histedit: use one editor when multiple folds happen in a row (issue3524) (BC)

This was the first ever feature request for histedit, originally filed
back on April 4, 2009. Finally fixed.

In the future we'll probably want to make it possible for other
preprocessing steps to be added to the list, but for now we're
skipping that because it's unclear what the API should look like
without a proposed consumer.

hgext/histedit.py

@@ -557,8 +557,21 b' class fold(histeditaction):'
                                middlecommits)
 
     def skipprompt(self):
+        """Returns true if the rule should skip the message editor.
+
+        For example, 'fold' wants to show an editor, but 'rollup'
+        doesn't want to.
+        """
         return False
 
+    def mergedescs(self):
+        """Returns true if the rule should merge messages of multiple changes.
+
+        This exists mainly so that 'rollup' rules can be a subclass of
+        'fold'.
+        """
+        return True
+
     def finishfold(self, ui, repo, ctx, oldctx, newnode, internalchanges):
         parent = ctx.parents()[0].node()
         hg.update(repo, parent)
@@ -566,7 +579,7 b' class fold(histeditaction):'
         commitopts = {}
         commitopts['user'] = ctx.user()
         # commit message
-        if self.skipprompt():
+        if not self.mergedescs():
             newmessage = ctx.description()
         else:
             newmessage = '\n***\n'.join(
@@ -601,7 +614,22 b' class fold(histeditaction):'
             replacements.append((ich, (n,)))
         return repo[n], replacements
 
+class _multifold(fold):
+    """fold subclass used for when multiple folds happen in a row
+
+    We only want to fire the editor for the folded message once when
+    (say) four changes are folded down into a single change. This is
+    similar to rollup, but we should preserve both messages so that
+    when the last fold operation runs we can show the user all the
+    commit messages in their editor.
+    """
+    def skipprompt(self):
+        return True
+
 class rollup(fold):
+    def mergedescs(self):
+        return False
+
     def skipprompt(self):
         return True
 
@@ -644,6 +672,7 b" actiontable = {'p': pick,"
                'edit': edit,
                'f': fold,
                'fold': fold,
+               '_multifold': _multifold,
                'r': rollup,
                'roll': rollup,
                'd': drop,
@@ -850,6 +879,14 b' def _histedit(ui, repo, state, *freeargs'
                                         'histedit')
         state.backupfile = backupfile
 
+    # preprocess rules so that we can hide inner folds from the user
+    # and only show one editor
+    rules = state.rules[:]
+    for idx, ((action, ha), (nextact, unused)) in enumerate(
+            zip(rules, rules[1:] + [(None, None)])):
+        if action == 'fold' and nextact == 'fold':
+            state.rules[idx] = '_multifold', ha
+
     while state.rules:
         state.write()
         action, ha = state.rules.pop(0)
@@ -995,7 +1032,7 b' def verifyrules(rules, repo, ctxs):'
             raise util.Abort(_('duplicated command for changeset %s') %
                     ha[:12])
         seen.add(ha)
-        if action not in actiontable:
+        if action not in actiontable or action.startswith('_'):
             raise util.Abort(_('unknown action "%s"') % action)
         parsed.append([action, ha])
     missing = sorted(expected - seen)  # sort to stabilize output

tests/test-histedit-fold.t

@@ -509,4 +509,64 b' into the hook command.'
   $ hg add amended.txt
   $ hg ci -q --config extensions.largefiles= --amend -I amended.txt
 
+Test that folding multiple changes in a row doesn't show multiple
+editors.
+
+  $ echo foo >> foo
+  $ hg add foo
+  $ hg ci -m foo1
+  $ echo foo >> foo
+  $ hg ci -m foo2
+  $ echo foo >> foo
+  $ hg ci -m foo3
+  $ hg logt
+  4:21679ff7675c foo3
+  3:b7389cc4d66e foo2
+  2:0e01aeef5fa8 foo1
+  1:578c7455730c a
+  0:79b99e9c8e49 b
+  $ cat > $TESTTMP/editor.sh <<EOF
+  > echo ran editor >> $TESTTMP/editorlog.txt
+  > cat \$1 >> $TESTTMP/editorlog.txt
+  > echo END >> $TESTTMP/editorlog.txt
+  > echo merged foos > \$1
+  > EOF
+  $ HGEDITOR="sh $TESTTMP/editor.sh" hg histedit 1 --commands - 2>&1 <<EOF | fixbundle
+  > pick 578c7455730c 1 a
+  > pick 0e01aeef5fa8 2 foo1
+  > fold b7389cc4d66e 3 foo2
+  > fold 21679ff7675c 4 foo3
+  > EOF
+  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  reverting foo
+  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
+  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  merging foo
+  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
+  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  $ hg logt
+  2:e8bedbda72c1 merged foos
+  1:578c7455730c a
+  0:79b99e9c8e49 b
+Editor should have run only once
+  $ cat $TESTTMP/editorlog.txt
+  ran editor
+  foo1
+  ***
+  foo2
+  ***
+  foo3
+  
+  
+  
+  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: added foo
+  END
+
   $ cd ..