patch 8.1.1122: char2nr() does not handle composing characters

Problem:    char2nr() does not handle composing characters.
Solution:   Add str2list() and list2str(). (Ozaki Kiichi, closes #4190)

runtime/doc/eval.txt

@@ -2442,6 +2442,7 @@ libcallnr({lib}, {func}, {arg})	Number	idem, but return a Number
 line({expr})			Number	line nr of cursor, last line or mark
 line2byte({lnum})		Number	byte count of line {lnum}
 lispindent({lnum})		Number	Lisp indent for line {lnum}
+list2str({list} [, {utf8}])	String	turn numbers in {list} into a String
 localtime()			Number	current time
 log({expr})			Float	natural logarithm (base e) of {expr}
 log10({expr})			Float	logarithm of Float {expr} to base 10
@@ -2609,6 +2610,8 @@ split({expr} [, {pat} [, {keepempty}]])
 				List	make |List| from {pat} separated {expr}
 sqrt({expr})			Float	square root of {expr}
 str2float({expr})		Float	convert String to Float
+str2list({expr} [, {utf8}])	List	convert each character of {expr} to
+					ASCII/UTF8 value
 str2nr({expr} [, {base}])	Number	convert String to Number
 strchars({expr} [, {skipcc}])	Number	character length of the String {expr}
 strcharpart({str}, {start} [, {len}])
@@ -6193,6 +6196,20 @@ lispindent({lnum})					*lispindent()*
 		When {lnum} is invalid or Vim was not compiled the
 		|+lispindent| feature, -1 is returned.
 
+list2str({list} [, {utf8}])				*list2str()*
+		Convert each number in {list} to a character string can
+		concatenate them all.  Examples: >
+			list2str([32])		returns " "
+			list2str([65, 66, 67])	returns "ABC"
+<		The same can be done (slowly) with: >
+			join(map(list, {nr, val -> nr2char(val)}), '')
+<		|str2list()| does the opposite.
+
+		When {utf8} is omitted or zero, the current 'encoding' is used.
+		With {utf8} is 1, always return utf-8 characters.
+		With utf-8 composing characters work as expected: >
+			list2str([97, 769])	returns "á"
+<
 localtime()						*localtime()*
 		Return the current time, measured as seconds since 1st Jan
 		1970.  See also |strftime()| and |getftime()|.
@@ -8722,6 +8739,18 @@ str2float({expr})					*str2float()*
 			let f = str2float(substitute(text, ',', '', 'g'))
 <		{only available when compiled with the |+float| feature}
 
+str2list({expr} [, {utf8}])				*str2list()*
+		Return a list containing the number values which represent
+		each character in String {expr}.  Examples: >
+			str2list(" ")		returns [32]
+			str2list("ABC")		returns [65, 66, 67]
+<		|list2str()| does the opposite.
+
+		When {utf8} is omitted or zero, the current 'encoding' is used.
+		With {utf8} set to 1, always treat the String as utf-8
+		characters.  With utf-8 composing characters are handled
+		properly: >
+			str2list("á")		returns [97, 769]
 
 str2nr({expr} [, {base}])				*str2nr()*
 		Convert string {expr} to a number.

runtime/doc/usr_41.txt

@@ -577,8 +577,10 @@ used for.  You can find an alphabetical list here: |functions|.  Use CTRL-] on
 the function name to jump to detailed help on it.
 
 String manipulation:					*string-functions*
-	nr2char()		get a character by its ASCII value
-	char2nr()		get ASCII value of a character
+	nr2char()		get a character by its number value
+	list2str()		get a character string from a list of numbers
+	char2nr()		get number value of a character
+	str2list()		get list of numbers from a string
 	str2nr()		convert a string to a Number
 	str2float()		convert a string to a Float
 	printf()		format a string according to % items

src/evalfunc.c

@@ -262,6 +262,7 @@ static void f_libcallnr(typval_T *argvars, typval_T *rettv);
 static void f_line(typval_T *argvars, typval_T *rettv);
 static void f_line2byte(typval_T *argvars, typval_T *rettv);
 static void f_lispindent(typval_T *argvars, typval_T *rettv);
+static void f_list2str(typval_T *argvars, typval_T *rettv);
 static void f_localtime(typval_T *argvars, typval_T *rettv);
 #ifdef FEAT_FLOAT
 static void f_log(typval_T *argvars, typval_T *rettv);
@@ -401,6 +402,7 @@ static void f_split(typval_T *argvars, typval_T *rettv);
 static void f_sqrt(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);
 static void f_str2nr(typval_T *argvars, typval_T *rettv);
 static void f_strchars(typval_T *argvars, typval_T *rettv);
 #ifdef HAVE_STRFTIME
@@ -752,6 +754,7 @@ static struct fst
     {"line",		1, 1, f_line},
     {"line2byte",	1, 1, f_line2byte},
     {"lispindent",	1, 1, f_lispindent},
+    {"list2str",	1, 2, f_list2str},
     {"localtime",	0, 0, f_localtime},
 #ifdef FEAT_FLOAT
     {"log",		1, 1, f_log},
@@ -902,6 +905,7 @@ static struct fst
     {"sqrt",		1, 1, f_sqrt},
     {"str2float",	1, 1, f_str2float},
 #endif
+    {"str2list",	1, 2, f_str2list},
     {"str2nr",		1, 2, f_str2nr},
     {"strcharpart",	2, 3, f_strcharpart},
     {"strchars",	1, 2, f_strchars},
@@ -7849,6 +7853,61 @@ f_lispindent(typval_T *argvars UNUSED, typval_T *rettv)
 	rettv->vval.v_number = -1;
 }
 
