[StGit PATCH 11/14] New command: stg undo

["Karl Hasselström" <kha@treskal.com>]

Basically, this is just a user-friendly way to access a subset of the
functionality of "stg reset".

Signed-off-by: Karl Hasselström <kha@treskal.com>

---

 stgit/commands/undo.py  |   40 +++++++---------------
 stgit/lib/log.py        |   38 +++++++++++++++++++++
 stgit/main.py           |    2 +
 t/t3102-undo.sh         |   86 +++++++++++++++++++++++++++++++++++++++++++++++
 t/t3103-undo-hard.sh    |   10 +++--
 5 files changed, 144 insertions(+), 32 deletions(-)
 copy stgit/commands/{reset.py => undo.py} (56%)
 create mode 100755 t/t3102-undo.sh
 copy t/{t3101-reset-hard.sh => t3103-undo-hard.sh} (82%)


diff --git a/stgit/commands/reset.py b/stgit/commands/undo.py
similarity index 56%
copy from stgit/commands/reset.py
copy to stgit/commands/undo.py
index 5ad9914..b1d7de9 100644
--- a/stgit/commands/reset.py
+++ b/stgit/commands/undo.py
@@ -22,42 +22,28 @@ from stgit.commands import common
 from stgit.lib import git, log, transaction
 from stgit.out import out
 
-help = 'reset the patch stack to an earlier state'
-usage = """%prog [options] <state> [<patchnames>]
+help = 'undo the last operation'
+usage = """%prog [options]
 
-Reset the patch stack to an earlier state. The state is specified with
-a commit from a stack log; for a branch foo, StGit stores the stack
-log in foo.stgit^. So to undo the last N StGit commands (or rather,
-the last N log entries; there is not an exact one-to-one
-relationship), you would say
-
-  stg reset foo.stgit^~N
-
-or, if you are not sure how many steps to undo, you can view the log
-with "git log" or gitk
-
-  gitk foo.stgit^
-
-and then reset to any sha1 you see in the log.
-
-If one or more patch names are given, reset only those patches, and
-leave the rest alone."""
+Reset the patch stack to the previous state. Consecutive invocations
+of "stg undo" will take you ever further into the past."""
 
 directory = common.DirectoryHasRepositoryLib()
-options = [make_option('--hard', action = 'store_true',
+options = [make_option('-n', '--number', type = 'int', metavar = 'N',
+                       default = 1,
+                       help = 'undo the last N commands'),
+           make_option('--hard', action = 'store_true',
                        help = 'discard changes in your index/worktree')]
 
 def func(parser, options, args):
     stack = directory.repository.current_stack
-    if len(args) >= 1:
-        ref, patches = args[0], args[1:]
-        state = log.Log(stack.repository, ref, stack.repository.rev_parse(ref))
-    else:
-        raise common.CmdException('Wrong number of arguments')
-    trans = transaction.StackTransaction(stack, 'reset',
+    if options.number < 1:
+        raise common.CmdException('Bad number of commands to undo')
+    state = log.undo_state(stack, options.number)
+    trans = transaction.StackTransaction(stack, 'undo %d' % options.number,
                                          discard_changes = options.hard)
     try:
-        log.reset_stack(trans, stack.repository.default_iw, state, patches)
+        log.reset_stack(trans, stack.repository.default_iw, state, [])
     except transaction.TransactionHalted:
         pass
     return trans.run(stack.repository.default_iw)
diff --git a/stgit/lib/log.py b/stgit/lib/log.py
index 2449913..3b242cd 100644
--- a/stgit/lib/log.py
+++ b/stgit/lib/log.py
@@ -95,6 +95,7 @@ except for the following:
 The simplified log contains no information not in the full log; its
 purpose is ease of visualization."""
 
+import re
 from stgit.lib import git, stack
 from stgit import exception
 from stgit.out import out
@@ -258,6 +259,16 @@ class Log(object):
             self.base = self.patches[self.applied[0]].data.parent
         else:
             self.base = self.head
+    @property
+    def top(self):
+        if self.applied:
+            return self.patches[self.applied[-1]]
+        else:
+            return self.head
+    @property
+    def parents(self):
+        num_refs = len(set([self.top, self.head]))
+        return self.commit.data.parents[(1 + num_refs):]
 
 class FullLog(Log):
     full_log = property(lambda self: self.commit)
@@ -347,3 +358,30 @@ def reset_stack(trans, iw, state, only_patches):
     else:
         # Recreate the exact order specified by the goal state.
         trans.reorder_patches(state.applied, state.unapplied, iw)
+
+def undo_state(stack, undo_steps):
+    """Find the log entry C{undo_steps} steps in the past. (Successive
+    undo operations are supposed to "add up", so if we find other undo
+    operations along the way we have to add those undo steps to
+    C{undo_steps}.)
+
+    @return: The log entry that is the destination of the undo
+             operation
+    @rtype: L{Log}"""
+    ref = log_ref(stack.name)
+    try:
+        commit = stack.repository.refs.get(ref)
+    except KeyError:
+        raise LogException('Log is empty')
+    log = Log(stack.repository, ref, commit)
+    while undo_steps > 0:
+        msg = log.commit.data.message.strip()
+        m = re.match(r'^undo\s+(\d+)$', msg)
+        if m:
+            undo_steps += int(m.group(1))
+        else:
+            undo_steps -= 1
+        if not log.parents:
+            raise LogException('Not enough undo information available')
+        log = Log(stack.repository, log.parents[0].sha1, log.parents[0])
+    return log
diff --git a/stgit/main.py b/stgit/main.py
index 83e6b08..cf7b404 100644
--- a/stgit/main.py
+++ b/stgit/main.py
@@ -99,6 +99,7 @@ commands = Commands({
     'top':              'top',
     'unapplied':        'unapplied',
     'uncommit':         'uncommit',
+    'undo':             'undo',
     'unhide':           'unhide'
     })
 
