hgext/record.py

record: allow splitting of hunks by manually editing patches

It is possible that unrelated changes in a file are on sequential lines.  The
current record extension does not allow these to be committed independently.

An example use case for this is in software development for deeply embedded
real-time systems.  In these environments, it is not always possible to use a
debugger (due to time-constraints) and hence inline UART-based printing is
often used.  When fixing a bug in a module, it is often convenient to add a
large number of 'printf's (linked to the UART via a custom fputc) to the module
in order to work out what is going wrong.  printf is a very slow function (and
also variadic so somewhat frowned upon by the MISRA standard) and hence it is
highly undesirable to commit these lines to the repository.  If only a partial
fix is implemented, however, it is desirable to commit the fix without deleting
all of the printf lines.  This is also simplifies removal of the printf lines
as once the final fix is committed, 'hg revert' does the rest.  It is likely
that the printf lines will be very near the actual fix, so being able to split
the hunk is very useful in this case.

There were two alternatives I considered for the user interface.  One was to
manually edit the patch, the other to allow a hunk to be split into individual
lines for consideration.  The latter option would require a significant
refactor of the record module and is less flexible.  While the former is
potentially more complicated to use, this is a feature that is likely to only
be used in certain exceptional cases (such as the use case proposed above) and
hence I felt that the complexity would not be a considerable issue.

I've also written a follow-up patch that refactors the 'prompt' code to base
everything on the choices variable.  This tidies up and clarifies the code a
bit (removes constructs like 'if ret == 7' and removes the 'e' option from the
file scope options as it's not relevant there.  It's not really a necessity, so
I've excluded it from this submission for now, but I can send it separately if
there's a desire and it's on bitbucket (see below) in the meantime.

Possible future improvements include:

* Tidying up the 'prompt' code to base everything on the choices variable.
  This would allow entries to be removed from the prompt as currently 'e' is
  offered even for entire file patches, which is currently unsupported.
* Allowing the entire file (or even multi-file) patch to be edited manually:
  this would require quite a large refactor without much benefit, so I decided
  to exclude it from the initial submission.
* Allow the option to retry if a patch fails to apply (this is what Git does).
  This would require quite a bit of refactoring given the current 'hg record'
  implementation, so it's debatable whether it's worth it.

Output is similar to existing record user interface except that an additional
option ('e') exists to allow manual editing of the patch.  This opens the
user's configured editor with the patch.  A comment is added to the bottom of
the patch explaining what to do (based on Git's one).

A large proportion of the changeset is test-case changes to update the options
reported by record (Ynesfdaq? instead of Ynsfdaq?).  Functional changes are in
record.py and there are some new test cases in test-record.t.

# 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 version 2 or any later version.

'''commands to interactively select changes for commit/qrefresh'''

from mercurial.i18n import gettext, _
from mercurial import cmdutil, commands, extensions, hg, mdiff, patch
from mercurial import util
import copy, cStringIO, errno, os, re, shutil, tempfile

cmdtable = {}
command = cmdutil.command(cmdtable)

lines_re = re.compile(r'@@ -(\d+),(\d+) \+(\d+),(\d+) @@\s*(.*)')

diffopts = [
    ('w', 'ignore-all-space', False,
     _('ignore white space when comparing lines')),
    ('b', 'ignore-space-change', None,
     _('ignore changes in the amount of white space')),
    ('B', 'ignore-blank-lines', None,
     _('ignore changes whose lines are all blank')),
]

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/') or line.startswith('diff -r '):
            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 ?
    """
    diffgit_re = re.compile('diff --git a/(.*) b/(.*)$')
    diff_re = re.compile('diff -r .* (.*)$')
    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):
        return util.any(h.startswith('index ') for h in self.header)

    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([max(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):
        return util.any(self.allhunks_re.match(h) for h in self.header)

    def files(self):
        match = self.diffgit_re.match(self.header[0])
        if match:
            fromfile, tofile = match.groups()
            if fromfile == tofile:
                return [fromfile]
            return [fromfile, tofile]
        else:
            return self.diff_re.match(self.header[0]).groups()

    def filename(self):
        return self.files()[-1]

    def __repr__(self):
        return '<header %s>' % (' '.join(map(repr, self.files())))

    def special(self):
        return util.any(self.special_re.match(h) for h in self.header)

