Add getDays function for Duration.

checker/src/main/java/dev/cel/checker/CelStandardDeclarations.java

@@ -213,6 +213,7 @@ public enum StandardFunction {
         "getDayOfWeek",
         Overload.DateTime.TIMESTAMP_TO_DAY_OF_WEEK,
         Overload.DateTime.TIMESTAMP_TO_DAY_OF_WEEK_WITH_TZ),
+    GET_DAYS("getDays", Overload.DateTime.DURATION_TO_DAYS),
     GET_HOURS(
         "getHours",
         Overload.DateTime.TIMESTAMP_TO_HOURS,
@@ -907,6 +908,10 @@ public enum DateTime implements StandardOverload {
                 SimpleType.TIMESTAMP,
                 SimpleType.STRING)),
 
+        DURATION_TO_DAYS(
+            CelOverloadDecl.newMemberOverload(
+                "duration_to_days", "get days from duration", SimpleType.INT, SimpleType.DURATION)),
+
         TIMESTAMP_TO_HOURS(
             CelOverloadDecl.newMemberOverload(
                 "timestamp_to_hours",

checker/src/test/resources/standardEnvDump.baseline

@@ -200,6 +200,9 @@ declare getDayOfYear {
   function timestamp_to_day_of_year google.protobuf.Timestamp.() -> int
   function timestamp_to_day_of_year_with_tz google.protobuf.Timestamp.(string) -> int
 }
+declare getDays {
+  function duration_to_days google.protobuf.Duration.() -> int
+}
 declare getFullYear {
   function timestamp_to_year google.protobuf.Timestamp.() -> int
   function timestamp_to_year_with_tz google.protobuf.Timestamp.(string) -> int

common/src/main/java/dev/cel/common/internal/ProtoTimeUtils.java

@@ -68,6 +68,7 @@ public final class ProtoTimeUtils {
 
   private static final long SECONDS_PER_MINUTE = 60L;
   private static final long SECONDS_PER_HOUR = SECONDS_PER_MINUTE * 60;
+  private static final long SECONDS_PER_DAY = SECONDS_PER_HOUR * 24;
 
   private static final ThreadLocal<SimpleDateFormat> TIMESTAMP_FORMAT =
       new ThreadLocal<SimpleDateFormat>() {
@@ -164,6 +165,14 @@ public static long toHours(Duration duration) {
     return checkValid(duration).getSeconds() / SECONDS_PER_HOUR;
   }
 
+  /**
+   * Convert a Duration to the number of days. The result will be rounded towards 0 to the nearest
+   * day.
+   */
+  public static long toDays(Duration duration) {
+    return checkValid(duration).getSeconds() / SECONDS_PER_DAY;
+  }
+
   /**
    * Convert a Duration to the number of minutes. The result will be rounded towards 0 to the
    * nearest minute.

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

@@ -628,6 +628,7 @@ java_library(
         "//runtime/standard:get_day_of_month",
         "//runtime/standard:get_day_of_week",
         "//runtime/standard:get_day_of_year",
+        "//runtime/standard:get_days",
         "//runtime/standard:get_full_year",
         "//runtime/standard:get_hours",
         "//runtime/standard:get_milliseconds",
@@ -686,6 +687,7 @@ cel_android_library(
         "//runtime/standard:get_day_of_month_android",
         "//runtime/standard:get_day_of_week_android",
         "//runtime/standard:get_day_of_year_android",
+        "//runtime/standard:get_days_android",
         "//runtime/standard:get_full_year_android",
         "//runtime/standard:get_hours_android",
         "//runtime/standard:get_milliseconds_android",

runtime/src/main/java/dev/cel/runtime/CelStandardFunctions.java

@@ -55,6 +55,8 @@
 import dev.cel.runtime.standard.GetDayOfWeekFunction.GetDayOfWeekOverload;
 import dev.cel.runtime.standard.GetDayOfYearFunction;
 import dev.cel.runtime.standard.GetDayOfYearFunction.GetDayOfYearOverload;
+import dev.cel.runtime.standard.GetDaysFunction;
+import dev.cel.runtime.standard.GetDaysFunction.GetDaysOverload;
 import dev.cel.runtime.standard.GetFullYearFunction;
 import dev.cel.runtime.standard.GetFullYearFunction.GetFullYearOverload;
 import dev.cel.runtime.standard.GetHoursFunction;
@@ -158,6 +160,7 @@ public final class CelStandardFunctions {
           GetDayOfMonthFunction.create(),
           GetDayOfWeekFunction.create(),
           GetDayOfYearFunction.create(),
+          GetDaysFunction.create(),
           GetFullYearFunction.create(),
           GetHoursFunction.create(),
           GetMillisecondsFunction.create(),
@@ -311,6 +314,8 @@ public enum StandardFunction {
         GetDayOfWeekOverload.TIMESTAMP_TO_DAY_OF_WEEK,
         GetDayOfWeekOverload.TIMESTAMP_TO_DAY_OF_WEEK_WITH_TZ),
 
