org.simantics.databoard.accessor.java
Class JavaObject

java.lang.Object
  extended by org.simantics.databoard.accessor.java.JavaObject
All Implemented Interfaces:
Accessor, ParametrisedAccessor
Direct Known Subclasses:
JavaArray, JavaBoolean, JavaByte, JavaDouble, JavaFloat, JavaInteger, JavaLong, JavaMap, JavaOptional, JavaRecord, JavaString, JavaUnion, JavaVariant

public abstract class JavaObject
extends java.lang.Object
implements Accessor, ParametrisedAccessor

Accessor to a Java Object.

The monitoring contract forbids modifications to the object outside this accessor object. If you do modifications to the value using other mechanisms, you must notify the listeners of the accessor with notifyValueChanged().

If a lock is not provided, operations cannot be performed simulataneously in multiple-threads.

Author:
Toni Kalajainen

Nested Class Summary
 
Nested classes/interfaces inherited from interface org.simantics.databoard.accessor.Accessor
Accessor.Listener
 
Constructor Summary
JavaObject(Accessor parent, Binding binding, java.lang.Object initialValue, AccessorParams params)
          Create a new accessor to a Java Object.
 
Method Summary
 void addListener(Accessor.Listener listener, InterestSet interestSet, ChildReference path, java.util.concurrent.Executor executor)
          Place a listener to an accessor node.
 void apply(java.util.List<Event> cs, java.util.LinkedList<Event> rollback)
          Apply a change set in a single transaction operation.
static JavaObject createAccessor(Accessor parent, Binding b, java.lang.Object v, AccessorParams params)
           
static JavaObject createSubAccessor(Accessor parent, Binding b, java.lang.Object v, AccessorParams params)
           
 Binding getBinding()
           
 java.lang.Object getObject()
          Get the Java Object
 AccessorParams getParams()
          Get accessor parameters
 java.util.concurrent.locks.Lock getReadLock()
          Get lock if available.
 java.lang.Object getValue(Binding binding)
          Get a snapshot of the object as a single data value.
 void getValue(Binding binding, java.lang.Object obj)
          Read a copy of the accessor's object into an instance.
 java.util.concurrent.locks.Lock getWriteLock()
          Get lock if available.
 void notifyValueChanged()
          The Java Object was changed by means other than Accessor.
 void removeListener(Accessor.Listener listener)
          Remove a listener.
 java.lang.String toString()
           
 Datatype type()
          Get structural represtentation of the accessor presented in databoard's type system.
 
Methods inherited from class java.lang.Object
equals, getClass, hashCode, notify, notifyAll, wait, wait, wait
 
Methods inherited from interface org.simantics.databoard.accessor.Accessor
getComponent, setValue
 

Constructor Detail

JavaObject

public JavaObject(Accessor parent,
                  Binding binding,
                  java.lang.Object initialValue,
                  AccessorParams params)
Create a new accessor to a Java Object.

Read and write locks may optionally be provided for locking mechanisms. ReadWriteLock can be provied or a signle MutualExclusion lock.

Parameters:
parent - parent, or null
binding -
initialValue - the java object
params - accessor params
Method Detail

getObject

public java.lang.Object getObject()
Get the Java Object

Returns:
Object

getBinding

public Binding getBinding()

getParams

public AccessorParams getParams()
Description copied from interface: ParametrisedAccessor
Get accessor parameters

Specified by:
getParams in interface ParametrisedAccessor
Returns:
accessor parameters

type

public Datatype type()
Description copied from interface: Accessor
Get structural represtentation of the accessor presented in databoard's type system.

Specified by:
type in interface Accessor
Returns:
type description

getReadLock

public java.util.concurrent.locks.Lock getReadLock()
Get lock if available.

Returns:
lock or null

getWriteLock

public java.util.concurrent.locks.Lock getWriteLock()
Get lock if available.

Returns:
lock or null

getValue

public java.lang.Object getValue(Binding binding)
                          throws AccessorException
Description copied from interface: Accessor
Get a snapshot of the object as a single data value.

Accessor makes type adaption to users binding if possible.

Specified by:
getValue in interface Accessor
Returns:
the value
Throws:
AccessorException

getValue

public void getValue(Binding binding,
                     java.lang.Object obj)
              throws AccessorException
Description copied from interface: Accessor
Read a copy of the accessor's object into an instance.

Accessor makes type adaption to users binding if possible.

Specified by:
getValue in interface Accessor
obj - object to read the value to
Throws:
AccessorException

addListener

public void addListener(Accessor.Listener listener,
                        InterestSet interestSet,
                        ChildReference path,
                        java.util.concurrent.Executor executor)
                 throws AccessorException
Description copied from interface: Accessor
Place a listener to an accessor node. The listener will be notified for changes in the node/node tree, depending on interest set.

When events are emited and in which thread processed is implementation specific. It is also implementation specific, whether the object can be mutated in the listener or whether it has to be done afterwards.

In many implementations there is a pluggable event handling strategy EventEmitter. The default behaviour is to emit events as they are spawned in the current thread.

There is a reference in each event instance that describes the path from the accessor where listener was placed to the node to which the event applies to.

Listener is attached to the object that holds the value at the time at the of the adding. For example, If a listener is attached to an array of element at index 3, and a new value is inserted at position 2, the listener still monitors the same container, which is now at index 4. The references of incoming the events are modified to have the new index.

Also, if a new value is assigned to the parent of an object that is listened, the listener keeps on monitoring the new value at the same reference. This doesn't apply when a new value is set to a union of different tag, to a variant with a new type, or value is removed from Optional type. In these two cases the listener is invalidated.

See ChangeSet is an implementation that collects events. Executor argument determines the thread where the onEvents method is handled. null argument denotes current thread.

Specified by:
addListener in interface Accessor
path - path to the accessor or null. This is used in the events the accessor produces
Throws:
AccessorException
See Also:
collects events

removeListener

public void removeListener(Accessor.Listener listener)
                    throws AccessorException
Description copied from interface: Accessor
Remove a listener. If the listener is added multiple times, the last one added is removed.

Specified by:
removeListener in interface Accessor
Throws:
AccessorException

createAccessor

public static JavaObject createAccessor(Accessor parent,
                                        Binding b,
                                        java.lang.Object v,
                                        AccessorParams params)
                                 throws AccessorConstructionException
Throws:
AccessorConstructionException

createSubAccessor

public static JavaObject createSubAccessor(Accessor parent,
                                           Binding b,
                                           java.lang.Object v,
                                           AccessorParams params)
                                    throws AccessorConstructionException
Throws:
AccessorConstructionException

apply

public void apply(java.util.List<Event> cs,
                  java.util.LinkedList<Event> rollback)
           throws AccessorException
Description copied from interface: Accessor
Apply a change set in a single transaction operation. If rollback log is supplied, it is filled with reverse events. If the operation fails, rollback log can be applied to cancel changes.

Specified by:
apply in interface Accessor
rollback - log to be filled with rollback events or null
Throws:
AccessorException - failed to apply change set

toString

public java.lang.String toString()
Overrides:
toString in class java.lang.Object

notifyValueChanged

public void notifyValueChanged()
The Java Object was changed by means other than Accessor. ValueAssigned event is emited to listeners.