sql parser support oceanbase hints

src/main/java/com/alibaba/druid/sql/dialect/mysql/ast/statement/MySqlDeleteStatement.java

@@ -15,6 +15,10 @@
  */
 package com.alibaba.druid.sql.dialect.mysql.ast.statement;
 
+import java.util.ArrayList;
+import java.util.List;
+
+import com.alibaba.druid.sql.ast.SQLCommentHint;
 import com.alibaba.druid.sql.ast.SQLOrderBy;
 import com.alibaba.druid.sql.ast.statement.SQLDeleteStatement;
 import com.alibaba.druid.sql.ast.statement.SQLTableSource;
@@ -26,17 +30,34 @@ import com.alibaba.druid.util.JdbcConstants;
 
 public class MySqlDeleteStatement extends SQLDeleteStatement {
 
-    private boolean        lowPriority = false;
-    private boolean        quick       = false;
-    private boolean        ignore      = false;
+    private boolean              lowPriority = false;
+    private boolean              quick       = false;
+    private boolean              ignore      = false;
 
-    private SQLTableSource from;
-    private SQLTableSource using;
-    private SQLOrderBy     orderBy;
-    private Limit          limit;
+    private SQLTableSource       from;
+    private SQLTableSource       using;
+    private SQLOrderBy           orderBy;
+    private Limit                limit;
+
+    private List<SQLCommentHint> hints;
+
+    public MySqlDeleteStatement(){
+        super(JdbcConstants.MYSQL);
+    }
+
+    public List<SQLCommentHint> getHints() {
+        if (hints == null) {
+            hints = new ArrayList<SQLCommentHint>();
+        }
+        return hints;
+    }
     
-    public MySqlDeleteStatement() {
-        super (JdbcConstants.MYSQL);
+    public int getHintsSize() {
+        if (hints == null) {
+            return 0;
+        }
+        
+        return hints.size();
     }
 
     public boolean isLowPriority() {

src/main/java/com/alibaba/druid/sql/dialect/mysql/parser/MySqlLexer.java

@@ -420,7 +420,9 @@ public class MySqlLexer extends Lexer {
 
             boolean isHint = false;
             int startHintSp = bufPos + 1;
-            if (ch == '!') {
+            if (ch == '!' //
+                    || ch == '+' // oceanbase hints
+                    ) {
                 isHint = true;
                 scanChar();
                 bufPos++;

src/main/java/com/alibaba/druid/sql/dialect/mysql/parser/MySqlStatementParser.java

@@ -262,6 +262,10 @@ public class MySqlStatementParser extends SQLStatementParser {
             if (lexer.token() == Token.COMMENT) {
                 lexer.nextToken();
             }
+            
+            if (lexer.token() == Token.HINT) {
+                this.getExprParser().parseHints(deleteStatement.getHints());
+            }
 
             if (identifierEquals(LOW_PRIORITY)) {
                 deleteStatement.setLowPriority(true);

src/main/java/com/alibaba/druid/sql/dialect/mysql/visitor/MySqlOutputVisitor.java

@@ -857,6 +857,12 @@ public class MySqlOutputVisitor extends SQLASTOutputVisitor implements MySqlASTV
     @Override
     public boolean visit(MySqlDeleteStatement x) {
         print0(ucase ? "DELETE " : "delete ");
+        
+        for (int i = 0, size = x.getHintsSize(); i < size; ++i) {
+            SQLCommentHint hint = x.getHints().get(i);
+            hint.accept(this);
+            print(' ');
+        }
 
         if (x.isLowPriority()) {
             print0(ucase ? "LOW_PRIORITY " : "low_priority ");