dirstate-item: add missing bit of docstring

Differential Revision: https://phab.mercurial-scm.org/D12517

mercurial/pure/parsers.py

@@ -1,974 +1,974 b''
 # parsers.py - Python implementation of parsers.c
 #
 # Copyright 2009 Olivia Mackall <[e-mail]> and others
 #
 # This software may be used and distributed according to the terms of the
 # GNU General Public License version 2 or any later version.
 
 
 import io
 import stat
 import struct
 import zlib
 
 from ..node import (
     nullrev,
     sha1nodeconstants,
 )
 from ..thirdparty import attr
 from .. import (
     error,
     revlogutils,
     util,
 )
 
 from ..revlogutils import nodemap as nodemaputil
 from ..revlogutils import constants as revlog_constants
 
 stringio = io.BytesIO
 
 
 _pack = struct.pack
 _unpack = struct.unpack
 _compress = zlib.compress
 _decompress = zlib.decompress
 
 
 # a special value used internally for `size` if the file come from the other parent
 FROM_P2 = -2
 
 # a special value used internally for `size` if the file is modified/merged/added
 NONNORMAL = -1
 
 # a special value used internally for `time` if the time is ambigeous
 AMBIGUOUS_TIME = -1
 
 # Bits of the `flags` byte inside a node in the file format
 DIRSTATE_V2_WDIR_TRACKED = 1 << 0
 DIRSTATE_V2_P1_TRACKED = 1 << 1
 DIRSTATE_V2_P2_INFO = 1 << 2
 DIRSTATE_V2_MODE_EXEC_PERM = 1 << 3
 DIRSTATE_V2_MODE_IS_SYMLINK = 1 << 4
 DIRSTATE_V2_HAS_FALLBACK_EXEC = 1 << 5
 DIRSTATE_V2_FALLBACK_EXEC = 1 << 6
 DIRSTATE_V2_HAS_FALLBACK_SYMLINK = 1 << 7
 DIRSTATE_V2_FALLBACK_SYMLINK = 1 << 8
 DIRSTATE_V2_EXPECTED_STATE_IS_MODIFIED = 1 << 9
 DIRSTATE_V2_HAS_MODE_AND_SIZE = 1 << 10
 DIRSTATE_V2_HAS_MTIME = 1 << 11
 DIRSTATE_V2_MTIME_SECOND_AMBIGUOUS = 1 << 12
 DIRSTATE_V2_DIRECTORY = 1 << 13
 DIRSTATE_V2_ALL_UNKNOWN_RECORDED = 1 << 14
 DIRSTATE_V2_ALL_IGNORED_RECORDED = 1 << 15
 
 
 @attr.s(slots=True, init=False)
 class DirstateItem:
     """represent a dirstate entry
 
     It hold multiple attributes
 
     # about file tracking
     - wc_tracked: is the file tracked by the working copy
     - p1_tracked: is the file tracked in working copy first parent
     - p2_info: the file has been involved in some merge operation. Either
                because it was actually merged, or because the p2 version was
                ahead, or because some rename moved it there. In either case
                `hg status` will want it displayed as modified.
 
     # about the file state expected from p1 manifest:
     - mode: the file mode in p1
     - size: the file size in p1
 
     These value can be set to None, which mean we don't have a meaningful value
     to compare with. Either because we don't really care about them as there
     `status` is known without having to look at the disk or because we don't
     know these right now and a full comparison will be needed to find out if
     the file is clean.
 
