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1 | 1 | # demandimport.py - global demand-loading of modules for Mercurial |
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2 | 2 | # |
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3 | 3 | # Copyright 2006, 2007 Matt Mackall <mpm@selenic.com> |
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4 | 4 | # |
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5 | 5 | # This software may be used and distributed according to the terms of the |
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6 | 6 | # GNU General Public License version 2 or any later version. |
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7 | 7 | |
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8 | 8 | ''' |
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9 | 9 | demandimport - automatic demandloading of modules |
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10 | 10 | |
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11 | 11 | To enable this module, do: |
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12 | 12 | |
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13 | 13 | import demandimport; demandimport.enable() |
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14 | 14 | |
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15 | 15 | Imports of the following forms will be demand-loaded: |
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16 | 16 | |
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17 | 17 | import a, b.c |
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18 | 18 | import a.b as c |
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19 | 19 | from a import b,c # a will be loaded immediately |
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20 | 20 | |
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21 | 21 | These imports will not be delayed: |
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22 | 22 | |
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23 | 23 | from a import * |
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24 | 24 | b = __import__(a) |
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25 | 25 | ''' |
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26 | 26 | |
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27 | 27 | from __future__ import absolute_import |
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28 | 28 | |
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29 | 29 | import contextlib |
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30 | 30 | import os |
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31 | 31 | import sys |
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32 | 32 | |
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33 | 33 | # __builtin__ in Python 2, builtins in Python 3. |
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34 | 34 | try: |
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35 | 35 | import __builtin__ as builtins |
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36 | 36 | except ImportError: |
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37 | 37 | import builtins |
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38 | 38 | |
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39 | 39 | contextmanager = contextlib.contextmanager |
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40 | 40 | |
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41 | 41 | _origimport = __import__ |
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42 | 42 | |
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43 | 43 | nothing = object() |
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44 | 44 | |
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45 | 45 | # Python 3 doesn't have relative imports nor level -1. |
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46 | 46 | level = -1 |
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47 | 47 | if sys.version_info[0] >= 3: |
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48 | 48 | level = 0 |
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49 | 49 | _import = _origimport |
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50 | 50 | |
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51 | 51 | def _hgextimport(importfunc, name, globals, *args, **kwargs): |
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52 | 52 | try: |
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53 | 53 | return importfunc(name, globals, *args, **kwargs) |
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54 | 54 | except ImportError: |
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55 | 55 | if not globals: |
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56 | 56 | raise |
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57 | 57 | # extensions are loaded with "hgext_" prefix |
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58 | 58 | hgextname = 'hgext_%s' % name |
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59 | 59 | nameroot = hgextname.split('.', 1)[0] |
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60 | 60 | contextroot = globals.get('__name__', '').split('.', 1)[0] |
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61 | 61 | if nameroot != contextroot: |
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62 | 62 | raise |
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63 | 63 | # retry to import with "hgext_" prefix |
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64 | 64 | return importfunc(hgextname, globals, *args, **kwargs) |
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65 | 65 | |
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66 | 66 | class _demandmod(object): |
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67 | 67 | """module demand-loader and proxy""" |
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68 | 68 | def __init__(self, name, globals, locals, level=level): |
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69 | 69 | if '.' in name: |
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70 | 70 | head, rest = name.split('.', 1) |
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71 | 71 | after = [rest] |
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72 | 72 | else: |
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73 | 73 | head = name |
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74 | 74 | after = [] |
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75 | 75 | object.__setattr__(self, "_data", |
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76 | 76 | (head, globals, locals, after, level, set())) |
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77 | 77 | object.__setattr__(self, "_module", None) |
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78 | 78 | def _extend(self, name): |
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79 | 79 | """add to the list of submodules to load""" |
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80 | 80 | self._data[3].append(name) |
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81 | 81 | |
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82 | 82 | def _addref(self, name): |
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83 | 83 | """Record that the named module ``name`` imports this module. |
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84 | 84 | |
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85 | 85 | References to this proxy class having the name of this module will be |
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86 | 86 | replaced at module load time. We assume the symbol inside the importing |
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87 | 87 | module is identical to the "head" name of this module. We don't |
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88 | 88 | actually know if "as X" syntax is being used to change the symbol name |
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89 | 89 | because this information isn't exposed to __import__. |
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90 | 90 | """ |
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91 | 91 | self._data[5].add(name) |
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92 | 92 | |
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93 | 93 | def _load(self): |
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94 | 94 | if not self._module: |
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95 | 95 | head, globals, locals, after, level, modrefs = self._data |
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96 | 96 | mod = _hgextimport(_import, head, globals, locals, None, level) |
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97 | 97 | # load submodules |
