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comparison: src/eric7/Plugins/CheckerPlugins/CodeStyleChecker/ast_unparse.py

src/eric7/Plugins/CheckerPlugins/CodeStyleChecker/ast_unparse.py

branch
eric7
changeset 10116
4a619fb7bd09
parent 9209
b99e7fd55fd3
child 10165
98c97c731e42
equal deleted inserted replaced
10115:8ca3f08c5ac8 10116:4a619fb7bd09
1 """
2 ast_unparse
3 ~~~~~~~~~~~
4
5 This module is a backport of the unparse function of the Python 3.9
6 ast module.
7
8 Original ast module code is
9 :copyright: Copyright 2008 by Armin Ronacher.
10 :license: Python License.
11 """
12
13 import ast
14 import sys
15 from enum import IntEnum, auto
16 from contextlib import contextmanager
17
18 import AstUtilities
19
20 try:
21 from contextlib import nullcontext
22 except ImportError:
23 # 'nullcontext'' was defined in Python 3.7. The following code is a copy
24 # of that class.
25
26 from contextlib import AbstractContextManager
27
28 class nullcontext(AbstractContextManager):
29 """Context manager that does no additional processing.
30
31 Used as a stand-in for a normal context manager, when a particular
32 block of code is only sometimes used with a normal context manager:
33
34 cm = optional_cm if condition else nullcontext()
35 with cm:
36 # Perform operation, using optional_cm if condition is True
37 """
38
39 def __init__(self, enter_result=None):
40 self.enter_result = enter_result
41
42 def __enter__(self):
43 return self.enter_result
44
45 def __exit__(self, *excinfo):
46 pass
47
48 # Large float and imaginary literals get turned into infinities in the AST.
49 # We unparse those infinities to INFSTR.
50 _INFSTR = "1e" + repr(sys.float_info.max_10_exp + 1)
51
52 class _Precedence(IntEnum):
53 """Precedence table that originated from python grammar."""
54
55 TUPLE = auto()
56 YIELD = auto() # 'yield', 'yield from'
57 TEST = auto() # 'if'-'else', 'lambda'
58 OR = auto() # 'or'
59 AND = auto() # 'and'
60 NOT = auto() # 'not'
61 CMP = auto() # '<', '>', '==', '>=', '<=', '!=',
62 # 'in', 'not in', 'is', 'is not'
63 EXPR = auto()
64 BOR = EXPR # '|'
65 BXOR = auto() # '^'
66 BAND = auto() # '&'
67 SHIFT = auto() # '<<', '>>'
68 ARITH = auto() # '+', '-'
69 TERM = auto() # '*', '@', '/', '%', '//'
70 FACTOR = auto() # unary '+', '-', '~'
71 POWER = auto() # '**'
72 AWAIT = auto() # 'await'
73 ATOM = auto()
74
75 def next(self):
76 try:
77 return self.__class__(self + 1)
78 except ValueError:
79 return self
80
81
82 _SINGLE_QUOTES = ("'", '"')
83 _MULTI_QUOTES = ('"""', "'''")
84 _ALL_QUOTES = (*_SINGLE_QUOTES, *_MULTI_QUOTES)
85
86 class _Unparser(ast.NodeVisitor):
87 """Methods in this class recursively traverse an AST and
88 output source code for the abstract syntax; original formatting
89 is disregarded."""
90
91 def __init__(self, *, _avoid_backslashes=False):
92 self._source = []
93 self._buffer = []
94 self._precedences = {}
95 self._type_ignores = {}
96 self._indent = 0
97 self._avoid_backslashes = _avoid_backslashes
98
99 def interleave(self, inter, f, seq):
100 """Call f on each item in seq, calling inter() in between."""
101 seq = iter(seq)
102 try:
103 f(next(seq))
104 except StopIteration:
105 pass
106 else:
107 for x in seq:
108 inter()
109 f(x)
110
111 def items_view(self, traverser, items):
112 """Traverse and separate the given *items* with a comma and append it to
113 the buffer. If *items* is a single item sequence, a trailing comma
114 will be added."""
