vim-patch:8.1.1120: cannot easily get directory entry matches #12222

Problem:    Cannot easily get directory entry matches.
Solution:   Add the readdir() function. (Yasuhiro Matsumoto, closes vim/vim#2439)
https://github.com/vim/vim/commit/543c9b1921d7605498b54afdef518e312f1b4515

closes #12212

5 files changed, 153 insertions, 13 deletions

diff --git a/runtime/doc/eval.txt b/runtime/doc/eval.txt
index 4ff6269004..6f13b34876 100644
--- a/runtime/doc/eval.txt
+++ b/runtime/doc/eval.txt
@@ -6689,6 +6689,33 @@ range({expr} [, {max} [, {stride}]])				*range()*
 			range(0)		" []
 			range(2, 0)		" error!
 <
+							*readdir()*
+readdir({directory} [, {expr}])
+		Return a list with file and directory names in {directory}.
+
+		When {expr} is omitted all entries are included.
+		When {expr} is given, it is evaluated to check what to do:
+			If {expr} results in -1 then no further entries will
+			be handled.
+			If {expr} results in 0 then this entry will not be
+			added to the list.
+			If {expr} results in 1 then this entry will be added
+			to the list.
+		Each time {expr} is evaluated |v:val| is set to the entry name.
+		When {expr} is a function the name is passed as the argument.
+		For example, to get a list of files ending in ".txt": >
+		  readdir(dirname, {n -> n =~ '.txt$'})
+<		To skip hidden and backup files: >
+		  readdir(dirname, {n -> n !~ '^\.\|\~$'})
+
+<		If you want to get a directory tree: >
+                  function! s:tree(dir)
+                      return {a:dir : map(readdir(a:dir),
+		      \ {_, x -> isdirectory(x) ?
+		      \          {x : s:tree(a:dir . '/' . x)} : x})}
+                  endfunction
+                  echo s:tree(".")
+<
 							*readfile()*
 readfile({fname} [, {binary} [, {max}]])
 		Read file {fname} and return a |List|, each line of the file
@@ -6720,17 +6747,6 @@ readfile({fname} [, {binary} [, {max}]])
 		the result is an empty list.
 		Also see |writefile()|.
 
-							*readdir()*
-readdir({directory} [, {expr}])
-		Return a list with file and directory names in {directory}.
-		You can also use |glob()| if you don't need to do complicated
-		things, such as limiting the number of matches.
-
-		When {expr} is omitted all entries are included.
-		When {expr} is given, it is evaluated to check what to do:
-			If {expr} results in -1 then no further entries will
-			be handled.
-
 reg_executing()						*reg_executing()*
 		Returns the single letter name of the register being executed.
 		Returns an empty string when no register is being executed.
diff --git a/src/nvim/eval.c b/src/nvim/eval.c
index a6162af472..4a0876a952 100644
--- a/src/nvim/eval.c
+++ b/src/nvim/eval.c
@@ -915,7 +915,7 @@ varnumber_T eval_to_number(char_u *expr)
  * Save the current typeval in "save_tv".
  * When not used yet add the variable to the v: hashtable.
  */
-static void prepare_vimvar(int idx, typval_T *save_tv)
+void prepare_vimvar(int idx, typval_T *save_tv)
 {
   *save_tv = vimvars[idx].vv_tv;
   if (vimvars[idx].vv_type == VAR_UNKNOWN)
@@ -926,7 +926,7 @@ static void prepare_vimvar(int idx, typval_T *save_tv)
  * Restore v: variable "idx" to typeval "save_tv".
  * When no longer defined, remove the variable from the v: hashtable.
  */
-static void restore_vimvar(int idx, typval_T *save_tv)
+void restore_vimvar(int idx, typval_T *save_tv)
 {
   hashitem_T  *hi;
 
diff --git a/src/nvim/eval.lua b/src/nvim/eval.lua
index d3e769a7ef..65c4cfe553 100644
--- a/src/nvim/eval.lua
+++ b/src/nvim/eval.lua
@@ -255,6 +255,7 @@ return {
     pyeval={args=1},
     pyxeval={args=1},
     range={args={1, 3}},
+    readdir={args={1, 2}},
     readfile={args={1, 3}},
     reg_executing={},
     reg_recording={},
diff --git a/src/nvim/eval/funcs.c b/src/nvim/eval/funcs.c
index 26e87df6d4..217490ad10 100644
--- a/src/nvim/eval/funcs.c
+++ b/src/nvim/eval/funcs.c
@@ -6316,6 +6316,99 @@ static void f_range(typval_T *argvars, typval_T *rettv, FunPtr fptr)
   }
 }
 
