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# Class w3c.tools.store.AttributeHolder

    java.lang.Object
       |
       +----w3c.tools.store.AttributeHolder

public class AttributeHolder
extends Object
implements Cloneable

An attribute holder is an object that holds a list of attributes. Each of the attributes maintained by a holder are described by an Attribute object, wich is able to pickle/unpickle its value, provides the status of the attribute (eg mandatory, editable, etc), etc.

Given this, an attribute holder is able to pickle its state (made of its attribute values), and unpickle it to any DataOutputStream (resp. DataInputStream).

See Also:
  Attribute, Resource

##

attributes
  Pointer to this class registered list of attributes.
slowpickle
  Turns on/off fast pickling.
values
  Attribute values.

##

AttributeHolder()
  Create an attribute holder.

##

definesAttribute(int)
  Does this resource has defined a value for the given attribute.
definesAttribute(String)
  Does this resource has defined a value for the given attribute.
getAttributes()
  Get this attribute holders attributes description.
getBoolean(int, boolean)
getChar(int, char)
getClone()
  Clone this attribute holder.
getClone(Hashtable)
  Clone this AttributeHolder instance, and initialize it with defaults.
getClone(Object[])
  Clone this attribute holder, and init it with the given attributes.
getDouble(int, double)
getFloat(int, float)
getInt(int, int)
getLong(int, long)
getString(int, String)
getValue(int, Object)
  Generic get of an attribute value.
getValue(String, Object)
  Generic get of an attribute value.
initialize(Hashtable)
  Initialization method for attribute holders.
initialize(Object[])
  Initialization method for attribute holders.
lookupAttribute(String)
  Lookup up the index of an attribute in our attribute description.
pickle(DataOutputStream)
  Pickle this attribute holder to the given stream.
print(PrintStream)
  Debugging purposes only, print this attribute holder.
setBoolean(int, boolean)
setChar(int, char)
setDouble(int, double)
setFloat(int, float)
setInt(int, int)
setLong(int, long)
setString(int, String)
setValue(int, Object)
  Set an attribute value.
setValue(String, Object)
  Set an attribute value.
unpickle(DataInputStream)
  Unpickle an attribute holder from the given input stream.
unpickle(DataInputStream, Hashtable)
  A short hand for unpickling and initializing a resource.
unpickle(DataInputStream, Hashtable, boolean)
  Unpickle an attribute holder from the given input stream.
unpickleInstance(DataInputStream, Hashtable)
  A short-hand for unpickling and initializing resources.
unpickleInstance(DataInputStream, Hashtable, boolean)
  Finish the instance part of the unpickling job.

##

slowpickle

      protected boolean slowpickle

  Turns on/off fast pickling.

  Fast pickling is a mode of pickling attribute holders in which evolutivity is lost in favor of speed. With slow pickling obtained by setting that flag to false, resources are dumped in a alist like format, so you can preserve informations if the attribute list changes.

attributes

      protected Attribute attributes[]

  Pointer to this class registered list of attributes.

values

      protected Object values[]

  Attribute values.

##

AttributeHolder

      public AttributeHolder()

  Create an attribute holder.

##

getClone

      public Object getClone(Object values[])

  Clone this attribute holder, and init it with the given attributes.
  Parameters:
    values - Attribute values to overide in the clone.
  Returns:
    A clone of this resource.

getClone

      public Object getClone()

  Clone this attribute holder. The resulting clone will share the attribute values of the cloned attribute holder.
  Returns:
    An attribute holder sharing its ancestor attribute values.

getClone

      public Object getClone(Hashtable defs)

  Clone this AttributeHolder instance, and initialize it with defaults. This method first clones the receiving attribute holder, and then uses the defaults provided to finish the initialization.
  Parameters:
    defs - The attribute values, in a Hashtable.
  Returns:
    The clone.
  Throws: CloneNotSupportedException
    In case of Java implementation bug !

getAttributes

      public Attribute[] getAttributes()

  Get this attribute holders attributes description. The attribute list is guaranteed to be returned always in the same order, wich is fixed at compilation time. This allows for fast access to resource by their position rather than by name.
  Returns:
    An array of Attribute objects, each one containing the description of one single attribute of the resource.
  See Also:
    Attribute

lookupAttribute

      public int lookupAttribute(String name)

  Lookup up the index of an attribute in our attribute description.
  Parameters:
    name - The name of the attribute to look for.
  Returns:
    An integer, positive if found, negative otherwise.

setValue

      public synchronized void setValue(int idx,
                                        Object value)

  Set an attribute value. This method sets the value of some attribute of the resource. It marks the resource as being modified, and alert its resource store (so that it knows it will have to save the object at some time in the future).
  Parameters:
    idx - The attribute index, in the list of attributes advertized by the resource.
    value - The new value for this attribute.
  Throws: IllegalAttributeValue
    if the provided value doesn't match the attribute expected type.
  Throws: UnknownAttribute
    If the provided index doesn't match an attribute of this object.

setValue

      public synchronized void setValue(String name,
                                        Object value)

  Set an attribute value. This method sets the value of an attribute, referenced by its name.
  Parameters:
    name - The attribute name.
    value - The new value for the attribute.
  Throws: IllegalAttributeValue
    if the provided value doesn't match the attribute expected type.
  Throws: UnknownAttribute
    if the given name doesn't match any of the attribute's name.

setBoolean

      public synchronized void setBoolean(int idx,
                                          boolean b)

setChar

      public synchronized void setChar(int idx,
                                       char ch) throws IllegalAttributeAccess

setDouble

      public synchronized void setDouble(int idx,
                                         double d) throws IllegalAttributeAccess

setFloat

      public synchronized void setFloat(int idx,
                                        float f) throws IllegalAttributeAccess

setInt

      public synchronized void setInt(int idx,
                                      int i) throws IllegalAttributeAccess

setLong

      public synchronized void setLong(int idx,
                                       long l) throws IllegalAttributeAccess

setString

      public synchronized void setString(int idx,
                                         String s) throws IllegalAttributeAccess

getValue

      public synchronized Object getValue(int idx,
                                          Object def) throws IllegalAttributeAccess

