mercurial/dicthelpers.py

hgweb: show as same parents as "hg parents -r REV FILE" in pages for file

Before this patch, "parents" in pages for file doesn't show as same
parents as "hg parents -r REV FILE", when the specified file is not
modified in the specified revision.

For example, it is assumed that revision A, B and D change file "f".

    changelog   (A) ---> (B) ---> (C) ---> (D)
    filelog "f" (x) ---> (y) ------------> (z)

"/file/D/f" invokes "webutil.parents()" with filectx(z) gotten from
changectx(D), and it returns changectx(B). This is as same result as
"hg parents -r D f".

In the other hand, "/file/C/f" invokes "webutil.parents()" with
filectx(y') gotten from changectx(C), and it returns changectx(A),
because filectx(y') is linked to changectx(B), and works like
filectx(y) in some cases.

In this case, revision B is hidden from users browsing file "f" in
revision C.

This patch shows as same parents as "hg parents -r REV FILE" in pages
for file, by making "webutil.parents()" return:

  - "linkrev()"-ed revision only, if:

    - specified context instance is "filectx" (because
      "webutil.parents()" is invoked with changectx, too), and

    - (1) the revision from which filectx is gotten and (2) the one to
      which filectx is linked are different from each other

  - revision gotten from "ctx.parents()", otherwise

# dicthelpers.py - helper routines for Python dicts
#
# Copyright 2013 Facebook
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

def diff(d1, d2, default=None):
    '''Return all key-value pairs that are different between d1 and d2.

    This includes keys that are present in one dict but not the other, and
    keys whose values are different. The return value is a dict with values
    being pairs of values from d1 and d2 respectively, and missing values
    treated as default, so if a value is missing from one dict and the same as
    default in the other, it will not be returned.'''
    res = {}
    if d1 is d2:
        # same dict, so diff is empty
        return res

    for k1, v1 in d1.iteritems():
        v2 = d2.get(k1, default)
        if v1 != v2:
            res[k1] = (v1, v2)

    for k2 in d2:
        if k2 not in d1:
            v2 = d2[k2]
            if v2 != default:
                res[k2] = (default, v2)

    return res

def join(d1, d2, default=None):
    '''Return all key-value pairs from both d1 and d2.

    This is akin to an outer join in relational algebra. The return value is a
    dict with values being pairs of values from d1 and d2 respectively, and
    missing values represented as default.'''
    res = {}

    for k1, v1 in d1.iteritems():
        if k1 in d2:
            res[k1] = (v1, d2[k1])
        else:
            res[k1] = (v1, default)

    if d1 is d2:
        return res

    for k2 in d2:
        if k2 not in d1:
            res[k2] = (default, d2[k2])

    return res