object.java
/*
** Module : object.java
** Abstract : Wrapper class for all OO 4GL instance references.
**
** Copyright (c) 2018-2025, Golden Code Development Corporation.
**
** -#- -I- --Date-- ---------------------------------------Description---------------------------------------
** 001 GES 20181210 First version.
** 002 CA 20190219 Runtime implementation.
** 003 HC 20190701 instantiateDefault must yield the correct class type.
** 004 CA 20190710 Allow this instance to be assigned a ref directly. Fixed issues related to
** working with legacy OE classes for which FWD provides support.
** CA 20190719 Plain object instance does not do reference counting.
** HC 20190721 Fixed object type not set when reference assigned.
** 005 CA 20191002 Added assign(object), to better isolate this usage (compared to assign(BDT))
** in FWD code.
** 006 ME 20200412 Update compare to use legacy toString for BaseObject.
** CA 20200427 Replaced isValid().booleanValue() calls with _isValid().
** GES 20200520 Fixed compareTo() to honor enums (or any other Comparable).
** GES 20200529 Added isTracked() and made all constructors safe for null input.
** GES 20200603 Moved BaseObject legacy class registration into a BaseObject static initializer.
** 007 IAS 20201007 Added Type enum
** OM 20201102 Overrode getTypeName().
** 008 ME 20201106 Delete the object reference when set to unknown (if valid, the destructor is called).
** 20201111 Decrement reference instead of delete when object set to unknown.
** 20201217 Revert compare method to only check if the reference is the same (eq <> Equal in 4GL)
** CA 20210213 Reverted ME/20201106 - only ObjectVar.setUnknown must decrement references.
** CA 20210305 The object resource ID as reported by toString() or used at the table field must be a
** numeric value (as indexes are affected).
** ME 20210504 Added isIncompatibleTypesOnConversion override for invalid POLY conversion.
** CA 20210609 Reworked INPUT/INPUT-OUTPUT parameters to a new approach, where they are explicitly
** initialized at the method's execution, and not at the caller's arguments.
** CA 20220304 Fixed 'invalid handle' error message text.
** AL2 20220319 Added value proxy check in assign.
** VVT 20221221 Serialization support added (see #4658).
** CA 20220520 Even when assigned to unknown, the object's legacy type must be set.
** CA 20220602 Added basic support for transport of object instances over appserver call.
** CA 20230110 Cache the helper for ProcedureManager, ObjectOps and others (as needed), to reduce
** context-local lookup.
** 009 CA 20230215 'duplicate()' method returns the real type instead of BDT.
** 010 CA 20230731 Legacy ENUM is stored in a EnumObject instance - this ensures that when they are created,
** no context is saved for them, as they are JVM-wide constants.
** 011 CA 20240324 Use logical constants for TRUE, FALSE, UNKNOWN, within internal FWD runtime.
** 012 CA 20250423 Added 'object(BDT)' constructor.
** 013 PBB 20250522 Fixed behavior for some weird BDT to object conversions.
** 014 AL2 20250530 Added getIndependentFromContext.
*/
/*
** This program is free software: you can redistribute it and/or modify
** it under the terms of the GNU Affero General Public License as
** published by the Free Software Foundation, either version 3 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 Affero General Public License for more details.
**
** You may find a copy of the GNU Affero GPL version 3 at the following
** location: https://www.gnu.org/licenses/agpl-3.0.en.html
**
** Additional terms under GNU Affero GPL version 3 section 7:
**
** Under Section 7 of the GNU Affero GPL version 3, the following additional
** terms apply to the works covered under the License. These additional terms
** are non-permissive additional terms allowed under Section 7 of the GNU
** Affero GPL version 3 and may not be removed by you.
**
** 0. Attribution Requirement.
**
** You must preserve all legal notices or author attributions in the covered
** work or Appropriate Legal Notices displayed by works containing the covered
** work. You may not remove from the covered work any author or developer
** credit already included within the covered work.
**
** 1. No License To Use Trademarks.
**
** This license does not grant any license or rights to use the trademarks
** Golden Code, FWD, any Golden Code or FWD logo, or any other trademarks
** of Golden Code Development Corporation. You are not authorized to use the
** name Golden Code, FWD, or the names of any author or contributor, for
** publicity purposes without written authorization.
**
** 2. No Misrepresentation of Affiliation.
**
** You may not represent yourself as Golden Code Development Corporation or FWD.
**
** You may not represent yourself for publicity purposes as associated with
** Golden Code Development Corporation, FWD, or any author or contributor to
** the covered work, without written authorization.
**
** 3. No Misrepresentation of Source or Origin.
**
** You may not represent the covered work as solely your work. All modified
** versions of the covered work must be marked in a reasonable way to make it
** clear that the modified work is not originating from Golden Code Development
** Corporation or FWD. All modified versions must contain the notices of
** attribution required in this license.
*/
package com.goldencode.p2j.util;
import java.io.*;
import com.goldencode.p2j.oo.lang.*;
/**
* Wrapper class for all OO 4GL instance references. This is needed for compatibility with
* unknown value, assignment, parameter passing, DELETE, SESSION:FIRST-OBJECT/LAST-OBJECT and
* UNDO.
