Fix Vtexplains StripComments

Signed-off-by: Saif Alharthi <saif@saifalharthi.me>

Modify for better readability

Signed-off-by: Saif Alharthi <saif@saifalharthi.me>

Make sure anything inside qoutations will not be removed

Signed-off-by: Saif Alharthi <saif@saifalharthi.me>

Modity test for readablity

Signed-off-by: Saif Alharthi <saif@saifalharthi.me>

go/vt/sqlparser/comments.go

@@ -178,6 +178,12 @@ func StripComments(sql string) string {
 		if end <= 1 {
 			break
 		}
+		if start > end {
+			start, end = end, start
+		}
+		if containsQuotations(sql, start, end) {
+			break
+		}
 		sql = sql[:start] + sql[end+2:]
 	}
 
@@ -186,6 +192,16 @@ func StripComments(sql string) string {
 	return sql
 }
 
+func containsQuotations(sql string, start, end int) bool {
+	indexBefore, indexAfter := start-1, end+2
+	// Check Boundaries
+	if indexBefore < 0 || indexAfter >= len(sql) {
+		return false
+	}
+	// Check if the character the index before comments start and end substring is a single or double quotation
+	return (sql[indexBefore] == '\'' && sql[indexAfter] == '\'') || (sql[indexBefore] == '"' && sql[indexAfter] == '"')
+}
+
 // ExtractMysqlComment extracts the version and SQL from a comment-only query
 // such as /*!50708 sql here */
 func ExtractMysqlComment(sql string) (version string, innerSQL string) {

go/vt/sqlparser/comments_test.go

@@ -281,6 +281,21 @@ a`,
 	}, {
 		input:  `-- foo bar`,
 		outSQL: "",
+	}, {
+		input:  "select * from customer where name like '*//*'",
+		outSQL: "select * from customer where name like '*//*'",
+	}, {
+		input:  "select * from customer where name like '*/%/*'",
+		outSQL: "select * from customer where name like '*/%/*'",
+	}, {
+		input:  "select * from customer where name like '*/%/*'",
+		outSQL: "select * from customer where name like '*/%/*'",
+	}, {
+		input:  "insert into customer values(1, '*//*')",
+		outSQL: "insert into customer values(1, '*//*')",
+	}, {
+		input:  "insert into t5 (col) values('/**/')",
+		outSQL: "insert into t5 (col) values('/**/')",
 	}}
 	for _, testCase := range testCases {
 		gotSQL := StripComments(testCase.input)