view mercurial/filesetlang.py @ 43913:4b7d5d10c45d

exchange: ensure all outgoing subrepo references are present before pushing

We've run into occasional problems with people committing a repo, and then
amending or rebasing in the subrepo.  That makes it so that the revision in the
parent can't be checked out, and the problem gets propagated on push.  Mercurial
already tries to defend against this sort of dangling reference by pushing *all*
subrepo revisions first.  This reuses the checks that trigger warnings in
`hg verify` to bail on the push unless using `--force`.

I thought about putting this on the server side, but at that point, all of the
data has been transferred, only to bail out.  Additionally, SCM Manager hosts
subrepos in a location that isn't nested in the parent, so normal subrepo code
would complain that the subrepo is missing when run on the server.

Because the push command pushes subrepos before calling this exchange code, a
subrepo will be pushed before the parent is verified.  Not great, but no
dangling references are exchanged, so it solves the problem.  This code isn't in
the loop that pushes the subrepos because:

  1) the list of outgoing revisions is needed to limit the scope of the check
  2) the loop only accesses the current revision, and therefore can miss
     subrepos that were dropped in previous commits
  3) this code is called when pushing a subrepo, so the protection is recursive

I'm not sure if there's a cheap check for the list of files in the outgoing
bundle.  If there is, that would provide a fast path to bypass this check for
people not using subrepos (or if no subrepo changes were made).  There's
probably also room for verifying other references like tags.  But since that
doesn't break checkouts, it's much less of a problem.

Differential Revision: https://phab.mercurial-scm.org/D7616

# filesetlang.py - parser, tokenizer and utility for file set language
#
# Copyright 2010 Matt Mackall <[e-mail]>
#
# 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 .pycompat import getattr
from . import (
    error,
    parser,
    pycompat,
)

# common weight constants for static optimization
# (see registrar.filesetpredicate for details)
WEIGHT_CHECK_FILENAME = 0.5
WEIGHT_READ_CONTENTS = 30
WEIGHT_STATUS = 10
WEIGHT_STATUS_THOROUGH = 50

elements = {
    # token-type: binding-strength, primary, prefix, infix, suffix
    b"(": (20, None, (b"group", 1, b")"), (b"func", 1, b")"), None),
    b":": (15, None, None, (b"kindpat", 15), None),
    b"-": (5, None, (b"negate", 19), (b"minus", 5), None),
    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"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",": (2, None, None, (b"list", 2), 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 = {}

globchars = b".*{}[]?/\\_"


def tokenize(program):
    pos, l = 0, len(program)
    program = pycompat.bytestr(program)
    while pos < l:
        c = program[pos]
        if c.isspace():  # skip inter-token whitespace
            pass
        elif c in b"(),-:|&+!":  # handle simple operators
            yield (c, None, pos)
        elif (
            c in b'"\''
            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)
        elif c.isalnum() or c in globchars or ord(c) > 127:
            # gather up a symbol/keyword
            s = pos
            pos += 1
            while pos < l:  # find end of symbol
                d = program[pos]
                if not (d.isalnum() or d in globchars or ord(d) > 127):
                    break
                pos += 1
            sym = program[s:pos]
            if sym in keywords:  # operator keywords
                yield (sym, None, s)
            else:
                yield (b'symbol', sym, s)
            pos -= 1
        else:
            raise error.ParseError(_(b"syntax error"), pos)
        pos += 1
    yield (b'end', None, pos)


def parse(expr):
    p = parser.parser(elements)
    tree, pos = p.parse(tokenize(expr))
    if pos != len(expr):
        raise error.ParseError(_(b"invalid token"), pos)
    return parser.simplifyinfixops(tree, {b'list', b'or'})


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 getkindpat(x, y, allkinds, err):
    kind = getsymbol(x)
    pat = getstring(y, err)
    if kind not in allkinds:
        raise error.ParseError(_(b"invalid pattern kind: %s") % kind)
    return b'%s:%s' % (kind, pat)


def getpattern(x, allkinds, err):
    if x and x[0] == b'kindpat':
        return getkindpat(x[1], x[2], allkinds, err)
    return getstring(x, err)


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


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


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

    op = x[0]
    if op in {b'string', b'symbol'}:
        return x
    if op == b'kindpat':
        getsymbol(x[1])  # kind must be a symbol
        t = _analyze(x[2])
        return (op, x[1], t)
    if op == b'group':
        return _analyze(x[1])
    if op == b'negate':
        raise error.ParseError(_(b"can't use negate operator in this context"))
    if op == b'not':
        t = _analyze(x[1])
        return (op, t)
    if op == b'and':
        ta = _analyze(x[1])
        tb = _analyze(x[2])
        return (op, ta, tb)
    if op == b'minus':
        return _analyze((b'and', x[1], (b'not', x[2])))
    if op in {b'list', b'or'}:
        ts = tuple(_analyze(y) for y in x[1:])
        return (op,) + ts
    if op == b'func':
        getsymbol(x[1])  # function name must be a symbol
        ta = _analyze(x[2])
        return (op, x[1], ta)
    raise error.ProgrammingError(b'invalid operator %r' % op)


def _insertstatushints(x):
    """Insert hint nodes where status should be calculated (first path)

    This works in bottom-up way, summing up status names and inserting hint
    nodes at 'and' and 'or' as needed. Thus redundant hint nodes may be left.

