+ /* Handle list operations */
+
+ case EITEM_FILTER:
+ case EITEM_MAP:
+ case EITEM_REDUCE:
+ {
+ int sep = 0;
+ int save_ptr = ptr;
+ uschar outsep[2] = { '\0', '\0' };
+ uschar *list, *expr, *temp;
+ uschar *save_iterate_item = iterate_item;
+ uschar *save_lookup_value = lookup_value;
+
+ while (isspace(*s)) s++;
+ if (*s++ != '{') goto EXPAND_FAILED_CURLY;
+
+ list = expand_string_internal(s, TRUE, &s, skipping);
+ if (list == NULL) goto EXPAND_FAILED;
+ if (*s++ != '}') goto EXPAND_FAILED_CURLY;
+
+ if (item_type == EITEM_REDUCE)
+ {
+ while (isspace(*s)) s++;
+ if (*s++ != '{') goto EXPAND_FAILED_CURLY;
+ temp = expand_string_internal(s, TRUE, &s, skipping);
+ if (temp == NULL) goto EXPAND_FAILED;
+ lookup_value = temp;
+ if (*s++ != '}') goto EXPAND_FAILED_CURLY;
+ }
+
+ while (isspace(*s)) s++;
+ if (*s++ != '{') goto EXPAND_FAILED_CURLY;
+
+ expr = s;
+
+ /* For EITEM_FILTER, call eval_condition once, with result discarded (as
+ if scanning a "false" part). This allows us to find the end of the
+ condition, because if the list is empty, we won't actually evaluate the
+ condition for real. For EITEM_MAP and EITEM_REDUCE, do the same, using
+ the normal internal expansion function. */
+
+ if (item_type == EITEM_FILTER)
+ {
+ temp = eval_condition(expr, NULL);
+ if (temp != NULL) s = temp;
+ }
+ else
+ {
+ temp = expand_string_internal(s, TRUE, &s, TRUE);
+ }
+
+ if (temp == NULL)
+ {
+ expand_string_message = string_sprintf("%s inside \"%s\" item",
+ expand_string_message, name);
+ goto EXPAND_FAILED;
+ }
+
+ while (isspace(*s)) s++;
+ if (*s++ != '}')
+ {
+ expand_string_message = string_sprintf("missing } at end of condition "
+ "or expression inside \"%s\"", name);
+ goto EXPAND_FAILED;
+ }
+
+ while (isspace(*s)) s++;
+ if (*s++ != '}')
+ {
+ expand_string_message = string_sprintf("missing } at end of \"%s\"",
+ name);
+ goto EXPAND_FAILED;
+ }
+
+ /* If we are skipping, we can now just move on to the next item. When
+ processing for real, we perform the iteration. */
+
+ if (skipping) continue;
+ while ((iterate_item = string_nextinlist(&list, &sep, NULL, 0)) != NULL)
+ {
+ *outsep = (uschar)sep; /* Separator as a string */
+
+ DEBUG(D_expand) debug_printf("%s: $item = \"%s\"\n", name, iterate_item);
+
+ if (item_type == EITEM_FILTER)
+ {
+ BOOL condresult;
+ if (eval_condition(expr, &condresult) == NULL)
+ {
+ iterate_item = save_iterate_item;
+ lookup_value = save_lookup_value;
+ expand_string_message = string_sprintf("%s inside \"%s\" condition",
+ expand_string_message, name);
+ goto EXPAND_FAILED;
+ }
+ DEBUG(D_expand) debug_printf("%s: condition is %s\n", name,
+ condresult? "true":"false");
+ if (condresult)
+ temp = iterate_item; /* TRUE => include this item */
+ else
+ continue; /* FALSE => skip this item */
+ }
+
+ /* EITEM_MAP and EITEM_REDUCE */
+
+ else
+ {
+ temp = expand_string_internal(expr, TRUE, NULL, skipping);
+ if (temp == NULL)
+ {
+ iterate_item = save_iterate_item;
+ expand_string_message = string_sprintf("%s inside \"%s\" item",
+ expand_string_message, name);
+ goto EXPAND_FAILED;
+ }
+ if (item_type == EITEM_REDUCE)
+ {
+ lookup_value = temp; /* Update the value of $value */
+ continue; /* and continue the iteration */
+ }
+ }
+
+ /* We reach here for FILTER if the condition is true, always for MAP,
+ and never for REDUCE. The value in "temp" is to be added to the output
+ list that is being created, ensuring that any occurrences of the
+ separator character are doubled. Unless we are dealing with the first
+ item of the output list, add in a space if the new item begins with the
+ separator character, or is an empty string. */
+
+ if (ptr != save_ptr && (temp[0] == *outsep || temp[0] == 0))
+ yield = string_cat(yield, &size, &ptr, US" ", 1);
+
+ /* Add the string in "temp" to the output list that we are building,
+ This is done in chunks by searching for the separator character. */
+
+ for (;;)
+ {
+ size_t seglen = Ustrcspn(temp, outsep);
+ yield = string_cat(yield, &size, &ptr, temp, seglen + 1);
+
+ /* If we got to the end of the string we output one character
+ too many; backup and end the loop. Otherwise arrange to double the
+ separator. */
+
+ if (temp[seglen] == '\0') { ptr--; break; }
+ yield = string_cat(yield, &size, &ptr, outsep, 1);
+ temp += seglen + 1;
+ }
+
+ /* Output a separator after the string: we will remove the redundant
+ final one at the end. */
+
+ yield = string_cat(yield, &size, &ptr, outsep, 1);
+ } /* End of iteration over the list loop */
+
+ /* REDUCE has generated no output above: output the final value of
+ $value. */
+
+ if (item_type == EITEM_REDUCE)
+ {
+ yield = string_cat(yield, &size, &ptr, lookup_value,
+ Ustrlen(lookup_value));
+ lookup_value = save_lookup_value; /* Restore $value */
+ }
+
+ /* FILTER and MAP generate lists: if they have generated anything, remove
+ the redundant final separator. Even though an empty item at the end of a
+ list does not count, this is tidier. */
+
+ else if (ptr != save_ptr) ptr--;
+
+ /* Restore preserved $item */
+
+ iterate_item = save_iterate_item;
+ continue;
+ }
+
+