Add functions DT_DATE_NOW and DT_DATE_TODAY

docs/references/functions.md

@@ -86,6 +86,8 @@ Available through the _ExpressionConfiguration.StandardFunctionsDictionary_ cons
 | DT_DATE_NEW(millis)                                                            | Returns a new DATE_TIME from the epoch of 1970-01-01T00:00:00Z in milliseconds.                                                                                                                                                                                         |
 | DT_DATE_PARSE(value [,zoneId] [,format, ...])                                  | Converts the given string value to a date time value by using the optional time zone and formats. All formats are used until the first matching format. Without a format, the configured formats are used. Time zone can be NULL, the the configured time zone is used. |
 | DT_DATE_FORMAT(value, [,format] [,zoneId])                                     | Formats the given date-time to a string using the given optional format and time zone. Without a format, the first configured format is used. The zone id defaults to the configured zone id.                                                                           |
+| DT_DATE_NOW()                                                                  | Produces a new DATE_TIME that represents the current date and time, in the system default time zone.                                                                                                                                                                    |
+| DT_DATE_TODAY()                                                                | Produces a new DATE_TIME that represents the current date, at midnight (00:00), in the system default time zone.                                                                                                                                                        |
 | DT_DATE_TO_EPOCH(value)                                                        | Converts the given value to epoch timestamp in millisecond.                                                                                                                                                                                                             |
 | DT_DURATION_NEW(days [,hours, minutes, seconds, nanos])                        | Returns a new DURATION value with the given parameters.                                                                                                                                                                                                                 |
 | DT_DURATION_PARSE(value)                                                       | Converts the given ISO-8601 duration string representation to a duration value. E.g. "P2DT3H4M" parses 2 days, 3 hours and 4 minutes.                                                                                                                                   | 

src/main/java/com/ezylang/evalex/config/ExpressionConfiguration.java

@@ -188,6 +188,8 @@ public class ExpressionConfiguration {
           Map.entry("DT_DATE_NEW", new DateTimeNewFunction()),
           Map.entry("DT_DATE_PARSE", new DateTimeParseFunction()),
           Map.entry("DT_DATE_FORMAT", new DateTimeFormatFunction()),
+          Map.entry("DT_DATE_NOW", new DateTimeNowFunction()),
+          Map.entry("DT_DATE_TODAY", new DateTimeTodayFunction()),
           Map.entry("DT_DATE_TO_EPOCH", new DateTimeToEpochFunction()),
           Map.entry("DT_DURATION_NEW", new DurationNewFunction()),
           Map.entry("DT_DURATION_FROM_MILLIS", new DurationFromMillisFunction()),

src/main/java/com/ezylang/evalex/functions/datetime/DateTimeNowFunction.java

@@ -0,0 +1,45 @@
+/*
+  Copyright 2012-2024 Udo Klimaschewski
+
+  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
+
+      http://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 com.ezylang.evalex.functions.datetime;
+
+import com.ezylang.evalex.Expression;
+import com.ezylang.evalex.data.EvaluationValue;
+import com.ezylang.evalex.functions.AbstractFunction;
+import com.ezylang.evalex.parser.Token;
+import java.time.Instant;
+
+/**
+ * Produces a new DATE_TIME that represents the current date and time.
+ *
+ * <p>It is useful to calculate a value based on the current date and time. For example, if you know
+ * the start DATE_TIME of a running process, you might use the following expression to find the
+ * DURATION that represents the process age:
+ *
+ * <blockquote>
+ *
+ * {@code DT_DATE_NOW() - startDateTime}
+ *
+ * </blockquote>
+ *
+ * @author oswaldobapvicjr
+ */
+public class DateTimeNowFunction extends AbstractFunction {
+  @Override
+  public EvaluationValue evaluate(
+      Expression expression, Token functionToken, EvaluationValue... parameterValues) {
+    return expression.convertValue(Instant.now());
+  }
+}

src/main/java/com/ezylang/evalex/functions/datetime/DateTimeTodayFunction.java

@@ -0,0 +1,48 @@
+/*
+  Copyright 2012-2024 Udo Klimaschewski
+
+  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
+
+      http://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 com.ezylang.evalex.functions.datetime;
+
+import com.ezylang.evalex.Expression;
+import com.ezylang.evalex.data.EvaluationValue;
+import com.ezylang.evalex.functions.AbstractFunction;
+import com.ezylang.evalex.parser.Token;
+import java.time.Instant;
+import java.time.LocalDate;
+import java.time.ZoneId;
+
+/**
+ * Produces a new DATE_TIME that represents the current date, at midnight (00:00), in the system
+ * default time-zone.
+ *
+ * <p>It is useful for DATE_TIME comparison, when the current time must not be considered. For
+ * example, in the expression:
+ *
+ * <blockquote>
+ *
+ * {@code IF(expiryDate > DT_DATE_TODAY(), "expired", "valid")}
+ *
+ * </blockquote>
+ *
+ * @author oswaldobapvicjr
+ */
+public class DateTimeTodayFunction extends AbstractFunction {
+  @Override
+  public EvaluationValue evaluate(
+      Expression expression, Token functionToken, EvaluationValue... parameterValues) {
+    Instant today = LocalDate.now().atStartOfDay(ZoneId.systemDefault()).toInstant();
+    return expression.convertValue(today);
+  }
+}

src/test/java/com/ezylang/evalex/functions/datetime/DateTimeFunctionsTest.java

@@ -23,17 +23,27 @@
 import com.ezylang.evalex.config.ExpressionConfiguration;
 import com.ezylang.evalex.config.TestConfigurationProvider;
 import com.ezylang.evalex.parser.ParseException;
+import java.time.LocalDate;
 import java.time.ZoneId;
+import java.util.TimeZone;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.provider.CsvSource;
 import org.junit.jupiter.params.provider.ValueSource;
 
 class DateTimeFunctionsTest extends BaseEvaluationTest {
 
+  private static final ZoneId DEFAULT_ZONE_ID = ZoneId.of("Europe/Berlin");
+
+  static {
+    // Let the default time-zone be set programmatically to standardize
+    // tests dependent on the default time-zone
+    TimeZone.setDefault(TimeZone.getTimeZone(DEFAULT_ZONE_ID));
+  }
+
   private static final ExpressionConfiguration DateTimeTestConfiguration =
       TestConfigurationProvider.StandardConfigurationWithAdditionalTestOperators.toBuilder()
-          .zoneId(ZoneId.of("Europe/Berlin"))
+          .zoneId(DEFAULT_ZONE_ID)
           .build();
 
   @ParameterizedTest
@@ -231,6 +241,24 @@ void testDateTimeToEpoch(String expression, String expectedResult)
     assertExpressionHasExpectedResult(expression, expectedResult);
   }
 
+  @ParameterizedTest
+  @CsvSource(
+      delimiter = '|',
+      value = {
+        "DT_DATE_NOW() > DT_DATE_TODAY() | true",
+        "DT_DATE_NOW() > (DT_DATE_TODAY() + DT_DURATION_PARSE(\"P1D\")) | false"
+      })
+  void testDateTimeNow(String expression, String expectedResult)
+      throws EvaluationException, ParseException {
+    assertExpressionHasExpectedResult(expression, expectedResult);
+  }
+
+  @Test
+  void testDateTimeToday() throws EvaluationException, ParseException {
+    String expected = LocalDate.now().atStartOfDay(DEFAULT_ZONE_ID).toInstant().toString();
+    assertExpressionHasExpectedResult("DT_DATE_TODAY()", expected, DateTimeTestConfiguration);
+  }
+
   @ParameterizedTest
   @CsvSource(
       delimiter = '|',