From 531ea5b3a21a5632789e592cfd71e9515849523b Mon Sep 17 00:00:00 2001
From: Vadim Levin <vadim.levin@xperience.ai>
Date: Sun, 1 Aug 2021 11:59:16 +0300
Subject: [PATCH] fix: convert arguments names that are keywords reserved by
 Python

---
 .../include/opencv2/core/bindings_utils.hpp     |  6 ++++++
 modules/python/src2/gen2.py                     | 12 ++++++++++++
 modules/python/test/test_misc.py                | 17 +++++++++++++++++
 3 files changed, 35 insertions(+)

diff --git a/modules/core/include/opencv2/core/bindings_utils.hpp b/modules/core/include/opencv2/core/bindings_utils.hpp
index 98a4a2b785..a3f83d9c2c 100644
--- a/modules/core/include/opencv2/core/bindings_utils.hpp
+++ b/modules/core/include/opencv2/core/bindings_utils.hpp
@@ -116,6 +116,12 @@ String dumpRange(const Range& argument)
     }
 }
 
+CV_WRAP static inline
+String testReservedKeywordConversion(int positional_argument, int lambda = 2, int from = 3)
+{
+    return format("arg=%d, lambda=%d, from=%d", positional_argument, lambda, from);
+}
+
 CV_WRAP static inline
 void testRaiseGeneralException()
 {
diff --git a/modules/python/src2/gen2.py b/modules/python/src2/gen2.py
index bccf0d2767..51566fc248 100755
--- a/modules/python/src2/gen2.py
+++ b/modules/python/src2/gen2.py
@@ -212,6 +212,16 @@ simple_argtype_mapping = {
     "c_string": ArgTypeInfo("char*", FormatStrings.string, '(char*)""')
 }
 
+# Set of reserved keywords for Python. Can be acquired via the following call
+# $ python -c "help('keywords')"
+# Keywords that are reserved in C/C++ are excluded because they can not be
+# used as variables identifiers
+python_reserved_keywords = {
+    "True", "None", "False", "as", "assert", "def", "del", "elif", "except", "exec",
+    "finally", "from", "global",  "import", "in", "is", "lambda", "nonlocal",
+    "pass", "print", "raise", "with", "yield"
+}
+
 
 def normalize_class_name(name):
     return re.sub(r"^cv\.", "", name).replace(".", "_")
@@ -369,6 +379,8 @@ class ArgInfo(object):
     def __init__(self, arg_tuple):
         self.tp = handle_ptr(arg_tuple[0])
         self.name = arg_tuple[1]
+        if self.name in python_reserved_keywords:
+            self.name += "_"
         self.defval = arg_tuple[2]
         self.isarray = False
         self.arraylen = 0
diff --git a/modules/python/test/test_misc.py b/modules/python/test/test_misc.py
index 121e86a64c..4d435a46b6 100644
--- a/modules/python/test/test_misc.py
+++ b/modules/python/test/test_misc.py
@@ -463,6 +463,23 @@ class Arguments(NewOpenCVTests):
             with self.assertRaises((TypeError), msg=get_no_exception_msg(not_convertible)):
                 _ = cv.utils.dumpRange(not_convertible)
 
+    def test_reserved_keywords_are_transformed(self):
+        default_lambda_value = 2
+        default_from_value = 3
+        format_str = "arg={}, lambda={}, from={}"
+        self.assertEqual(
+            cv.utils.testReservedKeywordConversion(20), format_str.format(20, default_lambda_value, default_from_value)
+        )
+        self.assertEqual(
+            cv.utils.testReservedKeywordConversion(10, lambda_=10), format_str.format(10, 10, default_from_value)
+        )
+        self.assertEqual(
+            cv.utils.testReservedKeywordConversion(10, from_=10), format_str.format(10, default_lambda_value, 10)
+        )
+        self.assertEqual(
+            cv.utils.testReservedKeywordConversion(20, lambda_=-4, from_=12), format_str.format(20, -4, 12)
+        )
+
 
 class SamplesFindFile(NewOpenCVTests):