c
+++ b/src/version.c
@@ -755,6 +755,8 @@
static int included_patches[] =
{ /* Add new patch number below this line */
/**/
+ 935,
+/**/
934,
/**/
933,