Remove re2 fallback to re behavior

Unnecessary after cloud-custodian#127. Moves function_matches back in place with the
other cel functions. Also, remove the documented fallback behavior from
the README.

Author: stefanvanburen

README.rst

@@ -45,17 +45,6 @@ CEL specifies that regular expressions use re2 syntax,
 https://github.com/google/re2/wiki/Syntax.
 As of the 0.4.0 release, the Google-RE2 module is part of the CEL distribution.
 
-.. warning:: Apple Silicon and Python 3.13
-
-    See https://github.com/google/re2/issues/453,
-    https://github.com/google/re2/issues/346,
-    https://github.com/google/re2/issues/516
-
-    Google-RE2 does not build for Python 3.13 on the "darwin" platform with the "arm64" architecture.
-    Currently, there is no pre-built binary for Python 3.13.
-
-    The built-in ``re`` is used as a fall-back, and does work for all but a few edge cases.
-
 Command Line
 ============
 

src/celpy/evaluation.py

@@ -55,9 +55,9 @@
 import operator
 import os
 import re
-from string import Template
 import sys
 from functools import reduce, wraps
+from string import Template
 from textwrap import dedent
 from typing import (
     Any,
@@ -80,37 +80,11 @@
 
 import lark
 import lark.visitors
+import re2
 
 import celpy.celtypes
 from celpy.celparser import tree_dump
 
-try:
-    import re2
-
-    def function_matches(text: str, pattern: str) -> "Result":
-        """Implementation of the ``match()`` function using ``re2``"""
-        try:
-            m = re2.search(pattern, text)
-        except re2.error as ex:
-            return CELEvalError("match error", ex.__class__, ex.args)
-
-        return celpy.celtypes.BoolType(m is not None)
-
-except ImportError:  # pragma: no cover
-    # There is a build issue with python_version=='3.13' and sys_platform=='darwin'
-    # See https://github.com/google/re2/issues/516
-    # We fall back to using re, which passes the essential tests
-
-    def function_matches(text: str, pattern: str) -> "Result":
-        """Alternative implementation of the ``match()`` function for systems where ``re2`` can't be installed."""
-        try:
-            m = re.search(pattern, text)
-        except re.error as ex:
-            return CELEvalError("match error", ex.__class__, ex.args)
-
-        return celpy.celtypes.BoolType(m is not None)
-
-
 # An Annotation describes a union of types, functions, and function types.
 Annotation = Union[
     celpy.celtypes.TypeType,
@@ -420,6 +394,16 @@ def function_endsWith(
     return celpy.celtypes.BoolType(string.endswith(fragment))
 
 
+def function_matches(text: str, pattern: str) -> Result:
+    """Implementation of the ``match()`` function using ``re2``"""
+    try:
+        m = re2.search(pattern, text)
+    except re2.error as ex:
+        return CELEvalError("match error", ex.__class__, ex.args)
+
+    return celpy.celtypes.BoolType(m is not None)
+
+
 def function_getDate(
     ts: celpy.celtypes.TimestampType,
     tz_name: Optional[celpy.celtypes.StringType] = None,