Split CelRegexExtensions into CelRegexCompilerLibrary and CelRegexRuntimeLibrary to allow its usage in Lite runtime.

extensions/BUILD.bazel

@@ -141,3 +141,25 @@ cel_android_library(
     name = "lists_runtime_library_android",
     exports = ["//extensions/src/main/java/dev/cel/extensions:lists_runtime_library_android"],
 )
+
+java_library(
+    name = "regex",
+    exports = ["//extensions/src/main/java/dev/cel/extensions:regex"],
+)
+
+java_library(
+    name = "regex_compiler_library",
+    visibility = ["//:internal"],
+    exports = ["//extensions/src/main/java/dev/cel/extensions:regex_compiler_library"],
+)
+
+java_library(
+    name = "regex_runtime_library",
+    visibility = ["//:internal"],
+    exports = ["//extensions/src/main/java/dev/cel/extensions:regex_runtime_library"],
+)
+
+cel_android_library(
+    name = "regex_runtime_library_android",
+    exports = ["//extensions/src/main/java/dev/cel/extensions:regex_runtime_library_android"],
+)

extensions/src/main/java/dev/cel/extensions/BUILD.bazel

@@ -483,20 +483,66 @@ cel_android_library(
 java_library(
     name = "regex",
     srcs = ["CelRegexExtensions.java"],
+    tags = [
+    ],
     deps = [
+        ":extension_library",
+        ":regex_compiler_library",
+        ":regex_runtime_library",
         "//checker:checker_builder",
-        "//common:compiler_common",
-        "//common/types",
+        "//common:cel_function_decl",
         "//compiler:compiler_builder",
-        "//extensions:extension_library",
         "//runtime",
+        "@maven//:com_google_errorprone_error_prone_annotations",
+        "@maven//:com_google_guava_guava",
+    ],
+)
+
+java_library(
+    name = "regex_compiler_library",
+    srcs = ["CelRegexCompilerLibrary.java"],
+    tags = [
+    ],
+    deps = [
+        ":extension_library",
+        "//checker:checker_builder",
+        "//common:cel_function_decl",
+        "//common:cel_overload_decl",
+        "//common/types",
+        "//compiler:compiler_builder",
+        "@maven//:com_google_errorprone_error_prone_annotations",
+        "@maven//:com_google_guava_guava",
+    ],
+)
+
+java_library(
+    name = "regex_runtime_library",
+    srcs = ["CelRegexRuntimeLibrary.java"],
+    tags = [
+    ],
+    deps = [
         "//runtime:function_binding",
+        "//runtime:lite_runtime",
         "@maven//:com_google_errorprone_error_prone_annotations",
         "@maven//:com_google_guava_guava",
         "@maven//:com_google_re2j_re2j",
     ],
 )
 
+cel_android_library(
+    name = "regex_runtime_library_android",
+    srcs = ["CelRegexRuntimeLibrary.java"],
+    tags = [
+    ],
+    deps = [
+        "//runtime:function_binding_android",
+        "//runtime:lite_runtime_android",
+        "@maven//:com_google_errorprone_error_prone_annotations",
+        "@maven//:com_google_re2j_re2j",
+        "@maven_android//:com_google_guava_guava",
+    ],
+)
+
 java_library(
     name = "comprehensions",
     srcs = ["CelComprehensionsExtensions.java"],

extensions/src/main/java/dev/cel/extensions/CelExtensions.java

@@ -341,6 +341,39 @@ public static CelRegexExtensions regex() {
     return REGEX_EXTENSIONS;
   }
 
+  /**
+   * Extended functions for Regular Expressions.
+   *
+   * <p>Refer to README.md for available functions.
+   */
+  public static CelRegexExtensions regex(int version) {
+    return CelRegexExtensions.library().version(version);
+  }
+
+  /**
+   * Extended functions for Regular Expressions.
+   *
+   * <p>Refer to README.md for available functions.
+   *
+   * <p>This will include only the specific functions denoted by {@link
+   * CelRegexExtensions.Function}.
+   */
+  public static CelRegexExtensions regex(CelRegexExtensions.Function... functions) {
+    return regex(ImmutableSet.copyOf(functions));
+  }
+
+  /**
+   * Extended functions for Regular Expressions.
+   *
+   * <p>Refer to README.md for available functions.
+   *
+   * <p>This will include only the specific functions denoted by {@link
+   * CelRegexExtensions.Function}.
+   */
+  public static CelRegexExtensions regex(Set<CelRegexExtensions.Function> functions) {
+    return new CelRegexExtensions(functions);
+  }
+
   /**
    * Extended functions for Two Variable Comprehensions Expressions.
    *