     # about the file state on disk last time we saw it:
     - mtime: the last known clean mtime for the file.
 
     This value can be set to None if no cachable state exist. Either because we
     do not care (see previous section) or because we could not cache something
     yet.
     """
 
     _wc_tracked = attr.ib()
     _p1_tracked = attr.ib()
     _p2_info = attr.ib()
     _mode = attr.ib()
     _size = attr.ib()
     _mtime_s = attr.ib()
     _mtime_ns = attr.ib()
     _fallback_exec = attr.ib()
     _fallback_symlink = attr.ib()
     _mtime_second_ambiguous = attr.ib()
 
     def __init__(
         self,
         wc_tracked=False,
         p1_tracked=False,
         p2_info=False,
         has_meaningful_data=True,
         has_meaningful_mtime=True,
         parentfiledata=None,
         fallback_exec=None,
         fallback_symlink=None,
     ):
         self._wc_tracked = wc_tracked
         self._p1_tracked = p1_tracked
         self._p2_info = p2_info
 
         self._fallback_exec = fallback_exec
         self._fallback_symlink = fallback_symlink
 
         self._mode = None
         self._size = None
         self._mtime_s = None
         self._mtime_ns = None
         self._mtime_second_ambiguous = False
         if parentfiledata is None:
             has_meaningful_mtime = False
             has_meaningful_data = False
         elif parentfiledata[2] is None:
             has_meaningful_mtime = False
         if has_meaningful_data:
             self._mode = parentfiledata[0]
             self._size = parentfiledata[1]
         if has_meaningful_mtime:
             (
                 self._mtime_s,
                 self._mtime_ns,
                 self._mtime_second_ambiguous,
             ) = parentfiledata[2]
 
     @classmethod
     def from_v2_data(cls, flags, size, mtime_s, mtime_ns):
         """Build a new DirstateItem object from V2 data"""
         has_mode_size = bool(flags & DIRSTATE_V2_HAS_MODE_AND_SIZE)
         has_meaningful_mtime = bool(flags & DIRSTATE_V2_HAS_MTIME)
         mode = None
 
         if flags & +DIRSTATE_V2_EXPECTED_STATE_IS_MODIFIED:
             # we do not have support for this flag in the code yet,
             # force a lookup for this file.
             has_mode_size = False
             has_meaningful_mtime = False
 
         fallback_exec = None
         if flags & DIRSTATE_V2_HAS_FALLBACK_EXEC:
             fallback_exec = flags & DIRSTATE_V2_FALLBACK_EXEC
 
         fallback_symlink = None
         if flags & DIRSTATE_V2_HAS_FALLBACK_SYMLINK:
             fallback_symlink = flags & DIRSTATE_V2_FALLBACK_SYMLINK
 
         if has_mode_size:
             assert stat.S_IXUSR == 0o100
             if flags & DIRSTATE_V2_MODE_EXEC_PERM:
                 mode = 0o755
             else:
                 mode = 0o644
             if flags & DIRSTATE_V2_MODE_IS_SYMLINK:
                 mode |= stat.S_IFLNK
             else:
                 mode |= stat.S_IFREG
 
         second_ambiguous = flags & DIRSTATE_V2_MTIME_SECOND_AMBIGUOUS
         return cls(
             wc_tracked=bool(flags & DIRSTATE_V2_WDIR_TRACKED),
             p1_tracked=bool(flags & DIRSTATE_V2_P1_TRACKED),
             p2_info=bool(flags & DIRSTATE_V2_P2_INFO),
             has_meaningful_data=has_mode_size,
             has_meaningful_mtime=has_meaningful_mtime,
             parentfiledata=(mode, size, (mtime_s, mtime_ns, second_ambiguous)),
             fallback_exec=fallback_exec,
             fallback_symlink=fallback_symlink,
         )
 
     @classmethod
     def from_v1_data(cls, state, mode, size, mtime):
         """Build a new DirstateItem object from V1 data
 
         Since the dirstate-v1 format is frozen, the signature of this function
         is not expected to change, unlike the __init__ one.
         """
         if state == b'm':
             return cls(wc_tracked=True, p1_tracked=True, p2_info=True)
         elif state == b'a':
             return cls(wc_tracked=True)
         elif state == b'r':
             if size == NONNORMAL:
                 p1_tracked = True
                 p2_info = True
             elif size == FROM_P2:
                 p1_tracked = False
                 p2_info = True
             else:
                 p1_tracked = True
                 p2_info = False
             return cls(p1_tracked=p1_tracked, p2_info=p2_info)
         elif state == b'n':
             if size == FROM_P2:
                 return cls(wc_tracked=True, p2_info=True)
             elif size == NONNORMAL:
                 return cls(wc_tracked=True, p1_tracked=True)
             elif mtime == AMBIGUOUS_TIME:
                 return cls(
                     wc_tracked=True,
                     p1_tracked=True,
                     has_meaningful_mtime=False,
                     parentfiledata=(mode, size, (42, 0, False)),
                 )
             else:
                 return cls(
                     wc_tracked=True,
                     p1_tracked=True,
                     parentfiledata=(mode, size, (mtime, 0, False)),
                 )
         else:
             raise RuntimeError(b'unknown state: %s' % state)
 
