source: branches/0.20.x/abcl/src/org/armedbear/lisp/JavaObject.java

/*
 * JavaObject.java
 *
 * Copyright (C) 2002-2005 Peter Graves
 * $Id: JavaObject.java 12583 2010-04-08 19:44:14Z astalla $
 *
 * 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.
 *
 * As a special exception, the copyright holders of this library give you
 * permission to link this library with independent modules to produce an
 * executable, regardless of the license terms of these independent
 * modules, and to copy and distribute the resulting executable under
 * terms of your choice, provided that you also meet, for each linked
 * independent module, the terms and conditions of the license of that
 * module.  An independent module is a module which is not derived from
 * or based on this library.  If you modify this library, you may extend
 * this exception to your version of the library, but you are not
 * obligated to do so.  If you do not wish to do so, delete this
 * exception statement from your version.
 */

package org.armedbear.lisp;

import static org.armedbear.lisp.Lisp.*;

import java.lang.reflect.Array;
import java.lang.reflect.Field;
import java.math.BigInteger;
import java.util.*;

public final class JavaObject extends LispObject {
    final Object obj;
    private final Class<?> intendedClass;

    public JavaObject(Object obj) {
        this.obj = obj;
  this.intendedClass =
      obj != null ? Java.maybeBoxClass(obj.getClass()) : null;
    }

    public static final Symbol JAVA_CLASS_JCLASS = PACKAGE_JAVA.intern("JAVA-CLASS-JCLASS");
    public static final Symbol JAVA_CLASS = PACKAGE_JAVA.intern("JAVA-CLASS");
    public static final Symbol ENSURE_JAVA_CLASS = PACKAGE_JAVA.intern("ENSURE-JAVA-CLASS");

    /**
     * Constructs a Java Object with the given intended class, used to access
     * the object reflectively. If the class represents a primitive type,
     * the corresponding wrapper type is used instead.
     * @throws ClassCastException if the object is not an instance of the
     *                            intended class.
     */
    public JavaObject(Object obj, Class<?> intendedClass) {
  if(obj != null && intendedClass == null) {
      intendedClass = obj.getClass();
  }
  if(intendedClass != null) {
      intendedClass = Java.maybeBoxClass(intendedClass);
      if(!intendedClass.isInstance(obj)) {
    throw new ClassCastException(obj + " can not be cast to " + intendedClass);
      }
  }
  this.obj = obj;
  this.intendedClass = intendedClass;
    }

    @Override
    public LispObject typeOf()
    {
        return Symbol.JAVA_OBJECT;
    }

    @Override
    public LispObject classOf()
    {
        if(obj == null) {
                return BuiltInClass.JAVA_OBJECT;
        } else {
      return ENSURE_JAVA_CLASS.execute(new JavaObject(obj.getClass()));
        }
    }

    @Override
    public LispObject typep(LispObject type) {
        if (type == Symbol.JAVA_OBJECT)
            return T;
        if (type == BuiltInClass.JAVA_OBJECT)
            return T;
  if(type.typep(LispClass.findClass(JAVA_CLASS, false)) != NIL) {
      if(obj != null) {
    Class c = (Class) JAVA_CLASS_JCLASS.execute(type).javaInstance();
    return c.isAssignableFrom(obj.getClass()) ? T : NIL;
      } else {
    return T;
      }
  }
        return super.typep(type);
    }

    public final Object getObject()
    {
        return obj;
    }

    /** Encapsulates obj, if required.
     * If obj is a {@link  LispObject}, it's returned as-is.
     * 
     * @param obj Any java object
     * @return obj or a new JavaObject encapsulating obj
     */
    public final static LispObject getInstance(Object obj) {
        if (obj == null)
            return new JavaObject(null);
        
        if (obj instanceof LispObject)
            return (LispObject)obj;

        return new JavaObject(obj);
    }

    /** Encapsulates obj, if required.
     * If obj is a {@link LispObject}, it's returned as-is.
     * If not, a java object with the specified intended class is returned.
     * 
     * @param obj Any java object
     * @param intendedClass the class that shall be used to access obj
     * @return obj or a new JavaObject encapsulating obj
     */
    public final static LispObject getInstance(Object obj, Class<?> intendedClass) {
        if (obj == null)
            return new JavaObject(null);
        
        if (obj instanceof LispObject)
            return (LispObject)obj;

        return new JavaObject(obj, intendedClass);
    }

    /** Encapsulates obj, if required.
     * If obj is a {@link LispObject}, it's returned as-is.
     * If obj is of a type which can be mapped to a lisp type,
     * an object of the mapped type is returned, if translated is true.
     *
     * @param obj
     * @param translated
     * @return a LispObject representing or encapsulating obj
     */
    public final static LispObject getInstance(Object obj, boolean translated) {
  return getInstance(obj, translated, obj != null ? obj.getClass() : null);
    }



