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bpo-38870: Simplify tuple like interleaves, roundtrip extslice properly #17892

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Merged
merged 1 commit into from
Mar 9, 2020
Merged

bpo-38870: Simplify tuple like interleaves, roundtrip extslice properly #17892

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37 changes: 14 additions & 23 deletions Lib/ast.py
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Original file line number Diff line number Diff line change
Expand Up @@ -613,6 +613,16 @@ def interleave(self, inter, f, seq):
inter()
f(x)

def items_view(self, traverser, items):
"""Traverse and separate the given *items* with a comma and append it to
the buffer. If *items* is a single item sequence, a trailing comma
will be added."""
if len(items) == 1:
traverser(items[0])
self.write(",")
else:
self.interleave(lambda: self.write(", "), traverser, items)

def fill(self, text=""):
"""Indent a piece of text and append it, according to the current
indentation level"""
Expand Down Expand Up @@ -1020,11 +1030,7 @@ def visit_Constant(self, node):
value = node.value
if isinstance(value, tuple):
with self.delimit("(", ")"):
if len(value) == 1:
self._write_constant(value[0])
self.write(",")
else:
self.interleave(lambda: self.write(", "), self._write_constant, value)
self.items_view(self._write_constant, value)
elif value is ...:
self.write("...")
else:
Expand Down Expand Up @@ -1116,12 +1122,7 @@ def write_item(item):

def visit_Tuple(self, node):
with self.delimit("(", ")"):
if len(node.elts) == 1:
elt = node.elts[0]
self.traverse(elt)
self.write(",")
else:
self.interleave(lambda: self.write(", "), self.traverse, node.elts)
self.items_view(self.traverse, node.elts)

unop = {"Invert": "~", "Not": "not", "UAdd": "+", "USub": "-"}
unop_precedence = {
Expand Down Expand Up @@ -1264,12 +1265,7 @@ def visit_Subscript(self, node):
if (isinstance(node.slice, Index)
and isinstance(node.slice.value, Tuple)
and node.slice.value.elts):
if len(node.slice.value.elts) == 1:
elt = node.slice.value.elts[0]
self.traverse(elt)
self.write(",")
else:
self.interleave(lambda: self.write(", "), self.traverse, node.slice.value.elts)
self.items_view(self.traverse, node.slice.value.elts)
else:
self.traverse(node.slice)

Expand All @@ -1296,12 +1292,7 @@ def visit_Slice(self, node):
self.traverse(node.step)

def visit_ExtSlice(self, node):
if len(node.dims) == 1:
elt = node.dims[0]
self.traverse(elt)
self.write(",")
else:
self.interleave(lambda: self.write(", "), self.traverse, node.dims)
self.items_view(self.traverse, node.dims)

def visit_arg(self, node):
self.write(node.arg)
Expand Down
34 changes: 20 additions & 14 deletions Lib/test/test_unparse.py
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Original file line number Diff line number Diff line change
Expand Up @@ -280,6 +280,20 @@ def test_dict_unpacking_in_dict(self):
self.check_ast_roundtrip(r"""{**{'y': 2}, 'x': 1}""")
self.check_ast_roundtrip(r"""{**{'y': 2}, **{'x': 1}}""")

def test_ext_slices(self):
self.check_ast_roundtrip("a[i]")
self.check_ast_roundtrip("a[i,]")
self.check_ast_roundtrip("a[i, j]")
self.check_ast_roundtrip("a[()]")
self.check_ast_roundtrip("a[i:j]")
self.check_ast_roundtrip("a[:j]")
self.check_ast_roundtrip("a[i:]")
self.check_ast_roundtrip("a[i:j:k]")
self.check_ast_roundtrip("a[:j:k]")
self.check_ast_roundtrip("a[i::k]")
self.check_ast_roundtrip("a[i:j,]")
self.check_ast_roundtrip("a[i:j, k]")

def test_invalid_raise(self):
self.check_invalid(ast.Raise(exc=None, cause=ast.Name(id="X")))

Expand Down Expand Up @@ -310,6 +324,12 @@ def test_docstrings(self):
# check as Module docstrings for easy testing
self.check_ast_roundtrip(f"'{docstring}'")

def test_constant_tuples(self):
self.check_src_roundtrip(ast.Constant(value=(1,), kind=None), "(1,)")
self.check_src_roundtrip(
ast.Constant(value=(1, 2, 3), kind=None), "(1, 2, 3)"
)


class CosmeticTestCase(ASTTestCase):
"""Test if there are cosmetic issues caused by unnecesary additions"""
Expand Down Expand Up @@ -344,20 +364,6 @@ def test_simple_expressions_parens(self):
self.check_src_roundtrip("call((yield x))")
self.check_src_roundtrip("return x + (yield x)")

def test_subscript(self):
self.check_src_roundtrip("a[i]")
self.check_src_roundtrip("a[i,]")
self.check_src_roundtrip("a[i, j]")
self.check_src_roundtrip("a[()]")
self.check_src_roundtrip("a[i:j]")
self.check_src_roundtrip("a[:j]")
self.check_src_roundtrip("a[i:]")
self.check_src_roundtrip("a[i:j:k]")
self.check_src_roundtrip("a[:j:k]")
self.check_src_roundtrip("a[i::k]")
self.check_src_roundtrip("a[i:j,]")
self.check_src_roundtrip("a[i:j, k]")

def test_docstrings(self):
docstrings = (
'"""simple doc string"""',
Expand Down