* <p>
* TODO: throwing errors from an appserver to the client will serialize the legacy instance.
*/
public class object<T extends _BaseObject_>
extends BaseDataType
{
/** The contained object instance. <code>null</code> is unknown value. */
protected T ref = null;
/** The object's type. */
private Class<T> type = null;
/**
* Helper to use the ObjectOps without any context local lookups.
* <p>
* WARNING: this instance is used only in {@link #_isValid()} and {@link #isUnknown()}. These methods
* are overridden in {@link EnumObject}. Any other usage must take care of this, as the enum must have no
* context saved when is created.
*/
protected ObjectOps.ObjectHelper helper = null;
/**
* Default constructor.
*/
public object()
{
helper = ObjectOps.getObjectHelper();
}
/**
* Initialize this object reference, allowing only assignment to objects compatible with the
* specified type.
*
* @param type
* The type of references this object can hold.
*/
public object(Class<? extends _BaseObject_> type)
{
this();
initialize(type, null);
}
/**
* Initialize this object with the given reference.
*
* @param ref
* The reference.
*/
public object(BaseDataType ref)
{
this();
assign(ref);
}
/**
* Initialize this object with the given reference.
*
* @param ref
* The reference.
*/
public object(T ref)
{
this();
if (ref == null)
return;
initialize(ref.getClass(), ref);
}
/**
* Initialize this object with the reference from the specified resource.
*
* @param res
* The object resource.
*/
public object(ObjectResource res)
{
this();
if (res == null)
{
return;
}
T ref = (T) res.ref();
if (ref == null)
{
return;
}
initialize(ref.getClass(), ref);
}
/**
* Copy constructor.
*
* @param other
* The object from which to copy.
*/
public object(object<T> other)
{
this();
// no need to avoid assignment if null, a straight copy is just as correct
this.ref = other.ref;
this.type = other.type;
// TODO: validate type?
}
/**
* Returns an ID for the resource-representation of this object's reference.
*
* @param obj
* The object for which the resource ID is required.
*
* @return See above.
*/
public static long resourceId(object<? extends _BaseObject_> obj)
{
Long id = ObjectOps.isValid(obj.ref) ? handle.resourceId(ObjectOps.asResource(obj.ref)) : 0;
return id;
}
/**
* Get the type.
*
* @return type
*/
@Override
public Type getType()
{
return Type.OBJECT;
}
/**
* Resolve the legacy instance and build an object referencing it.
*
* @param resId
* The resource ID.
*
* @return The object reference.
*/
public static object<? extends _BaseObject_> fromResourceId(long resId)
{
handle h = handle.fromResourceId(resId);
return h._isValid() ? new object<>((ObjectResource) h.get()) : new object<>();
}
/**
* Return the wrapped reference if this instance is not set to unknown value.
*
* @return The contained reference or raise an error if this is unknown value.
*/
public T ref()
{
if (isUnknown())
{
String msg = "Invalid handle. Not initialized or points to a deleted object";
ErrorManager.recordOrThrowError(3135, msg, false);
// TODO: is there any scenario where we can actually return null in silent error mode?
// (If so, that is very bad.)
return null;
}
return ref;
}
/**
* Compares this instance with the specified instance and returns -1 if this instance is less than the
* instance specified, 0 if the two instances are equal and 1 if this instance is greater than the
* specified instance. This is the implementation of the <code>Comparable</code> interface.
* <p>
* The algorithm will fail to give meaningful results in the case where one tries to sort against other
* objects that do not represent compatible values.
*
* @param obj
* The instance to compare against.
*
* @return -1, 0, or 1 depending on if this instance is less than, equal to or greater (respectively)
* than the specified instance <code>obj</code>.
*/
@Override
public int compareTo(Object obj)
{
if (obj instanceof object)
{
object other = (object) obj;
// isUnknown and isValid return the same (true/false) value when ref == null or ref has been deleted
boolean u1 = isUnknown();
boolean u2 = (other == null || other.isUnknown());
// both are unknown, then we are equal
if (u1 && u2)
{
return 0;
}
else if (u1)
{
return -1;
}
else if (u2)
{
return 1;
}
if (ref instanceof Comparable)
{
Comparable c = (Comparable) ref;
return c.compareTo(other.ref);
}
else
{
return ref.equals(other.ref) ? 0 : 1;
}
}
return -1;
}
/**
* A minimal implementation which satisfies the need for a concrete method.
