com.trolltech.qt.core
Class QAbstractFileEngineIterator

java.lang.Object
  extended by com.trolltech.qt.internal.QSignalEmitterInternal
      extended by com.trolltech.qt.QSignalEmitter
          extended by com.trolltech.qt.QtJambiObject
              extended by com.trolltech.qt.core.QAbstractFileEngineIterator
All Implemented Interfaces:
QtJambiInterface

public abstract class QAbstractFileEngineIterator
extends QtJambiObject

The QAbstractFileEngineIterator class provides an iterator interface for custom file engines. If all you want is to iterate over entries in a directory, see QDirIterator instead. This class is only for custom file engine authors.

QAbstractFileEngineIterator is a unidirectional single-use virtual iterator that plugs into QDirIterator, providing transparent proxy iteration for custom file engines.

You can subclass QAbstractFileEngineIterator to provide an iterator when writing your own file engine. To plug the iterator into your file system, you simply return an instance of this subclass from a reimplementation of QAbstractFileEngine::beginEntryList().

Example:

    class CustomFileEngine extends QAbstractFileEngine
    {
        QAbstractFileEngineIterator beginEntryList(QDir.Filters filters, java.util.List<String> nameFilters)
        {
            return new CustomFileEngineIterator(filters, nameFilters);
        }
        //...
    }
QAbstractFileEngineIterator is associated with a path, name filters, and entry filters. The path is the directory that the iterator lists entries in. The name filters and entry filters are provided for file engines that can optimize directory listing at the iterator level (e.g., network file systems that need to minimize network traffic), but they can also be ignored by the iterator subclass; QAbstractFileEngineIterator already provides the required filtering logics in the matchesFilters() function. You can call dirName() to get the directory name, nameFilters() to get a stringlist of name filters, and filters() to get the entry filters.

The pure virual function hasNext() returns true if the current directory has at least one more entry (i.e., the directory name is valid and accessible, and we have not reached the end of the entry list), and false otherwise. Reimplement next() to seek to the next entry.

The pure virtual function currentFileName() returns the name of the current entry without advancing the iterator. The currentFilePath() function is provided for convenience; it returns the full path of the current entry.

Here is an example of how to implement an interator that returns each of three fixed entries in sequence.

    class CustomIterator extends QAbstractFileEngineIterator
    {
        private java.util.List<String> entries;
        private int index;

        public CustomIterator(java.util.List<String> nameFilters, QDir.Filters filters)
        {
            super(filters, nameFilters);
            index = 0;

            // In a real iterator, these entries are fetched from the
            // file system based on the value of path().
            entries.add("entry1");
            entries.add("entry2");
            entries.add("entry3");
        }

        public boolean hasNext()
        {
            return index < entries.size() - 1;
        }

        public String next()
        {
           if (!hasNext())
               return "";
           ++index;
           return currentFilePath();
        }

        public String currentFileName()
        {
            return entries.get(index);
        }
    }
Note: QAbstractFileEngineIterator does not deal with QDir::IteratorFlags; it simply returns entries for a single directory.

See also:
QDirIterator.


Nested Class Summary
 
Nested classes/interfaces inherited from class com.trolltech.qt.QSignalEmitter
QSignalEmitter.AbstractSignal, QSignalEmitter.PrivateSignal0, QSignalEmitter.PrivateSignal1, QSignalEmitter.PrivateSignal2, QSignalEmitter.PrivateSignal3, QSignalEmitter.PrivateSignal4, QSignalEmitter.PrivateSignal5, QSignalEmitter.PrivateSignal6, QSignalEmitter.PrivateSignal7, QSignalEmitter.PrivateSignal8, QSignalEmitter.PrivateSignal9, QSignalEmitter.Signal0, QSignalEmitter.Signal1, QSignalEmitter.Signal2, QSignalEmitter.Signal3, QSignalEmitter.Signal4, QSignalEmitter.Signal5, QSignalEmitter.Signal6, QSignalEmitter.Signal7, QSignalEmitter.Signal8, QSignalEmitter.Signal9
 
