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1 #!/usr/bin/python2.5 |
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2 # |
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3 # Copyright 2008 the Melange authors. |
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4 # |
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5 # Licensed under the Apache License, Version 2.0 (the "License"); |
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6 # you may not use this file except in compliance with the License. |
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7 # You may obtain a copy of the License at |
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8 # |
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9 # http://www.apache.org/licenses/LICENSE-2.0 |
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10 # |
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11 # Unless required by applicable law or agreed to in writing, software |
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12 # distributed under the License is distributed on an "AS IS" BASIS, |
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13 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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14 # See the License for the specific language governing permissions and |
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15 # limitations under the License. |
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16 |
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17 """Path and link name manipulation functions. |
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18 """ |
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19 |
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20 __authors__ = [ |
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21 '"Todd Larsen" <tlarsen@google.com>', |
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22 ] |
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23 |
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24 |
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25 import re |
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26 |
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27 |
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28 # start with ASCII digit or lowercase |
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29 # (additional ASCII digit or lowercase |
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30 # -OR- |
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31 # underscore and ASCII digit or lowercase) |
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32 # zero or more of OR group |
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33 LINKNAME_PATTERN_CORE = r'[0-9a-z](?:[0-9a-z]|_[0-9a-z])*' |
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34 LINKNAME_ARG_PATTERN = r'(?P<linkname>%s)' % LINKNAME_PATTERN_CORE |
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35 LINKNAME_PATTERN = r'^%s$' % LINKNAME_PATTERN_CORE |
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36 LINKNAME_REGEX = re.compile(LINKNAME_PATTERN) |
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37 |
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38 # partial path is multiple linkname chunks, |
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39 # each separated by a trailing / |
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40 # (at least 1) |
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41 # followed by a single linkname with no trailing / |
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42 PATH_LINKNAME_ARGS_PATTERN = ( |
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43 r'(?P<partial_path>%(linkname)s(?:/%(linkname)s)*)/' |
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44 '(?P<linkname>%(linkname)s)' % { |
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45 'linkname': LINKNAME_PATTERN_CORE}) |
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46 |
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47 PATH_LINKNAME_PATTERN = r'^%s$' % PATH_LINKNAME_ARGS_PATTERN |
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48 PATH_LINKNAME_REGEX = re.compile(PATH_LINKNAME_PATTERN) |
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49 |
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50 |
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51 def getPartsFromPath(path): |
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52 """Splits path string into partial_path and link_name. |
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53 |
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54 Returns: |
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55 {'partial_path': 'everything/but', |
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56 'link_name': 'link_name'} |
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57 or {} (empty dict) if string did not match PATH_LINKNAME_PATTERN. |
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58 """ |
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59 path_linkname_match = PATH_LINKNAME_REGEX.match(path) |
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60 |
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61 if not path_linkname_match: |
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62 return {} |
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63 |
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64 return path_linkname_match.groupdict() |
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65 |
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66 |
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67 def combinePath(path_parts): |
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68 """Returns path components combined into a single string. |
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69 |
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70 Args: |
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71 path_parts: a single path string, or a list of path part strings, |
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72 or a nested list of path part strings (where the zeroeth element in |
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73 the list is itself a list); for example: |
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74 'a/complete/path/in/one/string' |
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75 ['some', 'path', 'parts'] |
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76 [['path', 'parts', 'and', 'a'], 'link name'] |
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77 |
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78 Returns: |
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79 None if path_parts is False (None, empty string, etc.) or if |
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80 any list elements are False (an empty list, empty string, etc.); |
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81 otherwise, the combined string with the necessary separators. |
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82 """ |
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83 if not path_parts: |
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84 # completely empty input, so return early |
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85 return None |
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86 |
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87 if not isinstance(path_parts, (list, tuple)): |
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88 # a single path string, so just return it as-is (nothing to do) |
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89 return path_parts |
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90 |
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91 flattened_parts = [] |
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92 |
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93 for part in path_parts: |
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94 if not part: |
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95 # encountered a "False" element, which invalidates everything else |
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96 return None |
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97 |
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98 if isinstance(part, (list, tuple)): |
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99 flattened_parts.extend(part) |
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100 else: |
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101 flattened_parts.append(part) |
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102 |
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103 return '/'.join(flattened_parts) |