mercurial/diffhelper.py

tests: make test-check-module-imports more robust

It failed for me without this in this way:
  tests/test-commandserver.t:19: relative import of stdlib module
  tests/test-lfs-serve.t:108: relative import of stdlib module
  tests/test-lfs-serve.t:255: relative import of stdlib module
  tests/test-lfs-serve.t:362: relative import of stdlib module
  tests/test-lfs-serve.t:406: relative import of stdlib module
  tests/test-lock.py:9: imports not lexically sorted: silenttestrunner < unittest, True, True
  tests/test-lrucachedict.py:5: imports not lexically sorted: silenttestrunner < unittest, True, True
  tests/test-match.py:5: imports not lexically sorted: silenttestrunner < unittest, True, True
  tests/test-remotefilelog-datapack.py:15: imports not lexically sorted: silenttestrunner < unittest, True, True
  tests/test-remotefilelog-histpack.py:14: imports not lexically sorted: silenttestrunner < unittest, True, True
  tests/test-simplekeyvaluefile.py:4: imports not lexically sorted: silenttestrunner < unittest, True, True
  tests/test-sshserver.py:6: imports not lexically sorted: silenttestrunner < unittest, True, True

This is because every module is considered a stdlib module, because
the stdlib_prefixes is /usr, and my repo is in /usr/local/home, which
means that sys.path contains a couple of
/usr/local/home/../hg/.. entries that count as "in the stdlib".
Fix this by preventing any path in sys.path that's inside the mercurial
source from being considered "in the stdlib".

Differential Revision: https://phab.mercurial-scm.org/D5294

# diffhelper.py - helper routines for patch
#
# Copyright 2009 Matt 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.

from __future__ import absolute_import

from .i18n import _

from . import (
    error,
    pycompat,
)

def addlines(fp, hunk, lena, lenb, a, b):
    """Read lines from fp into the hunk

    The hunk is parsed into two arrays, a and b. a gets the old state of
    the text, b gets the new state. The control char from the hunk is saved
    when inserting into a, but not b (for performance while deleting files.)
    """
    while True:
        todoa = lena - len(a)
        todob = lenb - len(b)
        num = max(todoa, todob)
        if num == 0:
            break
        for i in pycompat.xrange(num):
            s = fp.readline()
            if not s:
                raise error.ParseError(_('incomplete hunk'))
            if s == "\\ No newline at end of file\n":
                fixnewline(hunk, a, b)
                continue
            if s == '\n' or s == '\r\n':
                # Some patches may be missing the control char
                # on empty lines. Supply a leading space.
                s = ' ' + s
            hunk.append(s)
            if s.startswith('+'):
                b.append(s[1:])
            elif s.startswith('-'):
                a.append(s)
            else:
                b.append(s[1:])
                a.append(s)

def fixnewline(hunk, a, b):
    """Fix up the last lines of a and b when the patch has no newline at EOF"""
    l = hunk[-1]
    # tolerate CRLF in last line
    if l.endswith('\r\n'):
        hline = l[:-2]
    else:
        hline = l[:-1]

    if hline.startswith((' ', '+')):
        b[-1] = hline[1:]
    if hline.startswith((' ', '-')):
        a[-1] = hline
    hunk[-1] = hline

def testhunk(a, b, bstart):
    """Compare the lines in a with the lines in b

    a is assumed to have a control char at the start of each line, this char
    is ignored in the compare.
    """
    alen = len(a)
    blen = len(b)
    if alen > blen - bstart or bstart < 0:
        return False
    for i in pycompat.xrange(alen):
        if a[i][1:] != b[i + bstart]:
            return False
    return True