extensions/src/main/java/dev/cel/extensions/CelRegexCompilerLibrary.java

@@ -0,0 +1,160 @@
+// Copyright 2025 Google LLC
+//
+// 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
+//
+//      https://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.
+
+package dev.cel.extensions;
+
+import static com.google.common.collect.ImmutableSet.toImmutableSet;
+
+import com.google.common.collect.ImmutableSet;
+import com.google.errorprone.annotations.Immutable;
+import dev.cel.checker.CelCheckerBuilder;
+import dev.cel.common.CelFunctionDecl;
+import dev.cel.common.CelOverloadDecl;
+import dev.cel.common.types.ListType;
+import dev.cel.common.types.OptionalType;
+import dev.cel.common.types.SimpleType;
+import dev.cel.compiler.CelCompilerLibrary;
+import java.util.Set;
+
+/** Internal implementation of CEL regex compile-time extensions. */
+@Immutable
+public final class CelRegexCompilerLibrary
+    implements CelCompilerLibrary, CelExtensionLibrary.FeatureSet {
+
+  private static final String REGEX_REPLACE_FUNCTION = "regex.replace";
+  private static final String REGEX_EXTRACT_FUNCTION = "regex.extract";
+  private static final String REGEX_EXTRACT_ALL_FUNCTION = "regex.extractAll";
+
+  /** Supported functions for the Regex compiler extension. */
+  public enum Function {
+    REPLACE(
+        CelFunctionDecl.newFunctionDeclaration(
+            REGEX_REPLACE_FUNCTION,
+            CelOverloadDecl.newGlobalOverload(
+                "regex_replaceAll_string_string_string",
+                "Replaces all the matched values using the given replace string.",
+                SimpleType.STRING,
+                SimpleType.STRING,
+                SimpleType.STRING,
+                SimpleType.STRING),
+            CelOverloadDecl.newGlobalOverload(
+                "regex_replaceCount_string_string_string_int",
+                "Replaces the given number of matched values using the given replace string.",
+                SimpleType.STRING,
+                SimpleType.STRING,
+                SimpleType.STRING,
+                SimpleType.STRING,
+                SimpleType.INT))),
+    EXTRACT(
+        CelFunctionDecl.newFunctionDeclaration(
+            REGEX_EXTRACT_FUNCTION,
+            CelOverloadDecl.newGlobalOverload(
+                "regex_extract_string_string",
+                "Returns the first substring that matches the regex.",
+                OptionalType.create(SimpleType.STRING),
+                SimpleType.STRING,
+                SimpleType.STRING))),
+    EXTRACTALL(
+        CelFunctionDecl.newFunctionDeclaration(
+            REGEX_EXTRACT_ALL_FUNCTION,
+            CelOverloadDecl.newGlobalOverload(
+                "regex_extractAll_string_string",
+                "Returns an array of all substrings that match the regex.",
+                ListType.create(SimpleType.STRING),
+                SimpleType.STRING,
+                SimpleType.STRING)));
+
+    private final CelFunctionDecl functionDecl;
+
+    String getFunction() {
+      return functionDecl.name();
+    }
+
+    public CelFunctionDecl getFunctionDecl() {
+      return functionDecl;
+    }
+
+    Function(CelFunctionDecl functionDecl) {
+      this.functionDecl = functionDecl;
+    }
+  }
+
+  private static final class Library implements CelExtensionLibrary<CelRegexCompilerLibrary> {
+    private final CelRegexCompilerLibrary version0 =
+        new CelRegexCompilerLibrary(0, ImmutableSet.copyOf(Function.values()));
+
+    @Override
+    public String name() {
+      return "regex";
+    }
+
+    @Override
+    public ImmutableSet<CelRegexCompilerLibrary> versions() {
+      return ImmutableSet.of(version0);
+    }
+  }
+
+  private static final Library LIBRARY = new Library();
+
+  public static CelExtensionLibrary<CelRegexCompilerLibrary> library() {
+    return LIBRARY;
+  }
+
+  /** Returns the latest version of the 'regex' compiler extension. */
+  public static CelRegexCompilerLibrary regex() {
+    return library().latest();
+  }
+
+  /** Returns the specified version of the 'regex' compiler extension. */
+  public static CelRegexCompilerLibrary regex(int version) {
+    return library().version(version);
+  }
+
+  /** Returns the 'regex' compiler extension with only the specified functions. */
+  public static CelRegexCompilerLibrary regex(Function... functions) {
+    return regex(ImmutableSet.copyOf(functions));
+  }
+
+  /** Returns the 'regex' compiler extension with only the specified functions. */
+  public static CelRegexCompilerLibrary regex(Set<Function> functions) {
+    return new CelRegexCompilerLibrary(functions);
+  }
+
+  private final ImmutableSet<Function> functions;
+  private final int version;
+
+  CelRegexCompilerLibrary(Set<Function> functions) {
+    this(-1, functions);
+  }
+
+  private CelRegexCompilerLibrary(int version, Set<Function> functions) {
+    this.version = version;
+    this.functions = ImmutableSet.copyOf(functions);
+  }
+
+  @Override
+  public int version() {
+    return version;
+  }
+
+  @Override
+  public ImmutableSet<CelFunctionDecl> functions() {
+    return functions.stream().map(Function::getFunctionDecl).collect(toImmutableSet());
+  }
+
+  @Override
+  public void setCheckerOptions(CelCheckerBuilder checkerBuilder) {
+    functions.forEach(function -> checkerBuilder.addFunctionDeclarations(function.functionDecl));
+  }
+}