andexpr.java

来自「RESIN 3.2 最新源码」· Java 代码 · 共 181 行

/*
 * Copyright (c) 1998-2008 Caucho Technology -- all rights reserved
 *
 * This file is part of Resin(R) Open Source
 *
 * Each copy or derived work must preserve the copyright notice and this
 * notice unmodified.
 *
 * Resin Open Source is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * Resin Open Source is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE, or any warranty
 * of NON-INFRINGEMENT.  See the GNU General Public License for more
 * details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Resin Open Source; if not, write to the
 *   Free SoftwareFoundation, Inc.
 *   59 Temple Place, Suite 330
 *   Boston, MA 02111-1307  USA
 *
 * @author Scott Ferguson
 */

package com.caucho.db.sql;

import com.caucho.log.Log;
import com.caucho.util.CharBuffer;

import java.sql.SQLException;
import java.util.ArrayList;
import java.util.logging.Logger;

class AndExpr extends Expr {
  private static final Logger log = Log.open(AndExpr.class);

  private ArrayList<Expr> _exprs = new ArrayList<Expr>();

  AndExpr()
  {
  }

  void add(Expr expr)
  {
    _exprs.add(expr);
  }

  Expr getSingleExpr()
  {
    if (_exprs.size() == 0)
      return null;
    else if (_exprs.size() == 1)
      return _exprs.get(0);
    else
      return this;
  }

  protected Expr bind(Query query)
    throws SQLException
  {
    for (int i = 0; i < _exprs.size(); i++) {
      Expr expr = _exprs.get(i);

      expr = expr.bind(query);
      
      if (! expr.getType().equals(boolean.class))
	throw new SQLException(L.l("AND requires boolean operands at {0}",
				   expr));

      _exprs.set(i, expr);
    }

    return this;
  }

  /**
   * Returns the type of the expression.
   */
  public Class getType()
  {
    return boolean.class;
  }

  /**
   * Returns the cost based on the given FromList.
   */
  public long subCost(ArrayList<FromItem> fromList)
  {
    long cost = 0;

    for (int i = 0; i < _exprs.size(); i++) {
      cost += _exprs.get(i).subCost(fromList);
    }

    return cost;
  }

  /**
   * Splits the expr into and blocks.
   */
  public void splitAnd(ArrayList<Expr> andProduct)
  {
    for (int i = 0; i < _exprs.size(); i++) {
      _exprs.get(i).splitAnd(andProduct);
    }
  }

  /**
   * Returns true for a null expression
   */
  public boolean isNull(QueryContext context)
    throws SQLException
  {
    boolean isNull = false;
    for (int i = 0; i < _exprs.size(); i++) {
      int value = _exprs.get(i).evalBoolean(context);

      if (value == FALSE)
	return false;
      else if (value != TRUE)
	isNull = true;
    }

    return isNull;
  }

  /**
   * Evaluates the expression as a boolean.
   */
  public int evalBoolean(QueryContext context)
    throws SQLException
  {
    int value = TRUE;
    
    for (int i = 0; i < _exprs.size(); i++) {
      int subValue = _exprs.get(i).evalBoolean(context);
      
      if (subValue == FALSE)
	return FALSE;
      else if (subValue == UNKNOWN)
	value = UNKNOWN;
    }

    return value;
  }

  public String evalString(QueryContext context)
    throws SQLException
  {
    switch (evalBoolean(context)) {
    case TRUE:
      return "1";
    case FALSE:
      return "0";
    default:
      return null;
    }
  }

  public String toString()
  {
    CharBuffer cb = CharBuffer.allocate();
    cb.append("(");

    for (int i = 0; i < _exprs.size(); i++) {
      if (i != 0)
	cb.append(" AND ");

      cb.append(_exprs.get(i));
    }

    cb.append(")");
    
    return cb.close();
  }
}