Represent negative numbers as a USub UnaryOp so that the ast roundtrips

dflook · dflook · commit c81dbfb7438a · 2023-08-17T23:28:09.000+01:00
diff --git a/src/python_minifier/__init__.py b/src/python_minifier/__init__.py
@@ -8,6 +8,7 @@
 import re
 
 from python_minifier.ast_compare import CompareError, compare_ast
+from python_minifier.ast_printer import print_ast
 from python_minifier.module_printer import ModulePrinter
 from python_minifier.rename import (
     rename_literals,
@@ -154,7 +155,9 @@ def minify(
         module = RemoveExplicitReturnNone()(module)
 
     if constant_folding:
+        print(print_ast(module))
         module = FoldConstants()(module)
+        print(print_ast(module))
 
     bind_names(module)
     resolve_names(module)
@@ -220,6 +223,8 @@ def unparse(module):
     printer = ModulePrinter()
     printer(module)
 
+    print(printer.code)
+
     try:
         minified_module = ast.parse(printer.code, 'python_minifier.unparse output')
     except SyntaxError as syntax_error:
diff --git a/src/python_minifier/transforms/constant_folding.py b/src/python_minifier/transforms/constant_folding.py
@@ -39,7 +39,11 @@ def visit_BinOp(self, node):
         elif isinstance(value, bool):
             new_node = ast.NameConstant(value=value)
         elif isinstance(value, (int, float, complex)):
-            new_node = ast.Num(n=value)
+            if value < 0:
+                # Represent negative numbers as a USub UnaryOp, so that the ast roundtrip is correct
+                new_node = ast.UnaryOp(op=ast.USub(), operand=ast.Num(n=-value))
+            else:
+                new_node = ast.Num(n=value)
         else:
             return node
 
