This 'tree-read-api' branch is a feature branch to develop a new API.
As a 'feature' branch, it is maintained by periodic 'catch-up' (aka
'sync') merges from trunk, and may one day be reintegrated to trunk.

The new API is an abstraction of a generic tree of (probably) versioned
nodes -- files, directories and symbolic links, each node optionally
having a set of versioned properties.  The idea is that client code that
reads from a tree can use the same interface to read the WC base as it
uses to read revision X in a repository.  Some examples of such client
functionality are 'list', 'proplist', 'propget' and 'export'.

If this works out and can be made efficient, it should enable existing
libsvn_client code to be simplified and new client code to be written
more easily.

Then a more interesting stage: we should be able to write e.g. a 'diff'
routine that compares two arbitrary trees, such as r100 in repo A against
r100 in repo B, or the unversioned tree '/tmp/saved-tests' against the WC tree
'wc/subversion/tests'.  Diffing large unrelated trees byte-by-byte is
inherently expensive compared with Subversion's present diff methods, and we
might want to consider ways to shortcut the full comparison such as by
comparing checksums, but even without optimization, at least such diffs
become possible and can be much faster than a manual process.

At the time of this writing, the API is in subversion/libsvn_client/tree.h,
but I expect to move it.

- Julian Foad, October 2011