view mercurial/revsetlang.py @ 44950:f9734b2d59cc

py3: make stdout line-buffered if connected to a TTY Status messages that are to be shown on the terminal should be written to the file descriptor before anything further is done, to keep the user updated. One common way to achieve this is to make stdout line-buffered if it is connected to a TTY. This is done on Python 2 (except on Windows, where libc, which the CPython 2 streams depend on, does not properly support this). Python 3 rolls it own I/O streams. On Python 3, buffered binary streams can't be set line-buffered. The previous code (added in 227ba1afcb65) incorrectly assumed that on Python 3, pycompat.stdout (sys.stdout.buffer) is already line-buffered. However the interpreter initializes it with a block-buffered stream or an unbuffered stream (when the -u option or the PYTHONUNBUFFERED environment variable is set), never with a line-buffered stream. One example where the current behavior is unacceptable is when running `hg pull https://www.mercurial-scm.org/repo/hg` on Python 3, where the line "pulling from https://www.mercurial-scm.org/repo/hg" does not appear on the terminal before the hg process blocks while waiting for the server. Various approaches to fix this problem are possible, including: 1. Weaken the contract of procutil.stdout to not give any guarantees about buffering behavior. In this case, users of procutil.stdout need to be changed to do enough flushes. In particular, 1. either ui must insert enough flushes for ui.write() and friends, or 2. ui.write() and friends get split into flushing and fully buffered methods, or 3. users of ui.write() and friends must flush explicitly. 2. Make stdout unbuffered. 3. Make stdout line-buffered. Since Python 3 does not natively support that for binary streams, we must implement it ourselves. (2.) is problematic because using unbuffered I/O changes the performance characteristics significantly compared to line-buffered (which is used on Python 2) and this would be a regression. (1.2.) and (1.3) are a substantial amount of work. It’s unclear whether the added complexity would be justified, given that raw performance doesn’t matter that much when writing to a terminal much faster than the user could read it. (1.1.) pushes complexity into the ui class instead of separating the concern of how stdout is buffered. Other users of procutil.stdout would still need to take care of the flushes. This patch implements (3.). The general performance considerations are very similar to (1.1.). The extra method invocation and method forwarding add a little more overhead if the class is used. In exchange, it doesn’t add overhead if not used. For the benchmarks, I compared the previous implementation (incorrect on Python 3), (1.1.), (3.) and (2.). The command was chosen so that the streams were configured as if they were writing to a TTY, but actually write to a pager, which is also the default: HGRCPATH=/dev/null python3 ./hg --cwd ~/vcs/mozilla-central --time --pager yes --config pager.pager='cat > /dev/null' status --all previous: time: real 7.880 secs (user 7.290+0.050 sys 0.580+0.170) time: real 7.830 secs (user 7.220+0.070 sys 0.590+0.140) time: real 7.800 secs (user 7.210+0.050 sys 0.570+0.170) (1.1.) using Yuya Nishihara’s patch: time: real 9.860 secs (user 8.670+0.350 sys 1.160+0.830) time: real 9.540 secs (user 8.430+0.370 sys 1.100+0.770) time: real 9.830 secs (user 8.630+0.370 sys 1.180+0.840) (3.) using this patch: time: real 9.580 secs (user 8.480+0.350 sys 1.090+0.770) time: real 9.670 secs (user 8.480+0.330 sys 1.170+0.860) time: real 9.640 secs (user 8.500+0.350 sys 1.130+0.810) (2.) using a previous patch by me: time: real 10.480 secs (user 8.850+0.720 sys 1.590+1.500) time: real 10.490 secs (user 8.750+0.750 sys 1.710+1.470) time: real 10.240 secs (user 8.600+0.700 sys 1.590+1.510) As expected, there’s no difference on Python 2, as exactly the same code paths are used: previous: time: real 6.950 secs (user 5.870+0.330 sys 1.070+0.770) time: real 7.040 secs (user 6.040+0.360 sys 0.980+0.750) time: real 7.070 secs (user 5.950+0.360 sys 1.100+0.760) this patch: time: real 7.010 secs (user 5.900+0.390 sys 1.070+0.730) time: real 7.000 secs (user 5.850+0.350 sys 1.120+0.760) time: real 7.000 secs (user 5.790+0.380 sys 1.170+0.710)
author Manuel Jacob <me@manueljacob.de>
date Wed, 10 Jun 2020 13:02:39 +0200
parents d783f945a701
children 0fc8b066928a
line wrap: on
line source

