Implement LiteAttributeStep for evaluating optimized select qualifiers in lite runtime

common/src/main/java/dev/cel/common/values/BUILD.bazel

@@ -17,7 +17,9 @@ CEL_VALUES_SOURCES = [
     "ErrorValue.java",
     "NullValue.java",
     "OpaqueValue.java",
+    "OptimizedSelectable.java",
     "OptionalValue.java",
+    "SelectField.java",
     "SelectableValue.java",
     "StructValue.java",
 ]
@@ -167,6 +169,7 @@ java_library(
         ":preadapted_list",
         "//:auto_value",
         "//common/annotations",
+        "//common/exceptions:attribute_not_found",
         "//common/types",
         "//common/types:type_providers",
         "@maven//:com_google_errorprone_error_prone_annotations",
@@ -218,6 +221,7 @@ cel_android_library(
         ":preadapted_list_android",
         "//:auto_value",
         "//common/annotations",
+        "//common/exceptions:attribute_not_found",
         "//common/types:type_providers_android",
         "//common/types:types_android",
         "@maven//:com_google_errorprone_error_prone_annotations",
@@ -317,6 +321,7 @@ java_library(
     srcs = [
         "ProtoLiteCelValueConverter.java",
         "ProtoMessageLiteValue.java",
+        "RawProtoMessageLiteValue.java",
     ],
     tags = [
     ],
@@ -325,6 +330,7 @@ java_library(
         ":values",
         "//:auto_value",
         "//common/annotations",
+        "//common/exceptions:attribute_not_found",
         "//common/internal:cel_lite_descriptor_pool",
         "//common/internal:well_known_proto",
         "//common/types",
@@ -333,6 +339,7 @@ java_library(
         "//protobuf:cel_lite_descriptor",
         "@maven//:com_google_errorprone_error_prone_annotations",
         "@maven//:com_google_guava_guava",
+        "@maven//:org_jspecify_jspecify",
         "@maven_android//:com_google_protobuf_protobuf_javalite",
     ],
 )
@@ -342,6 +349,7 @@ cel_android_library(
     srcs = [
         "ProtoLiteCelValueConverter.java",
         "ProtoMessageLiteValue.java",
+        "RawProtoMessageLiteValue.java",
     ],
     tags = [
     ],
@@ -350,6 +358,7 @@ cel_android_library(
         ":values_android",
         "//:auto_value",
         "//common/annotations",
+        "//common/exceptions:attribute_not_found",
         "//common/internal:cel_lite_descriptor_pool_android",
         "//common/internal:well_known_proto_android",
         "//common/types:type_providers_android",
@@ -358,6 +367,7 @@ cel_android_library(
         "//protobuf:cel_lite_descriptor",
         "@maven//:com_google_errorprone_error_prone_annotations",
         "@maven//:com_google_guava_guava",
+        "@maven//:org_jspecify_jspecify",
         "@maven_android//:com_google_guava_guava",
         "@maven_android//:com_google_protobuf_protobuf_javalite",
     ],

