contrib/testparseutil.py

simplemerge: stop merging file flags

As 384df4db6520 (merge: merge file flags together with file content,
2013-01-09) explains, we shouldn't do a 3-way merge of the
symlink. However, since 84614212ae39 (flags: actually merge flags in
simplemerge, 2020-05-16), we do that in
`simplemerge.simplemerge()`. What's more, the merging of the
executable flag there isn't actually necessary; it was made a no-op by
the very next commit, i.e. 4234c9af515d (flags: read flag from
dirstate/disk for workingcopyctx (issue5743), 2020-05-16).

I found the overall flag-merging code (not the bit in
`simplemerge.py`) very hard to follow, but I think I now finally
understand how it works. `mergestate.resolve()` calculates the merged
file flags and sets them on the local side of the merge (confusingly
by calling `_restore_backup()`). Then it calls
`filemerge.filemerge()`, which in turn calls
`simplemerge.simplemerge()` (if premerge is enabled). That means that
the flags on the local side `fcs.flags()` are already correct when the
flag-merging code in `simplemerge.simplemerge()` runs. Interestingly,
that code still works when the local side already has the merged
value, it just doesn't change the value. Here's a truth table to
explain why:

```
BLOMCAR
0000000
0011111
0101011
0111111
1000000
1010000
1100000
1111101
```

B: Base
L: Local
O: Other
M: Merged flags from `mergestate.resolve()`, i.e. what's called "local"
   when we get to `simplemerge.simplemerge()`
C: `commonflags` in `simplemerge.simplemerge()`, i.e. `M & O`
A: `addedflags` in `simplemerge.simplemerge()`, i.e. `(M ^ O) - B`
R: Re-merged flags `simplemerge.simplemerge()`, i.e. `C | A`

As you can see, the re-merged flags are always unchanged compared to
the initial merged flags (R equals M).

Therefore, this patch effectively backs out 84614212ae39. (I might
later refactor this code to have the flags explicitly passed in.)

`simplemerge.simplemerge()` is also called from
`contrib/simplemerge.py`, but that code never passes any flags.

Differential Revision: https://phab.mercurial-scm.org/D11879

# testparseutil.py - utilities to parse test script for check tools
#
#  Copyright 2018 FUJIWARA Katsunori <[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, print_function

import abc
import re
import sys

####################
# for Python3 compatibility (almost comes from mercurial/pycompat.py)

ispy3 = sys.version_info[0] >= 3


def identity(a):
    return a


def _rapply(f, xs):
    if xs is None:
        # assume None means non-value of optional data
        return xs
    if isinstance(xs, (list, set, tuple)):
        return type(xs)(_rapply(f, x) for x in xs)
    if isinstance(xs, dict):
        return type(xs)((_rapply(f, k), _rapply(f, v)) for k, v in xs.items())
    return f(xs)


def rapply(f, xs):
    if f is identity:
        # fast path mainly for py2
        return xs
    return _rapply(f, xs)


if ispy3:
    import builtins

    def bytestr(s):
        # tiny version of pycompat.bytestr
        return s.encode('latin1')

    def sysstr(s):
        if isinstance(s, builtins.str):
            return s
        return s.decode('latin-1')

    def opentext(f):
        return open(f, 'r')


else:
    bytestr = str
    sysstr = identity

    opentext = open


def b2s(x):
    # convert BYTES elements in "x" to SYSSTR recursively
    return rapply(sysstr, x)


def writeout(data):
    # write "data" in BYTES into stdout
    sys.stdout.write(data)


def writeerr(data):
    # write "data" in BYTES into stderr
    sys.stderr.write(data)


####################


class embeddedmatcher(object):  # pytype: disable=ignored-metaclass
    """Base class to detect embedded code fragments in *.t test script"""

    __metaclass__ = abc.ABCMeta

    def __init__(self, desc):
        self.desc = desc

    @abc.abstractmethod
    def startsat(self, line):
        """Examine whether embedded code starts at line

        This can return arbitrary object, and it is used as 'ctx' for
        subsequent method invocations.
        """

    @abc.abstractmethod
    def endsat(self, ctx, line):
        """Examine whether embedded code ends at line"""

    @abc.abstractmethod
    def isinside(self, ctx, line):
        """Examine whether line is inside embedded code, if not yet endsat"""

    @abc.abstractmethod
    def ignores(self, ctx):
        """Examine whether detected embedded code should be ignored"""

    @abc.abstractmethod
    def filename(self, ctx):
        """Return filename of embedded code

        If filename isn't specified for embedded code explicitly, this
        returns None.
        """

    @abc.abstractmethod
    def codeatstart(self, ctx, line):
        """Return actual code at the start line of embedded code

        This might return None, if the start line doesn't contain
        actual code.
        """

    @abc.abstractmethod
    def codeatend(self, ctx, line):
        """Return actual code at the end line of embedded code

        This might return None, if the end line doesn't contain actual
        code.
        """

    @abc.abstractmethod
    def codeinside(self, ctx, line):
        """Return actual code at line inside embedded code"""


def embedded(basefile, lines, errors, matchers):
    """pick embedded code fragments up from given lines

    This is common parsing logic, which examines specified matchers on
    given lines.