@@ -129,6 +130,7 @@ stackcommands = (
     'top',
     'unapplied',
     'uncommit',
+    'undo',
     'unhide',
     )
 patchcommands = (
diff --git a/t/t3102-undo.sh b/t/t3102-undo.sh
new file mode 100755
index 0000000..1093f70
--- /dev/null
+++ b/t/t3102-undo.sh
@@ -0,0 +1,86 @@
+#!/bin/sh
+
+test_description='Simple test cases for "stg undo"'
+
+. ./test-lib.sh
+
+# Ignore our own output files.
+cat > .git/info/exclude <<EOF
+/expected.txt
+EOF
+
+test_expect_success 'Initialize StGit stack with three patches' '
+    stg init &&
+    echo 000 >> a &&
+    git add a &&
+    git commit -m a &&
+    echo 111 >> a &&
+    git commit -a -m p1 &&
+    echo 222 >> a &&
+    git commit -a -m p2 &&
+    echo 333 >> a &&
+    git commit -a -m p3 &&
+    stg uncommit -n 3 &&
+    stg pop
+'
+
+cat > expected.txt <<EOF
+000
+111
+EOF
+test_expect_success 'Pop one patch ...' '
+    stg pop &&
+    test "$(echo $(stg applied))" = "p1" &&
+    test "$(echo $(stg unapplied))" = "p2 p3" &&
+    test_cmp expected.txt a
+'
+
+cat > expected.txt <<EOF
+000
+111
+222
+EOF
+test_expect_success '... and undo it' '
+    stg undo &&
+    test "$(echo $(stg applied))" = "p1 p2" &&
+    test "$(echo $(stg unapplied))" = "p3" &&
+    test_cmp expected.txt a
+'
+
+cat > expected.txt <<EOF
+000
+EOF
+test_expect_success 'Pop two patches ...' '
+    stg pop &&
+    stg pop &&
+    test "$(echo $(stg applied))" = "" &&
+    test "$(echo $(stg unapplied))" = "p1 p2 p3" &&
+    test_cmp expected.txt a
+'
+
+cat > expected.txt <<EOF
+000
+111
+222
+EOF
+test_expect_success '... and undo it' '
+    stg undo &&
+    stg undo &&
+    test "$(echo $(stg applied))" = "p1 p2" &&
+    test "$(echo $(stg unapplied))" = "p3" &&
+    test_cmp expected.txt a
+'
+
+cat > expected.txt <<EOF
+000
+111
+222
+EOF
+test_expect_success 'Undo past end of history' '
+    ! stg undo -n 100 &&
+    test "$(echo $(stg applied))" = "p1 p2" &&
+    test "$(echo $(stg unapplied))" = "p3" &&
+    test_cmp expected.txt a
+'
+
+test_done
diff --git a/t/t3101-reset-hard.sh b/t/t3103-undo-hard.sh
similarity index 82%
copy from t/t3101-reset-hard.sh
copy to t/t3103-undo-hard.sh
index 1e02805..21412f7 100755
--- a/t/t3101-reset-hard.sh
+++ b/t/t3103-undo-hard.sh
@@ -1,6 +1,6 @@
 #!/bin/sh
 
-test_description='Simple test cases for "stg reset"'
+test_description='Simple test cases for "stg undo"'
 
 . ./test-lib.sh
 
@@ -35,8 +35,8 @@ test_expect_success 'Pop middle patch, creating a conflict' '
     test "$(echo $(stg unapplied))" = "p2"
 '
 
-test_expect_success 'Try to reset without --hard' '
-    ! stg reset master.stgit^~1 &&
+test_expect_success 'Try to undo without --hard' '
+    ! stg undo &&
     stg status a > actual.txt &&
     test_cmp expected.txt actual.txt &&
     test "$(echo $(stg applied))" = "p1 p3" &&
@@ -45,8 +45,8 @@ test_expect_success 'Try to reset without --hard' '
 
 cat > expected.txt <<EOF
 EOF
-test_expect_success 'Try to reset with --hard' '
-    stg reset --hard master.stgit^~1 &&
+test_expect_success 'Try to undo with --hard' '
+    stg undo --hard &&
     stg status a > actual.txt &&
     test_cmp expected.txt actual.txt &&
     test "$(echo $(stg applied))" = "p1" &&