+    GET_DAYS("getDays", GetDaysOverload.DURATION_TO_DAYS),
+
     GET_HOURS(
         "getHours",
         GetHoursOverload.TIMESTAMP_TO_HOURS,

runtime/src/main/java/dev/cel/runtime/standard/BUILD.bazel

@@ -519,6 +519,41 @@ cel_android_library(
     ],
 )
 
+java_library(
+    name = "get_days",
+    srcs = ["GetDaysFunction.java"],
+    tags = [
+    ],
+    deps = [
+        ":standard_function",
+        ":standard_overload",
+        "//common:options",
+        "//common/internal:proto_time_utils",
+        "//runtime:function_binding",
+        "//runtime:runtime_equality",
+        "//runtime/standard:standard_function",
+        "@maven//:com_google_guava_guava",
+        "@maven//:com_google_protobuf_protobuf_java",
+    ],
+)
+
+cel_android_library(
+    name = "get_days_android",
+    srcs = ["GetDaysFunction.java"],
+    tags = [
+    ],
+    deps = [
+        ":standard_function_android",
+        ":standard_overload_android",
+        "//common:options",
+        "//common/internal:proto_time_utils_android",
+        "//runtime:function_binding_android",
+        "//runtime:runtime_equality_android",
+        "@maven_android//:com_google_guava_guava",
+        "@maven_android//:com_google_protobuf_protobuf_javalite",
+    ],
+)
+
 java_library(
     name = "get_full_year",
     srcs = ["GetFullYearFunction.java"],

runtime/src/main/java/dev/cel/runtime/standard/GetDaysFunction.java

@@ -0,0 +1,71 @@
+// 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.runtime.standard;
+
+import com.google.common.collect.ImmutableSet;
+import com.google.protobuf.Duration;
+import dev.cel.common.CelOptions;
+import dev.cel.common.internal.ProtoTimeUtils;
+import dev.cel.runtime.CelFunctionBinding;
+import dev.cel.runtime.RuntimeEquality;
+import java.util.Arrays;
+
+/** Standard function for {@code getDays}. */
+public final class GetDaysFunction extends CelStandardFunction {
+  private static final GetDaysFunction ALL_OVERLOADS = create(GetDaysOverload.values());
+
+  public static GetDaysFunction create() {
+    return ALL_OVERLOADS;
+  }
+
+  public static GetDaysFunction create(GetDaysFunction.GetDaysOverload... overloads) {
+    return create(Arrays.asList(overloads));
+  }
+
+  public static GetDaysFunction create(Iterable<GetDaysFunction.GetDaysOverload> overloads) {
+    return new GetDaysFunction(ImmutableSet.copyOf(overloads));
+  }
+
+  /** Overloads for the standard function. */
+  public enum GetDaysOverload implements CelStandardOverload {
+    DURATION_TO_DAYS(
+        (celOptions, runtimeEquality) -> {
+          if (celOptions.evaluateCanonicalTypesToNativeValues()) {
+            return CelFunctionBinding.from(
+                "duration_to_days", java.time.Duration.class, java.time.Duration::toDays);
+          } else {
+            return CelFunctionBinding.from(
+                "duration_to_days", Duration.class, ProtoTimeUtils::toDays);
+          }
+        }),
+    ;
+
+    private final CelStandardOverload standardOverload;
+
+    @Override
+    public CelFunctionBinding newFunctionBinding(
+        CelOptions celOptions, RuntimeEquality runtimeEquality) {
+      return standardOverload.newFunctionBinding(celOptions, runtimeEquality);
+    }
+
+    GetDaysOverload(CelStandardOverload standardOverload) {
+      this.standardOverload = standardOverload;
+    }
+  }
+
+  private GetDaysFunction(ImmutableSet<CelStandardOverload> overloads) {
+    super("getDays", overloads);
+  }
+}

runtime/standard/BUILD.bazel

@@ -156,6 +156,16 @@ cel_android_library(
     exports = ["//runtime/src/main/java/dev/cel/runtime/standard:get_date_android"],
 )
 
+java_library(
+    name = "get_days",
+    exports = ["//runtime/src/main/java/dev/cel/runtime/standard:get_days"],
+)
+
+cel_android_library(
+    name = "get_days_android",
+    exports = ["//runtime/src/main/java/dev/cel/runtime/standard:get_days_android"],
+)
+
 java_library(
     name = "get_full_year",
     exports = ["//runtime/src/main/java/dev/cel/runtime/standard:get_full_year"],