    :basefile: a name of a file, from which lines to be parsed come.
    :lines: to be parsed (might be a value returned by "open(basefile)")
    :errors: an array, into which messages for detected error are stored
    :matchers: an array of embeddedmatcher objects

    This function yields '(filename, starts, ends, code)' tuple.

    :filename: a name of embedded code, if it is explicitly specified
               (e.g.  "foobar" of "cat >> foobar <<EOF").
               Otherwise, this is None
    :starts: line number (1-origin), at which embedded code starts (inclusive)
    :ends: line number (1-origin), at which embedded code ends (exclusive)
    :code: extracted embedded code, which is single-stringified

    >>> class ambigmatcher(object):
    ...     # mock matcher class to examine implementation of
    ...     # "ambiguous matching" corner case
    ...     def __init__(self, desc, matchfunc):
    ...         self.desc = desc
    ...         self.matchfunc = matchfunc
    ...     def startsat(self, line):
    ...         return self.matchfunc(line)
    >>> ambig1 = ambigmatcher('ambiguous #1',
    ...                       lambda l: l.startswith('  $ cat '))
    >>> ambig2 = ambigmatcher('ambiguous #2',
    ...                       lambda l: l.endswith('<< EOF\\n'))
    >>> lines = ['  $ cat > foo.py << EOF\\n']
    >>> errors = []
    >>> matchers = [ambig1, ambig2]
    >>> list(t for t in embedded('<dummy>', lines, errors, matchers))
    []
    >>> b2s(errors)
    ['<dummy>:1: ambiguous line for "ambiguous #1", "ambiguous #2"']

    """
    matcher = None
    ctx = filename = code = startline = None  # for pyflakes

    for lineno, line in enumerate(lines, 1):
        if not line.endswith('\n'):
            line += '\n'  # to normalize EOF line
        if matcher:  # now, inside embedded code
            if matcher.endsat(ctx, line):
                codeatend = matcher.codeatend(ctx, line)
                if codeatend is not None:
                    code.append(codeatend)
                if not matcher.ignores(ctx):
                    yield (filename, startline, lineno, ''.join(code))
                matcher = None
                # DO NOT "continue", because line might start next fragment
            elif not matcher.isinside(ctx, line):
                # this is an error of basefile
                # (if matchers are implemented correctly)
                errors.append(
                    '%s:%d: unexpected line for "%s"'
                    % (basefile, lineno, matcher.desc)
                )
                # stop extracting embedded code by current 'matcher',
                # because appearance of unexpected line might mean
                # that expected end-of-embedded-code line might never
                # appear
                matcher = None
                # DO NOT "continue", because line might start next fragment
            else:
                code.append(matcher.codeinside(ctx, line))
                continue

        # examine whether current line starts embedded code or not
        assert not matcher

        matched = []
        for m in matchers:
            ctx = m.startsat(line)
            if ctx:
                matched.append((m, ctx))
        if matched:
            if len(matched) > 1:
                # this is an error of matchers, maybe
                errors.append(
                    '%s:%d: ambiguous line for %s'
                    % (
                        basefile,
                        lineno,
                        ', '.join(['"%s"' % m.desc for m, c in matched]),
                    )
                )
                # omit extracting embedded code, because choosing
                # arbitrary matcher from matched ones might fail to
                # detect the end of embedded code as expected.
                continue
            matcher, ctx = matched[0]
            filename = matcher.filename(ctx)
            code = []
            codeatstart = matcher.codeatstart(ctx, line)
            if codeatstart is not None:
                code.append(codeatstart)
                startline = lineno
            else:
                startline = lineno + 1

    if matcher:
        # examine whether EOF ends embedded code, because embedded
        # code isn't yet ended explicitly
        if matcher.endsat(ctx, '\n'):
            codeatend = matcher.codeatend(ctx, '\n')
            if codeatend is not None:
                code.append(codeatend)
            if not matcher.ignores(ctx):
                yield (filename, startline, lineno + 1, ''.join(code))
        else:
            # this is an error of basefile
            # (if matchers are implemented correctly)
            errors.append(
                '%s:%d: unexpected end of file for "%s"'
                % (basefile, lineno, matcher.desc)
            )


