record: refactor record into generic record driver

rationale
---------

I'd like to make MQ version of record -- qrecord.

>From the first glance it seemed to be easy -- the task in essence would be to
change call to cmdutil.commit() to something like mq.qrefresh().

As it turned out queue.refresh() and cmdutil.commit() have different semantics
-- cmdutil.commit() first scans for changes and then delegate the actual commit
to lowlevel func. On the other hand queue.refresh() do it all in once, and I am
a bit scary to change it.

Maybe the right way would be to first refactor queue.refresh() to use
cmdutil.commit() machinery, and then trivially adjust record, but I feel I'm
not competent for the task right now.

Instead, I propose we refactor record to be some sort of high-level driver, or
like a high-level decorator one can say, which will first interactively filter
changes, and then delegate commit job to high-level commiter, e.g. 'commit' or
'qrefresh'


So, this patch does just that -- refactor record to be generic driver, and
update 'hg record' code to use the driver.

'hg qrecord' will follow.

hgext/record.py

@@ -1,450 +1,485 b''
 # record.py
 #
 # Copyright 2007 Bryan O'Sullivan <[e-mail]>
 #
 # This software may be used and distributed according to the terms of
 # the GNU General Public License, incorporated herein by reference.
 
 '''interactive change selection during commit'''
 
 from mercurial.i18n import _
 from mercurial import cmdutil, commands, cmdutil, hg, mdiff, patch, revlog
 from mercurial import util
 import copy, cStringIO, errno, operator, os, re, shutil, tempfile
 
 lines_re = re.compile(r'@@ -(\d+),(\d+) \+(\d+),(\d+) @@\s*(.*)')
 
 def scanpatch(fp):
     """like patch.iterhunks, but yield different events
 
     - ('file',    [header_lines + fromfile + tofile])
     - ('context', [context_lines])
     - ('hunk',    [hunk_lines])
     - ('range',   (-start,len, +start,len, diffp))
     """
     lr = patch.linereader(fp)
 
     def scanwhile(first, p):
         """scan lr while predicate holds"""
         lines = [first]
         while True:
             line = lr.readline()
             if not line:
                 break
             if p(line):
                 lines.append(line)
             else:
                 lr.push(line)
                 break
         return lines
 
     while True:
         line = lr.readline()
         if not line:
             break
         if line.startswith('diff --git a/'):
             def notheader(line):
                 s = line.split(None, 1)
                 return not s or s[0] not in ('---', 'diff')
             header = scanwhile(line, notheader)
             fromfile = lr.readline()
             if fromfile.startswith('---'):
                 tofile = lr.readline()
                 header += [fromfile, tofile]
             else:
                 lr.push(fromfile)
             yield 'file', header
         elif line[0] == ' ':
             yield 'context', scanwhile(line, lambda l: l[0] in ' \\')
         elif line[0] in '-+':
             yield 'hunk', scanwhile(line, lambda l: l[0] in '-+\\')
         else:
             m = lines_re.match(line)
             if m:
                 yield 'range', m.groups()
             else:
                 raise patch.PatchError('unknown patch content: %r' % line)
 
 class header(object):
     """patch header
     
     XXX shoudn't we move this to mercurial/patch.py ? 
     """
     diff_re = re.compile('diff --git a/(.*) b/(.*)$')
     allhunks_re = re.compile('(?:index|new file|deleted file) ')
     pretty_re = re.compile('(?:new file|deleted file) ')
     special_re = re.compile('(?:index|new|deleted|copy|rename) ')
 
     def __init__(self, header):
         self.header = header
         self.hunks = []
 
     def binary(self):
         for h in self.header:
             if h.startswith('index '):
                 return True
 
     def pretty(self, fp):
         for h in self.header:
             if h.startswith('index '):
                 fp.write(_('this modifies a binary file (all or nothing)\n'))
                 break
             if self.pretty_re.match(h):
                 fp.write(h)
                 if self.binary():
                     fp.write(_('this is a binary file\n'))
                 break
             if h.startswith('---'):
                 fp.write(_('%d hunks, %d lines changed\n') %
                          (len(self.hunks),
                           sum([h.added + h.removed for h in self.hunks])))
                 break
             fp.write(h)
 