     def set_possibly_dirty(self):
         """Mark a file as "possibly dirty"
 
         This means the next status call will have to actually check its content
         to make sure it is correct.
         """
         self._mtime_s = None
         self._mtime_ns = None
 
     def set_clean(self, mode, size, mtime):
         """mark a file as "clean" cancelling potential "possibly dirty call"
 
         Note: this function is a descendant of `dirstate.normal` and is
         currently expected to be call on "normal" entry only. There are not
         reason for this to not change in the future as long as the ccode is
         updated to preserve the proper state of the non-normal files.
         """
         self._wc_tracked = True
         self._p1_tracked = True
         self._mode = mode
         self._size = size
         self._mtime_s, self._mtime_ns, self._mtime_second_ambiguous = mtime
 
     def set_tracked(self):
         """mark a file as tracked in the working copy
 
         This will ultimately be called by command like `hg add`.
         """
         self._wc_tracked = True
         # `set_tracked` is replacing various `normallookup` call. So we mark
         # the files as needing lookup
         #
         # Consider dropping this in the future in favor of something less broad.
         self._mtime_s = None
         self._mtime_ns = None
 
     def set_untracked(self):
         """mark a file as untracked in the working copy
 
         This will ultimately be called by command like `hg remove`.
         """
         self._wc_tracked = False
         self._mode = None
         self._size = None
         self._mtime_s = None
         self._mtime_ns = None
 
     def drop_merge_data(self):
-        """remove all "merge-only" from a DirstateItem
+        """remove all "merge-only" information from a DirstateItem
 
         This is to be call by the dirstatemap code when the second parent is dropped
         """
         if self._p2_info:
             self._p2_info = False
             self._mode = None
             self._size = None
             self._mtime_s = None
             self._mtime_ns = None
 
     @property
     def mode(self):
         return self._v1_mode()
 
     @property
     def size(self):
         return self._v1_size()
 
     @property
     def mtime(self):
         return self._v1_mtime()
 
     def mtime_likely_equal_to(self, other_mtime):
         self_sec = self._mtime_s
         if self_sec is None:
             return False
         self_ns = self._mtime_ns
         other_sec, other_ns, second_ambiguous = other_mtime
         if self_sec != other_sec:
             # seconds are different theses mtime are definitly not equal
             return False
         elif other_ns == 0 or self_ns == 0:
             # at least one side as no nano-seconds information
 
             if self._mtime_second_ambiguous:
                 # We cannot trust the mtime in this case
                 return False
             else:
                 # the "seconds" value was reliable on its own. We are good to go.
                 return True
         else:
             # We have nano second information, let us use them !
             return self_ns == other_ns
 
     @property
     def state(self):
         """
         States are:
           n  normal
           m  needs merging
           r  marked for removal
           a  marked for addition
 
         XXX This "state" is a bit obscure and mostly a direct expression of the
         dirstatev1 format. It would make sense to ultimately deprecate it in
         favor of the more "semantic" attributes.
         """
         if not self.any_tracked:
             return b'?'
         return self._v1_state()
 
     @property
     def has_fallback_exec(self):
         """True if "fallback" information are available for the "exec" bit
 
         Fallback information can be stored in the dirstate to keep track of
         filesystem attribute tracked by Mercurial when the underlying file
         system or operating system does not support that property, (e.g.
         Windows).
 
