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@@ -1,208 +1,213 b'' | |||||
1 | """ |
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1 | """ | |
2 | Async helper function that are invalid syntax on Python 3.5 and below. |
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2 | Async helper function that are invalid syntax on Python 3.5 and below. | |
3 |
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3 | |||
4 | This code is best effort, and may have edge cases not behaving as expected. In |
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4 | This code is best effort, and may have edge cases not behaving as expected. In | |
5 | particular it contain a number of heuristics to detect whether code is |
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5 | particular it contain a number of heuristics to detect whether code is | |
6 | effectively async and need to run in an event loop or not. |
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6 | effectively async and need to run in an event loop or not. | |
7 |
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7 | |||
8 | Some constructs (like top-level `return`, or `yield`) are taken care of |
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8 | Some constructs (like top-level `return`, or `yield`) are taken care of | |
9 | explicitly to actually raise a SyntaxError and stay as close as possible to |
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9 | explicitly to actually raise a SyntaxError and stay as close as possible to | |
10 | Python semantics. |
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10 | Python semantics. | |
11 | """ |
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11 | """ | |
12 |
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12 | |||
13 |
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13 | |||
14 | import ast |
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14 | import ast | |
15 | import sys |
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15 | import sys | |
16 | import inspect |
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16 | import inspect | |
17 | from textwrap import dedent, indent |
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17 | from textwrap import dedent, indent | |
18 |
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18 | |||
19 |
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19 | |||
20 | class _AsyncIORunner: |
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20 | class _AsyncIORunner: | |
21 |
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21 | |||
22 | def __call__(self, coro): |
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22 | def __call__(self, coro): | |
23 | """ |
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23 | """ | |
24 | Handler for asyncio autoawait |
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24 | Handler for asyncio autoawait | |
25 | """ |
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25 | """ | |
26 | import asyncio |
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26 | import asyncio | |
27 |
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27 | |||
28 | return asyncio.get_event_loop().run_until_complete(coro) |
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28 | return asyncio.get_event_loop().run_until_complete(coro) | |
29 |
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29 | |||
30 | def __str__(self): |
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30 | def __str__(self): | |
31 | return 'asyncio' |
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31 | return 'asyncio' | |
32 |
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32 | |||
33 | _asyncio_runner = _AsyncIORunner() |
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33 | _asyncio_runner = _AsyncIORunner() | |
34 |
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34 | |||
35 |
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35 | |||
36 | def _curio_runner(coroutine): |
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36 | def _curio_runner(coroutine): | |
37 | """ |
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37 | """ | |
38 | handler for curio autoawait |
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38 | handler for curio autoawait | |
39 | """ |
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39 | """ | |
40 | import curio |
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40 | import curio | |
41 |
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41 | |||
42 | return curio.run(coroutine) |
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42 | return curio.run(coroutine) | |
43 |
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43 | |||
44 |
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44 | |||
45 | _TRIO_TOKEN = None |
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45 | _TRIO_TOKEN = None | |
46 | _TRIO_NURSERY = None |
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47 |
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46 | |||
48 |
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47 | |||
49 | def _init_trio(trio): |
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48 | def _init_trio(trio): | |
50 | global _TRIO_TOKEN |
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49 | global _TRIO_TOKEN | |
51 | import traceback |
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50 | import traceback | |
52 | import builtins |
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51 | import builtins | |
53 | import threading |
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52 | import threading | |
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53 | # We use an Event to avoid a race condition between starting the Trio thread | |||
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54 | # and running Trio code. | |||
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55 | thread_start = threading.Event() | |||
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56 | ||||
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57 | def log_nursery_exc(exc): | |||
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58 | import logging | |||
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59 | import traceback | |||
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60 | exc = '\n'.join(traceback.format_exception(type(exc), exc, | |||
