initial implementation of a CSS selector matching optimization

The idea is to avoid repeated checks of CssSimpleSelector against the
same part of the doctree.
E.g

.navigation * { background-color:green }

Would result in checking for class="navigation" all the way down to the
document root for all elements.
The optimization shortcuts this, for parts of the doctree that have been
checked before.

1 files changed, 1 insertions, 0 deletions

diff --git a/src/doctree.hh b/src/doctree.hh
index 97686e40..f74350b0 100644
--- a/src/doctree.hh
+++ b/src/doctree.hh
@@ -3,6 +3,7 @@
 
 class DoctreeNode {
    public:
+      int num; // unique ascending id
       int depth;
       int element;
       const char *klass;