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98 | 98 | def subload(mod, p): |
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99 | 99 | h, t = p, None |
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100 | 100 | if '.' in p: |
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101 | 101 | h, t = p.split('.', 1) |
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102 | 102 | if getattr(mod, h, nothing) is nothing: |
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103 | 103 | setattr(mod, h, _demandmod(p, mod.__dict__, mod.__dict__)) |
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104 | 104 | elif t: |
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105 | 105 | subload(getattr(mod, h), t) |
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106 | 106 | |
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107 | 107 | for x in after: |
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108 | 108 | subload(mod, x) |
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109 | 109 | |
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110 | 110 | # Replace references to this proxy instance with the actual module. |
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111 | 111 | if locals and locals.get(head) == self: |
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112 | 112 | locals[head] = mod |
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113 | 113 | |
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114 | 114 | for modname in modrefs: |
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115 | 115 | modref = sys.modules.get(modname, None) |
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116 | 116 | if modref and getattr(modref, head, None) == self: |
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117 | 117 | setattr(modref, head, mod) |
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118 | 118 | |
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119 | 119 | object.__setattr__(self, "_module", mod) |
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120 | 120 | |
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121 | 121 | def __repr__(self): |
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122 | 122 | if self._module: |
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123 | 123 | return "<proxied module '%s'>" % self._data[0] |
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124 | 124 | return "<unloaded module '%s'>" % self._data[0] |
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125 | 125 | def __call__(self, *args, **kwargs): |
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126 | 126 | raise TypeError("%s object is not callable" % repr(self)) |
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127 | 127 | def __getattribute__(self, attr): |
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128 | 128 | if attr in ('_data', '_extend', '_load', '_module', '_addref'): |
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129 | 129 | return object.__getattribute__(self, attr) |
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130 | 130 | self._load() |
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131 | 131 | return getattr(self._module, attr) |
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132 | 132 | def __setattr__(self, attr, val): |
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133 | 133 | self._load() |
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134 | 134 | setattr(self._module, attr, val) |
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135 | 135 | |
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136 | 136 | _pypy = '__pypy__' in sys.builtin_module_names |
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137 | 137 | |
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138 | 138 | def _demandimport(name, globals=None, locals=None, fromlist=None, level=level): |
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139 | 139 | if not locals or name in ignore or fromlist == ('*',): |
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140 | 140 | # these cases we can't really delay |
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141 | 141 | return _hgextimport(_import, name, globals, locals, fromlist, level) |
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142 | 142 | elif not fromlist: |
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143 | 143 | # import a [as b] |
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144 | 144 | if '.' in name: # a.b |
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145 | 145 | base, rest = name.split('.', 1) |
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146 | 146 | # email.__init__ loading email.mime |
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147 | 147 | if globals and globals.get('__name__', None) == base: |
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148 | 148 | return _import(name, globals, locals, fromlist, level) |
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149 | 149 | # if a is already demand-loaded, add b to its submodule list |
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150 | 150 | if base in locals: |
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151 | 151 | if isinstance(locals[base], _demandmod): |
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152 | 152 | locals[base]._extend(rest) |
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153 | 153 | return locals[base] |
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154 | 154 | return _demandmod(name, globals, locals, level) |
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155 | 155 | else: |
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156 | 156 | # There is a fromlist. |
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157 | 157 | # from a import b,c,d |
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158 | 158 | # from . import b,c,d |
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159 | 159 | # from .a import b,c,d |
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160 | 160 | |
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161 | 161 | # level == -1: relative and absolute attempted (Python 2 only). |
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162 | 162 | # level >= 0: absolute only (Python 2 w/ absolute_import and Python 3). |
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163 | 163 | # The modern Mercurial convention is to use absolute_import everywhere, |
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164 | 164 | # so modern Mercurial code will have level >= 0. |
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165 | 165 | |
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166 | 166 | # The name of the module the import statement is located in. |
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167 | 167 | globalname = globals.get('__name__') |
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168 | 168 | |
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169 | 169 | def processfromitem(mod, attr): |
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170 | 170 | """Process an imported symbol in the import statement. |
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171 | 171 | |
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172 | 172 | If the symbol doesn't exist in the parent module, it must be a |
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173 | 173 | module. We set missing modules up as _demandmod instances. |
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174 | 174 | """ |
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175 | 175 | symbol = getattr(mod, attr, nothing) |
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176 | 176 | if symbol is nothing: |
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177 | 177 | symbol = _demandmod(attr, mod.__dict__, locals, level=1) |
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178 | 178 | setattr(mod, attr, symbol) |
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179 | 179 | |
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180 | 180 | # Record the importing module references this symbol so we can |
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181 | 181 | # replace the symbol with the actual module instance at load |
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182 | 182 | # time. |
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183 | 183 | if globalname and isinstance(symbol, _demandmod): |
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184 | 184 | symbol._addref(globalname) |
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185 | 185 | |
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186 | 186 | if level >= 0: |