*
* @return The hash code for this object instance.
*/
@Override
public int hashCode()
{
int result = 17;
if (isUnknown())
{
return result;
}
result = 37 * result + ref.hashCode();
return result;
}
/**
* Set this instance {@link #ref} to the specified value, directly.
* <p>
* If <code>ref</code> is <code>null</code>, it will be set to unknown.
* <p>
* If the {@link #type} is not compatible with <code>ref</code>, an error condition is raised.
*
* @param ref
* The instance to assign.
*/
public void assign(_BaseObject_ ref)
{
assign(new object(ref));
}
/**
* Sets the state (data and unknown value) of this instance based on the state of the passed
* instance.
* <p>
* If the value is not of the same type, some form of automatic type conversion may occur, or
* an error will be raised.
* <p>
* This variant is meant to handle the cases of built-in functions and methods in the 4GL
* which have polymorphic return types (e.g. DYNAMIC-FUNCTION()). This should NOT be used for
* non-polymorphic assignments.
*
* @param value
* The instance from which to copy state.
*/
@Override
public void assign(BaseDataType value)
{
if (value != null)
{
value = value.val();
}
if (!(value instanceof object))
{
if ((value.isUnknown() && !(value instanceof longchar)) ||
(value instanceof character && !value.isUnknown() && ((character) value).getValue().isEmpty()) ||
(value instanceof integer && !value.isUnknown() && ((integer) value).intValue() == 0))
{
setUnknown();
}
else
{
incompatibleTypesOnConversion();
}
return;
}
assign((object<?>) value);
}
/**
* Copy the reference from another object instance to this one.
*
* @param value
* The instance from which to copy state.
*/
public void assign(object<?> value)
{
// the value may be a proxy; make sure to unwrap and work with the real value
if (BaseDataType.isProxy(value))
{
assign(value.val());
return;
}
if (value.isUnknown())
{
// don't call setUnknown here
ref = null;
if (type == null)
{
type = (Class<T>) value.type;
}
else
{
// TODO: validate it?
}
return;
}
_BaseObject_ vref = value.ref;
if (type != null && !type.isInstance(vref))
{
// must be a sub-class or the same as this one
String lt1 = ObjectOps.getLegacyName(vref.getClass());
String lt2 = ObjectOps.getLegacyName(type());
ErrorManager.recordOrThrowError(13448,
"A variable of class '" + lt1 + "' cannot be assigned " +
"to a variable of class '" + lt2 + "'");
// reference remains unchanged
return;
}
set(vref);
}
/**
* Modify the contained data of the instance to copy the instance data
* from the given instance. Generally, the class of the given instance
* must match the class upon which the <code>assign</code> method is
* called, although this is not a strict requirement.
*
* @param old
* The backup instance from which to copy data.
*/
@Override
public void assign(Undoable old)
{
if (old instanceof BaseDataType)
{
assign((BaseDataType) old);
}
else
{
// TODO: error out?
}
}
/**
* Reports if this instance represents the <code>unknown value</code>.
*
* @return <code>true</code> if this instance is set to the
* <code>unknown value</code>.
*/
@Override
public boolean isUnknown()
{
return !helper.isValid(ref);
}
/**
* Determines if this instance is valid (to be used).
*
* @return <code>true</code> if this instance can be used.
*/
public logical isValid()
{
return logical.of(_isValid());
}
/**
* Determines if this instance is valid (to be used).
*
* @return <code>true</code> if this instance can be used.
*/
public boolean _isValid()
{
return helper.isValid(ref);
}
/**
* Reports if the given instance is managed as part of the legacy 4GL object life cycle. This
* includes reference counting, linking in the SESSION object chain, managed construction and
* destruction.
*
* @return {@code true} if the instance is tracked and {@code false} if the instance exists
* outside of the OO 4GL life cycle mechanisms.
*/
public boolean isTracked()
{
return ref != null && ref.isTracked();
}
/**
* Sets the state of this instance's <code>unknown value</code> flag or state to
* <code>true</code>.
* <p>
* <b>Warning: the data stored in this instance will be invalid after calling this method.</b>
*/
@Override
public void setUnknown()
{
ref = null;
}
/**
* Does the same as standard <code>clone()</code> method but returns an
* instance of <code>BaseDataType</code> and doesn't throw the
* <code>CloneNotSupportedException</code>.
*
* @return A clone of this instance.
*/
@Override
public object<T> duplicate()
{
return new object<>(this);
}
/**
* Creates a new instance of the same type that represents the <code>unknown value</code>.
*
* @return An instance that represents the <code>unknown value</code>.
*/
@Override
public BaseDataType instantiateUnknown()
{
return new object<>();
}
/**
* Creates a string representation of the instance data using the given
* format string. If the instance represents the
* <code>unknown value</code>, a '?' will be returned.
*
* @param fmt
* The format string to use.
