Support now() in time range

Signed-off-by: Yuanchun Shen <yuanchu@amazon.com>

Author: yuancu

integ-test/src/test/java/org/opensearch/sql/ppl/ExplainIT.java

@@ -644,8 +644,9 @@ public void testSearchCommandWithAbsoluteTimeRange() throws IOException {
   public void testSearchCommandWithRelativeTimeRange() throws IOException {
     String expected = loadExpectedPlan("explain_search_with_relative_time_range.json");
     assertJsonEqualsIgnoreId(
-            expected,
-            explainQueryToString(String.format("source=%s earliest='-1q@year' latest=now", TEST_INDEX_TIME_DATA)));
+        expected,
+        explainQueryToString(
+            String.format("source=%s earliest='-1q@year' latest=now", TEST_INDEX_TIME_DATA)));
   }
 
   protected String loadExpectedPlan(String fileName) throws IOException {

integ-test/src/test/java/org/opensearch/sql/ppl/SearchCommandIT.java

@@ -923,19 +923,19 @@ public void testSearchWithDateINOperator() throws IOException {
   }
 
   @Test
-  public void testSearchWithEarliest() throws IOException {
+  public void testSearchWithAbsoluteEarliestAndNow() throws IOException {
     JSONObject result1 =
         executeQuery(
             String.format(
-                "search source=%s earliest='2025-08-01 03:47:41' | fields @timestamp",
+                "search source=%s earliest='2025-08-01 03:47:41' latest=now | fields @timestamp",
                 TEST_INDEX_TIME_DATA));
     verifySchema(result1, schema("@timestamp", "timestamp"));
     verifyDataRows(result1, rows("2025-08-01 03:47:41"));
 
     JSONObject result0 =
         executeQuery(
             String.format(
-                "search source=%s earliest='2025-08-01 03:47:42' | fields @timestamp",
+                "search source=%s earliest='2025-08-01 03:47:42' latest=now() | fields @timestamp",
                 TEST_INDEX_TIME_DATA));
     verifyNumOfRows(result0, 0);
 
@@ -946,4 +946,16 @@ public void testSearchWithEarliest() throws IOException {
                 TEST_INDEX_TIME_DATA));
     verifyDataRows(result2, rows("2025-08-01 02:00:56"), rows("2025-08-01 03:47:41"));
   }
+
+  @Test
+  public void testSearchWithChainedRelativeTimeRange() throws IOException {
+    JSONObject result1 =
+        executeQuery(
+            String.format(
+                "search source=%s earliest='2025-08-01 03:47:41' latest='+10months@year' | fields"
+                    + " @timestamp",
+                TEST_INDEX_TIME_DATA));
+    verifySchema(result1, schema("@timestamp", "timestamp"));
+    verifyDataRows(result1, rows("2025-08-01 03:47:41"));
+  }
 }

ppl/src/main/antlr/OpenSearchPPLParser.g4

@@ -763,6 +763,7 @@ timeModifier
 
 timeModifierValue
    : NOW
+   | NOW LT_PRTHS RT_PRTHS
    | stringLiteral
    | timeSnap
    | (PLUS | MINUS) (integerLiteral)? timeModifierUnit (timeSnap)?