     def write(self, fp):
         fp.write(''.join(self.header))
 
     def allhunks(self):
         for h in self.header:
             if self.allhunks_re.match(h):
                 return True
 
     def files(self):
         fromfile, tofile = self.diff_re.match(self.header[0]).groups()
         if fromfile == tofile:
             return [fromfile]
         return [fromfile, tofile]
 
     def filename(self):
         return self.files()[-1]
 
     def __repr__(self):
         return '<header %s>' % (' '.join(map(repr, self.files())))
 
     def special(self):
         for h in self.header:
             if self.special_re.match(h):
                 return True
 
 def countchanges(hunk):
     """hunk -> (n+,n-)"""
     add = len([h for h in hunk if h[0] == '+'])
     rem = len([h for h in hunk if h[0] == '-'])
     return add, rem
 
 class hunk(object):
     """patch hunk
     
     XXX shouldn't we merge this with patch.hunk ?
     """
     maxcontext = 3
 
     def __init__(self, header, fromline, toline, proc, before, hunk, after):
         def trimcontext(number, lines):
             delta = len(lines) - self.maxcontext
             if False and delta > 0:
                 return number + delta, lines[:self.maxcontext]
             return number, lines
 
         self.header = header
         self.fromline, self.before = trimcontext(fromline, before)
         self.toline, self.after = trimcontext(toline, after)
         self.proc = proc
         self.hunk = hunk
         self.added, self.removed = countchanges(self.hunk)
 
     def write(self, fp):
         delta = len(self.before) + len(self.after)
         fromlen = delta + self.removed
         tolen = delta + self.added
         fp.write('@@ -%d,%d +%d,%d @@%s\n' %
                  (self.fromline, fromlen, self.toline, tolen,
                   self.proc and (' ' + self.proc)))
         fp.write(''.join(self.before + self.hunk + self.after))
 
     pretty = write
 
     def filename(self):
         return self.header.filename()
 
     def __repr__(self):
         return '<hunk %r@%d>' % (self.filename(), self.fromline)
 
 def parsepatch(fp):
     """patch -> [] of hunks """
     class parser(object):
         """patch parsing state machine"""
         def __init__(self):
             self.fromline = 0
             self.toline = 0
             self.proc = ''
             self.header = None
             self.context = []
             self.before = []
             self.hunk = []
             self.stream = []
 
         def addrange(self, (fromstart, fromend, tostart, toend, proc)):
             self.fromline = int(fromstart)
             self.toline = int(tostart)
             self.proc = proc
 
         def addcontext(self, context):
             if self.hunk:
                 h = hunk(self.header, self.fromline, self.toline, self.proc,
                          self.before, self.hunk, context)
                 self.header.hunks.append(h)
                 self.stream.append(h)
                 self.fromline += len(self.before) + h.removed
                 self.toline += len(self.before) + h.added
                 self.before = []
                 self.hunk = []
                 self.proc = ''
             self.context = context
 
         def addhunk(self, hunk):
             if self.context:
                 self.before = self.context
                 self.context = []
             self.hunk = data
 
         def newfile(self, hdr):
             self.addcontext([])
             h = header(hdr)
             self.stream.append(h)
             self.header = h
 
         def finished(self):
             self.addcontext([])
             return self.stream
 
         transitions = {
             'file': {'context': addcontext,
                      'file': newfile,
                      'hunk': addhunk,
                      'range': addrange},
             'context': {'file': newfile,
                         'hunk': addhunk,
                         'range': addrange},
             'hunk': {'context': addcontext,
                      'file': newfile,
                      'range': addrange},
             'range': {'context': addcontext,
                       'hunk': addhunk},
             }
 
     p = parser()
 
