added cloudwatch style contains operator (#5219)

Author: ThyTran1402

core/src/main/java/org/opensearch/sql/expression/operator/predicate/BinaryPredicateOperators.java

@@ -53,6 +53,7 @@ public static void register(BuiltinFunctionRepository repository) {
     repository.register(greater());
     repository.register(gte());
     repository.register(like());
+    repository.register(ilike());
     repository.register(notLike());
     repository.register(regexp());
   }
@@ -391,6 +392,12 @@ private static DefaultFunctionResolver like() {
         impl(nullMissingHandling(OperatorUtils::matches3), BOOLEAN, STRING, STRING, BOOLEAN));
   }
 
+  private static DefaultFunctionResolver ilike() {
+    return define(
+        BuiltinFunctionName.ILIKE.getName(),
+        impl(nullMissingHandling(OperatorUtils::matches2), BOOLEAN, STRING, STRING));
+  }
+
   private static DefaultFunctionResolver regexp() {
     return define(
         BuiltinFunctionName.REGEXP.getName(),

docs/user/ppl/functions/condition.md

@@ -758,6 +758,71 @@ fetched rows / total rows = 1/1
 +-----+
 ```
 
+## CONTAINS
+
+### Description
+
+Usage: `field contains 'substring'` returns TRUE if the field value contains the given substring (case-insensitive), FALSE otherwise.
+
+The `contains` operator is a CloudWatch-style comparison operator that performs case-insensitive substring matching. It is sugar for an `ilike` comparison with `%substring%` wildcards.
+
+Syntax: `<field> contains '<string_literal>'`
+
+- The left-hand side must be a field reference.
+- The right-hand side must be a string literal. Using a field reference on the right-hand side will raise a semantic error.
+- Matching is case-insensitive.
+
+**Argument type:** `STRING`
+**Return type:** `BOOLEAN`
+
+### Example
+
+Basic substring filter:
+
+```ppl
+source=accounts
+| where firstname contains 'mbe'
+| fields firstname, age
+```
+
+Expected output:
+
+```text
+fetched rows / total rows = 1/1
++-----------+-----+
+| firstname | age |
+|-----------+-----|
+| Amber     | 32  |
++-----------+-----+
+```
+
+Case-insensitive matching (all of the following are equivalent):
+
+```ppl ignore
+source=accounts | where firstname contains 'mbe'
+source=accounts | where firstname CONTAINS 'MBE'
+source=accounts | where firstname Contains 'Mbe'
+```
+
+Combining with other conditions:
+
+```ppl
+source=accounts
+| where employer contains 'ami' AND age > 30
+| fields firstname, employer, age
+```
+
+Expected output:
+
+```text
+fetched rows / total rows = 1/1
++-----------+----------+-----+
+| firstname | employer | age |
+|-----------+----------+-----|
+| Amber     | Pyrami   | 32  |
++-----------+----------+-----+
+```
+
 ## REGEXP_MATCH  
 
 ### Description  

docs/user/ppl/functions/index.md

@@ -57,6 +57,7 @@ PPL supports a wide range of built-in functions for data processing and analysis
   - [EARLIEST](condition.md/#earliest)
   - [LATEST](condition.md/#latest)
   - [REGEXP_MATCH](condition.md/#regexp_match)
+  - [CONTAINS](condition.md/#contains)
 
 - [Type Conversion Functions](conversion.md)
   - [CAST](conversion.md/#cast)

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

@@ -144,6 +144,34 @@ public void testLikeOperatorCaseInsensitive() throws IOException {
     verifyDataRows(result3, rows("Amber"));
   }
 
+  @Test
+  public void testContainsOperator() throws IOException {
+    JSONObject result =
+        executeQuery(
+            String.format(
+                "source=%s | where firstname contains 'mbe' | fields firstname",
+                TEST_INDEX_ACCOUNT));
+    verifyDataRows(result, rows("Amber"), rows("Chambers"));
+
+    result =
+        executeQuery(
+            String.format(
+                "source=%s | where firstname contains 'zzz' | fields firstname",