# revsetlang.py - parser, tokenizer and utility for revision set language
#
# Copyright 2010 Matt Mackall <mpm@selenic.com>
#
# 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

import string

from .i18n import _
from .pycompat import getattr
from . import (
    error,
    node,
    parser,
    pycompat,
    smartset,
    util,
)
from .utils import stringutil

elements = {
    # token-type: binding-strength, primary, prefix, infix, suffix
    b"(": (21, None, (b"group", 1, b")"), (b"func", 1, b")"), None),
    b"[": (21, None, None, (b"subscript", 1, b"]"), None),
    b"#": (21, None, None, (b"relation", 21), None),
    b"##": (20, None, None, (b"_concat", 20), None),
    b"~": (18, None, None, (b"ancestor", 18), None),
    b"^": (18, None, None, (b"parent", 18), b"parentpost"),
    b"-": (5, None, (b"negate", 19), (b"minus", 5), None),
    b"::": (
        17,
        b"dagrangeall",
        (b"dagrangepre", 17),
        (b"dagrange", 17),
        b"dagrangepost",
    ),
    b"..": (
        17,
        b"dagrangeall",
        (b"dagrangepre", 17),
        (b"dagrange", 17),
        b"dagrangepost",
    ),
    b":": (15, b"rangeall", (b"rangepre", 15), (b"range", 15), b"rangepost"),
    b"not": (10, None, (b"not", 10), None, None),
    b"!": (10, None, (b"not", 10), None, None),
    b"and": (5, None, None, (b"and", 5), None),
    b"&": (5, None, None, (b"and", 5), None),
    b"%": (5, None, None, (b"only", 5), b"onlypost"),
    b"or": (4, None, None, (b"or", 4), None),
    b"|": (4, None, None, (b"or", 4), None),
    b"+": (4, None, None, (b"or", 4), None),
    b"=": (3, None, None, (b"keyvalue", 3), None),
    b",": (2, None, None, (b"list", 2), None),
    b")": (0, None, None, None, None),
    b"]": (0, None, None, None, None),
    b"symbol": (0, b"symbol", None, None, None),
    b"string": (0, b"string", None, None, None),
    b"end": (0, None, None, None, None),
}

keywords = {b'and', b'or', b'not'}

symbols = {}

_quoteletters = {b'"', b"'"}
_simpleopletters = set(pycompat.iterbytestr(b"()[]#:=,-|&+!~^%"))

# default set of valid characters for the initial letter of symbols
_syminitletters = set(
    pycompat.iterbytestr(
        pycompat.sysbytes(string.ascii_letters)
        + pycompat.sysbytes(string.digits)
        + b'._@'
    )
) | set(map(pycompat.bytechr, pycompat.xrange(128, 256)))

# default set of valid characters for non-initial letters of symbols
_symletters = _syminitletters | set(pycompat.iterbytestr(b'-/'))


def tokenize(program, lookup=None, syminitletters=None, symletters=None):
    '''
    Parse a revset statement into a stream of tokens

    ``syminitletters`` is the set of valid characters for the initial
    letter of symbols.

    By default, character ``c`` is recognized as valid for initial
    letter of symbols, if ``c.isalnum() or c in '._@' or ord(c) > 127``.

    ``symletters`` is the set of valid characters for non-initial
    letters of symbols.

    By default, character ``c`` is recognized as valid for non-initial
    letters of symbols, if ``c.isalnum() or c in '-._/@' or ord(c) > 127``.

