Filter: Implement for loops

For loops allow to iterate over elements in compound data like BGP paths
or community lists. The syntax is:

  for [ <type> ] <variable> in <expr> do <command-body>

3 files changed, 81 insertions, 0 deletions

diff --git a/nest/a-path.c b/nest/a-path.c
index d5b01635..6bb18285 100644
--- a/nest/a-path.c
+++ b/nest/a-path.c
@@ -669,6 +669,35 @@ as_path_filter(struct linpool *pool, const struct adata *path, const struct f_va
   return res;
 }
 
+int
+as_path_walk(const struct adata *path, uint *pos, uint *val)
+{
+  if (!path)
+    return 0;
+
+  const u8 *p = path->data;
+  const u8 *q = p + path->length;
+  uint n, x = *pos;
+
+  while (p < q)
+  {
+    n = p[1];
+    p += 2;
+
+    if (x < n)
+    {
+      *val = get_as(p + x * BS);
+      *pos += 1;
+      return 1;
+    }
+
+    p += n * BS;
+    x -= n;
+  }
+
+  return 0;
+}
+
 
 struct pm_pos
 {
diff --git a/nest/a-set.c b/nest/a-set.c
index 71fbac94..40ed573c 100644
--- a/nest/a-set.c
+++ b/nest/a-set.c
@@ -693,3 +693,51 @@ lc_set_max(const struct adata *list, lcomm *val)
   *val = (lcomm) { res[0], res[1], res[2] };
   return 1;
 }
+
+int
+int_set_walk(const struct adata *list, uint *pos, uint *val)
+{
+  if (!list)
+    return 0;
+
+  if (*pos >= (uint) int_set_get_size(list))
+    return 0;
+
+  u32 *res = int_set_get_data(list) + *pos;
+  *val = *res;
+  *pos += 1;
+
+  return 1;
+}
+
+int
+ec_set_walk(const struct adata *list, uint *pos, u64 *val)
+{
+  if (!list)
+    return 0;
+
+  if (*pos >= (uint) int_set_get_size(list))
+    return 0;
+
+  u32 *res = int_set_get_data(list) + *pos;
+  *val = ec_generic(res[0], res[1]);
+  *pos += 2;
+
+  return 1;
+}
+
+int
+lc_set_walk(const struct adata *list, uint *pos, lcomm *val)
+{
+  if (!list)
+    return 0;
+
+  if (*pos >= (uint) int_set_get_size(list))
+    return 0;
+
+  u32 *res = int_set_get_data(list) + *pos;
+  *val = (lcomm) { res[0], res[1], res[2] };
+  *pos += 3;
+
+  return 1;
+}
diff --git a/nest/attrs.h b/nest/attrs.h
index 22e2ff4a..9412439b 100644
--- a/nest/attrs.h
+++ b/nest/attrs.h
@@ -51,6 +51,7 @@ u32 as_path_get_last_nonaggregated(const struct adata *path);
 int as_path_contains(const struct adata *path, u32 as, int min);
 int as_path_match_set(const struct adata *path, const struct f_tree *set);
 const struct adata *as_path_filter(struct linpool *pool, const struct adata *path, const struct f_val *set, int pos);
+int as_path_walk(const struct adata *path, uint *pos, uint *val);
 
 static inline struct adata *as_path_prepend(struct linpool *pool, const struct adata *path, u32 as)
 { return as_path_prepend2(pool, path, AS_PATH_SEQUENCE, as); }
@@ -225,6 +226,9 @@ int lc_set_min(const struct adata *list, lcomm *val);
 int int_set_max(const struct adata *list, u32 *val);
 int ec_set_max(const struct adata *list, u64 *val);
 int lc_set_max(const struct adata *list, lcomm *val);
+int int_set_walk(const struct adata *list, uint *pos, u32 *val);
+int ec_set_walk(const struct adata *list, uint *pos, u64 *val);
+int lc_set_walk(const struct adata *list, uint *pos, lcomm *val);
 
 void ec_set_sort_x(struct adata *set); /* Sort in place */