Mercurial > hg
annotate mercurial/parser.py @ 23324:69f86b937035
cmdserver: protect pipe server streams against corruption caused by direct io
Because pipe-mode server uses stdio as IPC channel, other modules should not
touch stdio directly and use ui instead. However, this strategy is brittle
because several Python functions read and write stdio implicitly.
print 'hello' # should use ui.write()
# => ch = 'h', size = 1701604463 'ello', data = '\n'
This patch adds protection for such mistakes. Both stdio files and low-level
file descriptors are redirected to /dev/null while command server uses them.
author | Yuya Nishihara <yuya@tcha.org> |
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date | Sat, 15 Nov 2014 13:50:43 +0900 |
parents | 7c4778bc29f0 |
children | d647f97f88dd |
rev | line source |
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11274 | 1 # parser.py - simple top-down operator precedence parser for mercurial |
2 # | |
3 # Copyright 2010 Matt Mackall <mpm@selenic.com> | |
4 # | |
5 # This software may be used and distributed according to the terms of the | |
6 # GNU General Public License version 2 or any later version. | |
7 | |
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8 # see http://effbot.org/zone/simple-top-down-parsing.htm and |
11274 | 9 # http://eli.thegreenplace.net/2010/01/02/top-down-operator-precedence-parsing/ |
10 # for background | |
11 | |
12 # takes a tokenizer and elements | |
13 # tokenizer is an iterator that returns type, value pairs | |
14 # elements is a mapping of types to binding strength, prefix and infix actions | |
15 # an action is a tree node name, a tree label, and an optional match | |
17500 | 16 # __call__(program) parses program into a labeled tree |
11274 | 17 |
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18 import error |
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19 from i18n import _ |
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20 |
11274 | 21 class parser(object): |
22 def __init__(self, tokenizer, elements, methods=None): | |
23 self._tokenizer = tokenizer | |
24 self._elements = elements | |
25 self._methods = methods | |
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26 self.current = None |
11274 | 27 def _advance(self): |
28 'advance the tokenizer' | |
29 t = self.current | |
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30 try: |
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31 self.current = self._iter.next() |
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32 except StopIteration: |
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33 pass |
11274 | 34 return t |
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35 def _match(self, m, pos): |
11274 | 36 'make sure the tokenizer matches an end condition' |
37 if self.current[0] != m: | |
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38 raise error.ParseError(_("unexpected token: %s") % self.current[0], |
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39 self.current[2]) |
11274 | 40 self._advance() |
41 def _parse(self, bind=0): | |
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42 token, value, pos = self._advance() |
11274 | 43 # handle prefix rules on current token |
44 prefix = self._elements[token][1] | |
45 if not prefix: | |
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46 raise error.ParseError(_("not a prefix: %s") % token, pos) |
11274 | 47 if len(prefix) == 1: |
48 expr = (prefix[0], value) | |
49 else: | |
50 if len(prefix) > 2 and prefix[2] == self.current[0]: | |
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51 self._match(prefix[2], pos) |
11274 | 52 expr = (prefix[0], None) |
53 else: | |
54 expr = (prefix[0], self._parse(prefix[1])) | |
55 if len(prefix) > 2: | |
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56 self._match(prefix[2], pos) |
11274 | 57 # gather tokens until we meet a lower binding strength |
58 while bind < self._elements[self.current[0]][0]: | |
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59 token, value, pos = self._advance() |
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60 e = self._elements[token] |
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61 # check for suffix - next token isn't a valid prefix |
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62 if len(e) == 4 and not self._elements[self.current[0]][1]: |
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63 suffix = e[3] |
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64 expr = (suffix[0], expr) |
11274 | 65 else: |
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66 # handle infix rules |
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67 if len(e) < 3 or not e[2]: |
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68 raise error.ParseError(_("not an infix: %s") % token, pos) |
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69 infix = e[2] |
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70 if len(infix) == 3 and infix[2] == self.current[0]: |
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71 self._match(infix[2], pos) |
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72 expr = (infix[0], expr, (None)) |
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73 else: |
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74 expr = (infix[0], expr, self._parse(infix[1])) |
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75 if len(infix) == 3: |
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76 self._match(infix[2], pos) |
11274 | 77 return expr |
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78 def parse(self, message, lookup=None): |
11274 | 79 'generate a parse tree from a message' |
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80 if lookup: |
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81 self._iter = self._tokenizer(message, lookup) |
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82 else: |
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83 self._iter = self._tokenizer(message) |
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84 self._advance() |
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85 res = self._parse() |
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86 token, value, pos = self.current |
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87 return res, pos |
11274 | 88 def eval(self, tree): |
89 'recursively evaluate a parse tree using node methods' | |
90 if not isinstance(tree, tuple): | |
91 return tree | |
92 return self._methods[tree[0]](*[self.eval(t) for t in tree[1:]]) | |
93 def __call__(self, message): | |
94 'parse a message into a parse tree and evaluate if methods given' | |
95 t = self.parse(message) | |
96 if self._methods: | |
97 return self.eval(t) | |
98 return t |