    Check that @ is a valid unquoted token character (issue3686):
    >>> list(tokenize(b"@::"))
    [('symbol', '@', 0), ('::', None, 1), ('end', None, 3)]

    '''
    if not isinstance(program, bytes):
        raise error.ProgrammingError(
            b'revset statement must be bytes, got %r' % program
        )
    program = pycompat.bytestr(program)
    if syminitletters is None:
        syminitletters = _syminitletters
    if symletters is None:
        symletters = _symletters

    if program and lookup:
        # attempt to parse old-style ranges first to deal with
        # things like old-tag which contain query metacharacters
        parts = program.split(b':', 1)
        if all(lookup(sym) for sym in parts if sym):
            if parts[0]:
                yield (b'symbol', parts[0], 0)
            if len(parts) > 1:
                s = len(parts[0])
                yield (b':', None, s)
                if parts[1]:
                    yield (b'symbol', parts[1], s + 1)
            yield (b'end', None, len(program))
            return

    pos, l = 0, len(program)
    while pos < l:
        c = program[pos]
        if c.isspace():  # skip inter-token whitespace
            pass
        elif (
            c == b':' and program[pos : pos + 2] == b'::'
        ):  # look ahead carefully
            yield (b'::', None, pos)
            pos += 1  # skip ahead
        elif (
            c == b'.' and program[pos : pos + 2] == b'..'
        ):  # look ahead carefully
            yield (b'..', None, pos)
            pos += 1  # skip ahead
        elif (
            c == b'#' and program[pos : pos + 2] == b'##'
        ):  # look ahead carefully
            yield (b'##', None, pos)
            pos += 1  # skip ahead
        elif c in _simpleopletters:  # handle simple operators
            yield (c, None, pos)
        elif (
            c in _quoteletters
            or c == b'r'
            and program[pos : pos + 2] in (b"r'", b'r"')
        ):  # handle quoted strings
            if c == b'r':
                pos += 1
                c = program[pos]
                decode = lambda x: x
            else:
                decode = parser.unescapestr
            pos += 1
            s = pos
            while pos < l:  # find closing quote
                d = program[pos]
                if d == b'\\':  # skip over escaped characters
                    pos += 2
                    continue
                if d == c:
                    yield (b'string', decode(program[s:pos]), s)
                    break
                pos += 1
            else:
                raise error.ParseError(_(b"unterminated string"), s)
        # gather up a symbol/keyword
        elif c in syminitletters:
            s = pos
            pos += 1
            while pos < l:  # find end of symbol
                d = program[pos]
                if d not in symletters:
                    break
                if (
                    d == b'.' and program[pos - 1] == b'.'
                ):  # special case for ..
                    pos -= 1
                    break
                pos += 1
            sym = program[s:pos]
            if sym in keywords:  # operator keywords
                yield (sym, None, s)
            elif b'-' in sym:
                # some jerk gave us foo-bar-baz, try to check if it's a symbol
                if lookup and lookup(sym):
                    # looks like a real symbol
                    yield (b'symbol', sym, s)
                else:
                    # looks like an expression
                    parts = sym.split(b'-')
                    for p in parts[:-1]:
                        if p:  # possible consecutive -
                            yield (b'symbol', p, s)
                        s += len(p)
                        yield (b'-', None, s)
                        s += 1
                    if parts[-1]:  # possible trailing -
                        yield (b'symbol', parts[-1], s)
            else:
                yield (b'symbol', sym, s)
            pos -= 1
        else:
            raise error.ParseError(
                _(b"syntax error in revset '%s'") % program, pos
            )
        pos += 1
    yield (b'end', None, pos)


# helpers

_notset = object()


def getsymbol(x):
    if x and x[0] == b'symbol':
        return x[1]
    raise error.ParseError(_(b'not a symbol'))


def getstring(x, err):
    if x and (x[0] == b'string' or x[0] == b'symbol'):
        return x[1]
    raise error.ParseError(err)


def getinteger(x, err, default=_notset):
    if not x and default is not _notset:
        return default
    try:
        return int(getstring(x, err))
    except ValueError:
        raise error.ParseError(err)


def getboolean(x, err):
    value = stringutil.parsebool(getsymbol(x))
    if value is not None:
        return value
    raise error.ParseError(err)


def getlist(x):
    if not x:
        return []
    if x[0] == b'list':
        return list(x[1:])
    return [x]


def getrange(x, err):
    if not x:
        raise error.ParseError(err)
    op = x[0]
    if op == b'range':
        return x[1], x[2]
    elif op == b'rangepre':
        return None, x[1]
    elif op == b'rangepost':
        return x[1], None
    elif op == b'rangeall':
        return None, None
    raise error.ParseError(err)


def getintrange(x, err1, err2, deffirst=_notset, deflast=_notset):
    """Get [first, last] integer range (both inclusive) from a parsed tree