    /** Encapsulates obj, if required.
     * If obj is a {@link LispObject}, it's returned as-is.
     * If obj is of a type which can be mapped to a lisp type,
     * an object of the mapped type is returned, if translated is true.
     *
     * @param obj
     * @param translated
     * @param intendedClass the class that shall be used to reflectively 
     *                      access obj; it is an error for obj not to be
     *                      an instance of this class. This parameter is ignored
     *                      if translated == true and the object can be
     *                      converted to a Lisp object.
     * @return a LispObject representing or encapsulating obj
     */
    public final static LispObject getInstance(Object obj, boolean translated, Class<?> intendedClass) {
        if (! translated)
            return getInstance(obj, intendedClass);

        if (obj == null) return NIL;

        if (obj instanceof LispObject)
            return (LispObject)obj;

        if (obj instanceof String)
            return new SimpleString((String)obj);

        if (obj instanceof Number) {
            // Number types ordered according to decreasing
            // estimated chances of occurrance

            if (obj instanceof Integer)
                return Fixnum.getInstance(((Integer)obj).intValue());

            if (obj instanceof Float)
                return new SingleFloat((Float)obj);

            if (obj instanceof Double)
                return new DoubleFloat((Double)obj);

            if (obj instanceof Long)
                return LispInteger.getInstance(((Long)obj).longValue());

            if (obj instanceof BigInteger)
                return Bignum.getInstance((BigInteger)obj);

            if (obj instanceof Short)
                return Fixnum.getInstance(((Short)obj).shortValue());

            if (obj instanceof Byte)
                return Fixnum.getInstance(((Byte)obj).byteValue());
            // We don't handle BigDecimal: it doesn't map to a Lisp type
        }

        if (obj instanceof Boolean)
            return ((Boolean)obj).booleanValue() ? T : NIL;

        if (obj instanceof Character)
            return LispCharacter.getInstance((Character)obj);

        if (obj instanceof Object[]) {
            Object[] array = (Object[]) obj;
            SimpleVector v = new SimpleVector(array.length);
            for (int i = array.length; i-- > 0;)
                v.aset(i, JavaObject.getInstance(array[i], translated));
            return v;
        }
        // TODO
        // We might want to handle:
        //  - streams
        //  - others?
        return new JavaObject(obj, intendedClass);
    }

    @Override
    public Object javaInstance() {
        return obj;
    }

    @Override
    public Object javaInstance(Class<?> c) {
  if(obj == null) {
      if(c.isPrimitive()) {
    throw new NullPointerException("Cannot assign null to " + c);
      }
      return obj;
  } else {
      c = Java.maybeBoxClass(c);
      if (c.isAssignableFrom(intendedClass) || c.isInstance(obj)) {
              // XXX In the case that c.isInstance(obj) should we then
              // "fix" the intendedClass field with the (presumably)
              // narrower type of 'obj'?

              // ME 20100323: I decided not to because a) we don't
              // know the "proper" class to narrow to (i.e. maybe
              // there's something "narrower" and b) I'm not sure how
              // primitive types relate to their boxed
              // representations.  
    return obj;
      } else {
    return error(new TypeError(intendedClass.getName() + " is not assignable to " + c.getName()));
      }
  }
    }

    /** Returns the encapsulated Java object for
     * interoperability with wait, notify, synchronized, etc.
     *
     * @return The encapsulated object
     */
    @Override
    public Object lockableInstance() {
        return obj;
    }

    public Class<?> getIntendedClass() {
  return intendedClass;
    }

    public static final Object getObject(LispObject o)