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61 | exc.__traceback__)) | |||
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62 | logging.error('An exception occurred in a global nursery task.\n%s', | |||
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63 | exc) | |||
54 |
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64 | |||
55 | async def trio_entry(): |
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65 | async def trio_entry(): | |
56 | global _TRIO_TOKEN, _TRIO_NURSERY |
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66 | global _TRIO_TOKEN, _TRIO_NURSERY | |
57 | _TRIO_TOKEN = trio.hazmat.current_trio_token() |
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67 | _TRIO_TOKEN = trio.hazmat.current_trio_token() | |
58 | async with trio.open_nursery() as nursery: |
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68 | async with trio.open_nursery() as nursery: | |
59 | _TRIO_NURSERY = nursery |
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69 | # TODO This hack prevents the nursery from cancelling all child | |
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70 | # tasks when but it's ugly. | |||
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71 | nursery._add_exc = log_nursery_exc | |||
60 | builtins.GLOBAL_NURSERY = nursery |
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72 | builtins.GLOBAL_NURSERY = nursery | |
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73 | thread_start.set() | |||
61 | await trio.sleep_forever() |
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74 | await trio.sleep_forever() | |
62 |
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75 | |||
63 | def trio_entry_sync(): |
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76 | threading.Thread(target=trio.run, args=(trio_entry,)).start() | |
64 | while True: |
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77 | thread_start.wait() | |
65 | try: |
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66 | trio.run(trio_entry) |
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|||
67 | except Exception: |
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68 | print("Exception in trio event loop:", traceback.format_exc()) |
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69 |
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70 | threading.Thread(target=trio_entry_sync).start() |
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71 | #TODO fix this race condition |
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72 | import time |
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73 | while not _TRIO_TOKEN: |
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74 | time.sleep(0.1) |
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75 |
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78 | |||
76 |
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79 | |||
77 | def _trio_runner(async_fn): |
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80 | def _trio_runner(async_fn): | |
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81 | global _TRIO_TOKEN | |||
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82 | import logging | |||
78 | import trio |
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83 | import trio | |
79 |
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84 | |||
80 | if not _TRIO_TOKEN: |
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85 | if not _TRIO_TOKEN: | |
81 | _init_trio(trio) |
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86 | _init_trio(trio) | |
82 |
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87 | |||
83 | async def loc(coro): |
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88 | async def loc(coro): | |
84 | """ |
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89 | """ | |
85 | We need the dummy no-op async def to protect from |
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90 | We need the dummy no-op async def to protect from | |
86 | trio's internal. See https://github.com/python-trio/trio/issues/89 |
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91 | trio's internal. See https://github.com/python-trio/trio/issues/89 | |
87 | """ |
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92 | """ | |
88 | return await coro |
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93 | return await coro | |
89 |
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94 | |||
90 | return trio.from_thread.run(loc, async_fn, trio_token=_TRIO_TOKEN) |
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95 | return trio.from_thread.run(loc, async_fn, trio_token=_TRIO_TOKEN) | |
91 |
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96 | |||
92 |
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97 | |||
93 | def _pseudo_sync_runner(coro): |
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98 | def _pseudo_sync_runner(coro): | |
94 | """ |
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99 | """ | |
95 | A runner that does not really allow async execution, and just advance the coroutine. |
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100 | A runner that does not really allow async execution, and just advance the coroutine. | |
96 |
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101 | |||
97 | See discussion in https://github.com/python-trio/trio/issues/608, |
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102 | See discussion in https://github.com/python-trio/trio/issues/608, | |
98 |
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103 | |||
99 | Credit to Nathaniel Smith |
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104 | Credit to Nathaniel Smith | |
100 |
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105 | |||
101 | """ |
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106 | """ | |
102 | try: |
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107 | try: | |
103 | coro.send(None) |
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108 | coro.send(None) | |
104 | except StopIteration as exc: |
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109 | except StopIteration as exc: | |
105 | return exc.value |
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110 | return exc.value | |
106 | else: |
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111 | else: | |