    Returns (status-names, new-tree) at the given subtree, where status-names
    is a sum of status names referenced in the given subtree.
    """
    if x is None:
        return (), x

    op = x[0]
    if op in {b'string', b'symbol', b'kindpat'}:
        return (), x
    if op == b'not':
        h, t = _insertstatushints(x[1])
        return h, (op, t)
    if op == b'and':
        ha, ta = _insertstatushints(x[1])
        hb, tb = _insertstatushints(x[2])
        hr = ha + hb
        if ha and hb:
            return hr, (b'withstatus', (op, ta, tb), (b'string', b' '.join(hr)))
        return hr, (op, ta, tb)
    if op == b'or':
        hs, ts = zip(*(_insertstatushints(y) for y in x[1:]))
        hr = sum(hs, ())
        if sum(bool(h) for h in hs) > 1:
            return hr, (b'withstatus', (op,) + ts, (b'string', b' '.join(hr)))
        return hr, (op,) + ts
    if op == b'list':
        hs, ts = zip(*(_insertstatushints(y) for y in x[1:]))
        return sum(hs, ()), (op,) + ts
    if op == b'func':
        f = getsymbol(x[1])
        # don't propagate 'ha' crossing a function boundary
        ha, ta = _insertstatushints(x[2])
        if getattr(symbols.get(f), '_callstatus', False):
            return (f,), (b'withstatus', (op, x[1], ta), (b'string', f))
        return (), (op, x[1], ta)
    raise error.ProgrammingError(b'invalid operator %r' % op)


def _mergestatushints(x, instatus):
    """Remove redundant status hint nodes (second path)

    This is the top-down path to eliminate inner hint nodes.
    """
    if x is None:
        return x

    op = x[0]
    if op == b'withstatus':
        if instatus:
            # drop redundant hint node
            return _mergestatushints(x[1], instatus)
        t = _mergestatushints(x[1], instatus=True)
        return (op, t, x[2])
    if op in {b'string', b'symbol', b'kindpat'}:
        return x
    if op == b'not':
        t = _mergestatushints(x[1], instatus)
        return (op, t)
    if op == b'and':
        ta = _mergestatushints(x[1], instatus)
        tb = _mergestatushints(x[2], instatus)
        return (op, ta, tb)
    if op in {b'list', b'or'}:
        ts = tuple(_mergestatushints(y, instatus) for y in x[1:])
        return (op,) + ts
    if op == b'func':
        # don't propagate 'instatus' crossing a function boundary
        ta = _mergestatushints(x[2], instatus=False)
        return (op, x[1], ta)
    raise error.ProgrammingError(b'invalid operator %r' % op)


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

    All pseudo operations should be mapped to real operations or functions
    defined in methods or symbols table respectively.
    """
    t = _analyze(x)
    _h, t = _insertstatushints(t)
    return _mergestatushints(t, instatus=False)


def _optimizeandops(op, ta, tb):
    if tb is not None and tb[0] == b'not':
        return (b'minus', ta, tb[1])
    return (op, ta, tb)


def _optimizeunion(xs):
    # collect string patterns so they can be compiled into a single regexp
    ws, ts, ss = [], [], []
    for x in xs:
        w, t = _optimize(x)
        if t is not None and t[0] in {b'string', b'symbol', b'kindpat'}:
            ss.append(t)
            continue
        ws.append(w)
        ts.append(t)
    if ss:
        ws.append(WEIGHT_CHECK_FILENAME)
        ts.append((b'patterns',) + tuple(ss))
    return ws, ts


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

    op = x[0]
    if op == b'withstatus':
        w, t = _optimize(x[1])
        return w, (op, t, x[2])
    if op in {b'string', b'symbol'}:
        return WEIGHT_CHECK_FILENAME, x
    if op == b'kindpat':
        w, t = _optimize(x[2])
        return w, (op, x[1], t)
    if op == b'not':
        w, t = _optimize(x[1])
        return w, (op, t)
    if op == b'and':
        wa, ta = _optimize(x[1])
        wb, tb = _optimize(x[2])
        if wa <= wb:
            return wa, _optimizeandops(op, ta, tb)
        else:
            return wb, _optimizeandops(op, tb, ta)
    if op == b'or':
        ws, ts = _optimizeunion(x[1:])
        if len(ts) == 1:
            return ws[0], ts[0]  # 'or' operation is fully optimized out
        ts = tuple(
            it[1] for it in sorted(enumerate(ts), key=lambda it: ws[it[0]])
        )
        return max(ws), (op,) + ts
    if op == b'list':
        ws, ts = zip(*(_optimize(y) for y in x[1:]))
        return sum(ws), (op,) + ts
    if op == b'func':
        f = getsymbol(x[1])
        w = getattr(symbols.get(f), '_weight', 1)
        wa, ta = _optimize(x[2])
        return w + wa, (op, x[1], ta)
    raise error.ProgrammingError(b'invalid operator %r' % op)


def optimize(x):
    """Reorder/rewrite evaluatable tree for optimization

    All pseudo operations should be transformed beforehand.
    """
    _w, t = _optimize(x)
    return t


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