list, string: support any number of +/-n for index

It is especially convenient to add -1 for something like:

  lindex $list end-$BACK-1

or:

  string range $str $p $p+$len-1

Signed-off-by: Steve Bennett <steveb@workware.net.au>

1 files changed, 4 insertions, 3 deletions

diff --git a/jim.c b/jim.c
index 684905f..2ccd769 100644
--- a/jim.c
+++ b/jim.c
@@ -7815,16 +7815,17 @@ static int SetIndexFromAny(Jim_Interp *interp, Jim_Obj *objPtr)
         str = endptr;
     }
 
-    /* Now str may include or +<num> or -<num> */
-    if (*str == '+' || *str == '-') {
+    /* Now str may include any number of +<num> or -<num> */
+    while (*str == '+' || *str == '-') {
         int sign = (*str == '+' ? 1 : -1);
 
         idx += sign * jim_strtol(++str, &endptr);
-        if (str == endptr || *endptr) {
+        if (endptr == str) {
             goto badindex;
         }
         str = endptr;
     }
+
     /* The only thing left should be spaces */
     while (isspace(UCHAR(*str))) {
         str++;