+/* Returns true if a variable named NAME may be inserted in DICT;
+ that is, if there is not already a variable with that name in
+ DICT and if NAME is not a reserved word. (The caller's checks
+ have already verified that NAME is otherwise acceptable as a
+ variable name.) */
+static bool
+var_name_is_insertable (const struct dictionary *dict, const char *name)
+{
+ return (dict_lookup_var (dict, name) == NULL
+ && lex_id_to_token (ss_cstr (name)) == T_ID);
+}
+
+static bool
+make_hinted_name (const struct dictionary *dict, const char *hint,
+ char name[VAR_NAME_LEN + 1])
+{
+ bool dropped = false;
+ char *cp;
+
+ for (cp = name; *hint && cp < name + VAR_NAME_LEN; hint++)
+ {
+ if (cp == name
+ ? lex_is_id1 (*hint) && *hint != '$'
+ : lex_is_idn (*hint))
+ {
+ if (dropped)
+ {
+ *cp++ = '_';
+ dropped = false;
+ }
+ if (cp < name + VAR_NAME_LEN)
+ *cp++ = *hint;
+ }
+ else if (cp > name)
+ dropped = true;
+ }
+ *cp = '\0';
+
+ if (name[0] != '\0')
+ {
+ size_t len = strlen (name);
+ unsigned long int i;
+
+ if (var_name_is_insertable (dict, name))
+ return true;
+
+ for (i = 0; i < ULONG_MAX; i++)
+ {
+ char suffix[INT_BUFSIZE_BOUND (i) + 1];
+ int ofs;
+
+ suffix[0] = '_';
+ if (!str_format_26adic (i + 1, &suffix[1], sizeof suffix - 1))
+ NOT_REACHED ();
+
+ ofs = MIN (VAR_NAME_LEN - strlen (suffix), len);
+ strcpy (&name[ofs], suffix);
+
+ if (var_name_is_insertable (dict, name))
+ return true;
+ }
+ }
+
+ return false;
+}
+
+static bool
+make_numeric_name (const struct dictionary *dict, unsigned long int *num_start,
+ char name[VAR_NAME_LEN + 1])
+{
+ unsigned long int number;
+
+ for (number = num_start != NULL ? MAX (*num_start, 1) : 1;
+ number < ULONG_MAX;
+ number++)
+ {
+ sprintf (name, "VAR%03lu", number);
+ if (dict_lookup_var (dict, name) == NULL)
+ {
+ if (num_start != NULL)
+ *num_start = number + 1;
+ return true;
+ }
+ }
+
+ if (num_start != NULL)
+ *num_start = ULONG_MAX;
+ return false;
+}
+
+
+/* Attempts to devise a variable name unique within DICT.
+ Returns true if successful, in which case the new variable
+ name is stored into NAME. Returns false if all names that can
+ be generated have already been taken. (Returning false is
+ quite unlikely: at least ULONG_MAX unique names can be
+ generated.)
+
+ HINT, if it is non-null, is used as a suggestion that will be
+ modified for suitability as a variable name and for
+ uniqueness.
+
+ If HINT is null or entirely unsuitable, a name in the form
+ "VAR%03d" will be generated, where the smallest unused integer
+ value is used. If NUM_START is non-null, then its value is
+ used as the minimum numeric value to check, and it is updated
+ to the next value to be checked.
+ */
+bool
+dict_make_unique_var_name (const struct dictionary *dict, const char *hint,
+ unsigned long int *num_start,
+ char name[VAR_NAME_LEN + 1])
+{
+ return ((hint != NULL && make_hinted_name (dict, hint, name))
+ || make_numeric_name (dict, num_start, name));
+}
+