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)
        if self.after and self.after[-1] == '\\ No newline at end of file\n':
            delta -= 1
        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 headers -> [] 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.headers = []

        def addrange(self, limits):
            fromstart, fromend, tostart, toend, proc = limits
            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.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 = hunk

        def newfile(self, hdr):
            self.addcontext([])
            h = header(hdr)
            self.headers.append(h)
            self.header = h

        def finished(self):
            self.addcontext([])
            return self.headers

        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, headers):
    """Interactively filter patch chunks into applied-only chunks"""

    def prompt(skipfile, skipall, query, chunk):
        """prompt query, and process base inputs

        - y/n for the rest of file
        - y/n for the rest
        - ? (help)
        - q (quit)

        Return True/False and possibly updated skipfile and skipall.
        """
        newpatches = None
        if skipall is not None:
            return skipall, skipfile, skipall, newpatches
        if skipfile is not None:
            return skipfile, skipfile, skipall, newpatches
        while True:
            resps = _('[Ynesfdaq?]')
            choices = (_('&Yes, record this change'),
                    _('&No, skip this change'),
                    _('&Edit the change manually'),
                    _('&Skip remaining changes to this file'),
                    _('Record remaining changes to this &file'),
                    _('&Done, skip remaining changes and files'),
                    _('Record &all changes to all remaining files'),
                    _('&Quit, recording no changes'),
                    _('&?'))
            r = ui.promptchoice("%s %s" % (query, resps), choices)
            ui.write("\n")
            if r == 8: # ?
                doc = gettext(record.__doc__)
                c = doc.find('::') + 2
                for l in doc[c:].splitlines():
                    if l.startswith('      '):
                        ui.write(l.strip(), '\n')
                continue
            elif r == 0: # yes
                ret = True
            elif r == 1: # no
                ret = False
            elif r == 2: # Edit patch
                if chunk is None:
                    ui.write(_('cannot edit patch for whole file'))
                    ui.write("\n")
                    continue
                if chunk.header.binary():
                    ui.write(_('cannot edit patch for binary file'))
                    ui.write("\n")
                    continue
                # Patch comment based on the Git one (based on comment at end of
                # http://mercurial.selenic.com/wiki/RecordExtension)
                phelp = '---' + _("""
To remove '-' lines, make them ' ' lines (context).
To remove '+' lines, delete them.
Lines starting with # will be removed from the patch.

If the patch applies cleanly, the edited hunk will immediately be
added to the record list. If it does not apply cleanly, a rejects
file will be generated: you can use that when you try again. If
all lines of the hunk are removed, then the edit is aborted and
the hunk is left unchanged.
""")
                (patchfd, patchfn) = tempfile.mkstemp(prefix="hg-editor-",
                        suffix=".diff", text=True)
                try:
                    # Write the initial patch
                    f = os.fdopen(patchfd, "w")
                    chunk.header.write(f)
                    chunk.write(f)
                    f.write('\n'.join(['# ' + i for i in phelp.splitlines()]))
                    f.close()
                    # Start the editor and wait for it to complete
                    editor = ui.geteditor()
                    util.system("%s \"%s\"" % (editor, patchfn),
                            environ={'HGUSER': ui.username()},
                            onerr=util.Abort, errprefix=_("edit failed"),
                            out=ui.fout)
                    # Remove comment lines
                    patchfp = open(patchfn)
                    ncpatchfp = cStringIO.StringIO()
                    for line in patchfp:
                        if not line.startswith('#'):
                            ncpatchfp.write(line)
                    patchfp.close()
                    ncpatchfp.seek(0)
                    newpatches = parsepatch(ncpatchfp)
                finally:
                    os.unlink(patchfn)
                    del ncpatchfp
                # Signal that the chunk shouldn't be applied as-is, but
                # provide the new patch to be used instead.
                ret = False
            elif r == 3: # Skip
                ret = skipfile = False
            elif r == 4: # file (Record remaining)
                ret = skipfile = True
            elif r == 5: # done, skip remaining
                ret = skipall = False
            elif r == 6: # all
                ret = skipall = True
            elif r == 7: # quit
                raise util.Abort(_('user quit'))
            return ret, skipfile, skipall, newpatches

