mercurial/manifest.py

dagparser: parses and formats DAGs as concise text

As discussed during the sprint. See the doc comment and doctests
for specification and examples. This is used in subsequent patches
to export revlog and changelog DAGs, and to generate a repo with
a given changelog DAG.

# manifest.py - manifest revision class for mercurial
#
# Copyright 2005-2007 Matt Mackall <[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.

from i18n import _
import mdiff, parsers, error, revlog
import array, struct

class manifestdict(dict):
    def __init__(self, mapping=None, flags=None):
        if mapping is None:
            mapping = {}
        if flags is None:
            flags = {}
        dict.__init__(self, mapping)
        self._flags = flags
    def flags(self, f):
        return self._flags.get(f, "")
    def set(self, f, flags):
        self._flags[f] = flags
    def copy(self):
        return manifestdict(self, dict.copy(self._flags))

class manifest(revlog.revlog):
    def __init__(self, opener):
        self._mancache = None
        revlog.revlog.__init__(self, opener, "00manifest.i")

    def parse(self, lines):
        mfdict = manifestdict()
        parsers.parse_manifest(mfdict, mfdict._flags, lines)
        return mfdict

    def readdelta(self, node):
        r = self.rev(node)
        return self.parse(mdiff.patchtext(self.revdiff(r - 1, r)))

    def read(self, node):
        if node == revlog.nullid:
            return manifestdict() # don't upset local cache
        if self._mancache and self._mancache[0] == node:
            return self._mancache[1]
        text = self.revision(node)
        arraytext = array.array('c', text)
        mapping = self.parse(text)
        self._mancache = (node, mapping, arraytext)
        return mapping

    def _search(self, m, s, lo=0, hi=None):
        '''return a tuple (start, end) that says where to find s within m.

        If the string is found m[start:end] are the line containing
        that string.  If start == end the string was not found and
        they indicate the proper sorted insertion point.  This was
        taken from bisect_left, and modified to find line start/end as
        it goes along.

        m should be a buffer or a string
        s is a string'''
        def advance(i, c):
            while i < lenm and m[i] != c:
                i += 1
            return i
        if not s:
            return (lo, lo)
        lenm = len(m)
        if not hi:
            hi = lenm
        while lo < hi:
            mid = (lo + hi) // 2
            start = mid
            while start > 0 and m[start - 1] != '\n':
                start -= 1
            end = advance(start, '\0')
            if m[start:end] < s:
                # we know that after the null there are 40 bytes of sha1
                # this translates to the bisect lo = mid + 1
                lo = advance(end + 40, '\n') + 1
            else:
                # this translates to the bisect hi = mid
                hi = start
        end = advance(lo, '\0')
        found = m[lo:end]
        if cmp(s, found) == 0:
            # we know that after the null there are 40 bytes of sha1
            end = advance(end + 40, '\n')
            return (lo, end + 1)
        else:
            return (lo, lo)

    def find(self, node, f):
        '''look up entry for a single file efficiently.
        return (node, flags) pair if found, (None, None) if not.'''
        if self._mancache and self._mancache[0] == node:
            return self._mancache[1].get(f), self._mancache[1].flags(f)
        text = self.revision(node)
        start, end = self._search(text, f)
        if start == end:
            return None, None
        l = text[start:end]
        f, n = l.split('\0')
        return revlog.bin(n[:40]), n[40:-1]

    def add(self, map, transaction, link, p1=None, p2=None,
            changed=None):
        # apply the changes collected during the bisect loop to our addlist
        # return a delta suitable for addrevision
        def addlistdelta(addlist, x):
            # start from the bottom up
            # so changes to the offsets don't mess things up.
            for start, end, content in reversed(x):
                if content:
                    addlist[start:end] = array.array('c', content)
                else:
                    del addlist[start:end]
            return "".join(struct.pack(">lll", start, end, len(content)) + content
                           for start, end, content in x)

        def checkforbidden(l):
            for f in l:
                if '\n' in f or '\r' in f:
                    raise error.RevlogError(
                        _("'\\n' and '\\r' disallowed in filenames: %r") % f)

        # if we're using the cache, make sure it is valid and
        # parented by the same node we're diffing against
        if not (changed and self._mancache and p1 and self._mancache[0] == p1):
            files = sorted(map)
            checkforbidden(files)

            # if this is changed to support newlines in filenames,
            # be sure to check the templates/ dir again (especially *-raw.tmpl)
            hex, flags = revlog.hex, map.flags
            text = ''.join("%s\000%s%s\n" % (f, hex(map[f]), flags(f))
                           for f in files)
            arraytext = array.array('c', text)
            cachedelta = None
        else:
            added, removed = changed
            addlist = self._mancache[2]

            checkforbidden(added)
            # combine the changed lists into one list for sorting
            work = [(x, False) for x in added]
            work.extend((x, True) for x in removed)
            # this could use heapq.merge() (from python2.6+) or equivalent
            # since the lists are already sorted
            work.sort()

            delta = []
            dstart = None
            dend = None
            dline = [""]
            start = 0
            # zero copy representation of addlist as a buffer
            addbuf = buffer(addlist)

            # start with a readonly loop that finds the offset of
            # each line and creates the deltas
            for f, todelete in work:
                # bs will either be the index of the item or the insert point
                start, end = self._search(addbuf, f, start)
                if not todelete:
                    l = "%s\000%s%s\n" % (f, revlog.hex(map[f]), map.flags(f))
                else:
                    if start == end:
                        # item we want to delete was not found, error out
                        raise AssertionError(
                                _("failed to remove %s from manifest") % f)
                    l = ""
                if dstart != None and dstart <= start and dend >= start:
                    if dend < end:
                        dend = end
                    if l:
                        dline.append(l)
                else:
                    if dstart != None:
                        delta.append([dstart, dend, "".join(dline)])
                    dstart = start
                    dend = end
                    dline = [l]

            if dstart != None:
                delta.append([dstart, dend, "".join(dline)])
            # apply the delta to the addlist, and get a delta for addrevision
            cachedelta = addlistdelta(addlist, delta)

            # the delta is only valid if we've been processing the tip revision
            if p1 != self.tip():
                cachedelta = None
            arraytext = addlist
            text = buffer(arraytext)

        n = self.addrevision(text, transaction, link, p1, p2, cachedelta)
        self._mancache = (n, map, arraytext)

        return n