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GeezerVison is showing github.com — bpo-43521: Allow ast.unparse with empty sets and NaN by Kodiologist · Pull Request #24897 · python/cpython

bpo-43521: Allow ast.unparse with empty sets and NaN #24897

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Merged
miss-islington merged 1 commit into python:master from Kodiologist:unparse-empty-set-and-nan
Mar 18, 2021

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bpo-43521: Allow ast.unparse with empty sets and NaN #24897

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bpo-43521: Allow ast.unparse with empty sets and NaN
Kodiologist Mar 16, 2021
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20 changes: 14 additions & 6 deletions 20 Lib/ast.py
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Original file line number Diff line number Diff line change
Expand Up @@ -1199,8 +1199,13 @@ def _write_docstring(self, node):

def _write_constant(self, value):
if isinstance(value, (float, complex)):
# Substitute overflowing decimal literal for AST infinities.
self.write(repr(value).replace("inf", _INFSTR))
# Substitute overflowing decimal literal for AST infinities,
# and inf - inf for NaNs.
self.write(
repr(value)
.replace("inf", _INFSTR)
.replace("nan", f"({_INFSTR}-{_INFSTR})")
)
elif self._avoid_backslashes and isinstance(value, str):
self._write_str_avoiding_backslashes(value)
else:
Expand Down Expand Up @@ -1273,10 +1278,13 @@ def visit_IfExp(self, node):
self.traverse(node.orelse)

def visit_Set(self, node):
if not node.elts:
raise ValueError("Set node should have at least one item")
with self.delimit("{", "}"):
self.interleave(lambda: self.write(", "), self.traverse, node.elts)
if node.elts:
with self.delimit("{", "}"):
self.interleave(lambda: self.write(", "), self.traverse, node.elts)
else:
# `{}` would be interpreted as a dictionary literal, and
# `set` might be shadowed. Thus:
self.write('{*()}')

def visit_Dict(self, node):
def write_key_value_pair(k, v):
Expand Down
15 changes: 12 additions & 3 deletions 15 Lib/test/test_unparse.py
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Expand Up @@ -199,6 +199,12 @@ def test_huge_float(self):
self.check_ast_roundtrip("1e1000j")
self.check_ast_roundtrip("-1e1000j")

def test_nan(self):
self.assertASTEqual(
ast.parse(ast.unparse(ast.Constant(value=float('nan')))),
ast.parse('1e1000 - 1e1000')
)

def test_min_int(self):
self.check_ast_roundtrip(str(-(2 ** 31)))
self.check_ast_roundtrip(str(-(2 ** 63)))
Expand Down Expand Up @@ -252,6 +258,12 @@ def test_annotations(self):
def test_set_literal(self):
self.check_ast_roundtrip("{'a', 'b', 'c'}")

def test_empty_set(self):
self.assertASTEqual(
ast.parse(ast.unparse(ast.Set(elts=[]))),
ast.parse('{*()}')
)

def test_set_comprehension(self):
self.check_ast_roundtrip("{x for x in range(5)}")

Expand Down Expand Up @@ -326,9 +338,6 @@ def test_invalid_fstring_conversion(self):
def test_invalid_fstring_backslash(self):
self.check_invalid(ast.FormattedValue(value=ast.Constant(value="\\\\")))

def test_invalid_set(self):
self.check_invalid(ast.Set(elts=[]))

def test_invalid_yield_from(self):
self.check_invalid(ast.YieldFrom(value=None))

Expand Down
1 change: 1 addition & 0 deletions 1 Misc/NEWS.d/next/Library/2021-03-16-16-05-02.bpo-43521.mRT6fh.rst
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@@ -0,0 +1 @@
``ast.unparse`` can now render NaNs and empty sets.
Add this suggestion to a batch that can be applied as a single commit. This suggestion is invalid because no changes were made to the code. Suggestions cannot be applied while the pull request is closed. Suggestions cannot be applied while viewing a subset of changes. Only one suggestion per line can be applied in a batch. Add this suggestion to a batch that can be applied as a single commit. Applying suggestions on deleted lines is not supported. You must change the existing code in this line in order to create a valid suggestion. Outdated suggestions cannot be applied. This suggestion has been applied or marked resolved. Suggestions cannot be applied from pending reviews. Suggestions cannot be applied on multi-line comments. Suggestions cannot be applied while the pull request is queued to merge. Suggestion cannot be applied right now. Please check back later.
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