    {
        if (o instanceof JavaObject)
                return ((JavaObject)o).obj;        
        return             // Not reached.
        type_error(o, Symbol.JAVA_OBJECT);       
    }

    @Override
    public final boolean equal(LispObject other)
    {
        if (this == other)
            return true;
        if (other instanceof JavaObject)
            return (obj == ((JavaObject)other).obj);
        return false;
    }

    @Override
    public final boolean equalp(LispObject other)
    {
        return equal(other);
    }

    @Override
    public int sxhash()
    {
        return obj == null ? 0 : (obj.hashCode() & 0x7ffffff);
    }

    @Override
    public String writeToString()
    {
        if (obj instanceof ControlTransfer)
            return obj.toString();
  final String s;
  if(obj != null) {
      Class<?> c = obj.getClass();
      StringBuilder sb
    = new StringBuilder(c.isArray() ? "jarray" : c.getName());
      sb.append(' ');
      String ts = obj.toString();
      if(ts.length() > 32) { //random value, should be chosen sensibly
    sb.append(ts.substring(0, 32) + "...");
      } else {
    sb.append(ts);
      }
      s = sb.toString();
  } else {
      s = "null";
  }
        return unreadableString(s);
    }

    @Override
    public LispObject getDescription() {
  return new SimpleString(describeJavaObject(this));
    }

    @Override
    public LispObject getParts() {
  if(obj != null) {
      LispObject parts = NIL;
            parts = parts.push(new Cons("Java class",
                                        new JavaObject(obj.getClass())));
            if (intendedClass != null) {
                parts = parts.push(new Cons("intendedClass", new SimpleString(intendedClass.getCanonicalName())));
            }
      if (obj.getClass().isArray()) {
    int length = Array.getLength(obj);
    for (int i = 0; i < length; i++) {
        parts = parts
                        .push(new Cons(new SimpleString(i), 
                                       JavaObject.getInstance(Array.get(obj, i))));
    }
      } else {
    parts = Symbol.NCONC.execute(parts, getInspectedFields());
      }
      return parts.nreverse();
  } else {
      return NIL;
  }
    }

    private LispObject getInspectedFields()
  {
  final LispObject[] acc = new LispObject[] { NIL };
  doClassHierarchy(obj.getClass(), new Function() {
    @Override
    public LispObject execute(LispObject arg)
        {
        //No possibility of type error - we're mapping this function
        //over a list of classes
        Class<?> c = (Class) arg.javaInstance();
        for(Field f : c.getDeclaredFields()) {
      LispObject value = NIL;
      try {
          if(!f.isAccessible()) {
        f.setAccessible(true);
          }
          value = JavaObject.getInstance(f.get(obj));
      } catch(Exception e) {}
      acc[0] = acc[0].push(new Cons(f.getName(), value));
        }
        return acc[0];
    }
      });
  return acc[0].nreverse();
    }

    /**
     * Executes a function repeatedly over the minimal subtree of the
     * Java class hierarchy which contains every class in <classes>.
     */
    private static void doClassHierarchy(Collection<Class<?>> classes,
           LispObject callback,
           Set<Class<?>> visited)
  {
  Collection<Class<?>> newClasses = new LinkedList<Class<?>>();
  for(Class<?> clss : classes) {
      if(clss == null) {
    continue;
      }
      if(!visited.contains(clss)) {
    callback.execute(JavaObject.getInstance(clss, true));
    visited.add(clss);
      }
      if(!visited.contains(clss.getSuperclass())) {
    newClasses.add(clss.getSuperclass());
      }
      for(Class<?> iface : clss.getInterfaces()) {
    if (!visited.contains(iface)) {
        newClasses.add(iface);
    }
      }
  }
  if(!newClasses.isEmpty()) {
      doClassHierarchy(newClasses, callback, visited);
  }
    }

