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