115 if len(items) == 1:
116 traverser(items[0])
117 self.write(",")
118 else:
119 self.interleave(lambda: self.write(", "), traverser, items)
120
121 def maybe_newline(self):
122 """Adds a newline if it isn't the start of generated source"""
123 if self._source:
124 self.write("\n")
125
126 def fill(self, text=""):
127 """Indent a piece of text and append it, according to the current
128 indentation level"""
129 self.maybe_newline()
130 self.write(" " * self._indent + text)
131
132 def write(self, text):
133 """Append a piece of text"""
134 self._source.append(text)
135
136 def buffer_writer(self, text):
137 self._buffer.append(text)
138
139 @property
140 def buffer(self):
141 value = "".join(self._buffer)
142 self._buffer.clear()
143 return value
144
145 @contextmanager
146 def block(self, *, extra = None):
147 """A context manager for preparing the source for blocks. It adds
148 the character':', increases the indentation on enter and decreases
149 the indentation on exit. If *extra* is given, it will be directly
150 appended after the colon character.
151 """
152 self.write(":")
153 if extra:
154 self.write(extra)
155 self._indent += 1
156 yield
157 self._indent -= 1
158
159 @contextmanager
160 def delimit(self, start, end):
161 """A context manager for preparing the source for expressions. It adds
162 *start* to the buffer and enters, after exit it adds *end*."""
163
164 self.write(start)
165 yield
166 self.write(end)
167
168 def delimit_if(self, start, end, condition):
169 if condition:
170 return self.delimit(start, end)
171 else:
172 return nullcontext()
173
174 def require_parens(self, precedence, node):
175 """Shortcut to adding precedence related parens"""
176 return self.delimit_if("(", ")", self.get_precedence(node) > precedence)
177
178 def get_precedence(self, node):
179 return self._precedences.get(node, _Precedence.TEST)
180
181 def set_precedence(self, precedence, *nodes):
182 for node in nodes:
183 self._precedences[node] = precedence
184
185 def get_raw_docstring(self, node):
186 """If a docstring node is found in the body of the *node* parameter,
187 return that docstring node, None otherwise.
188
189 Logic mirrored from ``_PyAST_GetDocString``."""
190 if not isinstance(
191 node, (ast.AsyncFunctionDef, ast.FunctionDef, ast.ClassDef,
192 ast.Module)
193 ) or len(node.body) < 1:
194 return None
195 node = node.body[0]
196 if not isinstance(node, ast.Expr):
197 return None
198 node = node.value
199 if isinstance(node, ast.Constant) and isinstance(node.value, str):
200 return node
201
202 def get_type_comment(self, node):
203 comment = self._type_ignores.get(node.lineno) or node.type_comment
204 if comment is not None:
205 return f" # type: {comment}"
206
207 def traverse(self, node):
208 if isinstance(node, list):
209 for item in node:
210 self.traverse(item)
211 else:
212 super().visit(node)
213
214 def visit(self, node):
215 """Outputs a source code string that, if converted back to an ast
216 (using ast.parse) will generate an AST equivalent to *node*"""
217 self._source = []
218 self.traverse(node)
219 return "".join(self._source)
220
221 def _write_docstring_and_traverse_body(self, node):
222 docstring = self.get_raw_docstring(node)
223 if (docstring):
224 self._write_docstring(docstring)
225 self.traverse(node.body[1:])
226 else:
227 self.traverse(node.body)
228
229 def visit_Module(self, node):
230 self._type_ignores = {
231 ignore.lineno: f"ignore{ignore.tag}"
232 for ignore in node.type_ignores
233 }
234 self._write_docstring_and_traverse_body(node)
235 self._type_ignores.clear()