    /**
     * Executes a function recursively over <clss> and its superclasses and
     * interfaces.
     */
    public static void doClassHierarchy(Class<?> clss, LispObject callback)
  {
  if (clss != null) {
      Set<Class<?>> visited = new HashSet<Class<?>>();
      Collection<Class<?>> classes = new ArrayList<Class<?>>(1);
      classes.add(clss);
      doClassHierarchy(classes, callback, visited);
  }
    }

    public static LispObject mapcarClassHierarchy(Class<?> clss,
              final LispObject fn)
    {
  final LispObject[] acc = new LispObject[] { NIL };
  doClassHierarchy(clss, new Function() {
    @Override
    public LispObject execute(LispObject arg)
        {
        acc[0] = acc[0].push(fn.execute(arg));
        return acc[0];
    }
      });
  return acc[0].nreverse();
    }

    public static String describeJavaObject(final JavaObject javaObject)
  {
  final Object obj = javaObject.getObject();
  final StringBuilder sb =
      new StringBuilder(javaObject.writeToString());
  sb.append(" is an object of type ");
  sb.append(Symbol.JAVA_OBJECT.writeToString());
  sb.append(".");
  sb.append(System.getProperty("line.separator"));
  sb.append("The wrapped Java object is ");
  if (obj == null) {
      sb.append("null.");
  } else {
      sb.append("an ");
      final Class c = obj.getClass();
      String className = c.getName();
      if (c.isArray()) {
    sb.append("array of ");
    if (className.startsWith("[L") && className.endsWith(";")) {
        className = className.substring(1, className.length() - 1);
        sb.append(className);
        sb.append(" objects");
    } else if (className.startsWith("[") && className.length() > 1) {
        char descriptor = className.charAt(1);
        final String type;
        switch (descriptor) {
        case 'B': type = "bytes"; break;
        case 'C': type = "chars"; break;
        case 'D': type = "doubles"; break;
        case 'F': type = "floats"; break;
        case 'I': type = "ints"; break;
        case 'J': type = "longs"; break;
        case 'S': type = "shorts"; break;
        case 'Z': type = "booleans"; break;
        default:
      type = "unknown type";
        }
        sb.append(type);
    }
    sb.append(" with ");
    final int length = java.lang.reflect.Array.getLength(obj);
    sb.append(length);
    sb.append(" element");
    if (length != 1)
        sb.append('s');
    sb.append('.');
      } else {
    sb.append("instance of ");
    sb.append(className);
    sb.append(':');
    sb.append(System.getProperty("line.separator"));
    sb.append("  \"");
    sb.append(obj.toString());
    sb.append('"');
      }
  }
  return sb.toString();
    }

    // ### describe-java-object
    private static final Primitive DESCRIBE_JAVA_OBJECT =
        new Primitive("describe-java-object", PACKAGE_JAVA, true)
    {
        @Override
        public LispObject execute(LispObject first, LispObject second)

        {
            if (!(first instanceof JavaObject))
                return type_error(first, Symbol.JAVA_OBJECT);
            final Stream stream = checkStream(second);
            final JavaObject javaObject = (JavaObject) first;
            stream._writeString(describeJavaObject(javaObject));
            return LispThread.currentThread().nothing();
        }
    };

    //JAVA-CLASS support

    //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<?>, LispObject> javaClassMap = new HashMap<Class<?>, LispObject>();

    public static LispObject registerJavaClass(Class<?> javaClass, LispObject classMetaObject) {
  synchronized (javaClassMap) {
      javaClassMap.put(javaClass, classMetaObject);
      return classMetaObject;
  }
    }

    public static LispObject findJavaClass(Class<?> javaClass) {
  synchronized (javaClassMap) {
      LispObject c = javaClassMap.get(javaClass);
      if (c != null) {
    return c;
      } else {
    return NIL;
      }
  }
    }

    private static final Primitive _FIND_JAVA_CLASS = new Primitive("%find-java-class", PACKAGE_JAVA, false, "class-name-or-class") {
      public LispObject execute(LispObject arg) {
    try {
        if(arg instanceof AbstractString) {
      return findJavaClass(Class.forName((String) arg.getStringValue()));
        } else {
      return findJavaClass((Class<?>) arg.javaInstance());
        }
    } catch (ClassNotFoundException e) {
        return error(new LispError("Cannot find Java class " + arg.getStringValue()));
    }
      }
      
  };

    private static final Primitive _REGISTER_JAVA_CLASS = new Primitive("%register-java-class", PACKAGE_JAVA, false, "jclass class-metaobject") {
      public LispObject execute(LispObject jclass, LispObject classMetaObject) {
    return registerJavaClass((Class<?>) jclass.javaInstance(), classMetaObject);
      }
      
  };

}