common/src/main/java/dev/cel/common/values/OptimizedSelectable.java

@@ -0,0 +1,152 @@
+// Copyright 2026 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.common.values;
+
+import com.google.common.collect.ImmutableList;
+import com.google.errorprone.annotations.Immutable;
+import dev.cel.common.annotations.Internal;
+import dev.cel.common.exceptions.CelAttributeNotFoundException;
+import java.util.Map;
+import java.util.Optional;
+import org.jspecify.annotations.Nullable;
+
+/**
+ * Represents a value capable of evaluating optimized field selection and presence testing for field
+ * selection optimization.
+ *
+ * <p>CEL Library Internals. Do Not Use.
+ */
+@Internal
+@Immutable
+public interface OptimizedSelectable {
+
+  /**
+   * Evaluates a multi-hop qualification chain across the provided fields.
+   *
+   * <p>Implementations may override this method to provide an allocation-free traversal over
+   * underlying schema or message descriptors. The default implementation iterates sequentially over
+   * {@link #selectField} for intermediate submessages and the leaf.
+   */
+  default Object qualify(ImmutableList<SelectField> fields) {
+    Object current = this;
+    for (SelectField field : fields) {
+      if (current instanceof OptimizedSelectable) {
+        current = ((OptimizedSelectable) current).selectField(field);
+      } else if (current instanceof SelectableValue) {
+        Optional<Object> found =
+            SelectField.findField((SelectableValue<?>) current, field.fieldName());
+        if (found.isPresent()) {
+          current = found.get();
+        } else if (field.defaultValue() != null) {
+          current = field.defaultValue();
+        } else {
+          throw CelAttributeNotFoundException.forFieldResolution(field.fieldName());
+        }
+      } else if (current instanceof Map) {
+        Map<?, ?> map = (Map<?, ?>) current;
+        Object mapValue = map.get(field.fieldName());
+        if (mapValue != null) {
+          current = mapValue;
+        } else if (map.containsKey(field.fieldName())) {
+          current = NullValue.NULL_VALUE;
+        } else {
+          throw CelAttributeNotFoundException.forMissingMapKey(field.fieldName());
+        }
+      } else {
+        throw CelAttributeNotFoundException.forFieldResolution(field.fieldName());
+      }
+    }
+    return current;
+  }
+
+  /**
+   * Performs field selection for a single hop in an optimized selection chain.
+   *
+   * @param field The field hop descriptor containing field number, name, type code, and default
+   *     value.
+   * @return The selected field value, or default value / empty submessage if absent.
+   */
+  Object selectField(SelectField field);
+
+  /**
+   * Evaluates presence testing across the provided fields.
+   *
+   * <p>Implementations may override this method to provide an allocation-free traversal over
+   * underlying schema or message descriptors. The default implementation iterates sequentially over
+   * {@link #navigateField} for intermediate submessages and {@link #hasField} for the leaf.
+   */
+  default boolean hasField(ImmutableList<SelectField> fields) {
+    if (fields.isEmpty()) {
+      return false;
+    }
+    int lastIndex = fields.size() - 1;
+    Object current = this;
+    for (int i = 0; i < lastIndex; i++) {
+      SelectField field = fields.get(i);
+      if (current instanceof OptimizedSelectable) {
+        current = ((OptimizedSelectable) current).navigateField(field);
+        if (current == null) {
+          return false;
+        }
+      } else if (current instanceof SelectableValue) {
+        Optional<Object> found =
+            SelectField.findField((SelectableValue<?>) current, field.fieldName());
+        if (!found.isPresent()) {
+          return false;
+        }
+        current = found.get();
+      } else if (current instanceof Map) {
+        Map<?, ?> map = (Map<?, ?>) current;
+        if (!map.containsKey(field.fieldName())) {
+          return false;
+        }
+        Object mapValue = map.get(field.fieldName());
+        current = (mapValue != null) ? mapValue : NullValue.NULL_VALUE;
+      } else {
+        throw CelAttributeNotFoundException.forFieldResolution(field.fieldName());
+      }
+    }
+    SelectField terminalField = fields.get(lastIndex);
+    if (current instanceof OptimizedSelectable) {
+      return ((OptimizedSelectable) current).hasField(terminalField);
+    } else if (current instanceof SelectableValue) {
+      return SelectField.findField((SelectableValue<?>) current, terminalField.fieldName())
+          .isPresent();
+    } else if (current instanceof Map) {
+      return ((Map<?, ?>) current).containsKey(terminalField.fieldName());
+    } else {
+      throw CelAttributeNotFoundException.forFieldResolution(terminalField.fieldName());
+    }
+  }
+
+  /**
+   * Evaluates presence testing for a single hop in an optimized selection chain.
+   *
+   * @param field The field hop descriptor.
+   * @return True if the field is present, false otherwise.
+   */
+  boolean hasField(SelectField field);
+
+  /**
+   * Navigates into an intermediate submessage for presence testing.
+   *
+   * <p>Returns {@code null} instead of an {@link Optional} to avoid object allocation overhead on
+   * hot-path intermediate navigation hops.
+   *
+   * @param field The field hop descriptor.
+   * @return The submessage if present, or {@code null} if absent.
+   */
+  @Nullable Object navigateField(SelectField field);
+}