236
237 def visit_FunctionType(self, node):
238 with self.delimit("(", ")"):
239 self.interleave(
240 lambda: self.write(", "), self.traverse, node.argtypes
241 )
242
243 self.write(" -> ")
244 self.traverse(node.returns)
245
246 def visit_Expr(self, node):
247 self.fill()
248 self.set_precedence(_Precedence.YIELD, node.value)
249 self.traverse(node.value)
250
251 def visit_NamedExpr(self, node):
252 with self.require_parens(_Precedence.TUPLE, node):
253 self.set_precedence(_Precedence.ATOM, node.target, node.value)
254 self.traverse(node.target)
255 self.write(" := ")
256 self.traverse(node.value)
257
258 def visit_Import(self, node):
259 self.fill("import ")
260 self.interleave(lambda: self.write(", "), self.traverse, node.names)
261
262 def visit_ImportFrom(self, node):
263 self.fill("from ")
264 self.write("." * node.level)
265 if node.module:
266 self.write(node.module)
267 self.write(" import ")
268 self.interleave(lambda: self.write(", "), self.traverse, node.names)
269
270 def visit_Assign(self, node):
271 self.fill()
272 for target in node.targets:
273 self.traverse(target)
274 self.write(" = ")
275 self.traverse(node.value)
276 type_comment = self.get_type_comment(node)
277 if type_comment:
278 self.write(type_comment)
279
280 def visit_AugAssign(self, node):
281 self.fill()
282 self.traverse(node.target)
283 self.write(" " + self.binop[node.op.__class__.__name__] + "= ")
284 self.traverse(node.value)
285
286 def visit_AnnAssign(self, node):
287 self.fill()
288 with self.delimit_if("(", ")", not node.simple and isinstance(node.target, ast.Name)):
289 self.traverse(node.target)
290 self.write(": ")
291 self.traverse(node.annotation)
292 if node.value:
293 self.write(" = ")
294 self.traverse(node.value)
295
296 def visit_Return(self, node):
297 self.fill("return")
298 if node.value:
299 self.write(" ")
300 self.traverse(node.value)
301
302 def visit_Pass(self, node):
303 self.fill("pass")
304
305 def visit_Break(self, node):
306 self.fill("break")
307
308 def visit_Continue(self, node):
309 self.fill("continue")
310
311 def visit_Delete(self, node):
312 self.fill("del ")
313 self.interleave(lambda: self.write(", "), self.traverse, node.targets)
314
315 def visit_Assert(self, node):
316 self.fill("assert ")
317 self.traverse(node.test)
318 if node.msg:
319 self.write(", ")
320 self.traverse(node.msg)
321
322 def visit_Global(self, node):
323 self.fill("global ")
324 self.interleave(lambda: self.write(", "), self.write, node.names)
325
326 def visit_Nonlocal(self, node):
327 self.fill("nonlocal ")
328 self.interleave(lambda: self.write(", "), self.write, node.names)
329
330 def visit_Await(self, node):
331 with self.require_parens(_Precedence.AWAIT, node):
332 self.write("await")
333 if node.value:
334 self.write(" ")
335 self.set_precedence(_Precedence.ATOM, node.value)
336 self.traverse(node.value)
337
338 def visit_Yield(self, node):
339 with self.require_parens(_Precedence.YIELD, node):
340 self.write("yield")
341 if node.value:
342 self.write(" ")
343 self.set_precedence(_Precedence.ATOM, node.value)
344 self.traverse(node.value)
345
346 def visit_YieldFrom(self, node):
347 with self.require_parens(_Precedence.YIELD, node):
348 self.write("yield from ")
349 if not node.value:
350 raise ValueError("Node can't be used without a value attribute.")
351 self.set_precedence(_Precedence.ATOM, node.value)
352 self.traverse(node.value)
353
354 def visit_Raise(self, node):
355 self.fill("raise")
356 if not node.exc:
357 if node.cause:
358 raise ValueError("Node can't use cause without an exception.")
