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@@ -1,107 +1,145 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 | Known limitation and possible improvement. |
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4 | Known limitation and possible improvement. | |
5 |
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5 | |||
6 | Top level code that contain a return statement (instead of, or in addition to |
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6 | Top level code that contain a return statement (instead of, or in addition to | |
7 | await) will be detected as requiring being wrapped in async calls. This should |
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7 | await) will be detected as requiring being wrapped in async calls. This should | |
8 | be prevented as early return will not work. |
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8 | be prevented as early return will not work. | |
9 | """ |
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9 | """ | |
10 |
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10 | |||
11 |
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11 | |||
12 | import ast |
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12 | import ast | |
13 | import sys |
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13 | import sys | |
14 | import inspect |
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14 | import inspect | |
15 | from textwrap import dedent, indent |
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15 | from textwrap import dedent, indent | |
16 | from types import CodeType |
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16 | from types import CodeType | |
17 |
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17 | |||
18 |
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18 | |||
19 | def _asyncio_runner(coro): |
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19 | def _asyncio_runner(coro): | |
20 | """ |
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20 | """ | |
21 | Handler for asyncio autoawait |
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21 | Handler for asyncio autoawait | |
22 | """ |
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22 | """ | |
23 | import asyncio |
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23 | import asyncio | |
24 |
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24 | |||
25 | return asyncio.get_event_loop().run_until_complete(coro) |
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25 | return asyncio.get_event_loop().run_until_complete(coro) | |
26 |
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26 | |||
27 |
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27 | |||
28 | def _curio_runner(coroutine): |
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28 | def _curio_runner(coroutine): | |
29 | """ |
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29 | """ | |
30 | handler for curio autoawait |
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30 | handler for curio autoawait | |
31 | """ |
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31 | """ | |
32 | import curio |
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32 | import curio | |
33 |
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33 | |||
34 | return curio.run(coroutine) |
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34 | return curio.run(coroutine) | |
35 |
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35 | |||
36 |
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36 | |||
37 | def _trio_runner(async_fn): |
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37 | def _trio_runner(async_fn): | |
38 | import trio |
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38 | import trio | |
39 | async def loc(coro): |
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39 | async def loc(coro): | |
40 | """ |
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40 | """ | |
41 | We need the dummy no-op async def to protect from |
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41 | We need the dummy no-op async def to protect from | |
42 | trio's internal. See https://github.com/python-trio/trio/issues/89 |
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42 | trio's internal. See https://github.com/python-trio/trio/issues/89 | |
43 | """ |
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43 | """ | |
44 | return await coro |
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44 | return await coro | |
45 | return trio.run(loc, async_fn) |
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45 | return trio.run(loc, async_fn) | |
46 |
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46 | |||
47 |
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47 | |||
48 | def _pseudo_sync_runner(coro): |
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48 | def _pseudo_sync_runner(coro): | |
49 | """ |
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49 | """ | |
50 | A runner that does not really allow async execution, and just advance the coroutine. |
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50 | A runner that does not really allow async execution, and just advance the coroutine. | |
51 |
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51 | |||
52 | See discussion in https://github.com/python-trio/trio/issues/608, |
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52 | See discussion in https://github.com/python-trio/trio/issues/608, | |
53 |
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53 | |||
54 | Credit to Nathaniel Smith |
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54 | Credit to Nathaniel Smith | |
55 |
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55 | |||
56 | """ |
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56 | """ | |
57 | try: |
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57 | try: | |
58 | coro.send(None) |
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58 | coro.send(None) | |
59 | except StopIteration as exc: |
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59 | except StopIteration as exc: | |
60 | return exc.value |
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60 | return exc.value | |
61 | else: |
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61 | else: | |
62 | # TODO: do not raise but return an execution result with the right info. |
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62 | # TODO: do not raise but return an execution result with the right info. | |
63 | raise RuntimeError("{coro_name!r} needs a real async loop".format(coro_name=coro.__name__)) |
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63 | raise RuntimeError("{coro_name!r} needs a real async loop".format(coro_name=coro.__name__)) | |
64 |
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64 | |||
65 |
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65 | |||
66 | def _asyncify(code: str) -> str: |
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66 | def _asyncify(code: str) -> str: | |
67 | """wrap code in async def definition. |
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67 | """wrap code in async def definition. | |
68 |
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68 | |||
69 | And setup a bit of context to run it later. |
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69 | And setup a bit of context to run it later. | |
70 | """ |
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70 | """ | |
71 | res = dedent( |
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71 | res = dedent( | |
72 | """ |
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72 | """ | |
73 | async def __wrapper__(): |