# heredoc limit mark to ignore embedded code at check-code.py or so
heredocignorelimit = 'NO_CHECK_EOF'

# the pattern to match against cases below, and to return a limit mark
# string as 'lname' group
#
# - << LIMITMARK
# - << "LIMITMARK"
# - << 'LIMITMARK'
heredoclimitpat = r'\s*<<\s*(?P<lquote>["\']?)(?P<limit>\w+)(?P=lquote)'


class fileheredocmatcher(embeddedmatcher):
    """Detect "cat > FILE << LIMIT" style embedded code

    >>> matcher = fileheredocmatcher('heredoc .py file', r'[^<]+\\.py')
    >>> b2s(matcher.startsat('  $ cat > file.py << EOF\\n'))
    ('file.py', '  > EOF\\n')
    >>> b2s(matcher.startsat('  $ cat   >>file.py   <<EOF\\n'))
    ('file.py', '  > EOF\\n')
    >>> b2s(matcher.startsat('  $ cat>  \\x27any file.py\\x27<<  "EOF"\\n'))
    ('any file.py', '  > EOF\\n')
    >>> b2s(matcher.startsat("  $ cat > file.py << 'ANYLIMIT'\\n"))
    ('file.py', '  > ANYLIMIT\\n')
    >>> b2s(matcher.startsat('  $ cat<<ANYLIMIT>"file.py"\\n'))
    ('file.py', '  > ANYLIMIT\\n')
    >>> start = '  $ cat > file.py << EOF\\n'
    >>> ctx = matcher.startsat(start)
    >>> matcher.codeatstart(ctx, start)
    >>> b2s(matcher.filename(ctx))
    'file.py'
    >>> matcher.ignores(ctx)
    False
    >>> inside = '  > foo = 1\\n'
    >>> matcher.endsat(ctx, inside)
    False
    >>> matcher.isinside(ctx, inside)
    True
    >>> b2s(matcher.codeinside(ctx, inside))
    'foo = 1\\n'
    >>> end = '  > EOF\\n'
    >>> matcher.endsat(ctx, end)
    True
    >>> matcher.codeatend(ctx, end)
    >>> matcher.endsat(ctx, '  > EOFEOF\\n')
    False
    >>> ctx = matcher.startsat('  $ cat > file.py << NO_CHECK_EOF\\n')
    >>> matcher.ignores(ctx)
    True
    """

    _prefix = '  > '

    def __init__(self, desc, namepat):
        super(fileheredocmatcher, self).__init__(desc)

        # build the pattern to match against cases below (and ">>"
        # variants), and to return a target filename string as 'name'
        # group
        #
        # - > NAMEPAT
        # - > "NAMEPAT"
        # - > 'NAMEPAT'
        namepat = (
            r'\s*>>?\s*(?P<nquote>["\']?)(?P<name>%s)(?P=nquote)' % namepat
        )
        self._fileres = [
            # "cat > NAME << LIMIT" case
            re.compile(r' {2}\$ \s*cat' + namepat + heredoclimitpat),
            # "cat << LIMIT > NAME" case
            re.compile(r' {2}\$ \s*cat' + heredoclimitpat + namepat),
        ]

    def startsat(self, line):
        # ctx is (filename, END-LINE-OF-EMBEDDED-CODE) tuple
        for filere in self._fileres:
            matched = filere.match(line)
            if matched:
                return (
                    matched.group('name'),
                    '  > %s\n' % matched.group('limit'),
                )

    def endsat(self, ctx, line):
        return ctx[1] == line

    def isinside(self, ctx, line):
        return line.startswith(self._prefix)

    def ignores(self, ctx):
        return '  > %s\n' % heredocignorelimit == ctx[1]

    def filename(self, ctx):
        return ctx[0]

    def codeatstart(self, ctx, line):
        return None  # no embedded code at start line

    def codeatend(self, ctx, line):
        return None  # no embedded code at end line

    def codeinside(self, ctx, line):
        return line[len(self._prefix) :]  # strip prefix


####
# for embedded python script


class pydoctestmatcher(embeddedmatcher):
    """Detect ">>> code" style embedded python code

