literal.java

OLAP 的客户端代码

/*
 * ====================================================================
 * This software is subject to the terms of the Common Public License
 * Agreement, available at the following URL:
 *   http://www.opensource.org/licenses/cpl.html .
 * Copyright (C) 2003-2004 TONBELLER AG.
 * All Rights Reserved.
 * You must accept the terms of that agreement to use this software.
 * ====================================================================
 *
 * 
 */
package com.tonbeller.jpivot.olap.mdxparse;

/**
 * MDX parser Literal Expressions 
 */
public class Literal implements Exp {

  public int type;
  private Object o;

  public static final Literal emptyString = new Literal("", false);
  public static final Literal zero = new Literal(new Integer(0));
  public static final Literal one = new Literal(new Integer(1));
  public static final Literal doubleZero = new Literal(new Double(0.0));
  public static final Literal doubleOne = new Literal(new Double(1.0));

  public static final int TYPE_SYMBOL = 1;
  public static final int TYPE_STRING = 2;
  public static final int TYPE_NUMERIC = 3;

  private Literal(String s, boolean isSymbol) {
    this.o = s;
    this.type = isSymbol ? TYPE_SYMBOL : TYPE_STRING;
  }

  public static Literal createString(String s) {
    if (s.equals("")) {
      return emptyString;
    } else {
      return new Literal(s, false);
    }
  }

  public static Literal createSymbol(String s) {
    return new Literal(s, true);
  }

  private Literal(Double d) {
    this.o = d;
    this.type = TYPE_NUMERIC;
  }

  public static Literal create(Double d) {
    if (d.doubleValue() == 0.0) {
      return doubleZero;
    } else if (d.doubleValue() == 1.0) {
      return doubleOne;
    } else {
      return new Literal(d);
    }
  }

  private Literal(Integer i) {
    this.o = i;
    this.type = TYPE_NUMERIC;
  }

  public static Literal create(Integer i) {
    if (i.intValue() == 0) {
      return zero;
    } else if (i.intValue() == 1) {
      return one;
    } else {
      return new Literal(i);
    }
  }

  /**
   * format to MDX
   */
  public String toMdx() {
    return o.toString();
  }

  /**
   * Literal is immutable
   * @see java.lang.Object#clone()
   */
  public Object clone() {
    return this;
  }

  /**
   */
  public String stringValue() {
    if (type == TYPE_STRING) {
      // must remove enclosing double quotes
      String str = (String) o;
      return str.substring(1, str.length() - 1);
    } else
      return o.toString();
  }

  /**
   * @return
   */
  public Object getValueObject() {
    return o;
  }

  /**
   * @see com.tonbeller.jpivot.olap.mdxparse.Exp#accept
   */
  public void accept(ExpVisitor visitor) {
    visitor.visitLiteral(this);
  }
  
} // End Literal.java