source: branches/0.15.x/abcl/src/org/armedbear/lisp/JavaClass.java

/*
 * BuiltInClass.java
 *
 * Copyright (C) 2003-2007 Peter Graves
 * $Id: BuiltInClass.java 11297 2008-08-31 13:26:45Z ehuelsmann $
 *
 * This program 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.
 *
 * This program 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 org.armedbear.lisp;

import java.util.HashMap;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.Map;
import java.util.Queue;
import java.util.Set;
import java.util.Stack;

public class JavaClass extends LispClass {

  private Class<?> javaClass;
  //There is no point for this Map to be weak since values keep a reference to the corresponding
  //key (the Java class). This should not be a problem since Java classes are limited in number - 
  //if they grew indefinitely, the JVM itself would crash.
  private static final Map<Class<?>, JavaClass> cache = new HashMap<Class<?>, JavaClass>();

  private JavaClass(Class<?> javaClass) {
    this.javaClass = javaClass;
    setDirectSuperclass(BuiltInClass.JAVA_OBJECT);
  }

  private void initCPL() {
    LispObject cpl = Lisp.NIL;
    try {
      cpl = cpl.push(BuiltInClass.CLASS_T);
      cpl = cpl.push(BuiltInClass.JAVA_OBJECT);
      Set<Class<?>> alreadySeen = new HashSet<Class<?>>();
      Stack<JavaClass> stack = new Stack<JavaClass>();
      Class<?> theClass = javaClass;
      boolean stop = false;
      while(!stop && theClass != null) {
        stop = addClass(alreadySeen, stack, theClass);
        for(Class<?> c : theClass.getInterfaces()) {
          stop = addClass(alreadySeen, stack, c) && stop; //watch out for short-circuiting!
        }
        theClass = theClass.getSuperclass();
      }
      while(!stack.isEmpty()) {
        cpl = cpl.push(stack.pop());
      }
    } catch (ConditionThrowable e) {
      throw new Error("Cannot push class in class precedence list", e);
    }
    setCPL(cpl);
  }

  private static boolean addClass(Set<Class<?>> alreadySeen, Stack<JavaClass> stack, Class<?> theClass) {
    if(!alreadySeen.contains(theClass)) {
      alreadySeen.add(theClass);
      stack.push(findJavaClass(theClass));
      return false;
    }
    return true;
  }

  public LispObject typeOf() {
    return Symbol.JAVA_CLASS;
  }

  public LispObject classOf() {
    return StandardClass.JAVA_CLASS;
  }

  public LispObject typep(LispObject type) throws ConditionThrowable {
    if (type == Symbol.JAVA_CLASS)
      return T;
    if (type == StandardClass.JAVA_CLASS)
      return T;
    return super.typep(type);
  }

  public LispObject getDescription() throws ConditionThrowable {
    return new SimpleString(writeToString());
  }

  public String writeToString() throws ConditionThrowable {
    FastStringBuffer sb = new FastStringBuffer("#<JAVA-CLASS ");
    sb.append(javaClass.getCanonicalName());
    sb.append('>');
    return sb.toString();
  }

  public static JavaClass findJavaClass(Class<?> javaClass) {
    synchronized (cache) {
      JavaClass c = cache.get(javaClass);
      if (c == null) {
        c = new JavaClass(javaClass);
        cache.put(javaClass, c);
        c.initCPL();
      }
      return c;
    }
  }

  public Class<?> getJavaClass() {
    return javaClass;
  }

  public boolean subclassp(LispObject obj) throws ConditionThrowable {
    if(obj == BuiltInClass.CLASS_T) {
      return true;
    }
    if(obj == BuiltInClass.JAVA_OBJECT) {
      return true;
    }
    if(obj instanceof JavaClass) {
      return ((JavaClass) obj).getJavaClass().isAssignableFrom(javaClass);
    }
    return false;
  }

  private static final Primitive _FIND_JAVA_CLASS = new Primitive(
      "%find-java-class", PACKAGE_JAVA, false, "string") {
    public LispObject execute(LispObject arg) throws ConditionThrowable {
      try {
        return findJavaClass(Class.forName((String) arg.getStringValue()));
      } catch (ClassNotFoundException e) {
        throw new ConditionThrowable("Cannot find Java class " + arg.getStringValue());
      }
    }

  };

}