FieldExpr.java :  » Database-DBMS » db4o-6.4 » EDU » purdue » cs » bloat » tree » Java Open Source

/* Copyright (C) 2004 - 2007  db4objects Inc.  http://www.db4o.com

This file is part of the db4o open source object database.

db4o is free software; you can redistribute it and/or modify it under
the terms of version 2 of the GNU General Public License as published
by the Free Software Foundation and as clarified by db4objects' GPL 
interpretation policy, available at
http://www.db4o.com/about/company/legalpolicies/gplinterpretation/
Alternatively you can write to db4objects, Inc., 1900 S Norfolk Street,
Suite 350, San Mateo, CA 94403, USA.

db4o 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.  See the GNU General Public License
for more details.

You should have received a copy of the GNU General Public License along
with this program; if not, write to the Free Software Foundation, Inc.,
59 Temple Place - Suite 330, Boston, MA  02111-1307, USA. */
package EDU.purdue.cs.bloat.tree;

import EDU.purdue.cs.bloat.editor.*;

/**
 * FieldExpr represents the <i>getfield</i> opcode which fetches a field from
 * an object.
 * 
 * @see MemberRef
 */
public class FieldExpr extends MemRefExpr {
  // getfield

  Expr object; // The object whose field we are fetching

  MemberRef field; // The field to fetch

  /**
   * Constructor.
   * 
   * @param object The object (result of an Expr) whose field is to be
   *        fetched.
   * @param field
   *            The field of object to be fetched.
   * @param type
   *            The type of this expression.
   */
  public FieldExpr(final Expr object, final MemberRef field, final Type type) {
    super(type);
    this.object = object;
    this.field = field;

    object.setParent(this);
  }

  public Expr object() {
    return object;
  }

  public MemberRef field() {
    return field;
  }

  public void visitForceChildren(final TreeVisitor visitor) {
    if (visitor.reverse()) {
      object.visit(visitor);
    } else {
      object.visit(visitor);
    }
  }

  public void visit(final TreeVisitor visitor) {
    visitor.visitFieldExpr(this);
  }

  public int exprHashCode() {
    return 11 + object.exprHashCode() ^ type.simple().hashCode();
  }

  public boolean equalsExpr(final Expr other) {
    return (other != null) && (other instanceof FieldExpr)
        && ((FieldExpr) other).field.equals(field)
        && ((FieldExpr) other).object.equalsExpr(object);
  }

  public Object clone() {
    return copyInto(new FieldExpr((Expr) object.clone(), field, type));
  }
}