plugin/file: Rename do to walk and cleanup and document (#2987)

* plugin/file: Rename do to walk, cleanup and document

* This renames Do to Walk to be more inline with Go standards. Also make
  it return an error instead of a bool.
  Also give give walk access to rrs. Alternatively e.m could be
  exported, but just access the map of rrs should work as well. Another
  alternative would be adding a whole bunch of helper functions, but
  those need grab and return the data. Just having access to the rrs
  should be easiest for most Walks.
* It adds Type and TypeForWildcard to show the different functions
* *Removes* the identical RR check when inserting; this was only done
  for A, AAAA and MX and not finished; removed under the mantra garbage
  in garbage out.
* Reuses Types to return all the types in an *tree.Elem

Signed-off-by: Miek Gieben <miek@miek.nl>

* better comments

Signed-off-by: Miek Gieben <miek@miek.nl>

1 files changed, 30 insertions, 0 deletions

diff --git a/plugin/file/tree/walk.go b/plugin/file/tree/walk.go
new file mode 100644
index 000000000..00accbafa
--- /dev/null
+++ b/plugin/file/tree/walk.go
@@ -0,0 +1,30 @@
+package tree
+
+import "github.com/miekg/dns"
+
+// Walk performs fn on all values stored in the tree. If a non-nil error is returned the
+// Walk was interrupted by an fn returning that error. If fn alters stored values' sort
+// relationships, future tree operation behaviors are undefined.
+func (t *Tree) Walk(fn func(e *Elem, rrs map[uint16][]dns.RR) error) error {
+	if t.Root == nil {
+		return nil
+	}
+	return t.Root.walk(fn)
+}
+
+func (n *Node) walk(fn func(e *Elem, rrs map[uint16][]dns.RR) error) error {
+	if n.Left != nil {
+		if err := n.Left.walk(fn); err != nil {
+			return err
+		}
+	}
+	if err := fn(n.Elem, n.Elem.m); err != nil {
+		return err
+	}
+	if n.Right != nil {
+		if err := n.Right.walk(fn); err != nil {
+			return err
+		}
+	}
+	return nil
+}