107 | # TODO: do not raise but return an execution result with the right info. |
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112 | # TODO: do not raise but return an execution result with the right info. | |
108 | raise RuntimeError( |
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113 | raise RuntimeError( | |
109 | "{coro_name!r} needs a real async loop".format(coro_name=coro.__name__) |
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114 | "{coro_name!r} needs a real async loop".format(coro_name=coro.__name__) | |
110 | ) |
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115 | ) | |
111 |
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116 | |||
112 |
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117 | |||
113 | def _asyncify(code: str) -> str: |
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118 | def _asyncify(code: str) -> str: | |
114 | """wrap code in async def definition. |
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119 | """wrap code in async def definition. | |
115 |
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120 | |||
116 | And setup a bit of context to run it later. |
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121 | And setup a bit of context to run it later. | |
117 | """ |
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122 | """ | |
118 | res = dedent( |
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123 | res = dedent( | |
119 | """ |
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124 | """ | |
120 | async def __wrapper__(): |
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125 | async def __wrapper__(): | |
121 | try: |
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126 | try: | |
122 | {usercode} |
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127 | {usercode} | |
123 | finally: |
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128 | finally: | |
124 | locals() |
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129 | locals() | |
125 | """ |
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130 | """ | |
126 | ).format(usercode=indent(code, " " * 8)) |
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131 | ).format(usercode=indent(code, " " * 8)) | |
127 | return res |
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132 | return res | |
128 |
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133 | |||
129 |
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134 | |||
130 | class _AsyncSyntaxErrorVisitor(ast.NodeVisitor): |
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135 | class _AsyncSyntaxErrorVisitor(ast.NodeVisitor): | |
131 | """ |
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136 | """ | |
132 | Find syntax errors that would be an error in an async repl, but because |
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137 | Find syntax errors that would be an error in an async repl, but because | |
133 | the implementation involves wrapping the repl in an async function, it |
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138 | the implementation involves wrapping the repl in an async function, it | |
134 | is erroneously allowed (e.g. yield or return at the top level) |
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139 | is erroneously allowed (e.g. yield or return at the top level) | |
135 | """ |
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140 | """ | |
136 | def __init__(self): |
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141 | def __init__(self): | |
137 | if sys.version_info >= (3,8): |
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142 | if sys.version_info >= (3,8): | |
138 | raise ValueError('DEPRECATED in Python 3.8+') |
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143 | raise ValueError('DEPRECATED in Python 3.8+') | |
139 | self.depth = 0 |
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144 | self.depth = 0 | |
140 | super().__init__() |
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145 | super().__init__() | |
141 |
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146 | |||
142 | def generic_visit(self, node): |
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147 | def generic_visit(self, node): | |
143 | func_types = (ast.FunctionDef, ast.AsyncFunctionDef) |
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148 | func_types = (ast.FunctionDef, ast.AsyncFunctionDef) | |
144 | invalid_types_by_depth = { |
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149 | invalid_types_by_depth = { | |
145 | 0: (ast.Return, ast.Yield, ast.YieldFrom), |
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150 | 0: (ast.Return, ast.Yield, ast.YieldFrom), | |
146 | 1: (ast.Nonlocal,) |
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151 | 1: (ast.Nonlocal,) | |
147 | } |
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152 | } | |
148 |
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153 | |||
149 | should_traverse = self.depth < max(invalid_types_by_depth.keys()) |
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154 | should_traverse = self.depth < max(invalid_types_by_depth.keys()) | |
150 | if isinstance(node, func_types) and should_traverse: |
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155 | if isinstance(node, func_types) and should_traverse: | |
151 | self.depth += 1 |
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156 | self.depth += 1 | |
152 | super().generic_visit(node) |
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157 | super().generic_visit(node) | |
153 | self.depth -= 1 |
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158 | self.depth -= 1 | |
154 | elif isinstance(node, invalid_types_by_depth[self.depth]): |
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159 | elif isinstance(node, invalid_types_by_depth[self.depth]): | |
155 | raise SyntaxError() |
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160 | raise SyntaxError() | |
156 | else: |
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161 | else: | |
157 | super().generic_visit(node) |
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162 | super().generic_visit(node) | |
158 |
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163 | |||
159 |
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164 | |||
160 | def _async_parse_cell(cell: str) -> ast.AST: |
