* sexp.h (struct sexp_iterator): New field start.

* sexp.c (sexp_iterator_subexpr): New function.
(sexp_iterator_parse): Initialize ITERATOR->start.

Rev: src/nettle/sexp.c:1.11
Rev: src/nettle/sexp.h:1.8

sexp.c

@@ -99,6 +99,8 @@ sexp_iterator_simple(struct sexp_iterator *iterator,
 static int
 sexp_iterator_parse(struct sexp_iterator *iterator)
 {
+  iterator->start = iterator->pos;
+  
   if (EMPTY(iterator))
     {
       if (iterator->level)
@@ -208,6 +210,19 @@ sexp_iterator_exit_list(struct sexp_iterator *iterator)
   return sexp_iterator_parse(iterator);
 }
 
+const uint8_t *
+sexp_iterator_subexpr(struct sexp_iterator *iterator,
+		      unsigned *length)
+{
+  unsigned start = iterator->start;
+  if (!sexp_iterator_next(iterator))
+    return 0;
+
+  *length = iterator->start - start;
+  return iterator->buffer + start;
+}
+
+
 int
 sexp_iterator_check_type(struct sexp_iterator *iterator,
 			 const uint8_t *type)

sexp.h

@@ -37,6 +37,8 @@ struct sexp_iterator
   unsigned length;
   const uint8_t *buffer;
 
+  /* Points at the start of the current sub expression. */
+  unsigned start;
   /* If type is SEXP_LIST, pos points at the start of the current
    * element. Otherwise, it points at the end. */
   unsigned pos;
@@ -75,6 +77,12 @@ sexp_iterator_enter_list(struct sexp_iterator *iterator);
 int
 sexp_iterator_exit_list(struct sexp_iterator *iterator);
 
+/* Gets start and length of the current subexpression. Implies
+ * sexp_iterator_next. */
+const uint8_t *
+sexp_iterator_subexpr(struct sexp_iterator *iterator,
+		      unsigned *length);
+
 
 /* Checks the type of the current expression, which should be a list
  *