comparison mercurial/copies.py @ 15775:91eb4512edd0

copies: rewrite copy detection for non-merge users

The existing copy detection API was designed with merge in mind and
was ill-suited for doing status/diff. The new pathcopies
implementation gives more accurate, easier to use results for
comparing two revisions, and is much simpler to understand.

Test notes:

- test-mv-cp-st.t results finds more renames in the reverse direction now
- test-mq-merge.t was always wrong and duplicated a copy in diff that
  was already present in one of the parent revisions

15774:0bd17a4bed88

    if not hascommonancestor:
        return None
    return limit

def pathcopies(c1, c2):
    return mergecopies(c1._repo, c1, c2, c1._repo["null"], False)[0]

def mergecopies(repo, c1, c2, ca, checkdirs=True):
    """
    Find moves and copies between context c1 and c2
    """

15775:91eb4512edd0

    if not hascommonancestor:
        return None
    return limit

def _chain(src, dst, a, b):
    '''chain two sets of copies a->b'''
    t = a.copy()
    for k, v in b.iteritems():
        if v in t:
            # found a chain
            if t[v] != k:
                # file wasn't renamed back to itself
                t[k] = t[v]
            if v not in dst:
                # chain was a rename, not a copy
                del t[v]
        if v in src:
            # file is a copy of an existing file
            t[k] = v
    return t

def _tracefile(fctx, actx):
    '''return file context that is the ancestor of fctx present in actx'''
    stop = actx.rev()
    am = actx.manifest()

    for f in fctx.ancestors():
        if am.get(f.path(), None) == f.filenode():
            return f
        if f.rev() < stop:
            return None

def _dirstatecopies(d):
    ds = d._repo.dirstate
    c = ds.copies().copy()
    for k in c.keys():
        if ds[k] not in 'anm':
            del c[k]
    return c

def _forwardcopies(a, b):
    '''find {dst@b: src@a} copy mapping where a is an ancestor of b'''

    # check for working copy
    w = None
    if b.rev() is None:
        w = b
        b = w.p1()
        if a == b:
            # short-circuit to avoid issues with merge states
            return _dirstatecopies(w)

    # find where new files came from
    # we currently don't try to find where old files went, too expensive
    # this means we can miss a case like 'hg rm b; hg cp a b'
    cm = {}
    for f in b:
        if f not in a:
            ofctx = _tracefile(b[f], a)
            if ofctx:
                cm[f] = ofctx.path()

    # combine copies from dirstate if necessary
    if w is not None:
        cm = _chain(a, w, cm, _dirstatecopies(w))

    return cm

def _backwardcopies(a, b):
    # because the forward mapping is 1:n, we can lose renames here
    # in particular, we find renames better than copies
    f = _forwardcopies(b, a)
    r = {}
    for k, v in f.iteritems():
        r[v] = k
    return r

def pathcopies(x, y):
    '''find {dst@y: src@x} copy mapping for directed compare'''
    if x == y or not x or not y:
        return {}
    a = y.ancestor(x)
    if a == x:
        return _forwardcopies(x, y)
    if a == y:
        return _backwardcopies(x, y)
    return _chain(x, y, _backwardcopies(x, a), _forwardcopies(a, y))

def mergecopies(repo, c1, c2, ca, checkdirs=True):
    """
    Find moves and copies between context c1 and c2
    """