Re: Shelving v3 started

> > (2) Better capture of base state.

[Summarizing from IRC.]

Today I'm trying to figure out how to get Shelving v3 from last week's initial demo state (email "Shelving v3 started", branch "shelving-v3") to something that could be considered experimentally usable in a v1.12 release. My overall approach is to aim for high level APIs to do the required functional blocks; I'm not going to hack the wc-db.

The current state is to make a shelf we:
  - copy the whole (user's) WC to somewhere else where it will become the shelf storage for this shelf-version;
  - revert all the modifications in that copy so it is now a copy of the base state of the user's WC;
  - to shelve the *requested* changes we use the new high-level wc-copy-mods API to copy the requested local modifications from the user's WC to this shelf storage WC;
  - Finally, if requested ("shelve" versus "shelf-save"), we revert the requested mods from the user's WC.

The bit that needs work next is making a copy of the base state of the user's WC.

Here's the plan for that bit:

(1) Create the WC base checkout by using existing "checkout" code, initially driven from the repository, using URLs and revnums read from the user's WC (as in "svn info --x-viewspec").
(1a) For the whole WC; (1b) trimmed down to a given path specification.

(2) Create the WC base reading API (limited to a given path-spec) and think of a way to test/exercise it in isolation.

(3) Wire up (1) and (2) together.

For (1): The existing high level API to create a WC with a given base state (and no local modifications) is the client side of "checkout". Of course we only need to copy the base of locally modified nodes in the requested portions of the user's WC, not the whole WC. So we need an API that creates (a bit like checkout) a new WC that includes just those paths. I wonder if we could do that by using the "checkout" client-side machinery, unmodified, to create the WC, being driven from a "pretend Repository Access API" driver that feeds "real" data for the given paths and sets all other paths to depth-exclude.

For (2) the base-reading API: The existing high level API to read the base state of a WC is ... seems to be missing. "export" is but a small subset of it, lacking properties and repository URLs and revisions metadata. I can investigate starting from existing "diff -r0:BASE" code and see if that's useful. However, it writes directly to the diff-tree-processor API and I'm not sure if that's convertible to editor API.

Moving the shelf-storage-WCs location back inside .svn/experimental/... will be trivial after step (1a).

-- 
- Julian