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187 | 187 | # The "from a import b,c,d" or "from .a import b,c,d" |
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188 | 188 | # syntax gives errors with some modules for unknown |
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189 | 189 | # reasons. Work around the problem. |
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190 | 190 | if name: |
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191 | 191 | return _hgextimport(_origimport, name, globals, locals, |
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192 | 192 | fromlist, level) |
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193 | 193 | |
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194 | 194 | if _pypy: |
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195 | 195 | # PyPy's __import__ throws an exception if invoked |
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196 | 196 | # with an empty name and no fromlist. Recreate the |
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197 | 197 | # desired behaviour by hand. |
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198 | 198 | mn = globalname |
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199 | 199 | mod = sys.modules[mn] |
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200 | 200 | if getattr(mod, '__path__', nothing) is nothing: |
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201 | 201 | mn = mn.rsplit('.', 1)[0] |
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202 | 202 | mod = sys.modules[mn] |
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203 | 203 | if level > 1: |
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204 | 204 | mn = mn.rsplit('.', level - 1)[0] |
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205 | 205 | mod = sys.modules[mn] |
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206 | 206 | else: |
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207 | 207 | mod = _hgextimport(_origimport, name, globals, locals, |
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208 | 208 | level=level) |
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209 | 209 | |
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210 | 210 | for x in fromlist: |
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211 | 211 | processfromitem(mod, x) |
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212 | 212 | |
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213 | 213 | return mod |
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214 | 214 | |
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215 | 215 | # But, we still need to support lazy loading of standard library and 3rd |
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216 | 216 | # party modules. So handle level == -1. |
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217 | 217 | mod = _hgextimport(_origimport, name, globals, locals) |
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218 | 218 | # recurse down the module chain |
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219 | 219 | for comp in name.split('.')[1:]: |
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220 | 220 | if getattr(mod, comp, nothing) is nothing: |
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221 | 221 | setattr(mod, comp, |
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222 | 222 | _demandmod(comp, mod.__dict__, mod.__dict__)) |
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223 | 223 | mod = getattr(mod, comp) |
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224 | 224 | |
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225 | 225 | for x in fromlist: |
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226 | 226 | processfromitem(mod, x) |
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227 | 227 | |
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228 | 228 | return mod |
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229 | 229 | |
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230 | 230 | ignore = [ |
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231 | 231 | '__future__', |
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232 | 232 | '_hashlib', |
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233 | # ImportError during pkg_resources/__init__.py:fixup_namespace_package | |
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234 | '_imp', | |
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233 | 235 | '_xmlplus', |
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234 | 236 | 'fcntl', |
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235 | 237 | 'win32com.gen_py', |
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236 | 238 | '_winreg', # 2.7 mimetypes needs immediate ImportError |
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237 | 239 | 'pythoncom', |
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238 | 240 | # imported by tarfile, not available under Windows |
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239 | 241 | 'pwd', |
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240 | 242 | 'grp', |
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241 | 243 | # imported by profile, itself imported by hotshot.stats, |
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242 | 244 | # not available under Windows |
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243 | 245 | 'resource', |
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244 | 246 | # this trips up many extension authors |
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245 | 247 | 'gtk', |
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246 | 248 | # setuptools' pkg_resources.py expects "from __main__ import x" to |
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247 | 249 | # raise ImportError if x not defined |
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248 | 250 | '__main__', |
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249 | 251 | '_ssl', # conditional imports in the stdlib, issue1964 |
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250 | 252 | '_sre', # issue4920 |
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251 | 253 | 'rfc822', |
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252 | 254 | 'mimetools', |
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253 | 255 | # setuptools 8 expects this module to explode early when not on windows |
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254 | 256 | 'distutils.msvc9compiler' |
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255 | 257 | ] |
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256 | 258 | |
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257 | 259 | def isenabled(): |
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258 | 260 | return builtins.__import__ == _demandimport |
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259 | 261 | |
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260 | 262 | def enable(): |
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261 | 263 | "enable global demand-loading of modules" |
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262 | 264 | if os.environ.get('HGDEMANDIMPORT') != 'disable': |
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263 | 265 | builtins.__import__ = _demandimport |
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264 | 266 | |
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265 | 267 | def disable(): |
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266 | 268 | "disable global demand-loading of modules" |
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267 | 269 | builtins.__import__ = _origimport |
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268 | 270 | |
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269 | 271 | @contextmanager |
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270 | 272 | def deactivated(): |
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271 | 273 | "context manager for disabling demandimport in 'with' blocks" |
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272 | 274 | demandenabled = isenabled() |
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273 | 275 | if demandenabled: |
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274 | 276 | disable() |
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275 | 277 | |
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276 | 278 | try: |
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277 | 279 | yield |
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278 | 280 | finally: |
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279 | 281 | if demandenabled: |
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280 | 282 | enable() |
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