bundlerepo: enforce reading from core repo only
We do not want anything computed with the bundle overlay to be written back in
the repo. Such write will likely contains invalid data.
The short terms goal of this change is to drop use of `_cacheabletip` in bundle
repo.
# parser.py - simple top-down operator precedence parser for mercurial
#
# 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.
# see http://effbot.org/zone/simple-top-down-parsing.htm and
# http://eli.thegreenplace.net/2010/01/02/top-down-operator-precedence-parsing/
# for background
# takes a tokenizer and elements
# tokenizer is an iterator that returns type, value pairs
# elements is a mapping of types to binding strength, prefix and infix actions
# an action is a tree node name, a tree label, and an optional match
# __call__(program) parses program into a labeled tree
import error
from i18n import _
class parser(object):
def __init__(self, tokenizer, elements, methods=None):
self._tokenizer = tokenizer
self._elements = elements
self._methods = methods
self.current = None
def _advance(self):
'advance the tokenizer'
t = self.current
try:
self.current = self._iter.next()
except StopIteration:
pass
return t
def _match(self, m, pos):
'make sure the tokenizer matches an end condition'
if self.current[0] != m:
raise error.ParseError(_("unexpected token: %s") % self.current[0],
self.current[2])
self._advance()
def _parse(self, bind=0):
token, value, pos = self._advance()
# handle prefix rules on current token
prefix = self._elements[token][1]
if not prefix:
raise error.ParseError(_("not a prefix: %s") % token, pos)
if len(prefix) == 1:
expr = (prefix[0], value)
else:
if len(prefix) > 2 and prefix[2] == self.current[0]:
self._match(prefix[2], pos)
expr = (prefix[0], None)
else:
expr = (prefix[0], self._parse(prefix[1]))
if len(prefix) > 2:
self._match(prefix[2], pos)
# gather tokens until we meet a lower binding strength
while bind < self._elements[self.current[0]][0]:
token, value, pos = self._advance()
e = self._elements[token]
# check for suffix - next token isn't a valid prefix
if len(e) == 4 and not self._elements[self.current[0]][1]:
suffix = e[3]
expr = (suffix[0], expr)
else:
# handle infix rules
if len(e) < 3 or not e[2]:
raise error.ParseError(_("not an infix: %s") % token, pos)
infix = e[2]
if len(infix) == 3 and infix[2] == self.current[0]:
self._match(infix[2], pos)
expr = (infix[0], expr, (None))
else:
expr = (infix[0], expr, self._parse(infix[1]))
if len(infix) == 3:
self._match(infix[2], pos)
return expr
def parse(self, message):
'generate a parse tree from a message'
self._iter = self._tokenizer(message)
self._advance()
res = self._parse()
token, value, pos = self.current
return res, pos
def eval(self, tree):
'recursively evaluate a parse tree using node methods'
if not isinstance(tree, tuple):
return tree
return self._methods[tree[0]](*[self.eval(t) for t in tree[1:]])
def __call__(self, message):
'parse a message into a parse tree and evaluate if methods given'
t = self.parse(message)
if self._methods:
return self.eval(t)
return t