deep copy for deref tuple, list, dict (#184)

* do a copy for dictionary lookup

* Deep copy for list de-ref

* Tuple deref also now triggers a copy

Author: gordonwatts

func_adl/ast/function_simplifier.py

@@ -453,7 +453,7 @@ def visit_Subscript_Tuple(self, v: ast.Tuple, s: ast.Constant):
                 f" {len(v.elts)} values long."
             )
 
-        return v.elts[n]
+        return copy.deepcopy(v.elts[n])
 
     def visit_Subscript_List(self, v: ast.List, s: ast.Constant):
         """
@@ -470,7 +470,7 @@ def visit_Subscript_List(self, v: ast.List, s: ast.Constant):
                 f" only {len(v.elts)} values long."
             )
 
-        return v.elts[n]
+        return copy.deepcopy(v.elts[n])
 
     def visit_Subscript_Dict(self, v: ast.Dict, s: ast.Constant):
         """
@@ -485,7 +485,7 @@ def visit_Subscript_Dict_with_value(self, v: ast.Dict, s: Union[str, int]):
         for index, value in enumerate(v.keys):
             assert isinstance(value, ast.Constant)
             if value.value == s:
-                return v.values[index]
+                return copy.deepcopy(v.values[index])
 
         return ast.Subscript(v, s, ast.Load())  # type: ignore
 

tests/ast/test_function_simplifier.py

@@ -1,6 +1,9 @@
 import ast
+import copy
+from typing import cast
 
 from astunparse import unparse
+
 from func_adl.ast.function_simplifier import FuncADLIndexError, simplify_chained_calls
 from tests.util_debug_ast import normalize_ast
 
@@ -18,10 +21,14 @@ def util_process(ast_in, ast_out):
     a_updated_raw = simplify_chained_calls().visit(a_source)
 
     s_updated = ast.dump(
-        normalize_ast().visit(a_updated_raw), annotate_fields=False, include_attributes=False
+        normalize_ast().visit(copy.deepcopy(a_updated_raw)),
+        annotate_fields=False,
+        include_attributes=False,
     )
     s_expected = ast.dump(
-        normalize_ast().visit(a_expected), annotate_fields=False, include_attributes=False
+        normalize_ast().visit(copy.deepcopy(a_expected)),
+        annotate_fields=False,
+        include_attributes=False,
     )
 
     print(s_updated)
@@ -183,11 +190,27 @@ def test_tuple_select():
     util_process("(t1,t2)[0]", "t1")
 
 
+def test_tuple_select_copy_made():
+    # (t1, t2)[0] should be t1.
+    root = ast.parse("(t1,t2)[0]")
+    orig = root.body[0].value.value.elts[0]  # type: ignore
+    r1 = util_process(root, "t1")
+    assert r1.body[0].value != orig
+
+
 def test_list_select():
     # [t1, t2][0] should be t1.
     util_process("[t1,t2][0]", "t1")
 
 
+def test_list_select_copy_made():
+    # [t1, t2][0] should be t1.
+    root = ast.parse("[t1,t2][0]")
+    orig = root.body[0].value.value.elts[0]  # type: ignore
+    r1 = util_process(root, "t1")
+    assert r1.body[0].value != orig
+
+
 def test_tuple_select_past_end():
     # This should cause a crash!
     try:
@@ -260,3 +283,21 @@ def test_dict_around_first():
         'Select(events, lambda e: First(Select(e.jets, lambda j: {"j": j, "e": e})).j)',
         "Select(events, lambda e: First(e.jets))",
     )
+
+
+def test_dict_is_different_attrib():
+    "Make sure we are returning different ast's that have the same content"
+    root = cast(ast.expr, ast.parse('{"n1": t1, "n2": t2}.n1'))
+    orig_name = root.body[0].value.value.values[0]  # type: ignore
+    r1 = util_process(root, "t1")
+
+    assert r1.body[0].value != orig_name
+
+
+def test_dict_is_different():
+    "Make sure we are returning different ast's that have the same content"
+    root = cast(ast.expr, ast.parse('{"n1": t1, "n2": t2}["n1"]'))
+    orig_name = root.body[0].value.value.values[0]  # type: ignore
+    r1 = util_process(root, "t1")
+
+    assert r1.body[0].value != orig_name