+// Evaluate "expr" for readdir().
+static varnumber_T readdir_checkitem(typval_T *expr, const char *name)
+{
+  typval_T save_val;
+  typval_T rettv;
+  typval_T argv[2];
+  varnumber_T retval = 0;
+  bool error = false;
+
+  prepare_vimvar(VV_VAL, &save_val);
+  set_vim_var_string(VV_VAL, name, -1);
+  argv[0].v_type = VAR_STRING;
+  argv[0].vval.v_string = (char_u *)name;
+
+  if (eval_expr_typval(expr, argv, 1, &rettv) == FAIL) {
+    goto theend;
+  }
+
+  retval = tv_get_number_chk(&rettv, &error);
+  if (error) {
+    retval = -1;
+  }
+
+  tv_clear(&rettv);
+
+theend:
+  set_vim_var_string(VV_VAL, NULL, 0);
+  restore_vimvar(VV_VAL, &save_val);
+  return retval;
+}
+
+// "readdir()" function
+static void f_readdir(typval_T *argvars, typval_T *rettv, FunPtr fptr)
+{
+  typval_T *expr;
+  const char *path;
+  garray_T ga;
+  Directory dir;
+
+  tv_list_alloc_ret(rettv, kListLenUnknown);
+  path = tv_get_string(&argvars[0]);
+  expr = &argvars[1];
+  ga_init(&ga, (int)sizeof(char *), 20);
+
+  if (!os_scandir(&dir, path)) {
+    smsg(_(e_notopen), path);
+  } else {
+    for (;;) {
+      bool ignore;
+
+      path = os_scandir_next(&dir);
+      if (path == NULL) {
+        break;
+      }
+
+      ignore = (path[0] == '.'
+                && (path[1] == NUL || (path[1] == '.' && path[2] == NUL)));
+      if (!ignore && expr->v_type != VAR_UNKNOWN) {
+        varnumber_T r = readdir_checkitem(expr, path);
+
+        if (r < 0) {
+          break;
+        }
+        if (r == 0) {
+          ignore = true;
+        }
+      }
+
+      if (!ignore) {
+        ga_grow(&ga, 1);
+        ((char **)ga.ga_data)[ga.ga_len++] = xstrdup(path);
+      }
+    }
+
+    os_closedir(&dir);
+  }
+
+  rettv->vval.v_list = tv_list_alloc(kListLenShouldKnow);
+  if (rettv->vval.v_list != NULL) {
+    tv_list_ref(rettv->vval.v_list);
+    sort_strings((char_u **)ga.ga_data, ga.ga_len);
+    for (int i = 0; i < ga.ga_len; i++) {
+      path = ((const char **)ga.ga_data)[i];
+      tv_list_append_string(rettv->vval.v_list, path, -1);
+    }
+  }
+  for (int i = 0; i < ga.ga_len; i++) {
+    xfree(((uint8_t **)ga.ga_data)[i]);
+  }
+
+  ga_clear(&ga);
+}
+
 /*
  * "readfile()" function
  */
diff --git a/src/nvim/testdir/test_functions.vim b/src/nvim/testdir/test_functions.vim
index bd5cb6ad19..51689db9c4 100644
--- a/src/nvim/testdir/test_functions.vim
+++ b/src/nvim/testdir/test_functions.vim
@@ -1307,3 +1307,33 @@ func Test_bufadd_bufload()
   bwipe otherName
   call assert_equal(0, bufexists('someName'))
 endfunc
+
+func Test_readdir()
+  call mkdir('Xdir')
+  call writefile([], 'Xdir/foo.txt')
+  call writefile([], 'Xdir/bar.txt')
+  call mkdir('Xdir/dir')
+
+  " All results
+  let files = readdir('Xdir')
+  call assert_equal(['bar.txt', 'dir', 'foo.txt'], sort(files))
+
+  " Only results containing "f"
+  let files = readdir('Xdir', { x -> stridx(x, 'f') !=- 1 })
+  call assert_equal(['foo.txt'], sort(files))
+
+  " Only .txt files
+  let files = readdir('Xdir', { x -> x =~ '.txt$' })
+  call assert_equal(['bar.txt', 'foo.txt'], sort(files))
+
+  " Only .txt files with string
+  let files = readdir('Xdir', 'v:val =~ ".txt$"')
+  call assert_equal(['bar.txt', 'foo.txt'], sort(files))
+
+  " Limit to 1 result.
+  let l = []
+  let files = readdir('Xdir', {x -> len(add(l, x)) == 2 ? -1 : 1})
+  call assert_equal(1, len(files))
+
+  call delete('Xdir', 'rf')
+endfunc