Show More
@@ -1,166 +1,171 b'' | |||
|
1 | 1 | """ |
|
2 | 2 | Async helper function that are invalid syntax on Python 3.5 and below. |
|
3 | 3 | |
|
4 | 4 | This code is best effort, and may have edge cases not behaving as expected. In |
|
5 | 5 | particular it contain a number of heuristics to detect whether code is |
|
6 | 6 | effectively async and need to run in an event loop or not. |
|
7 | 7 | |
|
8 | 8 | Some constructs (like top-level `return`, or `yield`) are taken care of |
|
9 | 9 | explicitly to actually raise a SyntaxError and stay as close as possible to |
|
10 | 10 | Python semantics. |
|
11 | 11 | """ |
|
12 | 12 | |
|
13 | 13 | |
|
14 | 14 | import ast |
|
15 | 15 | import sys |
|
16 | import inspect | |
|
16 | 17 | from textwrap import dedent, indent |
|
17 | 18 | |
|
18 | 19 | |
|
19 | 20 | class _AsyncIORunner: |
|
20 | 21 | |
|
21 | 22 | def __call__(self, coro): |
|
22 | 23 | """ |
|
23 | 24 | Handler for asyncio autoawait |
|
24 | 25 | """ |
|
25 | 26 | import asyncio |
|
26 | 27 | |
|
27 | 28 | return asyncio.get_event_loop().run_until_complete(coro) |
|
28 | 29 | |
|
29 | 30 | def __str__(self): |
|
30 | 31 | return 'asyncio' |
|
31 | 32 | |
|
32 | 33 | _asyncio_runner = _AsyncIORunner() |
|
33 | 34 | |
|
34 | 35 | |
|
35 | 36 | def _curio_runner(coroutine): |
|
36 | 37 | """ |
|
37 | 38 | handler for curio autoawait |
|
38 | 39 | """ |
|
39 | 40 | import curio |
|
40 | 41 | |
|
41 | 42 | return curio.run(coroutine) |
|
42 | 43 | |
|
43 | 44 | |
|
44 | 45 | def _trio_runner(async_fn): |
|
45 | 46 | import trio |
|
46 | 47 | |
|
47 | 48 | async def loc(coro): |
|
48 | 49 | """ |
|
49 | 50 | We need the dummy no-op async def to protect from |
|
50 | 51 | trio's internal. See https://github.com/python-trio/trio/issues/89 |
|
51 | 52 | """ |
|
52 | 53 | return await coro |
|
53 | 54 | |
|
54 | 55 | return trio.run(loc, async_fn) |
|
55 | 56 | |
|
56 | 57 | |
|
57 | 58 | def _pseudo_sync_runner(coro): |
|
58 | 59 | """ |
|
59 | 60 | A runner that does not really allow async execution, and just advance the coroutine. |
|
60 | 61 | |
|
61 | 62 | See discussion in https://github.com/python-trio/trio/issues/608, |
|
62 | 63 | |
|
63 | 64 | Credit to Nathaniel Smith |
|
64 | 65 | |
|
65 | 66 | """ |
|
66 | 67 | try: |
|
67 | 68 | coro.send(None) |
|
68 | 69 | except StopIteration as exc: |
|
69 | 70 | return exc.value |
|
70 | 71 | else: |
|
71 | 72 | # TODO: do not raise but return an execution result with the right info. |
|
72 | 73 | raise RuntimeError( |
|
73 | 74 | "{coro_name!r} needs a real async loop".format(coro_name=coro.__name__) |
|
74 | 75 | ) |
|
75 | 76 | |
|
76 | 77 | |
|
77 | 78 | def _asyncify(code: str) -> str: |
|
78 | 79 | """wrap code in async def definition. |
|
79 | 80 | |
|
80 | 81 | And setup a bit of context to run it later. |
|
81 | 82 | """ |
|
82 | 83 | res = dedent( |
|
83 | 84 | """ |
|
84 | 85 | async def __wrapper__(): |
|
85 | 86 | try: |
|
86 | 87 | {usercode} |
|
87 | 88 | finally: |
|
88 | 89 | locals() |
|
89 | 90 | """ |
|
90 | 91 | ).format(usercode=indent(code, " " * 8)) |
|
91 | 92 | return res |
|
92 | 93 | |
|
93 | 94 | |
|
94 | 95 | class _AsyncSyntaxErrorVisitor(ast.NodeVisitor): |
|
95 | 96 | """ |
|
96 | 97 | Find syntax errors that would be an error in an async repl, but because |
|
97 | 98 | the implementation involves wrapping the repl in an async function, it |