*
* @return The formatted string.
*/
@Override
public String toString(String fmt)
{
return toStringMessage();
}
/**
* Creates a string representation of the instance data in a form that is
* compatible with the <code>MESSAGE</code> language statement. If the
* instance represents the <code>unknown value</code>, a '?' will be
* returned.
*
* @return The 'message' formatted string.
*/
@Override
public String toStringMessage()
{
return isUnknown() ? "?" : ref.toLegacyString().toStringMessage();
}
/**
* Creates a string representation of the instance data using the 'export'
* format. If the instance represents the <code>unknown value</code>, a
* '?' will be returned.
*
* @return The 'export' formatted string.
*/
@Override
public String toStringExport()
{
return toStringMessage();
}
/**
* Return the default display format string for this type.
*
* @return The default format string.
*/
@Override
public String defaultFormatString()
{
// objects can't be formatted
return null;
}
/**
* The object implements the writeExternal method to save its contents
* by calling the methods of DataOutput for its primitive values or
* calling the writeObject method of ObjectOutput for objects, strings,
* and arrays.
*
* @serialData Overriding methods should use this tag to describe
* the data layout of this Externalizable object.
* List the sequence of element types and, if possible,
* relate the element to a public/protected field and/or
* method of this Externalizable class.
*
* @param out the stream to write the object to
* @exception IOException Includes any I/O exceptions that may occur
*/
@Override
public void writeExternal(final ObjectOutput out)
throws IOException
{
out.writeObject(type);
out.writeObject(ref);
}
/**
* The object implements the readExternal method to restore its
* contents by calling the methods of DataInput for primitive
* types and readObject for objects, strings and arrays. The
* readExternal method must read the values in the same sequence
* and with the same types as were written by writeExternal.
*
* @param in the stream to read data from in order to restore the object
* @exception IOException if I/O errors occur
* @exception ClassNotFoundException If the class for an object being
* restored cannot be found.
*/
@Override
public void readExternal(final ObjectInput in)
throws IOException,
ClassNotFoundException
{
type = (Class<T>) in.readObject();
ref = (T) in.readObject();
}
/**
* Identify if this data is dependent upon the context local. This identifies
* if the data is safe to be cached in cross-session places or the data should
* not leak from the context. If is is not safe to be shared cross-session, then
* this should return {@code null}. If other representation is suitable for caching,
* then this can return another object that wraps internal values that are not
* dependent upon the context (e.g. date, date-time, date-time-tz).
*
* @return Always. {@code null}.
*/
@Override
public Object getIndependentFromContext()
{
return null;
}
/**
* Set this object's reference and type from the given instance.
*
* @param ref
* The object instance.
*/
void set(_BaseObject_ ref)
{
this.ref = (T) ref;
if (this.type == null && ref != null)
{
this.type = (Class<T>) ref.getClass();
}
}
/**
* Get the object's declared class.
*
* @return The {@link #type}.
*/
Class<T> type()
{
return type;
}
/**
* Creates a new instance of the same type that represents the
* default initialized value.
*
* @return An instance that represents the default value.
*/
@Override
public BaseDataType instantiateDefault()
{
object res = new object();
res.type = type;
return res;
}
/**
* Decrement the reference counter for this instance.
* <p>
* No-op for internal object instances.
*/
protected void decrement()
{
// no-op
}
/**
* Increment the reference counter for this instance.
* <p>
* No-op for internal object instances.
*/
protected void increment()
{
// no-op
}
/**
* Initialize this object with the given reference.
*
* @param type
* The type of references this object can hold. It is safe to pass {@code null}.
* @param ref
* The reference. It is safe to pass {@code null}.
*/
private void initialize(Class<? extends _BaseObject_> type, T ref)
{
if (ref != null && type == null)
{
type = ref.getClass();
}
if (type != null)
{
// this will not increment the reference count
this.type = (Class<T>) type;
String clsName = ObjectOps.getLegacyName(type);
if (clsName != null)
{
ObjectOps.registerClass(clsName, type);
}
}
this.ref = ref;
}
/**
* Obtain a short description of the current object/state to be used in debugging.
*
* @return a short description of the current object/state.
*/
@Override
public String toString()
{
if (_isValid())
{
return ref.toLegacyString().getValue();
}
return super.toString();
}
@Override
protected boolean isIncompatibleTypesOnConversion(BaseDataType value)
{
// invalid conversion is being thrown even if unknown
if (value instanceof raw || value instanceof blob || (value instanceof raw && !value.isUnknown()))
{
incompatibleTypesOnConversion();
}
// conversion is not attempted
else if (value instanceof clob || value instanceof handle || date.class.equals(value.getClass()) || value instanceof NumberType || value instanceof logical)
{
return true;
}
return super.isIncompatibleTypesOnConversion(value);
}
}