359 return
360 self.write(" ")
361 self.traverse(node.exc)
362 if node.cause:
363 self.write(" from ")
364 self.traverse(node.cause)
365
366 def visit_Try(self, node):
367 self.fill("try")
368 with self.block():
369 self.traverse(node.body)
370 for ex in node.handlers:
371 self.traverse(ex)
372 if node.orelse:
373 self.fill("else")
374 with self.block():
375 self.traverse(node.orelse)
376 if node.finalbody:
377 self.fill("finally")
378 with self.block():
379 self.traverse(node.finalbody)
380
381 def visit_ExceptHandler(self, node):
382 self.fill("except")
383 if node.type:
384 self.write(" ")
385 self.traverse(node.type)
386 if node.name:
387 self.write(" as ")
388 self.write(node.name)
389 with self.block():
390 self.traverse(node.body)
391
392 def visit_ClassDef(self, node):
393 self.maybe_newline()
394 for deco in node.decorator_list:
395 self.fill("@")
396 self.traverse(deco)
397 self.fill("class " + node.name)
398 with self.delimit_if("(", ")", condition = node.bases or node.keywords):
399 comma = False
400 for e in node.bases:
401 if comma:
402 self.write(", ")
403 else:
404 comma = True
405 self.traverse(e)
406 for e in node.keywords:
407 if comma:
408 self.write(", ")
409 else:
410 comma = True
411 self.traverse(e)
412
413 with self.block():
414 self._write_docstring_and_traverse_body(node)
415
416 def visit_FunctionDef(self, node):
417 self._function_helper(node, "def")
418
419 def visit_AsyncFunctionDef(self, node):
420 self._function_helper(node, "async def")
421
422 def _function_helper(self, node, fill_suffix):
423 self.maybe_newline()
424 for deco in node.decorator_list:
425 self.fill("@")
426 self.traverse(deco)
427 def_str = fill_suffix + " " + node.name
428 self.fill(def_str)
429 with self.delimit("(", ")"):
430 self.traverse(node.args)
431 if node.returns:
432 self.write(" -> ")
433 self.traverse(node.returns)
434 with self.block(extra=self.get_type_comment(node)):
435 self._write_docstring_and_traverse_body(node)
436
437 def visit_For(self, node):
438 self._for_helper("for ", node)
439
440 def visit_AsyncFor(self, node):
441 self._for_helper("async for ", node)
442
443 def _for_helper(self, fill, node):
444 self.fill(fill)
445 self.traverse(node.target)
446 self.write(" in ")
447 self.traverse(node.iter)
448 with self.block(extra=self.get_type_comment(node)):
449 self.traverse(node.body)
450 if node.orelse:
451 self.fill("else")
452 with self.block():
453 self.traverse(node.orelse)
454
455 def visit_If(self, node):
456 self.fill("if ")
457 self.traverse(node.test)
458 with self.block():
459 self.traverse(node.body)
460 # collapse nested ifs into equivalent elifs.
461 while node.orelse and len(node.orelse) == 1 and isinstance(node.orelse[0], ast.If):
462 node = node.orelse[0]
463 self.fill("elif ")
464 self.traverse(node.test)
465 with self.block():
466 self.traverse(node.body)
467 # final else
468 if node.orelse:
469 self.fill("else")
470 with self.block():
471 self.traverse(node.orelse)
472
473 def visit_While(self, node):
474 self.fill("while ")
475 self.traverse(node.test)
476 with self.block():
477 self.traverse(node.body)
478 if node.orelse:
479 self.fill("else")
480 with self.block():
481 self.traverse(node.orelse)
482
483 def visit_With(self, node):
484 self.fill("with ")
485 self.interleave(lambda: self.write(", "), self.traverse, node.items)
486 with self.block(extra=self.get_type_comment(node)):
487 self.traverse(node.body)
488
489 def visit_AsyncWith(self, node):
490 self.fill("async with ")
491 self.interleave(lambda: self.write(", "), self.traverse, node.items)
492 with self.block(extra=self.get_type_comment(node)):
493 self.traverse(node.body)
494
495 def _str_literal_helper(
496 self, string, *, quote_types=_ALL_QUOTES, escape_special_whitespace=False
497 ):
498 """Helper for writing string literals, minimizing escapes.
499 Returns the tuple (string literal to write, possible quote types).
500 """
501 def escape_char(c):
502 # \n and \t are non-printable, but we only escape them if
503 # escape_special_whitespace is True
504 if not escape_special_whitespace and c in "\n\t":
505 return c
506 # Always escape backslashes and other non-printable characters
507 if c == "\\" or not c.isprintable():
508 return c.encode("unicode_escape").decode("ascii")
509 return c
510
511 escaped_string = "".join(map(escape_char, string))
512 possible_quotes = quote_types
513 if "\n" in escaped_string:
514 possible_quotes = [q for q in possible_quotes if q in _MULTI_QUOTES]
515 possible_quotes = [q for q in possible_quotes if q not in escaped_string]
516 if not possible_quotes:
517 # If there aren't any possible_quotes, fallback to using repr
518 # on the original string. Try to use a quote from quote_types,
519 # e.g., so that we use triple quotes for docstrings.