    seen = set()
    applied = {}        # 'filename' -> [] of chunks
    skipfile, skipall = None, None
    pos, total = 1, sum(len(h.hunks) for h in headers)
    for h in headers:
        pos += len(h.hunks)
        skipfile = None
        fixoffset = 0
        hdr = ''.join(h.header)
        if hdr in seen:
            continue
        seen.add(hdr)
        if skipall is None:
            h.pretty(ui)
        msg = (_('examine changes to %s?') %
               _(' and ').join(map(repr, h.files())))
        r, skipfile, skipall, np = prompt(skipfile, skipall, msg, None)
        if not r:
            continue
        applied[h.filename()] = [h]
        if h.allhunks():
            applied[h.filename()] += h.hunks
            continue
        for i, chunk in enumerate(h.hunks):
            if skipfile is None and skipall is None:
                chunk.pretty(ui)
            if total == 1:
                msg = _('record this change to %r?') % chunk.filename()
            else:
                idx = pos - len(h.hunks) + i
                msg = _('record change %d/%d to %r?') % (idx, total,
                                                         chunk.filename())
            r, skipfile, skipall, newpatches = prompt(skipfile,
                    skipall, msg, chunk)
            if r:
                if fixoffset:
                    chunk = copy.copy(chunk)
                    chunk.toline += fixoffset
                applied[chunk.filename()].append(chunk)
            elif newpatches is not None:
                for newpatch in newpatches:
                    for newhunk in newpatch.hunks:
                        if fixoffset:
                            newhunk.toline += fixoffset
                        applied[newhunk.filename()].append(newhunk)
            else:
                fixoffset += chunk.removed - chunk.added
    return sum([h for h in applied.itervalues()
               if h[0].special() or len(h) > 1], [])

@command("record",
         # same options as commit + white space diff options
         commands.table['^commit|ci'][1][:] + diffopts,
          _('hg record [OPTION]... [FILE]...'))
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.

    See :hg:`help dates` for a list of formats valid for -d/--date.

    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
      e - edit this change manually

      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

    This command is not available when committing a merge.'''

    dorecord(ui, repo, commands.commit, 'commit', False, *pats, **opts)

def qrefresh(origfn, ui, repo, *pats, **opts):
    if not opts['interactive']:
        return origfn(ui, repo, *pats, **opts)

    mq = extensions.find('mq')

    def committomq(ui, repo, *pats, **opts):
        # At this point the working copy contains only changes that
        # were accepted. All other changes were reverted.
        # We can't pass *pats here since qrefresh will undo all other
        # changed files in the patch that aren't in pats.
        mq.refresh(ui, repo, **opts)

    # backup all changed files
    dorecord(ui, repo, committomq, 'qrefresh', True, *pats, **opts)

def qrecord(ui, repo, patch, *pats, **opts):
    '''interactively record a new patch

    See :hg:`help qnew` & :hg:`help record` for more information and
    usage.
    '''

    try:
        mq = extensions.find('mq')
    except KeyError:
        raise util.Abort(_("'mq' extension not loaded"))

    repo.mq.checkpatchname(patch)

    def committomq(ui, repo, *pats, **opts):
        opts['checkname'] = False
        mq.new(ui, repo, patch, *pats, **opts)

    dorecord(ui, repo, committomq, 'qnew', False, *pats, **opts)

def qnew(origfn, ui, repo, patch, *args, **opts):
    if opts['interactive']:
        return qrecord(ui, repo, patch, *args, **opts)
    return origfn(ui, repo, patch, *args, **opts)

def dorecord(ui, repo, commitfunc, cmdsuggest, backupall, *pats, **opts):
    if not ui.interactive():
        raise util.Abort(_('running non-interactively, use %s instead') %
                         cmdsuggest)

    def recordfunc(ui, repo, message, match, opts):
        """This is generic record driver.

