##// END OF EJS Templates
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Matthias Bussonnier -
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@@ -1,107 +1,107 b''
1 1 """
2 2 Async helper function that are invalid syntax on Python 3.5 and below.
3 3
4 4 Known limitation and possible improvement.
5 5
6 6 Top level code that contain a return statement (instead of, or in addition to
7 7 await) will be detected as requiring being wrapped in async calls. This should
8 8 be prevented as early return will not work.
9 9 """
10 10
11 11
12 12 import ast
13 13 import sys
14 14 import inspect
15 15 from textwrap import dedent, indent
16 16 from types import CodeType
17 17
18 18
19 19 def _asyncio_runner(coro):
20 20 """
21 21 Handler for asyncio autoawait
22 22 """
23 23 import asyncio
24 24
25 25 return asyncio.get_event_loop().run_until_complete(coro)
26 26
27 27
28 28 def _curio_runner(coroutine):
29 29 """
30 30 handler for curio autoawait
31 31 """
32 32 import curio
33 33
34 34 return curio.run(coroutine)
35 35
36 36
37 37 def _trio_runner(async_fn):
38 38 import trio
39 39 async def loc(coro):
40 40 """
41 41 We need the dummy no-op async def to protect from
42 42 trio's internal. See https://github.com/python-trio/trio/issues/89
43 43 """
44 44 return await coro
45 45 return trio.run(loc, async_fn)
46 46
47 47
48 48 def _pseudo_sync_runner(coro):
49 49 """
50 50 A runner that does not really allow async execution, and just advance the coroutine.
51 51
52 52 See discussion in https://github.com/python-trio/trio/issues/608,
53 53
54 54 Credit to Nathaniel Smith
55 55
56 56 """
57 57 try:
58 58 coro.send(None)
59 59 except StopIteration as exc:
60 60 return exc.value
61 61 else:
62 62 # TODO: do not raise but return an execution result with the right info.
63 raise RuntimeError(f"{coro.__name__!r} needs a real async loop")
63 raise RuntimeError("{coro_name!r} needs a real async loop".format(coro_name=coro.__name__))
64 64
65 65
66 66 def _asyncify(code: str) -> str:
67 67 """wrap code in async def definition.
68 68
69 69 And setup a bit of context to run it later.
70 70 """
71 71 res = dedent(
72 72 """
73 73 async def __wrapper__():
74 74 try:
75 75 {usercode}
76 76 finally:
77 77 locals()
78 78 """
79 79 ).format(usercode=indent(code, " " * 8)[8:])
80 80 return res
81 81
82 82
83 83 def _should_be_async(cell: str) -> bool:
84 84 """Detect if a block of code need to be wrapped in an `async def`
85 85
86 86 Attempt to parse the block of code, it it compile we're fine.
87 87 Otherwise we wrap if and try to compile.
88 88
89 89 If it works, assume it should be async. Otherwise Return False.
90 90
91 91 Not handled yet: If the block of code has a return statement as the top
92 92 level, it will be seen as async. This is a know limitation.
93 93 """
94 94
95 95 try:
96 96 # we can't limit ourself to ast.parse, as it __accepts__ to parse on
97 97 # 3.7+, but just does not _compile_
98 98 compile(cell, "<>", "exec")
99 99 return False
100 100 except SyntaxError:
101 101 try:
102 102 ast.parse(_asyncify(cell))
103 103 # TODO verify ast has not "top level" return or yield.
104 104 except SyntaxError:
105 105 return False
106 106 return True
107 107 return False
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