520 string = repr(string)
521 quote = next((q for q in quote_types if string[0] in q), string[0])
522 return string[1:-1], [quote]
523 if escaped_string:
524 # Sort so that we prefer '''"''' over """\""""
525 possible_quotes.sort(key=lambda q: q[0] == escaped_string[-1])
526 # If we're using triple quotes and we'd need to escape a final
527 # quote, escape it
528 if possible_quotes[0][0] == escaped_string[-1]:
529 assert len(possible_quotes[0]) == 3
530 escaped_string = escaped_string[:-1] + "\\" + escaped_string[-1]
531 return escaped_string, possible_quotes
532
533 def _write_str_avoiding_backslashes(self, string, *, quote_types=_ALL_QUOTES):
534 """Write string literal value with a best effort attempt to avoid backslashes."""
535 string, quote_types = self._str_literal_helper(string, quote_types=quote_types)
536 quote_type = quote_types[0]
537 self.write(f"{quote_type}{string}{quote_type}")
538
539 def visit_JoinedStr(self, node):
540 self.write("f")
541 if self._avoid_backslashes:
542 self._fstring_JoinedStr(node, self.buffer_writer)
543 self._write_str_avoiding_backslashes(self.buffer)
544 return
545
546 # If we don't need to avoid backslashes globally (i.e., we only need
547 # to avoid them inside FormattedValues), it's cosmetically preferred
548 # to use escaped whitespace. That is, it's preferred to use backslashes
549 # for cases like: f"{x}\n". To accomplish this, we keep track of what
550 # in our buffer corresponds to FormattedValues and what corresponds to
551 # Constant parts of the f-string, and allow escapes accordingly.
552 buffer = []
553 for value in node.values:
554 meth = getattr(self, "_fstring_" + type(value).__name__)
555 meth(value, self.buffer_writer)
556 buffer.append((self.buffer, isinstance(value, ast.Constant)))
557 new_buffer = []
558 quote_types = _ALL_QUOTES
559 for value, is_constant in buffer:
560 # Repeatedly narrow down the list of possible quote_types
561 value, quote_types = self._str_literal_helper(
562 value, quote_types=quote_types,
563 escape_special_whitespace=is_constant
564 )
565 new_buffer.append(value)
566 value = "".join(new_buffer)
567 quote_type = quote_types[0]
568 self.write(f"{quote_type}{value}{quote_type}")
569
570 def visit_FormattedValue(self, node):
571 self.write("f")
572 self._fstring_FormattedValue(node, self.buffer_writer)
573 self._write_str_avoiding_backslashes(self.buffer)
574
575 def _fstring_JoinedStr(self, node, write):
576 for value in node.values:
577 meth = getattr(self, "_fstring_" + type(value).__name__)
578 meth(value, write)
579
580 def _fstring_Constant(self, node, write):
581 if not isinstance(node.value, str):
582 raise ValueError("Constants inside JoinedStr should be a string.")
583 value = node.value.replace("{", "{{").replace("}", "}}")
584 write(value)
585
586 def _fstring_FormattedValue(self, node, write):
587 write("{")
588 unparser = type(self)(_avoid_backslashes=True)
589 unparser.set_precedence(_Precedence.TEST.next(), node.value)
590 expr = unparser.visit(node.value)
591 if expr.startswith("{"):
592 write(" ") # Separate pair of opening brackets as "{ {"
593 if "\\" in expr:
594 raise ValueError("Unable to avoid backslash in f-string expression part")
595 write(expr)
596 if node.conversion != -1:
597 conversion = chr(node.conversion)
598 if conversion not in "sra":
599 raise ValueError("Unknown f-string conversion.")
600 write(f"!{conversion}")
601 if node.format_spec:
602 write(":")
603 meth = getattr(self, "_fstring_" + type(node.format_spec).__name__)
604 meth(node.format_spec, write)
605 write("}")
606
607 def visit_Name(self, node):
608 self.write(node.id)
609
610 def _write_docstring(self, node):
611 self.fill()
612 if node.kind == "u":
613 self.write("u")
614 self._write_str_avoiding_backslashes(node.value, quote_types=_MULTI_QUOTES)
615
616 def _write_constant(self, value):
617 if isinstance(value, (float, complex)):
618 # Substitute overflowing decimal literal for AST infinities,
619 # and inf - inf for NaNs.
