Support line comment and block comment in PPL

docs/user/ppl/general/comments.rst

@@ -0,0 +1,44 @@
+========
+Comments
+========
+
+.. rubric:: Table of contents
+
+.. contents::
+   :local:
+   :depth: 2
+
+
+Comments are not evaluated texts. PPL supports both line comments and block comments.
+
+Line Comments
+-------------
+Line comments begin with two slashes ( // ) and end with a new line.
+
+Example::
+
+    os> source=accounts | top gender // finds most common gender of all the accounts
+    fetched rows / total rows = 2/2
+    +----------+
+    | gender   |
+    |----------|
+    | M        |
+    | F        |
+    +----------+
+
+Block Comments
+--------------
+Block comments begin with a slash followed by an asterisk ( /\* ) and end with an asterisk followed by a slash ( \*/ ).
+
+Example::
+
+    os> source=accounts | dedup 2 gender /* dedup the document with gender field keep 2 duplication */ | fields account_number, gender
+    fetched rows / total rows = 3/3
+    +------------------+----------+
+    | account_number   | gender   |
+    |------------------+----------|
+    | 1                | M        |
+    | 6                | M        |
+    | 13               | F        |
+    +------------------+----------+
+

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

@@ -0,0 +1,94 @@
+/*
+ * Copyright OpenSearch Contributors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package org.opensearch.sql.ppl;
+
+import static org.opensearch.sql.legacy.TestsConstants.TEST_INDEX_ACCOUNT;
+import static org.opensearch.sql.util.MatcherUtils.rows;
+import static org.opensearch.sql.util.MatcherUtils.verifyDataRows;
+
+import java.io.IOException;
+import org.json.JSONObject;
+import org.junit.jupiter.api.Test;
+
+public class CommentIT extends PPLIntegTestCase {
+  @Override
+  public void init() throws IOException {
+    loadIndex(Index.ACCOUNT);
+  }
+
+  @Test
+  public void testMultipleLinesCommand() throws IOException {
+    // source=accounts
+    // | fields firstname
+    // | where firstname='Amber'
+    // | fields firstname
+    JSONObject result =
+        executeQuery(
+            String.format(
+                "source=%s \\n"
+                    + "| fields firstname \\n"
+                    + "| where firstname='Amber' \\n"
+                    + "| fields firstname",
+                TEST_INDEX_ACCOUNT));
+    verifyDataRows(result, rows("Amber"));
+  }
+
+  @Test
+  public void testLineComment() throws IOException {
+    // // line comment
+    // source=accounts | fields firstname // line comment
+    // | where firstname='Amber' // line comment
+    // | fields firstname // line comment
+    // /////////line comment
+    JSONObject result =
+        executeQuery(
+            String.format(
+                "// line comment\\n"
+                    + "source=%s | fields firstname // line comment\\n"
+                    + "| where firstname='Amber' // line comment\\n"
+                    + "| fields firstname // line comment\\n"
+                    + "/////////line comment",
+                TEST_INDEX_ACCOUNT));
+    verifyDataRows(result, rows("Amber"));
+  }
+
+  @Test
+  public void testBlockComment() throws IOException {
+    // /*
+    // This is a
+    //     multiple
+    // line block
+    //     comment */
+    // search /* block comment */ source=accounts /* block comment */
+    // | fields /*
+    //     This is a
+    //         multiple
+    //     line
+    //         block
+    //             comment */ firstname
+    // | /* block comment */ where firstname='Amber'
+    // | fields /* block comment */ firstname
+    JSONObject result =
+        executeQuery(
+            String.format(
+                "/*\\n"
+                    + "This is a\\n"
+                    + "    multiple\\n"
+                    + "line block\\n"
+                    + "    comment */\\n"
+                    + "search /* block comment */ source=%s /* block comment */\\n"
+                    + "| fields /*\\n"
+                    + "    This is a\\n"
+                    + "        multiple\\n"
+                    + "    line\\n"
+                    + "        block\\n"
+                    + "            comment */ firstname\\n"
+                    + "| /* block comment */ where firstname='Amber'\\n"
+                    + "| fields /* block comment */ firstname",
+                TEST_INDEX_ACCOUNT));
+    verifyDataRows(result, rows("Amber"));
+  }
+}

ppl/src/main/antlr/OpenSearchPPLLexer.g4

@@ -397,5 +397,7 @@ SQUOTA_STRING:                      '\'' ('\\'. | '\'\'' | ~('\'' | '\\'))* '\''
 BQUOTA_STRING:                      '`' ( '\\'. | '``' | ~('`'|'\\'))* '`';
 fragment DEC_DIGIT:                 [0-9];
 
+LINE_COMMENT:                       '//' ('\\\n' | ~[\r\n])* '\r'? '\n'? -> channel(HIDDEN);
+BLOCK_COMMENT:                      '/*' .*? '*/' -> channel(HIDDEN);
 
 ERROR_RECOGNITION:                  .    -> channel(ERRORCHANNEL);

ppl/src/test/java/org/opensearch/sql/ppl/antlr/PPLSyntaxParserTest.java

@@ -417,4 +417,43 @@ public void testCanParseTimestampdiffFunction() {
         new PPLSyntaxParser()
             .parse("SOURCE=test | eval k = TIMESTAMPDIFF(WEEK,'2003-01-02','2003-01-02')"));
   }
+
+  @Test
+  public void testLineCommentShouldPass() {
+    assertNotNull(new PPLSyntaxParser().parse("search source=t a=1 b=2 //this is a comment"));
+    assertNotNull(new PPLSyntaxParser().parse("search source=t a=1 b=2 // this is a comment "));
+    assertNotNull(
+        new PPLSyntaxParser()
+            .parse(
+                """
+                    // test is a new line comment \
+                    search source=t a=1 b=2 // test is a line comment at the end of ppl command \
+                    | fields a,b // this is line comment inner ppl command\
+                    ////this is a new line comment
+                    """));
+  }
+
+  @Test
+  public void testBlockCommentShouldPass() {
+    assertNotNull(new PPLSyntaxParser().parse("search source=t a=1 b=2 /*block comment*/"));
+    assertNotNull(new PPLSyntaxParser().parse("search source=t a=1 b=2 /* block comment */"));
+    assertNotNull(
+        new PPLSyntaxParser()
+            .parse(
+                """
+                    /*
+                    This is a\
+                        multiple\
+                    line\
+                    block\
+                        comment */\
+                    search /* block comment */ source=t /* block comment */ a=1 b=2
+                    |/*
+                        This is a\
+                            multiple\
+                        line\
+                        block\
+                            comment */ fields a,b /* block comment */ \
+                    """));
+  }
 }