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165 | def _async_parse_cell(cell: str) -> ast.AST: | |
161 | """ |
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166 | """ | |
162 | This is a compatibility shim for pre-3.7 when async outside of a function |
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167 | This is a compatibility shim for pre-3.7 when async outside of a function | |
163 | is a syntax error at the parse stage. |
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168 | is a syntax error at the parse stage. | |
164 |
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169 | |||
165 | It will return an abstract syntax tree parsed as if async and await outside |
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170 | It will return an abstract syntax tree parsed as if async and await outside | |
166 | of a function were not a syntax error. |
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171 | of a function were not a syntax error. | |
167 | """ |
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172 | """ | |
168 | if sys.version_info < (3, 7): |
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173 | if sys.version_info < (3, 7): | |
169 | # Prior to 3.7 you need to asyncify before parse |
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174 | # Prior to 3.7 you need to asyncify before parse | |
170 | wrapped_parse_tree = ast.parse(_asyncify(cell)) |
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175 | wrapped_parse_tree = ast.parse(_asyncify(cell)) | |
171 | return wrapped_parse_tree.body[0].body[0] |
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176 | return wrapped_parse_tree.body[0].body[0] | |
172 | else: |
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177 | else: | |
173 | return ast.parse(cell) |
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178 | return ast.parse(cell) | |
174 |
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179 | |||
175 |
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180 | |||
176 | def _should_be_async(cell: str) -> bool: |
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181 | def _should_be_async(cell: str) -> bool: | |
177 | """Detect if a block of code need to be wrapped in an `async def` |
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182 | """Detect if a block of code need to be wrapped in an `async def` | |
178 |
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183 | |||
179 | Attempt to parse the block of code, it it compile we're fine. |
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184 | Attempt to parse the block of code, it it compile we're fine. | |
180 | Otherwise we wrap if and try to compile. |
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185 | Otherwise we wrap if and try to compile. | |
181 |
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186 | |||
182 | If it works, assume it should be async. Otherwise Return False. |
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187 | If it works, assume it should be async. Otherwise Return False. | |
183 |
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188 | |||
184 | Not handled yet: If the block of code has a return statement as the top |
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189 | Not handled yet: If the block of code has a return statement as the top | |
185 | level, it will be seen as async. This is a know limitation. |
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190 | level, it will be seen as async. This is a know limitation. | |
186 | """ |
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191 | """ | |
187 | if sys.version_info > (3, 8): |
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192 | if sys.version_info > (3, 8): | |
188 | try: |
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193 | try: | |
189 | code = compile(cell, "<>", "exec", flags=getattr(ast,'PyCF_ALLOW_TOP_LEVEL_AWAIT', 0x0)) |
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194 | code = compile(cell, "<>", "exec", flags=getattr(ast,'PyCF_ALLOW_TOP_LEVEL_AWAIT', 0x0)) | |
190 | return inspect.CO_COROUTINE & code.co_flags == inspect.CO_COROUTINE |
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195 | return inspect.CO_COROUTINE & code.co_flags == inspect.CO_COROUTINE | |
191 | except SyntaxError: |
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196 | except SyntaxError: | |
192 | return False |
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197 | return False | |
193 | try: |
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198 | try: | |
194 | # we can't limit ourself to ast.parse, as it __accepts__ to parse on |
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199 | # we can't limit ourself to ast.parse, as it __accepts__ to parse on | |
195 | # 3.7+, but just does not _compile_ |
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200 | # 3.7+, but just does not _compile_ | |
196 | code = compile(cell, "<>", "exec") |
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201 | code = compile(cell, "<>", "exec") | |
197 | except SyntaxError: |
|
202 | except SyntaxError: | |
198 | try: |
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203 | try: | |
199 | parse_tree = _async_parse_cell(cell) |
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204 | parse_tree = _async_parse_cell(cell) | |
200 |
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205 | |||
201 | # Raise a SyntaxError if there are top-level return or yields |
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206 | # Raise a SyntaxError if there are top-level return or yields | |
202 | v = _AsyncSyntaxErrorVisitor() |
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207 | v = _AsyncSyntaxErrorVisitor() | |
203 | v.visit(parse_tree) |
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208 | v.visit(parse_tree) | |
204 |
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209 | |||
205 | except SyntaxError: |
|
210 | except SyntaxError: | |
206 | return False |
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211 | return False | |
207 | return True |
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212 | return True | |
208 | return False |
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213 | return False |
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