620 self.write(
621 repr(value)
622 .replace("inf", _INFSTR)
623 .replace("nan", f"({_INFSTR}-{_INFSTR})")
624 )
625 elif self._avoid_backslashes and isinstance(value, str):
626 self._write_str_avoiding_backslashes(value)
627 else:
628 self.write(repr(value))
629
630 def visit_Constant(self, node):
631 value = AstUtilities.getValue(node)
632 if isinstance(value, tuple):
633 with self.delimit("(", ")"):
634 self.items_view(self._write_constant, value)
635 elif value is ...:
636 self.write("...")
637 else:
638 if hasattr(node, "kind") and node.kind == "u":
639 self.write("u")
640 self._write_constant(value)
641
642 visit_NameConstant = visit_Constant
643 visit_Num = visit_Constant
644 visit_Str = visit_Constant
645 visit_Bytes = visit_Constant
646 visit_Ellipsis = visit_Constant
647
648 def visit_List(self, node):
649 with self.delimit("[", "]"):
650 self.interleave(lambda: self.write(", "), self.traverse, node.elts)
651
652 def visit_ListComp(self, node):
653 with self.delimit("[", "]"):
654 self.traverse(node.elt)
655 for gen in node.generators:
656 self.traverse(gen)
657
658 def visit_GeneratorExp(self, node):
659 with self.delimit("(", ")"):
660 self.traverse(node.elt)
661 for gen in node.generators:
662 self.traverse(gen)
663
664 def visit_SetComp(self, node):
665 with self.delimit("{", "}"):
666 self.traverse(node.elt)
667 for gen in node.generators:
668 self.traverse(gen)
669
670 def visit_DictComp(self, node):
671 with self.delimit("{", "}"):
672 self.traverse(node.key)
673 self.write(": ")
674 self.traverse(node.value)
675 for gen in node.generators:
676 self.traverse(gen)
677
678 def visit_comprehension(self, node):
679 if node.is_async:
680 self.write(" async for ")
681 else:
682 self.write(" for ")
683 self.set_precedence(_Precedence.TUPLE, node.target)
684 self.traverse(node.target)
685 self.write(" in ")
686 self.set_precedence(_Precedence.TEST.next(), node.iter, *node.ifs)
687 self.traverse(node.iter)
688 for if_clause in node.ifs:
689 self.write(" if ")
690 self.traverse(if_clause)
691
692 def visit_IfExp(self, node):
693 with self.require_parens(_Precedence.TEST, node):
694 self.set_precedence(_Precedence.TEST.next(), node.body, node.test)
695 self.traverse(node.body)
696 self.write(" if ")
697 self.traverse(node.test)
698 self.write(" else ")
699 self.set_precedence(_Precedence.TEST, node.orelse)
700 self.traverse(node.orelse)
701
702 def visit_Set(self, node):
703 if node.elts:
704 with self.delimit("{", "}"):
705 self.interleave(lambda: self.write(", "), self.traverse, node.elts)
706 else:
707 # `{}` would be interpreted as a dictionary literal, and
708 # `set` might be shadowed. Thus:
709 self.write('{*()}')
710
711 def visit_Dict(self, node):
712 def write_key_value_pair(k, v):
713 self.traverse(k)
714 self.write(": ")
715 self.traverse(v)
716
717 def write_item(item):
718 k, v = item
719 if k is None:
720 # for dictionary unpacking operator in dicts {**{'y': 2}}
721 # see PEP 448 for details
722 self.write("**")
723 self.set_precedence(_Precedence.EXPR, v)
724 self.traverse(v)
725 else:
726 write_key_value_pair(k, v)
727
728 with self.delimit("{", "}"):
729 self.interleave(
730 lambda: self.write(", "), write_item, zip(node.keys, node.values)
731 )
732
733 def visit_Tuple(self, node):
734 with self.delimit("(", ")"):
735 self.items_view(self.traverse, node.elts)
736
737 unop = {"Invert": "~", "Not": "not", "UAdd": "+", "USub": "-"}
738 unop_precedence = {
739 "not": _Precedence.NOT,
740 "~": _Precedence.FACTOR,
