content: /*
   * Copyright 1999-2017 Alibaba Group Holding Ltd.
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package com.alibaba.druid.sql.dialect.db2.parser;
  
  import com.alibaba.druid.DbType;
  import com.alibaba.druid.sql.ast.SQLExpr;
  import com.alibaba.druid.sql.ast.SQLObject;
  import com.alibaba.druid.sql.ast.SQLOrderBy;
  import com.alibaba.druid.sql.ast.SQLSetQuantifier;
  import com.alibaba.druid.sql.ast.statement.SQLSelectGroupByClause;
  import com.alibaba.druid.sql.ast.statement.SQLSelectQuery;
  import com.alibaba.druid.sql.ast.statement.SQLSelectQueryBlock;
  import com.alibaba.druid.sql.dialect.db2.ast.stmt.DB2SelectQueryBlock;
  import com.alibaba.druid.sql.dialect.db2.ast.stmt.DB2SelectQueryBlock.Isolation;
  import com.alibaba.druid.sql.parser.*;
  import com.alibaba.druid.util.FnvHash;
  
  public class DB2SelectParser extends SQLSelectParser {
      public DB2SelectParser(SQLExprParser exprParser) {
          super(exprParser);
          dbType = DbType.db2;
      }
  
      public DB2SelectParser(SQLExprParser exprParser, SQLSelectListCache selectListCache) {
          super(exprParser, selectListCache);
          dbType = DbType.db2;
      }
  
      public DB2SelectParser(String sql) {
          this(new DB2ExprParser(sql));
      }
  
      protected SQLExprParser createExprParser() {
          return new DB2ExprParser(lexer);
      }
  
      @Override
      public SQLSelectQuery query(SQLObject parent, boolean acceptUnion) {
          if (lexer.token() == Token.LPAREN) {
              lexer.nextToken();
  
              SQLSelectQuery select = query();
              accept(Token.RPAREN);
  
              return queryRest(select, acceptUnion);
          }
  
          accept(Token.SELECT);
  
          if (lexer.token() == Token.COMMENT) {
              lexer.nextToken();
          }
  
          DB2SelectQueryBlock queryBlock = new DB2SelectQueryBlock();
  
          if (lexer.token() == Token.DISTINCT) {
              queryBlock.setDistionOption(SQLSetQuantifier.DISTINCT);
              lexer.nextToken();
          } else if (lexer.token() == Token.UNIQUE) {
              queryBlock.setDistionOption(SQLSetQuantifier.UNIQUE);
              lexer.nextToken();
          } else if (lexer.token() == Token.ALL) {
              queryBlock.setDistionOption(SQLSetQuantifier.ALL);
              lexer.nextToken();
          }
  
          parseSelectList(queryBlock);
  
          if (lexer.token() == Token.INTO) {
              lexer.nextToken();
  
              SQLExpr expr = expr();
              if (lexer.token() != Token.COMMA) {
                  queryBlock.setInto(expr);
              }
          }
  
          parseFrom(queryBlock);
  
          parseWhere(queryBlock);
  
          parseHierachical(queryBlock);
  
          parseGroupBy(queryBlock);
  
          if (lexer.token() == Token.ORDER) {
              SQLOrderBy orderBy = parseOrderBy();
              queryBlock.setOrderBy(orderBy);
          }
  
          for (; ; ) {
              if (lexer.token() == Token.FETCH) {
                  lexer.nextToken();
                  accept(Token.FIRST);
                  SQLExpr first = this.exprParser.primary();
                  queryBlock.setFirst(first);
                  if (lexer.identifierEquals("ROW") || lexer.identifierEquals("ROWS")) {
                      lexer.nextToken();
                  }
                  accept(Token.ONLY);
                  continue;
              }
  
