[SPARK-28880][SQL] Support ANSI nested bracketed comments

sql/catalyst/src/main/antlr4/org/apache/spark/sql/catalyst/parser/SqlBase.g4

@@ -61,6 +61,22 @@ grammar SqlBase;
    * When true, the behavior of keywords follows ANSI SQL standard.
    */
   public boolean SQL_standard_keyword_behavior = false;
+
+  /**
+   * This method will be called when we see '/*' and try to match it as a bracketed comment.
+   * If the next character is '+', it should be parsed as hint later, and we cannot match
+   * it as a bracketed comment.
+   *
+   * Returns true if the next character is '+'.
+   */
+  public boolean isHint() {
+    int nextChar = _input.LA(1);
+    if (nextChar == '+') {
+      return true;
+    } else {
+      return false;
+    }
+  }
 }
 
 singleStatement
@@ -1796,12 +1812,8 @@ SIMPLE_COMMENT
     : '--' ~[\r\n]* '\r'? '\n'? -> channel(HIDDEN)
     ;
 
-BRACKETED_EMPTY_COMMENT
-    : '/**/' -> channel(HIDDEN)
-    ;
-
 BRACKETED_COMMENT
-    : '/*' ~[+] .*? '*/' -> channel(HIDDEN)
+    : '/*' {!isHint()}? (BRACKETED_COMMENT|.)*? '*/' -> channel(HIDDEN)
     ;
 
 WS

sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/parser/PlanParserSuite.scala

@@ -55,6 +55,104 @@ class PlanParserSuite extends AnalysisTest {
     With(plan, ctes)
   }
 
+  test("single comment") {
+    val plan = table("a").select(star())
+    assertEqual("-- single comment\nSELECT * FROM a", plan)
+  }
+
+  test("bracketed comment case one") {
+    val plan = table("a").select(star())
+    assertEqual(
+      """
+        |/* This is an example of SQL which should not execute:
+        | * select 'multi-line';
+        | */
+        |SELECT * FROM a
+      """.stripMargin, plan)
+  }
+
+  test("bracketed comment case two") {
+    val plan = table("a").select(star())
+    assertEqual(
+      """
+        |/*
+        |SELECT 'trailing' as x1; -- inside block comment
+        |*/
+        |SELECT * FROM a
+      """.stripMargin, plan)
+  }
+
+  test("nested bracketed comment case one") {
+    val plan = table("a").select(star())
+    assertEqual(
+      """
+        |/* This block comment surrounds a query which itself has a block comment...
+        |SELECT /* embedded single line */ 'embedded' AS x2;
+        |*/
+        |SELECT * FROM a
+      """.stripMargin, plan)
+  }
+
+  test("nested bracketed comment case two") {
+    val plan = table("a").select(star())
+    assertEqual(
+      """
+        |SELECT -- continued after the following block comments...
+        |/* Deeply nested comment.
+        |   This includes a single apostrophe to make sure we aren't decoding this part as a string.
+        |SELECT 'deep nest' AS n1;
+        |/* Second level of nesting...
+        |SELECT 'deeper nest' as n2;
+        |/* Third level of nesting...
+        |SELECT 'deepest nest' as n3;
+        |*/
+        |Hoo boy. Still two deep...
+        |*/
+        |Now just one deep...
+        |*/
+        |* FROM a
+      """.stripMargin, plan)
+  }
+
+  test("nested bracketed comment case three") {
+    val plan = table("a").select(star())
+    assertEqual(
+      """
+        |/* This block comment surrounds a query which itself has a block comment...
+        |//* I am a nested bracketed comment.
+        |*/
+        |*/
+        |SELECT * FROM a
+      """.stripMargin, plan)
+  }
+
+  test("nested bracketed comment case four") {
+    val plan = table("a").select(star())
+    assertEqual(
+      """
+        |/*/**/*/
+        |SELECT * FROM a
+      """.stripMargin, plan)
+  }
+
+  test("nested bracketed comment case five") {
+    val plan = table("a").select(star())
+    assertEqual(
+      """
+        |/*/*abc*/*/
+        |SELECT * FROM a
+      """.stripMargin, plan)
+  }
+
+  test("nested bracketed comment case six") {
+    val plan = table("a").select(star())
+    assertEqual(
+      """
+        |/*/*foo*//*bar*/*/
+        |SELECT * FROM a
+      """.stripMargin, plan)
+  }
+
   test("case insensitive") {
     val plan = table("a").select(star())
     assertEqual("sELEct * FroM a", plan)

