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