         Not all version of the dirstate on-disk storage support preserving this
         information.
         """
         return self._fallback_exec is not None
 
     @property
     def fallback_exec(self):
         """ "fallback" information for the executable bit
 
         True if the file should be considered executable when we cannot get
         this information from the files system. False if it should be
         considered non-executable.
 
         See has_fallback_exec for details."""
         return self._fallback_exec
 
     @fallback_exec.setter
     def set_fallback_exec(self, value):
         """control "fallback" executable bit
 
         Set to:
         - True if the file should be considered executable,
         - False if the file should be considered non-executable,
         - None if we do not have valid fallback data.
 
         See has_fallback_exec for details."""
         if value is None:
             self._fallback_exec = None
         else:
             self._fallback_exec = bool(value)
 
     @property
     def has_fallback_symlink(self):
         """True if "fallback" information are available for symlink status
 
         Fallback information can be stored in the dirstate to keep track of
         filesystem attribute tracked by Mercurial when the underlying file
         system or operating system does not support that property, (e.g.
         Windows).
 
         Not all version of the dirstate on-disk storage support preserving this
         information."""
         return self._fallback_symlink is not None
 
     @property
     def fallback_symlink(self):
         """ "fallback" information for symlink status
 
         True if the file should be considered executable when we cannot get
         this information from the files system. False if it should be
         considered non-executable.
 
         See has_fallback_exec for details."""
         return self._fallback_symlink
 
     @fallback_symlink.setter
     def set_fallback_symlink(self, value):
         """control "fallback" symlink status
 
         Set to:
         - True if the file should be considered a symlink,
         - False if the file should be considered not a symlink,
         - None if we do not have valid fallback data.
 
         See has_fallback_symlink for details."""
         if value is None:
             self._fallback_symlink = None
         else:
             self._fallback_symlink = bool(value)
 
     @property
     def tracked(self):
         """True is the file is tracked in the working copy"""
         return self._wc_tracked
 
     @property
     def any_tracked(self):
         """True is the file is tracked anywhere (wc or parents)"""
         return self._wc_tracked or self._p1_tracked or self._p2_info
 
     @property
     def added(self):
         """True if the file has been added"""
         return self._wc_tracked and not (self._p1_tracked or self._p2_info)
 
     @property
     def maybe_clean(self):
         """True if the file has a chance to be in the "clean" state"""
         if not self._wc_tracked:
             return False
         elif not self._p1_tracked:
             return False
         elif self._p2_info:
             return False
         return True
 
     @property
     def p1_tracked(self):
         """True if the file is tracked in the first parent manifest"""
         return self._p1_tracked
 
     @property
     def p2_info(self):
         """True if the file needed to merge or apply any input from p2
 
         See the class documentation for details.
         """
         return self._wc_tracked and self._p2_info
 
     @property
     def removed(self):
         """True if the file has been removed"""
         return not self._wc_tracked and (self._p1_tracked or self._p2_info)
 
     def v2_data(self):
         """Returns (flags, mode, size, mtime) for v2 serialization"""
         flags = 0
         if self._wc_tracked:
             flags |= DIRSTATE_V2_WDIR_TRACKED
         if self._p1_tracked:
             flags |= DIRSTATE_V2_P1_TRACKED
         if self._p2_info:
             flags |= DIRSTATE_V2_P2_INFO
         if self._mode is not None and self._size is not None:
             flags |= DIRSTATE_V2_HAS_MODE_AND_SIZE
             if self.mode & stat.S_IXUSR:
                 flags |= DIRSTATE_V2_MODE_EXEC_PERM
             if stat.S_ISLNK(self.mode):
                 flags |= DIRSTATE_V2_MODE_IS_SYMLINK
         if self._mtime_s is not None:
             flags |= DIRSTATE_V2_HAS_MTIME
         if self._mtime_second_ambiguous:
             flags |= DIRSTATE_V2_MTIME_SECOND_AMBIGUOUS
 
         if self._fallback_exec is not None:
             flags |= DIRSTATE_V2_HAS_FALLBACK_EXEC
             if self._fallback_exec:
                 flags |= DIRSTATE_V2_FALLBACK_EXEC
 
         if self._fallback_symlink is not None:
             flags |= DIRSTATE_V2_HAS_FALLBACK_SYMLINK
             if self._fallback_symlink:
                 flags |= DIRSTATE_V2_FALLBACK_SYMLINK
 
