Add re2 as optional dependency (#346)

This adds `re2` as an optional dependency to protovalidate-python. With
this configured, users can choose to optionally install re2 if they
explicit re2 functionality.

For example

`pip install protovalidate[re2]`

Note that while CEL requires re2 as part of the spec, our current
version of cel-python (v0.2.0) doesn't. We are unable to upgrade
cel-python beyond v0.2.0 at this point due to some outstanding issues,
so since re2 now supports Python 3.13, we're adding it as an optional
dep directly to protovalidate-python rather than the re2 workaround we
had previously implemented.

Author: smaye81

Makefile

@@ -52,6 +52,12 @@ format: install $(BIN)/license-header ## Format code
 .PHONY: test
 test: generate install gettestdata ## Run unit tests
 	uv run -- python -m unittest
+	$(MAKE) testextra
+
+.PHONY: testextra
+testextra:
+	uv sync --extra re2
+	uv run -- python -m unittest
 
 .PHONY: conformance
 conformance: $(BIN)/protovalidate-conformance generate install ## Run conformance tests

README.md

@@ -52,6 +52,12 @@ To install the package, use `pip`:
 pip install protovalidate
 ```
 
+Protovalidate also has an optional dependency on [google-re2](https://pypi.org/project/google-re2/). If you require re2 syntax for your regular expressions, install the extra dep as follows:
+
+```shell
+pip install protovalidate[re2]
+```
+
 ## Documentation
 
 Comprehensive documentation for Protovalidate is available in [Buf's documentation library][protovalidate].

protovalidate/internal/extra_func.py

@@ -23,6 +23,12 @@
 from protovalidate.internal import string_format
 from protovalidate.internal.rules import MessageType, field_to_cel
 
+_USE_RE2 = True
+try:
+    import re2
+except ImportError:
+    _USE_RE2 = False
+
 # See https://html.spec.whatwg.org/multipage/input.html#valid-e-mail-address
 _email_regex = re.compile(
     r"^[a-zA-Z0-9.!#$%&'*+/=?^_`{|}~-]+@[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?(?:\.[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)*$"
@@ -1553,11 +1559,34 @@ def __peek(self, char: str) -> bool:
         return self._index < len(self._string) and self._string[self._index] == char
 
 
+def cel_matches_re(text: str, pattern: str) -> celpy.Result:
+    try:
+        m = re.search(pattern, text)
+    except re.error as ex:
+        return celpy.CELEvalError("match error", ex.__class__, ex.args)
+
+    return celtypes.BoolType(m is not None)
+
+
+def cel_matches_re2(text: str, pattern: str) -> celpy.Result:
+    try:
+        m = re2.search(pattern, text)
+    except re2.error as ex:
+        return celpy.CELEvalError("match error", ex.__class__, ex.args)
+
+    return celtypes.BoolType(m is not None)
+
+
+cel_matches = cel_matches_re2 if _USE_RE2 else cel_matches_re
+
+
 def make_extra_funcs() -> dict[str, celpy.CELFunction]:
     string_fmt = string_format.StringFormat()
     return {
         # Missing standard functions
         "format": string_fmt.format,
+        # Overridden standard functions
+        "matches": cel_matches,
         # protovalidate specific functions
         "getField": cel_get_field,
         "isNan": cel_is_nan,

pyproject.toml

@@ -24,6 +24,10 @@ dependencies = [
     "protobuf==6.*",
     "cel-python==0.2.*",
 ]
+[project.optional-dependencies]
+re2 = [
+    "google-re2==1.*",
+]
 
 [project.urls]
 Homepage = "https://github.com/bufbuild/protovalidate-python"
@@ -32,6 +36,7 @@ Issues = "https://github.com/bufbuild/protovalidate-python/issues"
 
 [dependency-groups]
 dev = [
+	"google-re2-stubs>=0.1.1",
 	"mypy",
 	"ruff",
 	"types-protobuf==6.30.2.20250503",

test/test_matches.py

@@ -0,0 +1,44 @@
+# Copyright 2023-2025 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.
+
+import importlib.util
+import unittest
+
+import celpy
+from celpy import celtypes
+
+from protovalidate.internal.extra_func import cel_matches_re, cel_matches_re2
+
+_USE_RE2 = True
+spec = importlib.util.find_spec("re2")
+if spec is None:
+    _USE_RE2 = False
+
+
+class TestCollectViolations(unittest.TestCase):
+    @unittest.skipUnless(_USE_RE2, "Requires 're2'")
+    def test_function_matches_re2(self):
+        empty_string = celtypes.StringType("")
+        # \z is valid re2 syntax for end of text
+        self.assertTrue(cel_matches_re2(empty_string, "^\\z"))
+        # \Z is invalid re2 syntax
+        self.assertIsInstance(cel_matches_re2(empty_string, "^\\Z"), celpy.CELEvalError)
+
+    @unittest.skipUnless(_USE_RE2 is False, "Requires 're'")
+    def test_function_matches_re(self):
+        empty_string = celtypes.StringType("")
+        # \z is invalid re syntax
+        self.assertIsInstance(cel_matches_re(empty_string, "^\\z"), celpy.CELEvalError)
+        # \Z is valid re syntax for end of text
+        self.assertTrue(cel_matches_re(empty_string, "^\\Z"))