    >>> matcher = pydoctestmatcher()
    >>> startline = '  >>> foo = 1\\n'
    >>> matcher.startsat(startline)
    True
    >>> matcher.startsat('  ... foo = 1\\n')
    False
    >>> ctx = matcher.startsat(startline)
    >>> matcher.filename(ctx)
    >>> matcher.ignores(ctx)
    False
    >>> b2s(matcher.codeatstart(ctx, startline))
    'foo = 1\\n'
    >>> inside = '  >>> foo = 1\\n'
    >>> matcher.endsat(ctx, inside)
    False
    >>> matcher.isinside(ctx, inside)
    True
    >>> b2s(matcher.codeinside(ctx, inside))
    'foo = 1\\n'
    >>> inside = '  ... foo = 1\\n'
    >>> matcher.endsat(ctx, inside)
    False
    >>> matcher.isinside(ctx, inside)
    True
    >>> b2s(matcher.codeinside(ctx, inside))
    'foo = 1\\n'
    >>> inside = '  expected output\\n'
    >>> matcher.endsat(ctx, inside)
    False
    >>> matcher.isinside(ctx, inside)
    True
    >>> b2s(matcher.codeinside(ctx, inside))
    '\\n'
    >>> inside = '  \\n'
    >>> matcher.endsat(ctx, inside)
    False
    >>> matcher.isinside(ctx, inside)
    True
    >>> b2s(matcher.codeinside(ctx, inside))
    '\\n'
    >>> end = '  $ foo bar\\n'
    >>> matcher.endsat(ctx, end)
    True
    >>> matcher.codeatend(ctx, end)
    >>> end = '\\n'
    >>> matcher.endsat(ctx, end)
    True
    >>> matcher.codeatend(ctx, end)
    """

    _prefix = '  >>> '
    _prefixre = re.compile(r' {2}(>>>|\.\.\.) ')

    # If a line matches against not _prefixre but _outputre, that line
    # is "an expected output line" (= not a part of code fragment).
    #
    # Strictly speaking, a line matching against "(#if|#else|#endif)"
    # is also treated similarly in "inline python code" semantics by
    # run-tests.py. But "directive line inside inline python code"
    # should be rejected by Mercurial reviewers. Therefore, this
    # regexp does not matche against such directive lines.
    _outputre = re.compile(r' {2}$| {2}[^$]')

    def __init__(self):
        super(pydoctestmatcher, self).__init__("doctest style python code")

    def startsat(self, line):
        # ctx is "True"
        return line.startswith(self._prefix)

    def endsat(self, ctx, line):
        return not (self._prefixre.match(line) or self._outputre.match(line))

    def isinside(self, ctx, line):
        return True  # always true, if not yet ended

    def ignores(self, ctx):
        return False  # should be checked always

    def filename(self, ctx):
        return None  # no filename

    def codeatstart(self, ctx, line):
        return line[len(self._prefix) :]  # strip prefix '  >>> '/'  ... '

    def codeatend(self, ctx, line):
        return None  # no embedded code at end line

    def codeinside(self, ctx, line):
        if self._prefixre.match(line):
            return line[len(self._prefix) :]  # strip prefix '  >>> '/'  ... '
        return '\n'  # an expected output line is treated as an empty line


class pyheredocmatcher(embeddedmatcher):
    """Detect "python << LIMIT" style embedded python code

    >>> matcher = pyheredocmatcher()
    >>> b2s(matcher.startsat('  $ python << EOF\\n'))
    '  > EOF\\n'
    >>> b2s(matcher.startsat('  $ $PYTHON   <<EOF\\n'))
    '  > EOF\\n'
    >>> b2s(matcher.startsat('  $ "$PYTHON"<<  "EOF"\\n'))
    '  > EOF\\n'
    >>> b2s(matcher.startsat("  $ $PYTHON << 'ANYLIMIT'\\n"))
    '  > ANYLIMIT\\n'
    >>> matcher.startsat('  $ "$PYTHON" < EOF\\n')
    >>> start = '  $ python << EOF\\n'
    >>> ctx = matcher.startsat(start)
    >>> matcher.codeatstart(ctx, start)
    >>> matcher.filename(ctx)
    >>> matcher.ignores(ctx)
    False
    >>> inside = '  > foo = 1\\n'
    >>> matcher.endsat(ctx, inside)
    False
    >>> matcher.isinside(ctx, inside)
    True
    >>> b2s(matcher.codeinside(ctx, inside))
    'foo = 1\\n'
    >>> end = '  > EOF\\n'
    >>> matcher.endsat(ctx, end)
    True
    >>> matcher.codeatend(ctx, end)
    >>> matcher.endsat(ctx, '  > EOFEOF\\n')
    False
    >>> ctx = matcher.startsat('  $ python << NO_CHECK_EOF\\n')
    >>> matcher.ignores(ctx)
    True
    """