    If any of the sides omitted, and if no default provided, ParseError will
    be raised.
    """
    if x and (x[0] == b'string' or x[0] == b'symbol'):
        n = getinteger(x, err1)
        return n, n
    a, b = getrange(x, err1)
    return getinteger(a, err2, deffirst), getinteger(b, err2, deflast)


def getargs(x, min, max, err):
    l = getlist(x)
    if len(l) < min or (max >= 0 and len(l) > max):
        raise error.ParseError(err)
    return l


def getargsdict(x, funcname, keys):
    return parser.buildargsdict(
        getlist(x),
        funcname,
        parser.splitargspec(keys),
        keyvaluenode=b'keyvalue',
        keynode=b'symbol',
    )


# cache of {spec: raw parsed tree} built internally
_treecache = {}


def _cachedtree(spec):
    # thread safe because parse() is reentrant and dict.__setitem__() is atomic
    tree = _treecache.get(spec)
    if tree is None:
        _treecache[spec] = tree = parse(spec)
    return tree


def _build(tmplspec, *repls):
    """Create raw parsed tree from a template revset statement

    >>> _build(b'f(_) and _', (b'string', b'1'), (b'symbol', b'2'))
    ('and', ('func', ('symbol', 'f'), ('string', '1')), ('symbol', '2'))
    """
    template = _cachedtree(tmplspec)
    return parser.buildtree(template, (b'symbol', b'_'), *repls)


def _match(patspec, tree):
    """Test if a tree matches the given pattern statement; return the matches

    >>> _match(b'f(_)', parse(b'f()'))
    >>> _match(b'f(_)', parse(b'f(1)'))
    [('func', ('symbol', 'f'), ('symbol', '1')), ('symbol', '1')]
    >>> _match(b'f(_)', parse(b'f(1, 2)'))
    """
    pattern = _cachedtree(patspec)
    return parser.matchtree(
        pattern, tree, (b'symbol', b'_'), {b'keyvalue', b'list'}
    )


def _matchonly(revs, bases):
    return _match(b'ancestors(_) and not ancestors(_)', (b'and', revs, bases))


def _fixops(x):
    """Rewrite raw parsed tree to resolve ambiguous syntax which cannot be
    handled well by our simple top-down parser"""
    if not isinstance(x, tuple):
        return x

    op = x[0]
    if op == b'parent':
        # x^:y means (x^) : y, not x ^ (:y)
        # x^:  means (x^) :,   not x ^ (:)
        post = (b'parentpost', x[1])
        if x[2][0] == b'dagrangepre':
            return _fixops((b'dagrange', post, x[2][1]))
        elif x[2][0] == b'dagrangeall':
            return _fixops((b'dagrangepost', post))
        elif x[2][0] == b'rangepre':
            return _fixops((b'range', post, x[2][1]))
        elif x[2][0] == b'rangeall':
            return _fixops((b'rangepost', post))
    elif op == b'or':
        # make number of arguments deterministic:
        # x + y + z -> (or x y z) -> (or (list x y z))
        return (op, _fixops((b'list',) + x[1:]))
    elif op == b'subscript' and x[1][0] == b'relation':
        # x#y[z] ternary
        return _fixops((b'relsubscript', x[1][1], x[1][2], x[2]))

    return (op,) + tuple(_fixops(y) for y in x[1:])


def _analyze(x):
    if x is None:
        return x

    op = x[0]
    if op == b'minus':
        return _analyze(_build(b'_ and not _', *x[1:]))
    elif op == b'only':
        return _analyze(_build(b'only(_, _)', *x[1:]))
    elif op == b'onlypost':
        return _analyze(_build(b'only(_)', x[1]))
    elif op == b'dagrangeall':
        raise error.ParseError(_(b"can't use '::' in this context"))
    elif op == b'dagrangepre':
        return _analyze(_build(b'ancestors(_)', x[1]))
    elif op == b'dagrangepost':
        return _analyze(_build(b'descendants(_)', x[1]))
    elif op == b'negate':
        s = getstring(x[1], _(b"can't negate that"))
        return _analyze((b'string', b'-' + s))
    elif op in (b'string', b'symbol', b'smartset'):
        return x
    elif op == b'rangeall':
        return (op, None)
    elif op in {b'or', b'not', b'rangepre', b'rangepost', b'parentpost'}:
        return (op, _analyze(x[1]))
    elif op == b'group':
        return _analyze(x[1])
    elif op in {
        b'and',
        b'dagrange',
        b'range',
        b'parent',
        b'ancestor',
        b'relation',
        b'subscript',
    }:
        ta = _analyze(x[1])
        tb = _analyze(x[2])
        return (op, ta, tb)
    elif op == b'relsubscript':
        ta = _analyze(x[1])
        tb = _analyze(x[2])
        tc = _analyze(x[3])
        return (op, ta, tb, tc)
    elif op == b'list':
        return (op,) + tuple(_analyze(y) for y in x[1:])
    elif op == b'keyvalue':
        return (op, x[1], _analyze(x[2]))
    elif op == b'func':
        return (op, x[1], _analyze(x[2]))
    raise ValueError(b'invalid operator %r' % op)