     state = 'context'
     for newstate, data in scanpatch(fp):
         try:
             p.transitions[state][newstate](p, data)
         except KeyError:
             raise patch.PatchError('unhandled transition: %s -> %s' %
                                    (state, newstate))
         state = newstate
     return p.finished()
 
 def filterpatch(ui, chunks):
     """Interactively filter patch chunks into applied-only chunks"""
     chunks = list(chunks)
     chunks.reverse()
     seen = {}
     def consumefile():
         """fetch next portion from chunks until a 'header' is seen
         NB: header == new-file mark
         """
         consumed = []
         while chunks:
             if isinstance(chunks[-1], header):
                 break
             else:
                 consumed.append(chunks.pop())
         return consumed
 
     resp_all = [None]   # this two are changed from inside prompt,
     resp_file = [None]  # so can't be usual variables
     applied = {}        # 'filename' -> [] of chunks
     def prompt(query):
         """prompt query, and process base inputs
         
         - y/n for the rest of file
         - y/n for the rest
         - ? (help)
         - q (quit)
 
         else, input is returned to the caller.
         """
         if resp_all[0] is not None:
             return resp_all[0]
         if resp_file[0] is not None:
             return resp_file[0]
         while True:
             r = (ui.prompt(query + _(' [Ynsfdaq?] '), '(?i)[Ynsfdaq?]?$')
                  or 'y').lower()
             if r == '?':
                 c = record.__doc__.find('y - record this change')
                 for l in record.__doc__[c:].splitlines():
                     if l: ui.write(_(l.strip()), '\n')
                 continue
             elif r == 's':
                 r = resp_file[0] = 'n'
             elif r == 'f':
                 r = resp_file[0] = 'y'
             elif r == 'd':
                 r = resp_all[0] = 'n'
             elif r == 'a':
                 r = resp_all[0] = 'y'
             elif r == 'q':
                 raise util.Abort(_('user quit'))
             return r
     while chunks:
         chunk = chunks.pop()
         if isinstance(chunk, header):
             # new-file mark
             resp_file = [None]
             fixoffset = 0
             hdr = ''.join(chunk.header)
             if hdr in seen:
                 consumefile()
                 continue
             seen[hdr] = True
             if resp_all[0] is None:
                 chunk.pretty(ui)
             r = prompt(_('examine changes to %s?') %
                        _(' and ').join(map(repr, chunk.files())))
             if r == 'y':
                 applied[chunk.filename()] = [chunk]
                 if chunk.allhunks():
                     applied[chunk.filename()] += consumefile()
             else:
                 consumefile()
         else:
             # new hunk
             if resp_file[0] is None and resp_all[0] is None:
                 chunk.pretty(ui)
             r = prompt(_('record this change to %r?') %
                        chunk.filename())
             if r == 'y':
                 if fixoffset:
                     chunk = copy.copy(chunk)
                     chunk.toline += fixoffset
                 applied[chunk.filename()].append(chunk)
             else:
                 fixoffset += chunk.removed - chunk.added
     return reduce(operator.add, [h for h in applied.itervalues()
                                  if h[0].special() or len(h) > 1], [])
 
 def record(ui, repo, *pats, **opts):
     '''interactively select changes to commit
 
     If a list of files is omitted, all changes reported by "hg status"
     will be candidates for recording.
 
     You will be prompted for whether to record changes to each
     modified file, and for files with multiple changes, for each
     change to use.  For each query, the following responses are
     possible:
 
     y - record this change
     n - skip this change
 
     s - skip remaining changes to this file
     f - record remaining changes to this file
 
     d - done, skip remaining changes and files
     a - record all changes to all remaining files
     q - quit, recording no changes
 
     ? - display help'''
 