  Generic get of an attribute value. Retreive an attribute value from its index in the resource's attribute list.
  Parameters:
    idx - The index of the attribute whose value is queried.
    def - The default value (if the attribute isn't defined).
  Returns:
    An object, giving the attribute value, or the provided default if this attribute isn't currently define for the resource.
  Throws: IllegalAttributeAccess
    if the given index doesn't match any of the resource's attributes.

getValue

      public synchronized Object getValue(String name,
                                          Object def) throws IllegalAttributeAccess

  Generic get of an attribute value. Get the method of an attribute, by name.
  Parameters:
    name - The name of the queried attribute.
    def - The default value.
  Throws: IllegalAttributeAccess
    if the given name doesn't match any of the attribute's name.

getBoolean

      public synchronized boolean getBoolean(int idx,
                                             boolean def)

getChar

      public synchronized char getChar(int idx,
                                       char def)

getDouble

      public synchronized double getDouble(int idx,
                                           double def)

getFloat

      public synchronized float getFloat(int idx,
                                         float def)

getInt

      public synchronized int getInt(int idx,
                                     int def)

getLong

      public synchronized long getLong(int idx,
                                       long def)

getString

      public synchronized String getString(int idx,
                                           String def)

definesAttribute

      public boolean definesAttribute(int idx) throws IllegalAttributeAccess

  Does this resource has defined a value for the given attribute.
  Parameters:
    idx - The index of the attribute to check.
  Returns:
    A boolean true if the resource has a value for this attribute, false otherwise.

definesAttribute

      public boolean definesAttribute(String name) throws IllegalAttributeAccess

  Does this resource has defined a value for the given attribute.
  Parameters:
    name - The name of the attribute to check.
  Returns:
    A boolean true if the resource has a value for this attribute, false otherwise.

pickle

      public void pickle(DataOutputStream out) throws IOException

  Pickle this attribute holder to the given stream.
  Parameters:
    out - The output stream we should pickle ourselve to.
  Throws: IOException
    If some IO error occured during pickling.

unpickle

      public static AttributeHolder unpickle(DataInputStream in,
                                             Hashtable defs,
                                             boolean init) throws IOException

  Unpickle an attribute holder from the given input stream. AttributeHolder unpickling is done in two stage: the first stage wich is not redefinable, consists in recreating an instance of the attribute holder (this method).

  The second stage restore the instance attributes (and whatever information the pickle method as written there). This is the `unpickleInstance` method.

  Parameters:
    defs - Set of default values for the holder.
    in - The input stream to read from.
    init - Should the resource be initialized ?
  Returns:
    An instance of AttributeHolder of one of its subclass.
  Throws: IOException
    If some IO error occured while reading the stream.
  Throws: AttributeHolderInitException
    If we weren't able to restore the attribute holder.

unpickle

      public static AttributeHolder unpickle(DataInputStream in,
                                             Hashtable defs) throws IOException

  A short hand for unpickling and initializing a resource.
  Parameters:
    defs - Set of default values for the holder.
    in - The input stream to read from.
    init - Should the resource be initialized ?
  Returns:
    An instance of AttributeHolder of one of its subclass.
  Throws: IOException
    If some IO error occured while reading the stream.
  Throws: AttributeHolderInitException
    If we weren't able to restore the attribute holder.

unpickleInstance

      public AttributeHolder unpickleInstance(DataInputStream in,
                                              Hashtable defs,
                                              boolean init) throws IOException

  Finish the instance part of the unpickling job. The standard way of redefining how your attribute holder should be pickled is as follow:
  - redefine the `pickle` method, make sure the first method it calls is it super-method, than pickle whatever additional infos you want to pickle.
  - Than, redefine the `unpickleInstance` method, make sure ut first calls its super class `unpickleInstance` method, and than unpickle the additional informations you have store at pickling time.
  Parameters:
    in - The input stream to read from.
    defs - The proposed attribute default values.
    init - Should we initialize the resource after unpickling.

unpickleInstance

      public AttributeHolder unpickleInstance(DataInputStream in,
                                              Hashtable defs) throws IOException

  A short-hand for unpickling and initializing resources.
  Parameters:
    in - The input stream to read.
    defs - The default attribute values.
  Returns:
    An AttributeHolder instance.

unpickle

      public static AttributeHolder unpickle(DataInputStream in) throws IOException

  Unpickle an attribute holder from the given input stream.
  Parameters:
    in - The input stream to read from.
  Returns:
    An instance of AttributeHolder of one of its subclass.
  Throws: IOException
    If some IO error occured while reading the stream.
  Throws: AttributeHolderInitException
    If we weren't able to restore the attribute holder.

initialize

      public void initialize(Object values[])

  Initialization method for attribute holders. Each time an attribute holder get restored, its `initialize` method gets called. The holder should initialize itself with the set of provided values and perform any additional startup code.
  Parameters:
    values - The attribute values the holder should initialize from.
  Throws: AttributeHolderInitException
    If tghe holder wasn't able to initialize itself from the given set of attribute values.

initialize

      public void initialize(Hashtable defs)

  Initialization method for attribute holders. This method allows to initialize an attribute holder by providing its attributes values through a Hashtable mapping attribute names to attribute values.
  Parameters:
    defs - The Hashtable containing the default values.

print

      public void print(PrintStream out)

  Debugging purposes only, print this attribute holder.
  Parameters:
    out - The print stream to print to.

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