core: add a way to count the suffix length in max chars displayed in cut of string ("cut:" and "cutscr:") (closes #963)

The format to use is one of:

- ${cut:+max,suffix,string}
- ${cutscr:+max,suffix,string}

With the "+" before max, WeeChat ensures there are at most "max" chars in
output, including the length of suffix string.

src/core/wee-command.c

@@ -7269,9 +7269,11 @@ command_init ()
            "  1. an evaluated sub-string (format: \"eval:xxx\")\n"
            "  2. a string with escaped chars (format: \"esc:xxx\" or \"\\xxx\")\n"
            "  3. a string with chars to hide (format: \"hide:char,string\")\n"
-           "  4. a string with max chars (format: \"cut:max,suffix,string\")\n"
+           "  4. a string with max chars (format: \"cut:max,suffix,string\" "
+           "or \"cut:+max,suffix,string\")\n"
            "     or max chars displayed on screen "
-           "(format: \"cutscr:max,suffix,string\")\n"
+           "(format: \"cutscr:max,suffix,string\" or "
+           "\"cutscr:+max,suffix,string\")\n"
            "  5. a color (format: \"color:xxx\", see \"Plugin API "
            "reference\", function \"color\")\n"
            "  6. an info (format: \"info:name,arguments\", arguments are "
@@ -7311,7 +7313,8 @@ command_init ()
            "  /eval -n ${window.buffer.number}               ==> 1\n"
            "  /eval -n ${\\t}                                 ==> <tab>\n"
            "  /eval -n ${hide:-,${relay.network.password}}   ==> --------\n"
-           "  /eval -n ${cut:2,+,test}                       ==> te+\n"
+           "  /eval -n ${cut:3,+,test}                       ==> tes+\n"
+           "  /eval -n ${cut:+3,+,test}                      ==> te+\n"
            "  /eval -n ${date:%H:%M:%S}                      ==> 07:46:40\n"
            "  /eval -n ${if:${info:term_width}>80?big:small} ==> big\n"
            "\n"

src/core/wee-eval.c

@@ -326,6 +326,7 @@ eval_replace_vars_cb (void *data, const char *text)
     struct t_hdata *hdata;
     void *pointer;
     int i, length_hide_char, length, index, rc, extra_vars_eval, screen;
+    int count_suffix;
     long number;
     long unsigned int ptr;
     time_t date;
@@ -436,6 +437,12 @@ eval_replace_vars_cb (void *data, const char *text)
         pos = strchr (text + length, ',');
         if (!pos)
             return strdup ("");
+        count_suffix = 0;
+        if (text[length] == '+')
+        {
+            length++;
+            count_suffix = 1;
+        }
         pos2 = strchr (pos + 1, ',');
         if (!pos2)
             return strdup ("");
@@ -452,7 +459,7 @@ eval_replace_vars_cb (void *data, const char *text)
         tmp = strndup (pos + 1, pos2 - pos - 1);
         if (!tmp)
             return strdup ("");
-        value = string_cut (pos2 + 1, number, screen, tmp);
+        value = string_cut (pos2 + 1, number, count_suffix, screen, tmp);
         free (tmp);
         return value;
     }

src/core/wee-string.c

@@ -96,13 +96,16 @@ string_strndup (const char *string, int length)
  * Cuts a string after max "length" chars, adds an optional suffix
  * after the string if it is cut.
  *
+ * If count_suffix == 1, the length of suffix is counted in the max length.
+ *
  * If screen == 1, the cut is based on width of chars displayed.
  *
  * Note: result must be freed after use.
  */
 
 char *
-string_cut (const char *string, int length, int screen, const char *cut_suffix)
+string_cut (const char *string, int length, int count_suffix, int screen,
+            const char *cut_suffix)
 {
     int length_result, length_cut_suffix;
     char *result;
@@ -113,7 +116,7 @@ string_cut (const char *string, int length, int screen, const char *cut_suffix)
     else
         ptr_string = gui_chat_string_add_offset (string, length);
 
-    if (!ptr_string[0])
+    if (!ptr_string || !ptr_string[0])
     {
         /* no cut */
         return strdup (string);
@@ -122,6 +125,24 @@ string_cut (const char *string, int length, int screen, const char *cut_suffix)
     if (cut_suffix && cut_suffix[0])
     {
         length_cut_suffix = strlen (cut_suffix);
+        if (count_suffix)
+        {
+            if (screen)
+                length -= utf8_strlen_screen (cut_suffix);
+            else
+                length -= length_cut_suffix;
+            if (length < 0)
+                return strdup ("");
+            if (screen)
+                ptr_string = gui_chat_string_add_offset_screen (string, length);
+            else
+                ptr_string = gui_chat_string_add_offset (string, length);
+            if (!ptr_string || !ptr_string[0])
+            {
+                /* no cut */
+                return strdup (string);
+            }
+        }
         length_result = (ptr_string - string) + length_cut_suffix + 1;
         result = malloc (length_result);
         if (!result)

src/core/wee-string.h

@@ -36,8 +36,8 @@ struct t_string_dyn
 struct t_hashtable;
 
 extern char *string_strndup (const char *string, int length);
-extern char *string_cut (const char *string, int length, int screen,
-                         const char *cut_suffix);
+extern char *string_cut (const char *string, int length, int count_suffix,
+                         int screen, const char *cut_suffix);
 extern void string_tolower (char *string);
 extern void string_toupper (char *string);
 extern int string_strcasecmp (const char *string1, const char *string2);