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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one or more
3    * contributor license agreements.  See the NOTICE file distributed with
4    * this work for additional information regarding copyright ownership.
5    * The ASF licenses this file to You under the Apache License, Version 2.0
6    * (the "License"); you may not use this file except in compliance with
7    * the License.  You may obtain a copy of the License at
8    *
9    *     http://www.apache.org/licenses/LICENSE-2.0
10   *
11   * Unless required by applicable law or agreed to in writing, software
12   * distributed under the License is distributed on an "AS IS" BASIS,
13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14   * See the License for the specific language governing permissions and
15   * limitations under the License.
16   */
17  
18  package org.apache.shardingsphere.distsql.parser.core.utility;
19  
20  import org.antlr.v4.runtime.misc.ParseCancellationException;
21  import org.antlr.v4.runtime.tree.ErrorNode;
22  import org.apache.shardingsphere.sql.parser.api.ASTNode;
23  import org.apache.shardingsphere.sql.parser.core.ParseASTNode;
24  import org.apache.shardingsphere.sql.parser.core.SQLParserFactory;
25  import org.apache.shardingsphere.sql.parser.exception.SQLParsingException;
26  import org.apache.shardingsphere.sql.parser.sql.common.statement.SQLStatement;
27  
28  /**
29   * SQL statement parser engine for utility DistSQL.
30   */
31  public final class UtilityDistSQLStatementParserEngine {
32      
33      /**
34       * Parse SQL.
35       *
36       * @param sql SQL to be parsed
37       * @return SQL statement
38       */
39      public SQLStatement parse(final String sql) {
40          ASTNode astNode = parseToASTNode(sql);
41          return getSQLStatement(sql, (ParseASTNode) astNode);
42      }
43      
44      private ASTNode parseToASTNode(final String sql) {
45          try {
46              return SQLParserFactory.newInstance(sql, UtilityDistSQLLexer.class, UtilityDistSQLParser.class).parse();
47          } catch (final ParseCancellationException ignored) {
48              throw new SQLParsingException(sql);
49          }
50      }
51      
52      private SQLStatement getSQLStatement(final String sql, final ParseASTNode parseASTNode) {
53          if (parseASTNode.getRootNode() instanceof ErrorNode) {
54              throw new SQLParsingException(sql);
55          }
56          return (SQLStatement) (new UtilityDistSQLStatementVisitor()).visit(parseASTNode.getRootNode());
57      }
58  }