Mercurial > hg
annotate mercurial/parser.py @ 20202:a6014018ec28
util: remove unused realpath (issue4063)
util.realpath was in use for only 5 days from dbdb777502dc
until it was backed out in c519cd8f0169 because it caused
issue3077 and issue3071.
author | Christian Ebert <blacktrash@gmx.net> |
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date | Sun, 29 Dec 2013 13:54:04 +0000 |
parents | 8ac8db8dc346 |
children | 7c4778bc29f0 |
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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 |
78 def parse(self, message): | |
79 'generate a parse tree from a message' | |
80 self._iter = self._tokenizer(message) | |
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81 self._advance() |
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82 res = self._parse() |
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83 token, value, pos = self.current |
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84 return res, pos |
11274 | 85 def eval(self, tree): |
86 'recursively evaluate a parse tree using node methods' | |
87 if not isinstance(tree, tuple): | |
88 return tree | |
89 return self._methods[tree[0]](*[self.eval(t) for t in tree[1:]]) | |
90 def __call__(self, message): | |
91 'parse a message into a parse tree and evaluate if methods given' | |
92 t = self.parse(message) | |
93 if self._methods: | |
94 return self.eval(t) | |
95 return t |