content: /*
   * Copyright 1999-2012 Alibaba Group.
   *  
   * 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.
   */
  /**
   * (created at 2011-1-23)
   */
  package com.alibaba.cobar.parser.ast.expression.primary.function.string;
  
  import java.util.ArrayList;
  import java.util.List;
  
  import com.alibaba.cobar.parser.ast.expression.Expression;
  import com.alibaba.cobar.parser.ast.expression.primary.function.FunctionExpression;
  import com.alibaba.cobar.parser.visitor.SQLASTVisitor;
  
  /**
   * @author <a href="mailto:shuo.qius@alibaba-inc.com">QIU Shuo</a>
   */
  public class Trim extends FunctionExpression {
      public static enum Direction {
          /** no tag for direction */
          DEFAULT,
          BOTH,
          LEADING,
          TRAILING
      }
  
      private final Direction direction;
  
      private static List<Expression> wrapList(Expression str, Expression remstr) {
          if (str == null)
              throw new IllegalArgumentException("str is null");
          List<Expression> list = remstr != null ? new ArrayList<Expression>(2) : new ArrayList<Expression>(1);
          list.add(str);
          if (remstr != null)
              list.add(remstr);
          return list;
      }
  
      public Trim(Direction direction, Expression remstr, Expression str) {
          super("TRIM", wrapList(str, remstr));
          this.direction = direction;
      }
  
      /**
       * @return never null
       */
      public Expression getString() {
          return getArguments().get(0);
      }
  
      public Expression getRemainString() {
          List<Expression> args = getArguments();
          if (args.size() < 2)
              return null;
          return getArguments().get(1);
      }
  
      public Direction getDirection() {
          return direction;
      }
  
      @Override
      public FunctionExpression constructFunction(List<Expression> arguments) {
          throw new UnsupportedOperationException("function of trim has special arguments");
      }
  
      @Override
      public void accept(SQLASTVisitor visitor) {
          visitor.visit(this);
      }
  }
  