def analyze(x):
    """Transform raw parsed tree to evaluatable tree which can be fed to
    optimize() or getset()

    All pseudo operations should be mapped to real operations or functions
    defined in methods or symbols table respectively.
    """
    return _analyze(x)


def _optimize(x):
    if x is None:
        return 0, x

    op = x[0]
    if op in (b'string', b'symbol', b'smartset'):
        return 0.5, x  # single revisions are small
    elif op == b'and':
        wa, ta = _optimize(x[1])
        wb, tb = _optimize(x[2])
        w = min(wa, wb)

        # (draft/secret/_notpublic() & ::x) have a fast path
        m = _match(b'_() & ancestors(_)', (b'and', ta, tb))
        if m and getsymbol(m[1]) in {b'draft', b'secret', b'_notpublic'}:
            return w, _build(b'_phaseandancestors(_, _)', m[1], m[2])

        # (::x and not ::y)/(not ::y and ::x) have a fast path
        m = _matchonly(ta, tb) or _matchonly(tb, ta)
        if m:
            return w, _build(b'only(_, _)', *m[1:])

        m = _match(b'not _', tb)
        if m:
            return wa, (b'difference', ta, m[1])
        if wa > wb:
            op = b'andsmally'
        return w, (op, ta, tb)
    elif op == b'or':
        # fast path for machine-generated expression, that is likely to have
        # lots of trivial revisions: 'a + b + c()' to '_list(a b) + c()'
        ws, ts, ss = [], [], []

        def flushss():
            if not ss:
                return
            if len(ss) == 1:
                w, t = ss[0]
            else:
                s = b'\0'.join(t[1] for w, t in ss)
                y = _build(b'_list(_)', (b'string', s))
                w, t = _optimize(y)
            ws.append(w)
            ts.append(t)
            del ss[:]

        for y in getlist(x[1]):
            w, t = _optimize(y)
            if t is not None and (t[0] == b'string' or t[0] == b'symbol'):
                ss.append((w, t))
                continue
            flushss()
            ws.append(w)
            ts.append(t)
        flushss()
        if len(ts) == 1:
            return ws[0], ts[0]  # 'or' operation is fully optimized out
        return max(ws), (op, (b'list',) + tuple(ts))
    elif op == b'not':
        # Optimize not public() to _notpublic() because we have a fast version
        if _match(b'public()', x[1]):
            o = _optimize(_build(b'_notpublic()'))
            return o[0], o[1]
        else:
            o = _optimize(x[1])
            return o[0], (op, o[1])
    elif op == b'rangeall':
        return 1, x
    elif op in (b'rangepre', b'rangepost', b'parentpost'):
        o = _optimize(x[1])
        return o[0], (op, o[1])
    elif op in (b'dagrange', b'range'):
        wa, ta = _optimize(x[1])
        wb, tb = _optimize(x[2])
        return wa + wb, (op, ta, tb)
    elif op in (b'parent', b'ancestor', b'relation', b'subscript'):
        w, t = _optimize(x[1])
        return w, (op, t, x[2])
    elif op == b'relsubscript':
        w, t = _optimize(x[1])
        return w, (op, t, x[2], x[3])
    elif op == b'list':
        ws, ts = zip(*(_optimize(y) for y in x[1:]))
        return sum(ws), (op,) + ts
    elif op == b'keyvalue':
        w, t = _optimize(x[2])
        return w, (op, x[1], t)
    elif op == b'func':
        f = getsymbol(x[1])
        wa, ta = _optimize(x[2])
        w = getattr(symbols.get(f), '_weight', 1)
        m = _match(b'commonancestors(_)', ta)

