Package org.eclipse.ui

Interface IMemento

All Known Implementing Classes:
XMLMemento
public interface IMemento
Interface to a memento used for saving the important state of an object in a form that can be persisted in the file system.

Mementos were designed with the following requirements in mind:

  1. Certain objects need to be saved and restored across platform sessions.
  2. When an object is restored, an appropriate class for an object might not be available. It must be possible to skip an object in this case.
  3. When an object is restored, the appropriate class for the object may be different from the one when the object was originally saved. If so, the new class should still be able to read the old form of the data.

Mementos meet these requirements by providing support for storing a mapping of arbitrary string keys to primitive values, and by allowing mementos to have other mementos as children (arranged into a tree). A robust external storage format based on XML is used.

The key for an attribute may be any alpha numeric value that doesn't start with a number. eg: [A-Za-z][A-Za-z0-9]* Using '.' is unsupported. However, the value of TAG_ID is reserved for internal use.

The default implementation can throw a DOMException for createChild and put operations. See XMLMemento.

This interface is not intended to be implemented or extended by clients.

See Also:
Restriction:
This interface is not intended to be implemented by clients.

  • Field Details

  • Method Details

    • createChild

      IMemento createChild(String type)
      Creates a new child of this memento with the given type.

      The getChild and getChildren methods are used to retrieve children of a given type.

      Parameters:
      type - the type
      Returns:
      a new child memento
      See Also:

    • createChild

      IMemento createChild(String type, String id)
      Creates a new child of this memento with the given type and id. The id is stored in the child memento (using a special reserved key, TAG_ID) and can be retrieved using getId.

      The getChild and getChildren methods are used to retrieve children of a given type.

      Parameters:
      type - the type
      id - the child id
      Returns:
      a new child memento with the given type and id
      See Also:

    • getChild

      IMemento getChild(String type)
      Returns the first child with the given type id.
      Parameters:
      type - the type id
      Returns:
      the first child with the given type. May return null .

    • getChildren

      IMemento[] getChildren()
      Returns all children of this node.
      Returns:
      an array of children of this node. This will not be null. If there are no children, an array of length zero will be returned.
      Since:
      3.8

    • getChildren

      IMemento[] getChildren(String type)
      Returns all children with the given type id.
      Parameters:
      type - the type id
      Returns:
      an array of children with the given type. This will not be null. If there are no keys, an array of length zero will be returned.

    • getFloat

      Float getFloat(String key)
      Returns the floating point value of the given key.
      Parameters:
      key - the key
      Returns:
      the value, or null if the key was not found or was found but was not a floating point number

    • getType

      String getType()
      Returns the type for this memento.
      Returns:
      the memento type
      Since:
      3.4
      See Also:

    • getID

      String getID()
      Returns the id for this memento.
      Returns:
      the memento id, or null if none
      See Also:

    • getInteger

      Integer getInteger(String key)
      Returns the integer value of the given key.
      Parameters:
      key - the key
      Returns:
      the value, or null if the key was not found or was found but was not an integer

    • getString

      String getString(String key)
      Returns the string value of the given key.
      Parameters:
      key - the key
      Returns:
      the value, or null if the key was not found

    • getBoolean

      Boolean getBoolean(String key)
      Returns the boolean value of the given key.
      Parameters:
      key - the key
      Returns:
      the value, or null if the key was not found
      Since:
      3.4

    • getTextData

      String getTextData()
      Returns the data of the Text node of the memento. Each memento is allowed only one Text node.
      Returns:
      the data of the Text node of the memento, or null if the memento has no Text node.
      Since:
      2.0

    • getAttributeKeys

      String[] getAttributeKeys()
      Returns an array of all the attribute keys of the memento. This will not be null. If there are no keys, an array of length zero will be returned.
      Returns:
      an array with all the attribute keys of the memento
      Since:
      3.4

    • putFloat

      void putFloat(String key, float value)
      Sets the value of the given key to the given floating point number.
      Parameters:
      key - the key
      value - the value

    • putInteger

      void putInteger(String key, int value)
      Sets the value of the given key to the given integer.
      Parameters:
      key - the key
      value - the value

    • putMemento

      void putMemento(IMemento memento)
      Copy the attributes and children from memento to the receiver.
      Parameters:
      memento - the IMemento to be copied.

    • putString

      void putString(String key, String value)
      Sets the value of the given key to the given string.
      Parameters:
      key - the key
      value - the value

    • putBoolean

      void putBoolean(String key, boolean value)
      Sets the value of the given key to the given boolean value.
      Parameters:
      key - the key
      value - the value
      Since:
      3.4

    • putTextData

      void putTextData(String data)
      Sets the memento's Text node to contain the given data. Creates the Text node if none exists. If a Text node does exist, it's current contents are replaced. Each memento is allowed only one text node.
      Parameters:
      data - the data to be placed on the Text node
      Since:
      2.0