    _prefix = '  > '

    _startre = re.compile(
        r' {2}\$ (\$PYTHON|"\$PYTHON"|python).*' + heredoclimitpat
    )

    def __init__(self):
        super(pyheredocmatcher, self).__init__("heredoc python invocation")

    def startsat(self, line):
        # ctx is END-LINE-OF-EMBEDDED-CODE
        matched = self._startre.match(line)
        if matched:
            return '  > %s\n' % matched.group('limit')

    def endsat(self, ctx, line):
        return ctx == line

    def isinside(self, ctx, line):
        return line.startswith(self._prefix)

    def ignores(self, ctx):
        return '  > %s\n' % heredocignorelimit == ctx

    def filename(self, ctx):
        return None  # no filename

    def codeatstart(self, ctx, line):
        return None  # no embedded code at start line

    def codeatend(self, ctx, line):
        return None  # no embedded code at end line

    def codeinside(self, ctx, line):
        return line[len(self._prefix) :]  # strip prefix


_pymatchers = [
    pydoctestmatcher(),
    pyheredocmatcher(),
    # use '[^<]+' instead of '\S+', in order to match against
    # paths including whitespaces
    fileheredocmatcher('heredoc .py file', r'[^<]+\.py'),
]


def pyembedded(basefile, lines, errors):
    return embedded(basefile, lines, errors, _pymatchers)


####
# for embedded shell script

_shmatchers = [
    # use '[^<]+' instead of '\S+', in order to match against
    # paths including whitespaces
    fileheredocmatcher('heredoc .sh file', r'[^<]+\.sh'),
]


def shembedded(basefile, lines, errors):
    return embedded(basefile, lines, errors, _shmatchers)


####
# for embedded hgrc configuration

_hgrcmatchers = [
    # use '[^<]+' instead of '\S+', in order to match against
    # paths including whitespaces
    fileheredocmatcher(
        'heredoc hgrc file', r'(([^/<]+/)+hgrc|\$HGRCPATH|\${HGRCPATH})'
    ),
]


def hgrcembedded(basefile, lines, errors):
    return embedded(basefile, lines, errors, _hgrcmatchers)


####

if __name__ == "__main__":
    import optparse
    import sys

    def showembedded(basefile, lines, embeddedfunc, opts):
        errors = []
        for name, starts, ends, code in embeddedfunc(basefile, lines, errors):
            if not name:
                name = '<anonymous>'
            writeout("%s:%d: %s starts\n" % (basefile, starts, name))
            if opts.verbose and code:
                writeout("  |%s\n" % "\n  |".join(l for l in code.splitlines()))
            writeout("%s:%d: %s ends\n" % (basefile, ends, name))
        for e in errors:
            writeerr("%s\n" % e)
        return len(errors)

    def applyembedded(args, embeddedfunc, opts):
        ret = 0
        if args:
            for f in args:
                with opentext(f) as fp:
                    if showembedded(f, fp, embeddedfunc, opts):
                        ret = 1
        else:
            lines = [l for l in sys.stdin.readlines()]
            if showembedded('<stdin>', lines, embeddedfunc, opts):
                ret = 1
        return ret

    commands = {}

    def command(name, desc):
        def wrap(func):
            commands[name] = (desc, func)

        return wrap

    @command("pyembedded", "detect embedded python script")
    def pyembeddedcmd(args, opts):
        return applyembedded(args, pyembedded, opts)

    @command("shembedded", "detect embedded shell script")
    def shembeddedcmd(args, opts):
        return applyembedded(args, shembedded, opts)

    @command("hgrcembedded", "detect embedded hgrc configuration")
    def hgrcembeddedcmd(args, opts):
        return applyembedded(args, hgrcembedded, opts)

    availablecommands = "\n".join(
        ["  - %s: %s" % (key, value[0]) for key, value in commands.items()]
    )

    parser = optparse.OptionParser(
        """%prog COMMAND [file ...]

Pick up embedded code fragments from given file(s) or stdin, and list
up start/end lines of them in standard compiler format
("FILENAME:LINENO:").

Available commands are:
"""
        + availablecommands
        + """
"""
    )
    parser.add_option(
        "-v",
        "--verbose",
        help="enable additional output (e.g. actual code)",
        action="store_true",
    )
    (opts, args) = parser.parse_args()

    if not args or args[0] not in commands:
        parser.print_help()
        sys.exit(255)

    sys.exit(commands[args[0]][1](args[1:], opts))