1 | #!/usr/bin/env python2
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2 | """
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3 | scoped_resource.py
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4 | """
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5 | from __future__ import print_function
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6 |
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7 | import os
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8 | import sys
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9 |
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10 | from mycpp import mylib
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11 | from mycpp.mylib import log
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12 | from typing import List, Optional, Any
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13 |
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14 |
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15 | class MyError(Exception):
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16 |
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17 | def __init__(self):
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18 | # type: () -> None
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19 | pass
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20 |
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21 |
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22 | def Error(error):
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23 | # type: (bool) -> None
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24 | if error:
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25 | raise MyError()
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26 |
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27 |
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28 | #class BadName(object):
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29 | class ctx_BadName(object):
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30 |
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31 | def __init__(self):
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32 | # type: () -> None
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33 | self.i = 42
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34 |
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35 | def __exit__(self, type, value, traceback):
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36 | # type: (Any, Any, Any) -> None
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37 | self.i = 43
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38 |
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39 |
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40 | class ctx_NoArgs(object):
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41 | """Regression for most vexing parse."""
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42 |
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43 | def __init__(self):
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44 | # type: () -> None
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45 | print('> NoArgs')
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46 |
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47 | def __enter__(self):
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48 | # type: () -> None
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49 | """no-op, but it has to exist to be used as context manager."""
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50 | pass
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51 |
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52 | def __exit__(self, type, value, traceback):
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53 | # type: (Any, Any, Any) -> None
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54 | print('< NoArgs')
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55 |
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56 |
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57 | class ctx_DirStack(object):
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58 |
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59 | def __init__(self, state, entry):
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60 | # type: (DirStack, str) -> None
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61 | self.state = state
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62 | state.Push(entry)
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63 |
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64 | # Bug #1986: add heap-allocated member of context manager
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65 | self.restored = [] # type: List[str]
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66 | self.restored.append('foo')
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67 | self.non_pointer_member = 42 # make sure we don't root this
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68 |
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69 | def __enter__(self):
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70 | # type: () -> None
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71 | """no-op, but it has to exist to be used as context manager."""
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72 | pass
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73 |
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74 | def __exit__(self, type, value, traceback):
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75 | # type: (Any, Any, Any) -> None
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76 | self.restored.pop()
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77 | self.state.Pop()
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78 |
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79 |
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80 | class DirStack(object):
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81 | """For pushd/popd/dirs."""
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82 |
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83 | def __init__(self):
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84 | # type: () -> None
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85 | self.stack = [] # type: List[str]
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86 | self.Reset() # Invariant: it always has at least ONE entry.
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87 |
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88 | def Reset(self):
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89 | # type: () -> None
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90 | del self.stack[:]
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91 | self.stack.append('CWD')
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92 |
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93 | def Push(self, entry):
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94 | # type: (str) -> None
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95 | self.stack.append(entry)
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96 |
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97 | def Pop(self):
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98 | # type: () -> Optional[str]
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99 | if len(self.stack) <= 1:
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100 | return None
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101 | self.stack.pop() # remove last
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102 | return self.stack[-1] # return second to last
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103 |
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104 | def Iter(self):
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105 | # type: () -> List[str]
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106 | """Iterate in reverse order."""
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107 | # mycpp REWRITE:
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108 | #return reversed(self.stack)
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109 | ret = [] # type: List[str]
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110 | ret.extend(self.stack)
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111 | ret.reverse()
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112 | return ret
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113 |
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114 | def __repr__(self):
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115 | # type: () -> str
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116 | return repr(self.stack)
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117 |
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118 |
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119 | # C++ translation
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120 | #
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121 | # class _ErrExit__Context; // forward declaration
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122 | # class _ErrExit {
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123 | # };
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124 | #
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125 | # class _ErrExit__Context {
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126 | # _ErrExit__Context(_ErrExit* state) : state_(state) {
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127 | # state->Push();
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128 | # }
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129 | # ~_ErrExit__Context() {
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130 | # state->Pop();
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131 | # }
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132 | # };
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133 |
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134 |
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135 | def DoWork(d, do_raise):
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136 | # type: (DirStack, bool) -> None
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137 |
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138 | # problem
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139 | # with self.mem.ctx_Call(...)
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140 | # PushCall/PopCall
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141 | # with self.mem.ctx_Temp(...)
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142 | # PushTemp/PopCall
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143 | # with self.mem.ctx_Source(...)
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144 | # PushSource/PopSource
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145 | #
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146 | # Scope_Call
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147 | # Scope_Temp
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148 |
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149 | # PROBLEM: WE LOST TYPE CHECKING!
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150 | #with e.Context('zz') as _:
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151 | with ctx_DirStack(d, 'foo') as _:
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152 | log(' in context stack %d', len(d.stack))
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153 | if do_raise:
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154 | Error(do_raise)
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155 |
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156 |
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157 | def run_tests():
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158 | # type: () -> None
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159 |
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160 | # Use cases:
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161 | #
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162 | # Many in cmd_exec.py
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163 | #
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164 | # fd_state.Push(...) and Pop
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165 | # BeginAlias, EndAlias
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166 | # PushSource, PopSource (opens files)
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167 | # source
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168 | # eval -- no file opened, but need to change the current file
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169 | # PushTemp, PopTemp for env bindings
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170 | # PushErrExit, PopErrExit
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171 | # loop_level in cmd_exec
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172 |
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173 | d = DirStack()
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174 |
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175 | for do_raise in [False, True]:
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176 | log('')
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177 | log('-> dir stack %d', len(d.stack))
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178 | try:
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179 | DoWork(d, do_raise)
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180 | except MyError:
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181 | log('exited with exception')
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182 | log('<- dir stack %d', len(d.stack))
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183 |
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184 | # C++ translation
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185 | #
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186 | # _Errexit e;
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187 | # e.errexit = true;
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188 | #
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189 | # log("-> errexit %d", e.errexit)
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190 | # {
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191 | # _ErrExit__Context(e);
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192 | # log(" errexit %d", e.errexit)
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193 | # }
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194 | # log("<- errexit %d", e.errexit)
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195 |
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196 | with ctx_NoArgs():
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197 | print('hi')
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198 |
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199 |
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200 | def run_benchmarks():
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201 | # type: () -> None
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202 | d = DirStack()
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203 | for i in xrange(1000000):
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204 | # Does NOT trigger the bug!
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205 | #mylib.MaybeCollect()
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206 | try:
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207 | with ctx_DirStack(d, 'foo') as _:
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208 | # Bug #1986: add collection in this loop
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209 | mylib.MaybeCollect()
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210 | if i % 10000 == 0:
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211 | raise MyError()
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212 | except MyError:
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213 | log('exception')
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214 |
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215 |
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216 | if __name__ == '__main__':
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217 | if os.getenv('BENCHMARK'):
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218 | log('Benchmarking...')
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219 | run_benchmarks()
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220 | else:
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221 | run_tests()
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