sql/core/src/test/resources/sql-tests/inputs/comments.sql

@@ -0,0 +1,90 @@
+-- Test comments.
+
+-- the first case of bracketed comment
+--QUERY-DELIMITER-START
+/* This is the first example of bracketed comment.
+SELECT 'ommented out content' AS first;
+*/
+SELECT 'selected content' AS first;
+--QUERY-DELIMITER-END
+
+-- the second case of bracketed comment
+--QUERY-DELIMITER-START
+/* This is the second example of bracketed comment.
+SELECT '/', 'ommented out content' AS second;
+*/
+SELECT '/', 'selected content' AS second;
+--QUERY-DELIMITER-END
+
+-- the third case of bracketed comment
+--QUERY-DELIMITER-START
+/* This is the third example of bracketed comment.
+ *SELECT '*', 'ommented out content' AS third;
+ */
+SELECT '*', 'selected content' AS third;
+--QUERY-DELIMITER-END
+
+-- the first case of empty bracketed comment
+--QUERY-DELIMITER-START
+/**/
+SELECT 'selected content' AS fourth;
+--QUERY-DELIMITER-END
+
+-- the first case of nested bracketed comment
+--QUERY-DELIMITER-START
+/* This is the first example of nested bracketed comment.
+/* I am a nested bracketed comment.*/
+*/
+SELECT 'selected content' AS fifth;
+--QUERY-DELIMITER-END
+
+-- the second case of nested bracketed comment
+--QUERY-DELIMITER-START
+/* This is the second example of nested bracketed comment.
+/* I am a nested bracketed comment.
+ */
+ */
+SELECT 'selected content' AS sixth;
+--QUERY-DELIMITER-END
+
+-- the third case of nested bracketed comment
+--QUERY-DELIMITER-START
+/*
+ * This is the third example of nested bracketed comment.
+  /*
+   * I am a nested bracketed comment.
+   */
+ */
+SELECT 'selected content' AS seventh;
+--QUERY-DELIMITER-END
+
+-- the fourth case of nested bracketed comment
+--QUERY-DELIMITER-START
+/* 
+ * This is the fourth example of nested bracketed comment.
+SELECT /* I am a nested bracketed comment.*/ * FROM testData;
+ */
+SELECT 'selected content' AS eighth;
+--QUERY-DELIMITER-END
+
+-- the fifth case of nested bracketed comment
+--QUERY-DELIMITER-START
+SELECT /*
+ * This is the fifth example of nested bracketed comment.
+/* I am a second level of nested bracketed comment.
+/* I am a third level of nested bracketed comment.
+Other information of third level.
+SELECT 'ommented out content' AS ninth;
+*/
+Other information of second level.
+*/
+Other information of first level.
+*/
+'selected content' AS ninth;
+--QUERY-DELIMITER-END
+
+-- the first case of empty nested bracketed comment
+--QUERY-DELIMITER-START
+/*/**/*/
+SELECT 'selected content' AS tenth;
+--QUERY-DELIMITER-END

sql/core/src/test/resources/sql-tests/inputs/postgreSQL/comments.sql

@@ -12,14 +12,12 @@ SELECT /* both embedded and trailing single line */ 'both' AS third; -- trailing
 
 SELECT 'before multi-line' AS fourth;
 --QUERY-DELIMITER-START
--- [SPARK-28880] ANSI SQL: Bracketed comments
 /* This is an example of SQL which should not execute:
  * select 'multi-line';
  */
 SELECT 'after multi-line' AS fifth;
 --QUERY-DELIMITER-END
 
--- [SPARK-28880] ANSI SQL: Bracketed comments
 --
 -- Nested comments
 --
@@ -47,4 +45,5 @@ Now just one deep...
 */
 'deeply nested example' AS sixth;
 --QUERY-DELIMITER-END
-/* and this is the end of the file */
+-- [SPARK-30824] Support submit sql content only contains comments.
+-- /* and this is the end of the file */

sql/core/src/test/resources/sql-tests/results/comments.sql.out

@@ -0,0 +1,121 @@
+-- Automatically generated by SQLQueryTestSuite
+-- Number of queries: 10
+
+
+-- !query
+/* This is the first example of bracketed comment.
+SELECT 'ommented out content' AS first;
+*/
+SELECT 'selected content' AS first
+-- !query schema
+struct<first:string>
+-- !query output
+selected content
+
+
+-- !query
+/* This is the second example of bracketed comment.
+SELECT '/', 'ommented out content' AS second;
+*/
+SELECT '/', 'selected content' AS second
+-- !query schema
+struct</:string,second:string>
+-- !query output
+/	selected content
+
+
+-- !query
+/* This is the third example of bracketed comment.
+ *SELECT '*', 'ommented out content' AS third;
+ */
+SELECT '*', 'selected content' AS third
+-- !query schema
+struct<*:string,third:string>
+-- !query output
+*	selected content
+
+
+-- !query
+/**/
+SELECT 'selected content' AS fourth
+-- !query schema
+struct<fourth:string>
+-- !query output
+selected content
+
+
+-- !query
+/* This is the first example of nested bracketed comment.
+/* I am a nested bracketed comment.*/
+*/
+SELECT 'selected content' AS fifth
+-- !query schema
+struct<fifth:string>
+-- !query output
+selected content
+
+
+-- !query
+/* This is the second example of nested bracketed comment.
+/* I am a nested bracketed comment.
+ */
+ */
+SELECT 'selected content' AS sixth
+-- !query schema
+struct<sixth:string>
+-- !query output
+selected content
+
+
+-- !query
+/*
+ * This is the third example of nested bracketed comment.
+  /*
+   * I am a nested bracketed comment.
+   */
+ */
+SELECT 'selected content' AS seventh
+-- !query schema
+struct<seventh:string>
+-- !query output
+selected content
+
+
+-- !query
+/* 
+ * This is the fourth example of nested bracketed comment.
+SELECT /* I am a nested bracketed comment.*/ * FROM testData;
+ */
+SELECT 'selected content' AS eighth
+-- !query schema
+struct<eighth:string>
+-- !query output
+selected content
+
+
+-- !query
+SELECT /*
+ * This is the fifth example of nested bracketed comment.
+/* I am a second level of nested bracketed comment.
+/* I am a third level of nested bracketed comment.
+Other information of third level.
+SELECT 'ommented out content' AS ninth;
+*/
+Other information of second level.
+*/
+Other information of first level.
+*/
+'selected content' AS ninth
+-- !query schema
+struct<ninth:string>
+-- !query output
+selected content
+
+
+-- !query
+/*/**/*/
+SELECT 'selected content' AS tenth
+-- !query schema
+struct<tenth:string>
+-- !query output
+selected content