         # Note: we do not need to do anything regarding
         # DIRSTATE_V2_ALL_UNKNOWN_RECORDED and DIRSTATE_V2_ALL_IGNORED_RECORDED
         # since we never set _DIRSTATE_V2_HAS_DIRCTORY_MTIME
         return (flags, self._size or 0, self._mtime_s or 0, self._mtime_ns or 0)
 
     def _v1_state(self):
         """return a "state" suitable for v1 serialization"""
         if not self.any_tracked:
             # the object has no state to record, this is -currently-
             # unsupported
             raise RuntimeError('untracked item')
         elif self.removed:
             return b'r'
         elif self._p1_tracked and self._p2_info:
             return b'm'
         elif self.added:
             return b'a'
         else:
             return b'n'
 
     def _v1_mode(self):
         """return a "mode" suitable for v1 serialization"""
         return self._mode if self._mode is not None else 0
 
     def _v1_size(self):
         """return a "size" suitable for v1 serialization"""
         if not self.any_tracked:
             # the object has no state to record, this is -currently-
             # unsupported
             raise RuntimeError('untracked item')
         elif self.removed and self._p1_tracked and self._p2_info:
             return NONNORMAL
         elif self._p2_info:
             return FROM_P2
         elif self.removed:
             return 0
         elif self.added:
             return NONNORMAL
         elif self._size is None:
             return NONNORMAL
         else:
             return self._size
 
     def _v1_mtime(self):
         """return a "mtime" suitable for v1 serialization"""
         if not self.any_tracked:
             # the object has no state to record, this is -currently-
             # unsupported
             raise RuntimeError('untracked item')
         elif self.removed:
             return 0
         elif self._mtime_s is None:
             return AMBIGUOUS_TIME
         elif self._p2_info:
             return AMBIGUOUS_TIME
         elif not self._p1_tracked:
             return AMBIGUOUS_TIME
         elif self._mtime_second_ambiguous:
             return AMBIGUOUS_TIME
         else:
             return self._mtime_s
 
 
 def gettype(q):
     return int(q & 0xFFFF)
 
 
 class BaseIndexObject:
     # Can I be passed to an algorithme implemented in Rust ?
     rust_ext_compat = 0
     # Format of an index entry according to Python's `struct` language
     index_format = revlog_constants.INDEX_ENTRY_V1
     # Size of a C unsigned long long int, platform independent
     big_int_size = struct.calcsize(b'>Q')
     # Size of a C long int, platform independent
     int_size = struct.calcsize(b'>i')
     # An empty index entry, used as a default value to be overridden, or nullrev
     null_item = (
         0,
         0,
         0,
         -1,
         -1,
         -1,
         -1,
         sha1nodeconstants.nullid,
         0,
         0,
         revlog_constants.COMP_MODE_INLINE,
         revlog_constants.COMP_MODE_INLINE,
         revlog_constants.RANK_UNKNOWN,
     )
 
     @util.propertycache
     def entry_size(self):
         return self.index_format.size
 
     @util.propertycache
     def _nodemap(self):
         nodemap = nodemaputil.NodeMap({sha1nodeconstants.nullid: nullrev})
         for r in range(0, len(self)):
             n = self[r][7]
             nodemap[n] = r
         return nodemap
 
     def has_node(self, node):
         """return True if the node exist in the index"""
         return node in self._nodemap
 
     def rev(self, node):
         """return a revision for a node
 
         If the node is unknown, raise a RevlogError"""
         return self._nodemap[node]
 
     def get_rev(self, node):
         """return a revision for a node
 
         If the node is unknown, return None"""
         return self._nodemap.get(node)
 
     def _stripnodes(self, start):
         if '_nodemap' in vars(self):
             for r in range(start, len(self)):
                 n = self[r][7]
                 del self._nodemap[n]
 