        # Optimize heads(commonancestors(_)) because we have a fast version
        if f == b'heads' and m:
            return w + wa, _build(b'_commonancestorheads(_)', m[1])

        return w + wa, (op, x[1], ta)
    raise ValueError(b'invalid operator %r' % op)


def optimize(tree):
    """Optimize evaluatable tree

    All pseudo operations should be transformed beforehand.
    """
    _weight, newtree = _optimize(tree)
    return newtree


# the set of valid characters for the initial letter of symbols in
# alias declarations and definitions
_aliassyminitletters = _syminitletters | {b'$'}


def _parsewith(spec, lookup=None, syminitletters=None):
    """Generate a parse tree of given spec with given tokenizing options

    >>> _parsewith(b'foo($1)', syminitletters=_aliassyminitletters)
    ('func', ('symbol', 'foo'), ('symbol', '$1'))
    >>> _parsewith(b'$1')
    Traceback (most recent call last):
      ...
    ParseError: ("syntax error in revset '$1'", 0)
    >>> _parsewith(b'foo bar')
    Traceback (most recent call last):
      ...
    ParseError: ('invalid token', 4)
    """
    if lookup and spec.startswith(b'revset(') and spec.endswith(b')'):
        lookup = None
    p = parser.parser(elements)
    tree, pos = p.parse(
        tokenize(spec, lookup=lookup, syminitletters=syminitletters)
    )
    if pos != len(spec):
        raise error.ParseError(_(b'invalid token'), pos)
    return _fixops(parser.simplifyinfixops(tree, (b'list', b'or')))


class _aliasrules(parser.basealiasrules):
    """Parsing and expansion rule set of revset aliases"""

    _section = _(b'revset alias')

    @staticmethod
    def _parse(spec):
        """Parse alias declaration/definition ``spec``

        This allows symbol names to use also ``$`` as an initial letter
        (for backward compatibility), and callers of this function should
        examine whether ``$`` is used also for unexpected symbols or not.
        """
        return _parsewith(spec, syminitletters=_aliassyminitletters)

    @staticmethod
    def _trygetfunc(tree):
        if tree[0] == b'func' and tree[1][0] == b'symbol':
            return tree[1][1], getlist(tree[2])


def expandaliases(tree, aliases, warn=None):
    """Expand aliases in a tree, aliases is a list of (name, value) tuples"""
    aliases = _aliasrules.buildmap(aliases)
    tree = _aliasrules.expand(aliases, tree)
    # warn about problematic (but not referred) aliases
    if warn is not None:
        for name, alias in sorted(pycompat.iteritems(aliases)):
            if alias.error and not alias.warned:
                warn(_(b'warning: %s\n') % (alias.error))
                alias.warned = True
    return tree


def foldconcat(tree):
    """Fold elements to be concatenated by `##`
    """
    if not isinstance(tree, tuple) or tree[0] in (
        b'string',
        b'symbol',
        b'smartset',
    ):
        return tree
    if tree[0] == b'_concat':
        pending = [tree]
        l = []
        while pending:
            e = pending.pop()
            if e[0] == b'_concat':
                pending.extend(reversed(e[1:]))
            elif e[0] in (b'string', b'symbol'):
                l.append(e[1])
            else:
                msg = _(b"\"##\" can't concatenate \"%s\" element") % (e[0])
                raise error.ParseError(msg)
        return (b'string', b''.join(l))
    else:
        return tuple(foldconcat(t) for t in tree)


def parse(spec, lookup=None):
    try:
        return _parsewith(spec, lookup=lookup)
    except error.ParseError as inst:
        if len(inst.args) > 1:  # has location
            loc = inst.args[1]
            # Remove newlines -- spaces are equivalent whitespace.
            spec = spec.replace(b'\n', b' ')
            # We want the caret to point to the place in the template that
            # failed to parse, but in a hint we get a open paren at the
            # start. Therefore, we print "loc + 1" spaces (instead of "loc")
            # to line up the caret with the location of the error.
            inst.hint = spec + b'\n' + b' ' * (loc + 1) + b'^ ' + _(b'here')
        raise


def _quote(s):
    r"""Quote a value in order to make it safe for the revset engine.