Nested classes/interfaces inherited from class com.trolltech.qt.internal.QSignalEmitterInternal
com.trolltech.qt.internal.QSignalEmitterInternal.AbstractSignalInternal
 
Field Summary
 
Fields inherited from class com.trolltech.qt.internal.QSignalEmitterInternal
currentSender
 
Constructor Summary
QAbstractFileEngineIterator(QDir.Filters filters, java.util.List nameFilters)
          Constructs a QAbstractFileEngineIterator, using the entry filters filters, and wildcard name filters nameFilters.
 
Method Summary
 QFileInfo currentFileInfo()
          The virtual function returns a QFileInfo for the current directory entry.
abstract  java.lang.String currentFileName()
          This pure virtual function returns the name of the current directory entry, excluding the path.
 java.lang.String currentFilePath()
          Returns the path to the current directory entry.
 QDir.Filters filters()
          Returns the entry filters for this iterator.
abstract  boolean hasNext()
          This pure virtual function returns true if there is at least one more entry in the current directory (i.
 java.util.List nameFilters()
          Returns the name filters for this iterator.
abstract  java.lang.String next()
          This pure virtual function advances the iterator to the next directory entry, and returns the file path to the current entry.
 java.lang.String path()
          Returns the path for this iterator.
 
Methods inherited from class com.trolltech.qt.QtJambiObject
dispose, disposed, equals, finalize, reassignNativeResources, tr, tr, tr
 
Methods inherited from class com.trolltech.qt.QSignalEmitter
blockSignals, disconnect, disconnect, signalsBlocked, signalSender, thread
 
Methods inherited from class com.trolltech.qt.internal.QSignalEmitterInternal
__qt_signalInitialization
 
Methods inherited from class java.lang.Object
clone, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 
Methods inherited from interface com.trolltech.qt.QtJambiInterface
disableGarbageCollection, nativeId, nativePointer, reenableGarbageCollection, setJavaOwnership
 

Constructor Detail

QAbstractFileEngineIterator

public QAbstractFileEngineIterator(QDir.Filters filters,
                                   java.util.List nameFilters)
Constructs a QAbstractFileEngineIterator, using the entry filters filters, and wildcard name filters nameFilters.

Method Detail

currentFilePath

public final java.lang.String currentFilePath()
Returns the path to the current directory entry. It's the same as prepending path() to the return value of currentFileName().

See also:
currentFileName().


filters

public final QDir.Filters filters()
Returns the entry filters for this iterator.

See also:
QDir::filter(), nameFilters(), and path().


nameFilters

public final java.util.List nameFilters()
Returns the name filters for this iterator.

See also:
QDir::nameFilters(), filters(), and path().


path

public final java.lang.String path()
Returns the path for this iterator. QDirIterator is responsible for assigning this path; it cannot change during the iterator's lifetime.

See also:
nameFilters(), and filters().


currentFileInfo

public QFileInfo currentFileInfo()
The virtual function returns a QFileInfo for the current directory entry. This function is provided for convenience. It can also be slightly faster that creating a QFileInfo object yourself, as the object returned by this function might contain cached information that QFileInfo otherwise would have to access through the file engine.

See also:
currentFileName().


currentFileName

public abstract java.lang.String currentFileName()
This pure virtual function returns the name of the current directory entry, excluding the path.

See also:
currentFilePath().


hasNext

public abstract boolean hasNext()
This pure virtual function returns true if there is at least one more entry in the current directory (i. ., the iterator path is valid and accessible, and the iterator has not reached the end of the entry list).

See also:
QDirIterator::hasNext().


next

public abstract java.lang.String next()
This pure virtual function advances the iterator to the next directory entry, and returns the file path to the current entry.

This function can optionally make use of nameFilters() and filters() to optimize its performance.

Reimplement this function in a subclass to advance the iterator.

See also:
QDirIterator::next().