              if (lexer.token() == Token.WITH) {
                  lexer.nextToken();
                  if (lexer.identifierEquals("RR")) {
                      queryBlock.setIsolation(Isolation.RR);
                      parseLockRequest(queryBlock);
                  } else if (lexer.identifierEquals("RS")) {
                      queryBlock.setIsolation(Isolation.RS);
                      parseLockRequest(queryBlock);
                  } else if (lexer.identifierEquals("CS")) {
                      queryBlock.setIsolation(Isolation.CS);
                  } else if (lexer.identifierEquals("UR")) {
                      queryBlock.setIsolation(Isolation.UR);
                  } else {
                      throw new ParserException("TODO. " + lexer.info());
                  }
                  lexer.nextToken();
                  continue;
              }
  
              if (lexer.token() == Token.FOR) {
                  lexer.nextToken();
  
                  if (lexer.token() == Token.UPDATE) {
                      queryBlock.setForUpdate(true);
                      lexer.nextToken();
                  } else {
                      acceptIdentifier("READ");
                      accept(Token.ONLY);
                      queryBlock.setForReadOnly(true);
                  }
                  continue;
              }
  
              if (lexer.token() == Token.OPTIMIZE) {
                  lexer.nextToken();
                  accept(Token.FOR);
  
                  queryBlock.setOptimizeFor(this.expr());
                  if (lexer.identifierEquals("ROW")) {
                      lexer.nextToken();
                  } else {
                      acceptIdentifier("ROWS");
                  }
              }
  
              break;
          }
  
          return queryRest(queryBlock, acceptUnion);
      }
  
      private void parseLockRequest(DB2SelectQueryBlock queryBlock) {
          lexer.nextToken();
          accept(Token.USE);
          accept(Token.AND);
          if (!lexer.identifierEquals("KEEP")) {
              throw new ParserException("TODO. " + lexer.info());
          }
          lexer.nextToken();
          DB2SelectQueryBlock.LockRequest lockRequest = null;
          switch (lexer.token()) {
              case SHARE: {
                  lockRequest = DB2SelectQueryBlock.LockRequest.SHARE;
                  break;
              }
              case UPDATE: {
                  lockRequest = DB2SelectQueryBlock.LockRequest.UPDATE;
                  break;
              }
              case EXCLUSIVE: {
                  lockRequest = DB2SelectQueryBlock.LockRequest.EXCLUSIVE;
                  break;
              }
              default:
                  throw new ParserException("TODO. " + lexer.info());
          }
          lexer.nextToken();
          if (lexer.identifierEquals("LOCKS")) {
              queryBlock.setLockRequest(lockRequest);
          } else {
              throw new ParserException("TODO. " + lexer.info());
          }
      }
  
      @Override
      protected void parseOrderByWith(SQLSelectGroupByClause groupBy, SQLSelectQueryBlock queryBlock) {
          Lexer.SavePoint mark = lexer.mark();
          lexer.nextToken();
  
          if (lexer.identifierEquals(FnvHash.Constants.CUBE)) {
              lexer.nextToken();
              groupBy.setWithCube(true);
          } else if (lexer.identifierEquals(FnvHash.Constants.ROLLUP)) {
              lexer.nextToken();
              groupBy.setWithRollUp(true);
          } else if (lexer.identifierEquals(FnvHash.Constants.RS)) {
              lexer.nextToken();
              ((DB2SelectQueryBlock) queryBlock).setIsolation(DB2SelectQueryBlock.Isolation.RS);
          } else if (lexer.identifierEquals(FnvHash.Constants.RR)) {
              lexer.nextToken();
              ((DB2SelectQueryBlock) queryBlock).setIsolation(DB2SelectQueryBlock.Isolation.RR);
          } else if (lexer.identifierEquals(FnvHash.Constants.CS)) {
              lexer.nextToken();
              ((DB2SelectQueryBlock) queryBlock).setIsolation(DB2SelectQueryBlock.Isolation.CS);
          } else if (lexer.identifierEquals(FnvHash.Constants.UR)) {
              lexer.nextToken();
              ((DB2SelectQueryBlock) queryBlock).setIsolation(DB2SelectQueryBlock.Isolation.UR);
          } else {
              lexer.reset(mark);
          }
      }
  }
  