histedit: fold in memory

Update the folding code to works in memory instead of applying patches on the
working directory. This is cleaner, faster and prepare the removal of the whole
patching logic.

This new collapse function will probably move into core sooner or later. A lot
of other rewriting operation may benefit from it.

hgext/histedit.py

@@ -149,6 +149,8 b' from mercurial import bookmarks'
 from mercurial import cmdutil
 from mercurial import discovery
 from mercurial import error
+from mercurial import copies
+from mercurial import context
 from mercurial import hg
 from mercurial import lock as lockmod
 from mercurial import node
@@ -195,6 +197,76 b' def foldchanges(ui, repo, node1, node2, '
         os.unlink(patchfile)
     return files
 
+def collapse(repo, first, last, commitopts):
+    """collapse the set of revisions from first to last as new one.
+
+    Expected commit options are:
+        - message
+        - date
+        - username
+    Edition of commit message is trigered in all case.
+
+    This function works in memory."""
+    ctxs = list(repo.set('%d::%d', first, last))
+    if not ctxs:
+        return None
+    base = first.parents()[0]
+
+    # commit a new version of the old changeset, including the update
+    # collect all files which might be affected
+    files = set()
+    for ctx in ctxs:
+        files.update(ctx.files())
+
+    # Recompute copies (avoid recording a -> b -> a)
+    copied = copies.pathcopies(first, last)
+
+    # prune files which were reverted by the updates
+    def samefile(f):
+        if f in last.manifest():
+            a = last.filectx(f)
+            if f in base.manifest():
+                b = base.filectx(f)
+                return (a.data() == b.data()
+                        and a.flags() == b.flags())
+            else:
+                return False
+        else:
+            return f not in base.manifest()
+    files = [f for f in files if not samefile(f)]
+    # commit version of these files as defined by head
+    headmf = last.manifest()
+    def filectxfn(repo, ctx, path):
+        if path in headmf:
+            fctx = last[path]
+            flags = fctx.flags()
+            mctx = context.memfilectx(fctx.path(), fctx.data(),
+                                      islink='l' in flags,
+                                      isexec='x' in flags,
+                                      copied=copied.get(path))
+            return mctx
+        raise IOError()
+
+    if commitopts.get('message'):
+        message = commitopts['message']
+    else:
+        message = first.description()
+    user = commitopts.get('user')
+    date = commitopts.get('date')
+    extra = first.extra()
+
+    parents = (first.p1().node(), first.p2().node())
+    new = context.memctx(repo,
+                         parents=parents,
+                         text=message,
+                         files=files,
+                         filectxfn=filectxfn,
+                         user=user,
+                         date=date,
+                         extra=extra)
+    new._text = cmdutil.commitforceeditor(repo, new, [])
+    return repo.commitctx(new)
+
 def pick(ui, repo, ctx, ha, opts):
     oldctx = repo[ha]
     if oldctx.parents()[0] == ctx:
@@ -245,19 +317,26 b' def fold(ui, repo, ctx, ha, opts):'
 def finishfold(ui, repo, ctx, oldctx, newnode, opts, internalchanges):
     parent = ctx.parents()[0].node()
     hg.update(repo, parent)
-    foldchanges(ui, repo, parent, newnode, opts)
+    ### prepare new commit data
+    commitopts = opts.copy()
+    # username
+    if ctx.user() == oldctx.user():
+        username = ctx.user()
+    else:
+        username = ui.username()
+    commitopts['user'] = username
+    # commit message
     newmessage = '\n***\n'.join(
         [ctx.description()] +
         [repo[r].description() for r in internalchanges] +
         [oldctx.description()]) + '\n'
-    # If the changesets are from the same author, keep it.
-    if ctx.user() == oldctx.user():
-        username = ctx.user()
-    else:
-        username = ui.username()
-    newmessage = ui.edit(newmessage, username)
-    n = repo.commit(text=newmessage, user=username,
-                    date=max(ctx.date(), oldctx.date()), extra=oldctx.extra())
+    commitopts['message'] = newmessage
+    # date
+    commitopts['date'] = max(ctx.date(), oldctx.date())
+    n = collapse(repo, ctx, repo[newnode], commitopts)
+    if n is None:
+        return ctx, [], [], []
+    hg.update(repo, n)
     return repo[n], [n], [oldctx.node(), ctx.node()], [newnode]
 
 def drop(ui, repo, ctx, ha, opts):

tests/test-histedit-fold-non-commute.t

@@ -92,6 +92,17 b' fix up'
   
   
   
+  HG: Enter commit message.  Lines beginning with 'HG:' are removed.
+  HG: Leave message empty to abort commit.
+  HG: --
+  HG: user: test
+  HG: branch 'default'
+  HG: changed d
+  HG: changed e
+  
+  
+  
+  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
   0 files updated, 0 files merged, 0 files removed, 0 files unresolved
   file e already exists
   1 out of 1 hunks FAILED -- saving rejects to file e.rej

tests/test-histedit-fold.t

@@ -66,6 +66,7 b' edit the history'
   0 files updated, 0 files merged, 0 files removed, 0 files unresolved
   0 files updated, 0 files merged, 0 files removed, 0 files unresolved
   0 files updated, 0 files merged, 2 files removed, 0 files unresolved
+  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
   0 files updated, 0 files merged, 0 files removed, 0 files unresolved
   0 files updated, 0 files merged, 0 files removed, 0 files unresolved
 
@@ -232,6 +233,16 b' dropped revision.'
   +5.2
   ***
   +6
+  
+  
+  
+  HG: Enter commit message.  Lines beginning with 'HG:' are removed.
+  HG: Leave message empty to abort commit.
+  HG: --
+  HG: user: test
+  HG: branch 'default'
+  HG: changed file
+  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
   0 files updated, 0 files merged, 0 files removed, 0 files unresolved
   saved backup bundle to $TESTTMP/fold-with-dropped/.hg/strip-backup/617f94f13c0f-backup.hg (glob)
   $ cd ..