+/*
+ * "list2str()" function
+ */
+    static void
+f_list2str(typval_T *argvars, typval_T *rettv)
+{
+    list_T	*l;
+    listitem_T	*li;
+    garray_T	ga;
+    int		utf8 = FALSE;
+
+    rettv->v_type = VAR_STRING;
+    rettv->vval.v_string = NULL;
+    if (argvars[0].v_type != VAR_LIST)
+    {
+	emsg(_(e_invarg));
+	return;
+    }
+
+    l = argvars[0].vval.v_list;
+    if (l == NULL)
+	return;  // empty list results in empty string
+
+    if (argvars[1].v_type != VAR_UNKNOWN)
+	utf8 = (int)tv_get_number_chk(&argvars[1], NULL);
+
+    ga_init2(&ga, 1, 80);
+    if (has_mbyte || utf8)
+    {
+	char_u	buf[MB_MAXBYTES + 1];
+	int	(*char2bytes)(int, char_u *);
+
+	if (utf8 || enc_utf8)
+	    char2bytes = utf_char2bytes;
+	else
+	    char2bytes = mb_char2bytes;
+
+	for (li = l->lv_first; li != NULL; li = li->li_next)
+	{
+	    buf[(*char2bytes)(tv_get_number(&li->li_tv), buf)] = NUL;
+	    ga_concat(&ga, buf);
+	}
+	ga_append(&ga, NUL);
+    }
+    else if (ga_grow(&ga, list_len(l) + 1) == OK)
+    {
+	for (li = l->lv_first; li != NULL; li = li->li_next)
+	    ga_append(&ga, tv_get_number(&li->li_tv));
+	ga_append(&ga, NUL);
+    }
+
+    rettv->v_type = VAR_STRING;
+    rettv->vval.v_string = ga.ga_data;
+}
+
 /*
  * "localtime()" function
  */
@@ -12900,6 +12959,47 @@ f_str2float(typval_T *argvars, typval_T *rettv)
 }
 #endif
 
+/*
+ * "str2list()" function
+ */
+    static void
+f_str2list(typval_T *argvars, typval_T *rettv)
+{
+    char_u	*p;
+    int		utf8 = FALSE;
+
+    if (rettv_list_alloc(rettv) == FAIL)
+	return;
+
+    if (argvars[1].v_type != VAR_UNKNOWN)
+	utf8 = (int)tv_get_number_chk(&argvars[1], NULL);
+
+    p = tv_get_string(&argvars[0]);
+
+    if (has_mbyte || utf8)
+    {
+	int (*ptr2len)(char_u *);
+	int (*ptr2char)(char_u *);
+
+	if (utf8 || enc_utf8)
+	{
+	    ptr2len = utf_ptr2len;
+	    ptr2char = utf_ptr2char;
+	}
+	else
+	{
+	    ptr2len = mb_ptr2len;
+	    ptr2char = mb_ptr2char;
+	}
+
+	for ( ; *p != NUL; p += (*ptr2len)(p))
+	    list_append_number(rettv->vval.v_list, (*ptr2char)(p));
+    }
+    else
+	for ( ; *p != NUL; ++p)
+	    list_append_number(rettv->vval.v_list, *p);
+}
+
 /*
  * "str2nr()" function
  */

src/testdir/test_utf8.vim

@@ -62,6 +62,49 @@ func Test_getvcol()
   call assert_equal(2, virtcol("']"))
 endfunc
 
+func Test_list2str_str2list_utf8()
+  " One Unicode codepoint
+  let s = "\u3042\u3044"
+  let l = [0x3042, 0x3044]
+  call assert_equal(l, str2list(s, 1))
+  call assert_equal(s, list2str(l, 1))
+  if &enc ==# 'utf-8'
+    call assert_equal(str2list(s), str2list(s, 1))
+    call assert_equal(list2str(l), list2str(l, 1))
+  endif
+
+  " With composing characters
+  let s = "\u304b\u3099\u3044"
+  let l = [0x304b, 0x3099, 0x3044]
+  call assert_equal(l, str2list(s, 1))
+  call assert_equal(s, list2str(l, 1))
+  if &enc ==# 'utf-8'
+    call assert_equal(str2list(s), str2list(s, 1))
+    call assert_equal(list2str(l), list2str(l, 1))
+  endif
+
+  " Null list is the same as an empty list
+  call assert_equal('', list2str([]))
+  call assert_equal('', list2str(test_null_list()))
+endfunc
+
+func Test_list2str_str2list_latin1()
+  " When 'encoding' is not multi-byte can still get utf-8 string.
+  " But we need to create the utf-8 string while 'encoding' is utf-8.
+  let s = "\u3042\u3044"
+  let l = [0x3042, 0x3044]
+
+  let save_encoding = &encoding
+  set encoding=latin1
+
+  let lres = str2list(s, 1)
+  let sres = list2str(l, 1)
+
+  let &encoding = save_encoding
+  call assert_equal(l, lres)
+  call assert_equal(s, sres)
+endfunc
+
 func Test_screenchar_utf8()
   new
 

src/version.c

@@ -771,6 +771,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1122,
 /**/
     1121,
 /**/