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73 | async def __wrapper__(): | |
74 | try: |
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74 | try: | |
75 | {usercode} |
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75 | {usercode} | |
76 | finally: |
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76 | finally: | |
77 | locals() |
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77 | locals() | |
78 | """ |
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78 | """ | |
79 | ).format(usercode=indent(code, " " * 8)[8:]) |
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79 | ).format(usercode=indent(code, " " * 8)[8:]) | |
80 | return res |
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80 | return res | |
81 |
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81 | |||
82 |
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82 | |||
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83 | class _AsyncSyntaxErrorVisitor(ast.NodeVisitor): | |||
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84 | """ | |||
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85 | Find syntax errors that would be an error in an async repl, but because | |||
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86 | the implementation involves wrapping the repl in an async function, it | |||
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87 | is erroneously allowed (e.g. yield or return at the top level) | |||
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88 | """ | |||
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89 | def generic_visit(self, node): | |||
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90 | func_types = (ast.FunctionDef, ast.AsyncFunctionDef) | |||
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91 | invalid_types = (ast.Return, ast.Yield, ast.YieldFrom) | |||
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92 | ||||
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93 | if isinstance(node, func_types): | |||
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94 | return # Don't recurse into functions | |||
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95 | elif isinstance(node, invalid_types): | |||
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96 | raise SyntaxError() | |||
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97 | else: | |||
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98 | super().generic_visit(node) | |||
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99 | ||||
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100 | ||||
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101 | def _async_parse_cell(cell: str) -> ast.AST: | |||
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102 | """ | |||
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103 | This is a compatibility shim for pre-3.7 when async outside of a function | |||
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104 | is a syntax error at the parse stage. | |||
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105 | ||||
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106 | It will return an abstract syntax tree parsed as if async and await outside | |||
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107 | of a function were not a syntax error. | |||
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108 | """ | |||
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109 | if sys.version_info < (3, 7): | |||
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110 | # Prior to 3.7 you need to asyncify before parse | |||
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111 | wrapped_parse_tree = ast.parse(_asyncify(cell)) | |||
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112 | return wrapped_parse_tree.body[0].body[0] | |||
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113 | else: | |||
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114 | return ast.parse(cell) | |||
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115 | ||||
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116 | ||||
83 | def _should_be_async(cell: str) -> bool: |
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117 | def _should_be_async(cell: str) -> bool: | |
84 | """Detect if a block of code need to be wrapped in an `async def` |
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118 | """Detect if a block of code need to be wrapped in an `async def` | |
85 |
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119 | |||
86 | Attempt to parse the block of code, it it compile we're fine. |
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120 | Attempt to parse the block of code, it it compile we're fine. | |
87 | Otherwise we wrap if and try to compile. |
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121 | Otherwise we wrap if and try to compile. | |
88 |
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122 | |||
89 | If it works, assume it should be async. Otherwise Return False. |
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123 | If it works, assume it should be async. Otherwise Return False. | |
90 |
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124 | |||
91 | Not handled yet: If the block of code has a return statement as the top |
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125 | Not handled yet: If the block of code has a return statement as the top | |
92 | level, it will be seen as async. This is a know limitation. |
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126 | level, it will be seen as async. This is a know limitation. | |
93 | """ |
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127 | """ | |
94 |
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128 | |||
95 | try: |
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129 | try: | |
96 | # we can't limit ourself to ast.parse, as it __accepts__ to parse on |
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130 | # we can't limit ourself to ast.parse, as it __accepts__ to parse on | |
97 | # 3.7+, but just does not _compile_ |
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131 | # 3.7+, but just does not _compile_ | |
98 | compile(cell, "<>", "exec") |
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132 | compile(cell, "<>", "exec") | |
99 | return False |
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133 | return False | |
100 | except SyntaxError: |
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134 | except SyntaxError: | |
101 | try: |
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135 | try: | |
102 |
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136 | parse_tree = _async_parse_cell(cell) | |
103 | # TODO verify ast has not "top level" return or yield. |
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137 | ||
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138 | # Raise a SyntaxError if there are top-level return or yields | |||
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139 | v = _AsyncSyntaxErrorVisitor() | |||
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140 | v.visit(parse_tree) | |||
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141 | ||||
104 | except SyntaxError: |
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142 | except SyntaxError: | |
105 | return False |
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143 | return False | |
106 | return True |
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144 | return True | |
107 | return False |
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145 | return False |
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