+    def record_commiter(ui, repo, pats, opts):
+        commands.commit(ui, repo, *pats, **opts)
+
+    dorecord(ui, repo, record_commiter, *pats, **opts)
+
+
+def dorecord(ui, repo, committer, *pats, **opts):
     if not ui.interactive:
         raise util.Abort(_('running non-interactively, use commit instead'))
 
     def recordfunc(ui, repo, files, message, match, opts):
+        """This is generic record driver.
+
+        It's job is to interactively filter local changes, and accordingly
+        prepare working dir into a state, where the job can be delegated to
+        non-interactive commit command such as 'commit' or 'qrefresh'.
+
+        After the actual job is done by non-interactive command, working dir
+        state is restored to original.
+
+        In the end we'll record intresting changes, and everything else will be
+        left in place, so the user can continue his work.
+        """
         if files:
             changes = None
         else:
             changes = repo.status(files=files, match=match)[:5]
             modified, added, removed = changes[:3]
             files = modified + added + removed
         diffopts = mdiff.diffopts(git=True, nodates=True)
         fp = cStringIO.StringIO()
         patch.diff(repo, repo.dirstate.parents()[0], files=files,
                    match=match, changes=changes, opts=diffopts, fp=fp)
         fp.seek(0)
 
+        # 1. filter patch, so we have intending-to apply subset of it
         chunks = filterpatch(ui, parsepatch(fp))
         del fp
 
         contenders = {}
         for h in chunks:
             try: contenders.update(dict.fromkeys(h.files()))
             except AttributeError: pass
 
         newfiles = [f for f in files if f in contenders]
 
         if not newfiles:
             ui.status(_('no changes to record\n'))
             return 0
 
         if changes is None:
             changes = repo.status(files=newfiles, match=match)[:5]
         modified = dict.fromkeys(changes[0])
 
+        # 2. backup changed files, so we can restore them in the end
         backups = {}
         backupdir = repo.join('record-backups')
         try:
             os.mkdir(backupdir)
         except OSError, err:
             if err.errno != errno.EEXIST:
                 raise
         try:
+            # backup continues
             for f in newfiles:
                 if f not in modified:
                     continue
                 fd, tmpname = tempfile.mkstemp(prefix=f.replace('/', '_')+'.',
                                                dir=backupdir)
                 os.close(fd)
                 ui.debug('backup %r as %r\n' % (f, tmpname))
                 util.copyfile(repo.wjoin(f), tmpname)
                 backups[f] = tmpname
 
             fp = cStringIO.StringIO()
             for c in chunks:
                 if c.filename() in backups:
                     c.write(fp)
             dopatch = fp.tell()
             fp.seek(0)
 
+            # 3a. apply filtered patch to clean repo  (clean)
             if backups:
                 hg.revert(repo, repo.dirstate.parents()[0], backups.has_key)
 
+            # 3b. (apply)
             if dopatch:
                 ui.debug('applying patch\n')
                 ui.debug(fp.getvalue())
                 patch.internalpatch(fp, ui, 1, repo.root)
             del fp
 
-            repo.commit(newfiles, message, opts['user'], opts['date'], match,
-                        force_editor=opts.get('force_editor'))
+            # 4. We prepared working directory according to filtered patch.
+            #    Now is the time to delegate the job to commit/qrefresh or the like!
+
+            # it is important to first chdir to repo root -- we'll call a
+            # highlevel command with list of pathnames relative to repo root
+            cwd = os.getcwd()
+            os.chdir(repo.root)
+            try:
+                committer(ui, repo, newfiles, opts)
+            finally:
+                os.chdir(cwd)
+
             return 0
         finally:
+            # 5. finally restore backed-up files
             try:
                 for realname, tmpname in backups.iteritems():
                     ui.debug('restoring %r to %r\n' % (tmpname, realname))
                     util.copyfile(tmpname, repo.wjoin(realname))
                     os.unlink(tmpname)
                 os.rmdir(backupdir)
             except OSError:
                 pass
     return cmdutil.commit(ui, repo, recordfunc, pats, opts)
 
 cmdtable = {
     "record":
         (record,
          [('A', 'addremove', None,
            _('mark new/missing files as added/removed before committing')),
          ] + commands.walkopts + commands.commitopts + commands.commitopts2,
          _('hg record [OPTION]... [FILE]...')),
 }