|
98 | 99 | is erroneously allowed (e.g. yield or return at the top level) |
|
99 | 100 | """ |
|
100 | 101 | def __init__(self): |
|
102 | if sys.version_info >= (3,8): | |
|
103 | raise ValueError('DEPRECATED in Python 3.8+') | |
|
101 | 104 | self.depth = 0 |
|
102 | 105 | super().__init__() |
|
103 | 106 | |
|
104 | 107 | def generic_visit(self, node): |
|
105 | 108 | func_types = (ast.FunctionDef, ast.AsyncFunctionDef) |
|
106 | 109 | invalid_types_by_depth = { |
|
107 | 110 | 0: (ast.Return, ast.Yield, ast.YieldFrom), |
|
108 | 111 | 1: (ast.Nonlocal,) |
|
109 | 112 | } |
|
110 | 113 | |
|
111 | 114 | should_traverse = self.depth < max(invalid_types_by_depth.keys()) |
|
112 | 115 | if isinstance(node, func_types) and should_traverse: |
|
113 | 116 | self.depth += 1 |
|
114 | 117 | super().generic_visit(node) |
|
115 | 118 | self.depth -= 1 |
|
116 | 119 | elif isinstance(node, invalid_types_by_depth[self.depth]): |
|
117 | 120 | raise SyntaxError() |
|
118 | 121 | else: |
|
119 | 122 | super().generic_visit(node) |
|
120 | 123 | |
|
121 | 124 | |
|
122 | 125 | def _async_parse_cell(cell: str) -> ast.AST: |
|
123 | 126 | """ |
|
124 | 127 | This is a compatibility shim for pre-3.7 when async outside of a function |
|
125 | 128 | is a syntax error at the parse stage. |
|
126 | 129 | |
|
127 | 130 | It will return an abstract syntax tree parsed as if async and await outside |
|
128 | 131 | of a function were not a syntax error. |
|
129 | 132 | """ |
|
130 | 133 | if sys.version_info < (3, 7): |
|
131 | 134 | # Prior to 3.7 you need to asyncify before parse |
|
132 | 135 | wrapped_parse_tree = ast.parse(_asyncify(cell)) |
|
133 | 136 | return wrapped_parse_tree.body[0].body[0] |
|
134 | 137 | else: |
|
135 | 138 | return ast.parse(cell) |
|
136 | 139 | |
|
137 | 140 | |
|
138 | 141 | def _should_be_async(cell: str) -> bool: |
|
139 | 142 | """Detect if a block of code need to be wrapped in an `async def` |
|
140 | 143 | |
|
141 | 144 | Attempt to parse the block of code, it it compile we're fine. |
|
142 | 145 | Otherwise we wrap if and try to compile. |
|
143 | 146 | |
|
144 | 147 | If it works, assume it should be async. Otherwise Return False. |
|
145 | 148 | |
|
146 | 149 | Not handled yet: If the block of code has a return statement as the top |
|
147 | 150 | level, it will be seen as async. This is a know limitation. |
|
148 | 151 | """ |
|
149 | 152 | |
|
150 | 153 | try: |
|
151 | 154 | # we can't limit ourself to ast.parse, as it __accepts__ to parse on |
|
152 | 155 | # 3.7+, but just does not _compile_ |
|
153 | compile(cell, "<>", "exec") | |
|
154 | return False | |
|
156 | code = compile(cell, "<>", "exec", flags=ast.PyCF_ALLOW_TOP_LEVEL_AWAIT) | |
|
157 | return inspect.CO_COROUTINE & code.co_flags == inspect.CO_COROUTINE | |
|
155 | 158 | except SyntaxError: |
|
159 | #if sys.version_info > (3, 8): | |
|
160 | # raise | |
|
156 | 161 | try: |
|
157 | 162 | parse_tree = _async_parse_cell(cell) |
|
158 | 163 | |
|
159 | 164 | # Raise a SyntaxError if there are top-level return or yields |
|
160 | 165 | v = _AsyncSyntaxErrorVisitor() |
|
161 | 166 | v.visit(parse_tree) |
|
162 | 167 | |
|
163 | 168 | except SyntaxError: |
|
164 | 169 | return False |
|
165 | 170 | return True |
|
166 | 171 | return False |
General Comments 0
You need to be logged in to leave comments.
Login now