     def clearcaches(self):
         self.__dict__.pop('_nodemap', None)
 
     def __len__(self):
         return self._lgt + len(self._extra)
 
     def append(self, tup):
         if '_nodemap' in vars(self):
             self._nodemap[tup[7]] = len(self)
         data = self._pack_entry(len(self), tup)
         self._extra.append(data)
 
     def _pack_entry(self, rev, entry):
         assert entry[8] == 0
         assert entry[9] == 0
         return self.index_format.pack(*entry[:8])
 
     def _check_index(self, i):
         if not isinstance(i, int):
             raise TypeError(b"expecting int indexes")
         if i < 0 or i >= len(self):
             raise IndexError(i)
 
     def __getitem__(self, i):
         if i == -1:
             return self.null_item
         self._check_index(i)
         if i >= self._lgt:
             data = self._extra[i - self._lgt]
         else:
             index = self._calculate_index(i)
             data = self._data[index : index + self.entry_size]
         r = self._unpack_entry(i, data)
         if self._lgt and i == 0:
             offset = revlogutils.offset_type(0, gettype(r[0]))
             r = (offset,) + r[1:]
         return r
 
     def _unpack_entry(self, rev, data):
         r = self.index_format.unpack(data)
         r = r + (
             0,
             0,
             revlog_constants.COMP_MODE_INLINE,
             revlog_constants.COMP_MODE_INLINE,
             revlog_constants.RANK_UNKNOWN,
         )
         return r
 
     def pack_header(self, header):
         """pack header information as binary"""
         v_fmt = revlog_constants.INDEX_HEADER
         return v_fmt.pack(header)
 
     def entry_binary(self, rev):
         """return the raw binary string representing a revision"""
         entry = self[rev]
         p = revlog_constants.INDEX_ENTRY_V1.pack(*entry[:8])
         if rev == 0:
             p = p[revlog_constants.INDEX_HEADER.size :]
         return p
 
 
 class IndexObject(BaseIndexObject):
     def __init__(self, data):
         assert len(data) % self.entry_size == 0, (
             len(data),
             self.entry_size,
             len(data) % self.entry_size,
         )
         self._data = data
         self._lgt = len(data) // self.entry_size
         self._extra = []
 
     def _calculate_index(self, i):
         return i * self.entry_size
 
     def __delitem__(self, i):
         if not isinstance(i, slice) or not i.stop == -1 or i.step is not None:
             raise ValueError(b"deleting slices only supports a:-1 with step 1")
         i = i.start
         self._check_index(i)
         self._stripnodes(i)
         if i < self._lgt:
             self._data = self._data[: i * self.entry_size]
             self._lgt = i
             self._extra = []
         else:
             self._extra = self._extra[: i - self._lgt]
 
 
 class PersistentNodeMapIndexObject(IndexObject):
     """a Debug oriented class to test persistent nodemap
 
     We need a simple python object to test API and higher level behavior. See
     the Rust implementation for  more serious usage. This should be used only
     through the dedicated `devel.persistent-nodemap` config.
     """
 
     def nodemap_data_all(self):
         """Return bytes containing a full serialization of a nodemap
 
         The nodemap should be valid for the full set of revisions in the
         index."""
         return nodemaputil.persistent_data(self)
 
     def nodemap_data_incremental(self):
         """Return bytes containing a incremental update to persistent nodemap
 
         This containst the data for an append-only update of the data provided
         in the last call to `update_nodemap_data`.
         """
         if self._nm_root is None:
             return None
         docket = self._nm_docket
         changed, data = nodemaputil.update_persistent_data(
             self, self._nm_root, self._nm_max_idx, self._nm_docket.tip_rev
         )
 
         self._nm_root = self._nm_max_idx = self._nm_docket = None
         return docket, changed, data
 
     def update_nodemap_data(self, docket, nm_data):
         """provide full block of persisted binary data for a nodemap
 