741 "+": _Precedence.FACTOR,
742 "-": _Precedence.FACTOR,
743 }
744
745 def visit_UnaryOp(self, node):
746 operator = self.unop[node.op.__class__.__name__]
747 operator_precedence = self.unop_precedence[operator]
748 with self.require_parens(operator_precedence, node):
749 self.write(operator)
750 # factor prefixes (+, -, ~) shouldn't be seperated
751 # from the value they belong, (e.g: +1 instead of + 1)
752 if operator_precedence is not _Precedence.FACTOR:
753 self.write(" ")
754 self.set_precedence(operator_precedence, node.operand)
755 self.traverse(node.operand)
756
757 binop = {
758 "Add": "+",
759 "Sub": "-",
760 "Mult": "*",
761 "MatMult": "@",
762 "Div": "/",
763 "Mod": "%",
764 "LShift": "<<",
765 "RShift": ">>",
766 "BitOr": "|",
767 "BitXor": "^",
768 "BitAnd": "&",
769 "FloorDiv": "//",
770 "Pow": "**",
771 }
772
773 binop_precedence = {
774 "+": _Precedence.ARITH,
775 "-": _Precedence.ARITH,
776 "*": _Precedence.TERM,
777 "@": _Precedence.TERM,
778 "/": _Precedence.TERM,
779 "%": _Precedence.TERM,
780 "<<": _Precedence.SHIFT,
781 ">>": _Precedence.SHIFT,
782 "|": _Precedence.BOR,
783 "^": _Precedence.BXOR,
784 "&": _Precedence.BAND,
785 "//": _Precedence.TERM,
786 "**": _Precedence.POWER,
787 }
788
789 binop_rassoc = frozenset(("**",))
790 def visit_BinOp(self, node):
791 operator = self.binop[node.op.__class__.__name__]
792 operator_precedence = self.binop_precedence[operator]
793 with self.require_parens(operator_precedence, node):
794 if operator in self.binop_rassoc:
795 left_precedence = operator_precedence.next()
796 right_precedence = operator_precedence
797 else:
798 left_precedence = operator_precedence
799 right_precedence = operator_precedence.next()
800
801 self.set_precedence(left_precedence, node.left)
802 self.traverse(node.left)
803 self.write(f" {operator} ")
804 self.set_precedence(right_precedence, node.right)
805 self.traverse(node.right)
806
807 cmpops = {
808 "Eq": "==",
809 "NotEq": "!=",
810 "Lt": "<",
811 "LtE": "<=",
812 "Gt": ">",
813 "GtE": ">=",
814 "Is": "is",
815 "IsNot": "is not",
816 "In": "in",
817 "NotIn": "not in",
818 }
819
820 def visit_Compare(self, node):
821 with self.require_parens(_Precedence.CMP, node):
822 self.set_precedence(_Precedence.CMP.next(), node.left, *node.comparators)
823 self.traverse(node.left)
824 for o, e in zip(node.ops, node.comparators):
825 self.write(" " + self.cmpops[o.__class__.__name__] + " ")
826 self.traverse(e)
827
828 boolops = {"And": "and", "Or": "or"}
829 boolop_precedence = {"and": _Precedence.AND, "or": _Precedence.OR}
830
831 def visit_BoolOp(self, node):
832 operator = self.boolops[node.op.__class__.__name__]
833 operator_precedence = self.boolop_precedence[operator]
834
835 def increasing_level_traverse(node):
836 nonlocal operator_precedence
837 operator_precedence = operator_precedence.next()
838 self.set_precedence(operator_precedence, node)
839 self.traverse(node)
840
841 with self.require_parens(operator_precedence, node):
842 s = f" {operator} "
843 self.interleave(lambda: self.write(s), increasing_level_traverse, node.values)
844
845 def visit_Attribute(self, node):
846 self.set_precedence(_Precedence.ATOM, node.value)
847 self.traverse(node.value)
848 # Special case: 3.__abs__() is a syntax error, so if node.value
849 # is an integer literal then we need to either parenthesize
850 # it or add an extra space to get 3 .__abs__().
851 if isinstance(node.value, ast.Constant) and isinstance(node.value.value, int):
852 self.write(" ")
853 self.write(".")