+                TEST_INDEX_ACCOUNT));
+    assertEquals(0, result.getInt("total"));
+  }
+
+  @Test
+  public void testContainsOperatorCaseInsensitive() throws IOException {
+    // contains uses ilike semantics - case insensitive
+    JSONObject result =
+        executeQuery(
+            String.format(
+                "source=%s | where firstname contains 'MBE' | fields firstname",
+                TEST_INDEX_ACCOUNT));
+    verifyDataRows(result, rows("Amber"), rows("Chambers"));
+  }
+
   @Test
   public void testIsNullFunction() throws IOException {
     JSONObject result =

language-grammar/src/main/antlr4/OpenSearchPPLLexer.g4

@@ -413,6 +413,7 @@ REDUCE:                             'REDUCE';
 
 // BOOL FUNCTIONS
 LIKE:                               'LIKE';
+CONTAINS:                           'CONTAINS';
 ISNULL:                             'ISNULL';
 ISNOTNULL:                          'ISNOTNULL';
 BETWEEN:                            'BETWEEN';

language-grammar/src/main/antlr4/OpenSearchPPLParser.g4

@@ -945,6 +945,7 @@ geoIpProperty
    | GREATER
    | NOT_GREATER
    | REGEXP
+   | CONTAINS
    ;
 
 singleFieldRelevanceFunctionName

opensearch/src/main/java/org/opensearch/sql/opensearch/storage/script/filter/FilterQueryBuilder.java

@@ -68,6 +68,7 @@ public ScriptQueryUnSupportedException(String message) {
           .put(BuiltinFunctionName.LTE.getName(), new RangeQuery(Comparison.LTE))
           .put(BuiltinFunctionName.GTE.getName(), new RangeQuery(Comparison.GTE))
           .put(BuiltinFunctionName.LIKE.getName(), new LikeQuery())
+          .put(BuiltinFunctionName.ILIKE.getName(), new LikeQuery())
           .put(BuiltinFunctionName.MATCH.getName(), new MatchQuery())
           .put(BuiltinFunctionName.MATCH_PHRASE.getName(), new MatchPhraseQuery())
           .put(BuiltinFunctionName.MATCHPHRASE.getName(), new MatchPhraseQuery())

ppl/src/main/antlr/OpenSearchPPLLexer.g4

@@ -464,6 +464,7 @@ CAST:                               'CAST';
 // BOOL FUNCTIONS
 LIKE:                               'LIKE';
 ILIKE:                              'ILIKE';
+CONTAINS:                           'CONTAINS';
 ISNULL:                             'ISNULL';
 ISNOTNULL:                          'ISNOTNULL';
 CIDRMATCH:                          'CIDRMATCH';

ppl/src/main/antlr/OpenSearchPPLParser.g4

@@ -1448,6 +1448,7 @@ positionFunctionName
    | REGEXP
    | LIKE
    | ILIKE
+   | CONTAINS
    ;
 
 singleFieldRelevanceFunctionName
@@ -1613,6 +1614,7 @@ searchableKeyWord
    | ELSE
    | ARROW
    | BETWEEN
+   | CONTAINS
    | EXISTS
    | SOURCE
    | INDEX

ppl/src/main/java/org/opensearch/sql/ppl/parser/AstExpressionBuilder.java

@@ -213,6 +213,18 @@ public UnresolvedExpression visitCompareExpr(CompareExprContext ctx) {
     String operator = ctx.comparisonOperator().getText();
     if ("==".equals(operator)) {
       operator = EQUAL.getName().getFunctionName();
+    } else if ("contains".equalsIgnoreCase(operator)) {
+      UnresolvedExpression left = visit(ctx.left);
+      UnresolvedExpression right = visit(ctx.right);
+      if (!(right instanceof Literal) || ((Literal) right).getType() != DataType.STRING) {
+        throw new SemanticCheckException(
+            "The right-hand side of 'contains' must be a string literal");
+      }
+      String raw = ((Literal) right).getValue().toString();
+      String escaped = raw.replace("\\", "\\\\").replace("%", "\\%").replace("_", "\\_");
+      String wrapped = "%" + escaped + "%";
+      return new Compare(
+          ILIKE.getName().getFunctionName(), left, new Literal(wrapped, DataType.STRING));
     } else if (LIKE.getName().getFunctionName().equalsIgnoreCase(operator)
         && UnresolvedPlanHelper.isCalciteEnabled(astBuilder.getSettings())) {
       operator =