SquirrelJME/SquirrelJME

// -*- Mode: Java; indent-tabs-mode: t; tab-width: 4 -*-
// ---------------------------------------------------------------------------
// SquirrelJME
//     Copyright (C) Stephanie Gawroriski <xer@multiphasicapps.net>
// ---------------------------------------------------------------------------
// SquirrelJME is under the Mozilla Public License Version 2.0.
// See license.mkd for licensing and copyright information.
// ---------------------------------------------------------------------------

package cc.squirreljme.vm.springcoat;

import cc.squirreljme.jdwp.host.JDWPHostState;
import cc.squirreljme.jdwp.host.JDWPHostValue;
import cc.squirreljme.jdwp.host.views.JDWPViewObject;
import java.lang.ref.Reference;

/**
 * This is a view around an object within the debugger.
 *
 * @since 2021/04/10
 */
public class DebugViewObject
    implements JDWPViewObject
{
    /** The state of the debugger. */
    protected final Reference<JDWPHostState> state;
    
    /**
     * Initializes the object viewer.
     * 
     * @param __state The state.
     * @throws NullPointerException On null arguments.
     * @since 2021/04/10
     */
    public DebugViewObject(Reference<JDWPHostState> __state)
        throws NullPointerException
    {
        if (__state == null)
            throw new NullPointerException("NARG");
        
        this.state = __state;
    }
    
    /**
     * {@inheritDoc}
     * @since 2021/04/10
     */
    @Override
    public boolean isValid(Object __which)
    {
        return (__which instanceof SpringObject);
    }
    
    /**
     * {@inheritDoc}
     * @since 2021/04/11
     */
    @Override
    public int arrayLength(Object __which)
    {
        if (__which instanceof SpringArrayObject)
            return ((SpringArrayObject)__which).length;
        return -1;
    }
    
    /**
     * {@inheritDoc}
     * @since 2022/09/21
     */
    @Override
    public boolean isNullObject(Object __value)
    {
        return (__value == null || __value == SpringNullObject.NULL);
    }
    
    /**
     * {@inheritDoc}
     * @since 2021/04/11
     */
    @Override
    public boolean readArray(Object __which, int __index, JDWPHostValue __out)
    {
        __out.set(DebugViewObject.__normalizeNull(
            ((SpringArrayObject)__which).get(Object.class, __index)));
        return true;
    }
    
    /**
     * {@inheritDoc}
     * @since 2021/04/10
     */
    @Override
    public boolean readValue(Object __which, int __index, JDWPHostValue __out)
    {
        // Nulls never have a value
        if (__which == SpringNullObject.NULL)
            return false;
        
        // Is a simple object representation, so we can read a field value
        // directly from the object representation without knowing about
        // the class details.
        if (__which instanceof SpringSimpleObject)
        {
            SpringSimpleObject which = (SpringSimpleObject)__which;
            
            SpringFieldStorage[] store = (which)._fields;
            if (__index >= 0 && __index < store.length)
                return DebugViewType.__readValue(__out, store[__index],
                    which.type.classLoader().machine());
        }
        
        // Not a valid object or one where a value can be read from
        return false;
    }
    
    /**
     * {@inheritDoc}
     * @since 2021/04/11
     */
    @Override
    public Object type(Object __which)
    {
        return ((SpringObject)__which).type();
    }
    
    /**
     * Normalizes a null value so null references become null and not the
     * special holder value.
     * 
     * @param __o The value to normalize.
     * @return If the value points to a null object it becomes null.
     * @since 2021/04/11
     */
    static Object __normalizeNull(Object __o)
    {
        if (__o == SpringNullObject.NULL)
            return null;
        return __o;
    }
}