Optimize regex implementations & fix tool configs

Change RegexImplementation to dispatch between variants at init time,
so that each call to the relevant methods is faster and does not
re-check the variant.

Minor tool config fixes:
- flake8 ignore vs extend-ignore (whoops)
- tox.ini depends needed to run in parallel

.flake8

@@ -2,4 +2,4 @@
 exclude = .git,.tox,__pycache__,dist,.venv*,docs,build
 max-line-length = 90
 # black related: W503/W504 conflict, black causes E203
-ignore = W503,W504,E203,B019
+extend-ignore = W503,W504,E203,B019

src/check_jsonschema/regex_variants.py

@@ -11,24 +11,68 @@ class RegexVariantName(enum.Enum):
     python = "python"
 
 
+class _ConcreteImplementation(t.Protocol):
+    def check_format(self, instance: t.Any) -> bool: ...
+
+    def pattern_keyword(
+        self, validator: t.Any, pattern: str, instance: str, schema: t.Any
+    ) -> t.Iterator[jsonschema.ValidationError]: ...
+
+
 class RegexImplementation:
+    """
+    A high-level interface for getting at the different possible
+    implementations of regex behaviors.
+    """
+
+    _real_implementation: _ConcreteImplementation
+
     def __init__(self, variant: RegexVariantName) -> None:
         self.variant = variant
 
+        if self.variant == RegexVariantName.default:
+            self._real_implementation = _RegressImplementation()
+        else:
+            self._real_implementation = _PythonImplementation()
+
+        self.check_format = self._real_implementation.check_format
+        self.pattern_keyword = self._real_implementation.pattern_keyword
+
+
+class _RegressImplementation:
     def check_format(self, instance: t.Any) -> bool:
         if not isinstance(instance, str):
             return True
-
         try:
-            if self.variant == RegexVariantName.default:
-                regress.Regex(instance)
-            else:
-                re.compile(instance)
+            regress.Regex(instance)
         # something is wrong with RegressError getting into the published types
         # needs investigation... for now, ignore the error
-        except (regress.RegressError, re.error):  # type: ignore[attr-defined]
+        except regress.RegressError:  # type: ignore[attr-defined]
             return False
+        return True
 
+    def pattern_keyword(
+        self, validator: t.Any, pattern: str, instance: str, schema: t.Any
+    ) -> t.Iterator[jsonschema.ValidationError]:
+        if not validator.is_type(instance, "string"):
+            return
+
+        try:
+            regress_pattern = regress.Regex(pattern)
+        except regress.RegressError:  # type: ignore[attr-defined]
+            yield jsonschema.ValidationError(f"pattern {pattern!r} failed to compile")
+        if not regress_pattern.find(instance):
+            yield jsonschema.ValidationError(f"{instance!r} does not match {pattern!r}")
+
+
+class _PythonImplementation:
+    def check_format(self, instance: t.Any) -> bool:
+        if not isinstance(instance, str):
+            return True
+        try:
+            re.compile(instance)
+        except re.error:
+            return False
         return True
 
     def pattern_keyword(
@@ -37,25 +81,9 @@ def pattern_keyword(
         if not validator.is_type(instance, "string"):
             return
 
-        if self.variant == RegexVariantName.default:
-            try:
-                regress_pattern = regress.Regex(pattern)
-            except regress.RegressError:  # type: ignore[attr-defined]
-                yield jsonschema.ValidationError(
-                    f"pattern {pattern!r} failed to compile"
-                )
-            if not regress_pattern.find(instance):
-                yield jsonschema.ValidationError(
-                    f"{instance!r} does not match {pattern!r}"
-                )
-        else:
-            try:
-                re_pattern = re.compile(pattern)
-            except re.error:
-                yield jsonschema.ValidationError(
-                    f"pattern {pattern!r} failed to compile"
-                )
-            if not re_pattern.search(instance):
-                yield jsonschema.ValidationError(
-                    f"{instance!r} does not match {pattern!r}"
-                )
+        try:
+            re_pattern = re.compile(pattern)
+        except re.error:
+            yield jsonschema.ValidationError(f"pattern {pattern!r} failed to compile")
+        if not re_pattern.search(instance):
+            yield jsonschema.ValidationError(f"{instance!r} does not match {pattern!r}")

tox.ini

@@ -31,19 +31,22 @@ deps =
     format: jsonschema[format]
 commands =
     coverage run -m pytest {posargs:--junitxml={envdir}/pytest.xml}
+depends = cov_clean
 
 [testenv:cov_clean]
 description = "erase coverage data to prepare for a new run"
 deps = coverage
 skip_install = true
 commands = coverage erase
+depends =
 
 [testenv:cov]
 description = "combine and report coverage data"
 deps = coverage
 skip_install = true
 commands_pre = - coverage combine
 commands = coverage report --skip-covered
+depends = py{,38,39,310,311,312}{,-mindeps,-format,-json5,-pyjson5,-disable_orjson}
 
 [testenv:mypy]
 description = "check type annotations with mypy"
@@ -52,6 +55,7 @@ deps = mypy
        types-requests
        click
 commands = mypy src/ {posargs}
+depends =
 
 [testenv:pyright]
 description = "check type annotations with pyright"