        Its job is to interactively filter local changes, and
        accordingly prepare working directory into a state in which the
        job can be delegated to a non-interactive commit command such as
        'commit' or 'qrefresh'.

        After the actual job is done by non-interactive command, the
        working directory is restored to its original state.

        In the end we'll record interesting changes, and everything else
        will be left in place, so the user can continue working.
        """

        merge = len(repo[None].parents()) > 1
        if merge:
            raise util.Abort(_('cannot partially commit a merge '
                               '(use "hg commit" instead)'))

        changes = repo.status(match=match)[:3]
        diffopts = mdiff.diffopts(git=True, nodates=True,
                                  ignorews=opts.get('ignore_all_space'),
                                  ignorewsamount=opts.get('ignore_space_change'),
                                  ignoreblanklines=opts.get('ignore_blank_lines'))
        chunks = patch.diff(repo, changes=changes, opts=diffopts)
        fp = cStringIO.StringIO()
        fp.write(''.join(chunks))
        fp.seek(0)

        # 1. filter patch, so we have intending-to apply subset of it
        chunks = filterpatch(ui, parsepatch(fp))
        del fp

        contenders = set()
        for h in chunks:
            try:
                contenders.update(set(h.files()))
            except AttributeError:
                pass

        changed = changes[0] + changes[1] + changes[2]
        newfiles = [f for f in changed if f in contenders]
        if not newfiles:
            ui.status(_('no changes to record\n'))
            return 0

        modified = set(changes[0])

        # 2. backup changed files, so we can restore them in the end
        if backupall:
            tobackup = changed
        else:
            tobackup = [f for f in newfiles if f in modified]

        backups = {}
        if tobackup:
            backupdir = repo.join('record-backups')
            try:
                os.mkdir(backupdir)
            except OSError, err:
                if err.errno != errno.EEXIST:
                    raise
        try:
            # backup continues
            for f in tobackup:
                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)
                shutil.copystat(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.p1(),
                          lambda key: key in backups)

            # 3b. (apply)
            if dopatch:
                try:
                    ui.debug('applying patch\n')
                    ui.debug(fp.getvalue())
                    patch.internalpatch(ui, repo, fp, 1, eolmode=None)
                except patch.PatchError, err:
                    raise util.Abort(str(err))
            del fp

            # 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:
                commitfunc(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))
                    # Our calls to copystat() here and above are a
                    # hack to trick any editors that have f open that
                    # we haven't modified them.
                    #
                    # Also note that this racy as an editor could
                    # notice the file's mtime before we've finished
                    # writing it.
                    shutil.copystat(tmpname, repo.wjoin(realname))
                    os.unlink(tmpname)
                if tobackup:
                    os.rmdir(backupdir)
            except OSError:
                pass

    # wrap ui.write so diff output can be labeled/colorized
    def wrapwrite(orig, *args, **kw):
        label = kw.pop('label', '')
        for chunk, l in patch.difflabel(lambda: args):
            orig(chunk, label=label + l)
    oldwrite = ui.write
    extensions.wrapfunction(ui, 'write', wrapwrite)
    try:
        return cmdutil.commit(ui, repo, recordfunc, pats, opts)
    finally:
        ui.write = oldwrite

cmdtable["qrecord"] = \
    (qrecord, [], # placeholder until mq is available
     _('hg qrecord [OPTION]... PATCH [FILE]...'))

def uisetup(ui):
    try:
        mq = extensions.find('mq')
    except KeyError:
        return

    cmdtable["qrecord"] = \
        (qrecord,
         # same options as qnew, but copy them so we don't get
         # -i/--interactive for qrecord and add white space diff options
         mq.cmdtable['^qnew'][1][:] + diffopts,
         _('hg qrecord [OPTION]... PATCH [FILE]...'))

    _wrapcmd('qnew', mq.cmdtable, qnew, _("interactively record a new patch"))
    _wrapcmd('qrefresh', mq.cmdtable, qrefresh,
             _("interactively select changes to refresh"))

def _wrapcmd(cmd, table, wrapfn, msg):
    entry = extensions.wrapcommand(table, cmd, wrapfn)
    entry[1].append(('i', 'interactive', None, msg))