bpo-38870: Don't start generated output with newlines in ast.unparse (GH-19636)
diff --git a/Lib/ast.py b/Lib/ast.py
index 401af56..5c68c4a 100644
--- a/Lib/ast.py
+++ b/Lib/ast.py
@@ -669,10 +669,16 @@
else:
self.interleave(lambda: self.write(", "), traverser, items)
+ def maybe_newline(self):
+ """Adds a newline if it isn't the start of generated source"""
+ if self._source:
+ self.write("\n")
+
def fill(self, text=""):
"""Indent a piece of text and append it, according to the current
indentation level"""
- self.write("\n" + " " * self._indent + text)
+ self.maybe_newline()
+ self.write(" " * self._indent + text)
def write(self, text):
"""Append a piece of text"""
@@ -916,7 +922,7 @@
self.traverse(node.body)
def visit_ClassDef(self, node):
- self.write("\n")
+ self.maybe_newline()
for deco in node.decorator_list:
self.fill("@")
self.traverse(deco)
@@ -946,7 +952,7 @@
self._function_helper(node, "async def")
def _function_helper(self, node, fill_suffix):
- self.write("\n")
+ self.maybe_newline()
for deco in node.decorator_list:
self.fill("@")
self.traverse(deco)
@@ -1043,7 +1049,7 @@
write("{")
unparser = type(self)()
unparser.set_precedence(_Precedence.TEST.next(), node.value)
- expr = unparser.visit(node.value).rstrip("\n")
+ expr = unparser.visit(node.value)
if expr.startswith("{"):
write(" ") # Separate pair of opening brackets as "{ {"
write(expr)
diff --git a/Lib/test/test_unparse.py b/Lib/test/test_unparse.py
index d4089a3..2be44b2 100644
--- a/Lib/test/test_unparse.py
+++ b/Lib/test/test_unparse.py
@@ -128,19 +128,17 @@
def check_invalid(self, node, raises=ValueError):
self.assertRaises(raises, ast.unparse, node)
- def get_source(self, code1, code2=None, strip=True):
+ def get_source(self, code1, code2=None):
code2 = code2 or code1
code1 = ast.unparse(ast.parse(code1))
- if strip:
- code1 = code1.strip()
return code1, code2
- def check_src_roundtrip(self, code1, code2=None, strip=True):
- code1, code2 = self.get_source(code1, code2, strip)
+ def check_src_roundtrip(self, code1, code2=None):
+ code1, code2 = self.get_source(code1, code2)
self.assertEqual(code2, code1)
- def check_src_dont_roundtrip(self, code1, code2=None, strip=True):
- code1, code2 = self.get_source(code1, code2, strip)
+ def check_src_dont_roundtrip(self, code1, code2=None):
+ code1, code2 = self.get_source(code1, code2)
self.assertNotEqual(code2, code1)
class UnparseTestCase(ASTTestCase):