    >>> _quote(b'asdf')
    "'asdf'"
    >>> _quote(b"asdf'\"")
    '\'asdf\\\'"\''
    >>> _quote(b'asdf\'')
    "'asdf\\''"
    >>> _quote(1)
    "'1'"
    """
    return b"'%s'" % stringutil.escapestr(pycompat.bytestr(s))


def _formatargtype(c, arg):
    if c == b'd':
        return b'_rev(%d)' % int(arg)
    elif c == b's':
        return _quote(arg)
    elif c == b'r':
        if not isinstance(arg, bytes):
            raise TypeError
        parse(arg)  # make sure syntax errors are confined
        return b'(%s)' % arg
    elif c == b'n':
        return _quote(node.hex(arg))
    elif c == b'b':
        try:
            return _quote(arg.branch())
        except AttributeError:
            raise TypeError
    raise error.ParseError(_(b'unexpected revspec format character %s') % c)


def _formatlistexp(s, t):
    l = len(s)
    if l == 0:
        return b"_list('')"
    elif l == 1:
        return _formatargtype(t, s[0])
    elif t == b'd':
        return _formatintlist(s)
    elif t == b's':
        return b"_list(%s)" % _quote(b"\0".join(s))
    elif t == b'n':
        return b"_hexlist('%s')" % b"\0".join(node.hex(a) for a in s)
    elif t == b'b':
        try:
            return b"_list('%s')" % b"\0".join(a.branch() for a in s)
        except AttributeError:
            raise TypeError

    m = l // 2
    return b'(%s or %s)' % (_formatlistexp(s[:m], t), _formatlistexp(s[m:], t))


def _formatintlist(data):
    try:
        l = len(data)
        if l == 0:
            return b"_list('')"
        elif l == 1:
            return _formatargtype(b'd', data[0])
        return b"_intlist('%s')" % b"\0".join(b'%d' % int(a) for a in data)
    except (TypeError, ValueError):
        raise error.ParseError(_(b'invalid argument for revspec'))


def _formatparamexp(args, t):
    return b', '.join(_formatargtype(t, a) for a in args)


_formatlistfuncs = {
    b'l': _formatlistexp,
    b'p': _formatparamexp,
}


def formatspec(expr, *args):
    '''
    This is a convenience function for using revsets internally, and
    escapes arguments appropriately. Aliases are intentionally ignored
    so that intended expression behavior isn't accidentally subverted.

    Supported arguments:

    %r = revset expression, parenthesized
    %d = rev(int(arg)), no quoting
    %s = string(arg), escaped and single-quoted
    %b = arg.branch(), escaped and single-quoted
    %n = hex(arg), single-quoted
    %% = a literal '%'

    Prefixing the type with 'l' specifies a parenthesized list of that type,
    and 'p' specifies a list of function parameters of that type.

    >>> formatspec(b'%r:: and %lr', b'10 or 11', (b"this()", b"that()"))
    '(10 or 11):: and ((this()) or (that()))'
    >>> formatspec(b'%d:: and not %d::', 10, 20)
    '_rev(10):: and not _rev(20)::'
    >>> formatspec(b'%ld or %ld', [], [1])
    "_list('') or _rev(1)"
    >>> formatspec(b'keyword(%s)', b'foo\\xe9')
    "keyword('foo\\\\xe9')"
    >>> b = lambda: b'default'
    >>> b.branch = b
    >>> formatspec(b'branch(%b)', b)
    "branch('default')"
    >>> formatspec(b'root(%ls)', [b'a', b'b', b'c', b'd'])
    "root(_list('a\\\\x00b\\\\x00c\\\\x00d'))"
    >>> formatspec(b'sort(%r, %ps)', b':', [b'desc', b'user'])
    "sort((:), 'desc', 'user')"
    >>> formatspec(b'%ls', [b'a', b"'"])
    "_list('a\\\\x00\\\\'')"
    '''
    parsed = _parseargs(expr, args)
    ret = []
    for t, arg in parsed:
        if t is None:
            ret.append(arg)
        elif t == b'baseset':
            if isinstance(arg, set):
                arg = sorted(arg)
            ret.append(_formatintlist(list(arg)))
        else:
            raise error.ProgrammingError(b"unknown revspec item type: %r" % t)
    return b''.join(ret)