         The data are expected to come from disk. See `nodemap_data_all` for a
         produceur of such data."""
         if nm_data is not None:
             self._nm_root, self._nm_max_idx = nodemaputil.parse_data(nm_data)
             if self._nm_root:
                 self._nm_docket = docket
             else:
                 self._nm_root = self._nm_max_idx = self._nm_docket = None
 
 
 class InlinedIndexObject(BaseIndexObject):
     def __init__(self, data, inline=0):
         self._data = data
         self._lgt = self._inline_scan(None)
         self._inline_scan(self._lgt)
         self._extra = []
 
     def _inline_scan(self, lgt):
         off = 0
         if lgt is not None:
             self._offsets = [0] * lgt
         count = 0
         while off <= len(self._data) - self.entry_size:
             start = off + self.big_int_size
             (s,) = struct.unpack(
                 b'>i',
                 self._data[start : start + self.int_size],
             )
             if lgt is not None:
                 self._offsets[count] = off
             count += 1
             off += self.entry_size + s
         if off != len(self._data):
             raise ValueError(b"corrupted data")
         return count
 
     def __delitem__(self, i):
         if not isinstance(i, slice) or not i.stop == -1 or i.step is not None:
             raise ValueError(b"deleting slices only supports a:-1 with step 1")
         i = i.start
         self._check_index(i)
         self._stripnodes(i)
         if i < self._lgt:
             self._offsets = self._offsets[:i]
             self._lgt = i
             self._extra = []
         else:
             self._extra = self._extra[: i - self._lgt]
 
     def _calculate_index(self, i):
         return self._offsets[i]
 
 
 def parse_index2(data, inline, format=revlog_constants.REVLOGV1):
     if format == revlog_constants.CHANGELOGV2:
         return parse_index_cl_v2(data)
     if not inline:
         if format == revlog_constants.REVLOGV2:
             cls = IndexObject2
         else:
             cls = IndexObject
         return cls(data), None
     cls = InlinedIndexObject
     return cls(data, inline), (0, data)
 
 
 def parse_index_cl_v2(data):
     return IndexChangelogV2(data), None
 
 
 class IndexObject2(IndexObject):
     index_format = revlog_constants.INDEX_ENTRY_V2
 
     def replace_sidedata_info(
         self,
         rev,
         sidedata_offset,
         sidedata_length,
         offset_flags,
         compression_mode,
     ):
         """
         Replace an existing index entry's sidedata offset and length with new
         ones.
         This cannot be used outside of the context of sidedata rewriting,
         inside the transaction that creates the revision `rev`.
         """
         if rev < 0:
             raise KeyError
         self._check_index(rev)
         if rev < self._lgt:
             msg = b"cannot rewrite entries outside of this transaction"
             raise KeyError(msg)
         else:
             entry = list(self[rev])
             entry[0] = offset_flags
             entry[8] = sidedata_offset
             entry[9] = sidedata_length
             entry[11] = compression_mode
             entry = tuple(entry)
             new = self._pack_entry(rev, entry)
             self._extra[rev - self._lgt] = new
 
     def _unpack_entry(self, rev, data):
         data = self.index_format.unpack(data)
         entry = data[:10]
         data_comp = data[10] & 3
         sidedata_comp = (data[10] & (3 << 2)) >> 2
         return entry + (data_comp, sidedata_comp, revlog_constants.RANK_UNKNOWN)
 
     def _pack_entry(self, rev, entry):
         data = entry[:10]
         data_comp = entry[10] & 3
         sidedata_comp = (entry[11] & 3) << 2
         data += (data_comp | sidedata_comp,)
 
         return self.index_format.pack(*data)
 
     def entry_binary(self, rev):
         """return the raw binary string representing a revision"""
         entry = self[rev]
         return self._pack_entry(rev, entry)
 
     def pack_header(self, header):
         """pack header information as binary"""
         msg = 'version header should go in the docket, not the index: %d'
         msg %= header
         raise error.ProgrammingError(msg)
 
 
 class IndexChangelogV2(IndexObject2):
     index_format = revlog_constants.INDEX_ENTRY_CL_V2
 
