Extract _field_path_string into internal

Author: John Chadwick

protovalidate/internal/field_path.py

@@ -0,0 +1,36 @@
+# Copyright 2023 Buf Technologies, Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from buf.validate import validate_pb2
+from . import string_format
+
+
+def string(path: validate_pb2.FieldPath) -> str:
+    result: list[str] = []
+    for element in path.elements:
+        if len(result) > 0:
+            result.append(".")
+        subscript_case = element.WhichOneof("subscript")
+        if subscript_case is not None:
+            result.extend(
+                (
+                    element.field_name,
+                    "[",
+                    string_format.format_value(getattr(element, subscript_case)),
+                    "]",
+                )
+            )
+        else:
+            result.append(element.field_name)
+    return "".join(result)

protovalidate/validator.py

@@ -16,7 +16,7 @@
 
 from buf.validate import validate_pb2  # type: ignore
 from protovalidate.internal import constraints as _constraints
-from protovalidate.internal import extra_func, string_format
+from protovalidate.internal import extra_func, field_path
 
 CompilationError = _constraints.CompilationError
 Violations = validate_pb2.Violations
@@ -89,29 +89,9 @@ def collect_violations(
                 violation.field.elements.reverse()
             if violation.HasField("rule"):
                 violation.rule.elements.reverse()
-            violation.field_path = Validator._field_path_string(violation.field)
+            violation.field_path = field_path.string(violation.field)
         return ctx.violations
 
-    @classmethod
-    def _field_path_string(cls, path: validate_pb2.FieldPath) -> str:
-        result: list[str] = []
-        for element in path.elements:
-            if len(result) > 0:
-                result.append(".")
-            subscript_case = element.WhichOneof("subscript")
-            if subscript_case is not None:
-                result.extend(
-                    (
-                        element.field_name,
-                        "[",
-                        string_format.format_value(getattr(element, subscript_case)),
-                        "]",
-                    )
-                )
-            else:
-                result.append(element.field_name)
-        return "".join(result)
-
 
 class ValidationError(ValueError):
     """