def spectree(expr, *args):
    """similar to formatspec but return a parsed and optimized tree"""
    parsed = _parseargs(expr, args)
    ret = []
    inputs = []
    for t, arg in parsed:
        if t is None:
            ret.append(arg)
        elif t == b'baseset':
            newtree = (b'smartset', smartset.baseset(arg))
            inputs.append(newtree)
            ret.append(b"$")
        else:
            raise error.ProgrammingError(b"unknown revspec item type: %r" % t)
    expr = b''.join(ret)
    tree = _parsewith(expr, syminitletters=_aliassyminitletters)
    tree = parser.buildtree(tree, (b'symbol', b'$'), *inputs)
    tree = foldconcat(tree)
    tree = analyze(tree)
    tree = optimize(tree)
    return tree


def _parseargs(expr, args):
    """parse the expression and replace all inexpensive args

    return a list of tuple [(arg-type, arg-value)]

    Arg-type can be:
    * None:      a string ready to be concatenated into a final spec
    * 'baseset': an iterable of revisions
    """
    expr = pycompat.bytestr(expr)
    argiter = iter(args)
    ret = []
    pos = 0
    while pos < len(expr):
        q = expr.find(b'%', pos)
        if q < 0:
            ret.append((None, expr[pos:]))
            break
        ret.append((None, expr[pos:q]))
        pos = q + 1
        try:
            d = expr[pos]
        except IndexError:
            raise error.ParseError(_(b'incomplete revspec format character'))
        if d == b'%':
            ret.append((None, d))
            pos += 1
            continue

        try:
            arg = next(argiter)
        except StopIteration:
            raise error.ParseError(_(b'missing argument for revspec'))
        f = _formatlistfuncs.get(d)
        if f:
            # a list of some type, might be expensive, do not replace
            pos += 1
            islist = d == b'l'
            try:
                d = expr[pos]
            except IndexError:
                raise error.ParseError(
                    _(b'incomplete revspec format character')
                )
            if islist and d == b'd' and arg:
                # we don't create a baseset yet, because it come with an
                # extra cost. If we are going to serialize it we better
                # skip it.
                ret.append((b'baseset', arg))
                pos += 1
                continue
            try:
                ret.append((None, f(list(arg), d)))
            except (TypeError, ValueError):
                raise error.ParseError(_(b'invalid argument for revspec'))
        else:
            # a single entry, not expensive, replace
            try:
                ret.append((None, _formatargtype(d, arg)))
            except (TypeError, ValueError):
                raise error.ParseError(_(b'invalid argument for revspec'))
        pos += 1

    try:
        next(argiter)
        raise error.ParseError(_(b'too many revspec arguments specified'))
    except StopIteration:
        pass
    return ret


def prettyformat(tree):
    return parser.prettyformat(tree, (b'string', b'symbol'))


def depth(tree):
    if isinstance(tree, tuple):
        return max(map(depth, tree)) + 1
    else:
        return 0


def funcsused(tree):
    if not isinstance(tree, tuple) or tree[0] in (b'string', b'symbol'):
        return set()
    else:
        funcs = set()
        for s in tree[1:]:
            funcs |= funcsused(s)
        if tree[0] == b'func':
            funcs.add(tree[1][1])
        return funcs


_hashre = util.re.compile(b'[0-9a-fA-F]{1,40}$')


def _ishashlikesymbol(symbol):
    """returns true if the symbol looks like a hash"""
    return _hashre.match(symbol)


def gethashlikesymbols(tree):
    """returns the list of symbols of the tree that look like hashes

    >>> gethashlikesymbols(parse(b'3::abe3ff'))
    ['3', 'abe3ff']
    >>> gethashlikesymbols(parse(b'precursors(.)'))
    []
    >>> gethashlikesymbols(parse(b'precursors(34)'))
    ['34']
    >>> gethashlikesymbols(parse(b'abe3ffZ'))
    []
    """
    if not tree:
        return []

    if tree[0] == b"symbol":
        if _ishashlikesymbol(tree[1]):
            return [tree[1]]
    elif len(tree) >= 3:
        results = []
        for subtree in tree[1:]:
            results += gethashlikesymbols(subtree)
        return results
    return []