     null_item = (
         IndexObject2.null_item[: revlog_constants.ENTRY_RANK]
         + (0,)  # rank of null is 0
         + IndexObject2.null_item[revlog_constants.ENTRY_RANK :]
     )
 
     def _unpack_entry(self, rev, data, r=True):
         items = self.index_format.unpack(data)
         return (
             items[revlog_constants.INDEX_ENTRY_V2_IDX_OFFSET],
             items[revlog_constants.INDEX_ENTRY_V2_IDX_COMPRESSED_LENGTH],
             items[revlog_constants.INDEX_ENTRY_V2_IDX_UNCOMPRESSED_LENGTH],
             rev,
             rev,
             items[revlog_constants.INDEX_ENTRY_V2_IDX_PARENT_1],
             items[revlog_constants.INDEX_ENTRY_V2_IDX_PARENT_2],
             items[revlog_constants.INDEX_ENTRY_V2_IDX_NODEID],
             items[revlog_constants.INDEX_ENTRY_V2_IDX_SIDEDATA_OFFSET],
             items[
                 revlog_constants.INDEX_ENTRY_V2_IDX_SIDEDATA_COMPRESSED_LENGTH
             ],
             items[revlog_constants.INDEX_ENTRY_V2_IDX_COMPRESSION_MODE] & 3,
             (items[revlog_constants.INDEX_ENTRY_V2_IDX_COMPRESSION_MODE] >> 2)
             & 3,
             items[revlog_constants.INDEX_ENTRY_V2_IDX_RANK],
         )
 
     def _pack_entry(self, rev, entry):
 
         base = entry[revlog_constants.ENTRY_DELTA_BASE]
         link_rev = entry[revlog_constants.ENTRY_LINK_REV]
         assert base == rev, (base, rev)
         assert link_rev == rev, (link_rev, rev)
         data = (
             entry[revlog_constants.ENTRY_DATA_OFFSET],
             entry[revlog_constants.ENTRY_DATA_COMPRESSED_LENGTH],
             entry[revlog_constants.ENTRY_DATA_UNCOMPRESSED_LENGTH],
             entry[revlog_constants.ENTRY_PARENT_1],
             entry[revlog_constants.ENTRY_PARENT_2],
             entry[revlog_constants.ENTRY_NODE_ID],
             entry[revlog_constants.ENTRY_SIDEDATA_OFFSET],
             entry[revlog_constants.ENTRY_SIDEDATA_COMPRESSED_LENGTH],
             entry[revlog_constants.ENTRY_DATA_COMPRESSION_MODE] & 3
             | (entry[revlog_constants.ENTRY_SIDEDATA_COMPRESSION_MODE] & 3)
             << 2,
             entry[revlog_constants.ENTRY_RANK],
         )
         return self.index_format.pack(*data)
 
 
 def parse_index_devel_nodemap(data, inline):
     """like parse_index2, but alway return a PersistentNodeMapIndexObject"""
     return PersistentNodeMapIndexObject(data), None
 
 
 def parse_dirstate(dmap, copymap, st):
     parents = [st[:20], st[20:40]]
     # dereference fields so they will be local in loop
     format = b">cllll"
     e_size = struct.calcsize(format)
     pos1 = 40
     l = len(st)
 
     # the inner loop
     while pos1 < l:
         pos2 = pos1 + e_size
         e = _unpack(b">cllll", st[pos1:pos2])  # a literal here is faster
         pos1 = pos2 + e[4]
         f = st[pos2:pos1]
         if b'\0' in f:
             f, c = f.split(b'\0')
             copymap[f] = c
         dmap[f] = DirstateItem.from_v1_data(*e[:4])
     return parents
 
 
 def pack_dirstate(dmap, copymap, pl):
     cs = stringio()
     write = cs.write
     write(b"".join(pl))
     for f, e in dmap.items():
         if f in copymap:
             f = b"%s\0%s" % (f, copymap[f])
         e = _pack(
             b">cllll",
             e._v1_state(),
             e._v1_mode(),
             e._v1_size(),
             e._v1_mtime(),
             len(f),
         )
         write(e)
         write(f)
     return cs.getvalue()