854 self.write(node.attr)
855
856 def visit_Call(self, node):
857 self.set_precedence(_Precedence.ATOM, node.func)
858 self.traverse(node.func)
859 with self.delimit("(", ")"):
860 comma = False
861 for e in node.args:
862 if comma:
863 self.write(", ")
864 else:
865 comma = True
866 self.traverse(e)
867 for e in node.keywords:
868 if comma:
869 self.write(", ")
870 else:
871 comma = True
872 self.traverse(e)
873
874 def visit_Subscript(self, node):
875 def is_simple_tuple(slice_value):
876 # when unparsing a non-empty tuple, the parantheses can be safely
877 # omitted if there aren't any elements that explicitly requires
878 # parantheses (such as starred expressions).
879 return (
880 isinstance(slice_value, ast.Tuple)
881 and slice_value.elts
882 and not any(isinstance(elt, ast.Starred) for elt in slice_value.elts)
883 )
884
885 self.set_precedence(_Precedence.ATOM, node.value)
886 self.traverse(node.value)
887 with self.delimit("[", "]"):
888 if is_simple_tuple(node.slice):
889 self.items_view(self.traverse, node.slice.elts)
890 else:
891 if isinstance(node.slice, ast.Index):
892 self.traverse(node.slice.value)
893 else:
894 self.traverse(node.slice)
895
896 def visit_Starred(self, node):
897 self.write("*")
898 self.set_precedence(_Precedence.EXPR, node.value)
899 self.traverse(node.value)
900
901 def visit_Ellipsis(self, node):
902 self.write("...")
903
904 def visit_Slice(self, node):
905 if node.lower:
906 self.traverse(node.lower)
907 self.write(":")
908 if node.upper:
909 self.traverse(node.upper)
910 if node.step:
911 self.write(":")
912 self.traverse(node.step)
913
914 def visit_arg(self, node):
915 self.write(node.arg)
916 if node.annotation:
917 self.write(": ")
918 self.traverse(node.annotation)
919
920 def visit_arguments(self, node):
921 first = True
922 # normal arguments
923 all_args = node.posonlyargs + node.args
924 defaults = [None] * (len(all_args) - len(node.defaults)) + node.defaults
925 for index, elements in enumerate(zip(all_args, defaults), 1):
926 a, d = elements
927 if first:
928 first = False
929 else:
930 self.write(", ")
931 self.traverse(a)
932 if d:
933 self.write("=")
934 self.traverse(d)
935 if index == len(node.posonlyargs):
936 self.write(", /")
937
938 # varargs, or bare '*' if no varargs but keyword-only arguments present
939 if node.vararg or node.kwonlyargs:
940 if first:
941 first = False
942 else:
943 self.write(", ")
944 self.write("*")
945 if node.vararg:
946 self.write(node.vararg.arg)
947 if node.vararg.annotation:
948 self.write(": ")
949 self.traverse(node.vararg.annotation)
950
951 # keyword-only arguments
952 if node.kwonlyargs:
953 for a, d in zip(node.kwonlyargs, node.kw_defaults):
954 self.write(", ")
955 self.traverse(a)
956 if d:
957 self.write("=")
958 self.traverse(d)
959
960 # kwargs
961 if node.kwarg:
962 if first:
963 first = False
964 else:
965 self.write(", ")
966 self.write("**" + node.kwarg.arg)
967 if node.kwarg.annotation:
968 self.write(": ")
969 self.traverse(node.kwarg.annotation)
970
971 def visit_keyword(self, node):
972 if node.arg is None:
973 self.write("**")
974 else:
975 self.write(node.arg)
976 self.write("=")
977 self.traverse(node.value)
978
979 def visit_Lambda(self, node):
980 with self.require_parens(_Precedence.TEST, node):
981 self.write("lambda ")
982 self.traverse(node.args)
983 self.write(": ")
984 self.set_precedence(_Precedence.TEST, node.body)
985 self.traverse(node.body)
986
987 def visit_alias(self, node):
988 self.write(node.name)
989 if node.asname:
990 self.write(" as " + node.asname)
991
992 def visit_withitem(self, node):
993 self.traverse(node.context_expr)
994 if node.optional_vars:
995 self.write(" as ")
996 self.traverse(node.optional_vars)
997
998 def unparse(ast_obj):
999 unparser = _Unparser()
1000 return unparser.visit(ast_obj)

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