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/* Copyright 2016 Software Freedom Conservancy Inc.
*
* This software is licensed under the GNU Lesser General Public License
* (version 2.1 or later). See the COPYING file in this distribution.
*/
namespace Core {
// A TrackerAccumulator is called by Tracker indicating when a DataObject should be included or
// unincluded in its accumulated data. All methods return true if their data has changed,
// indicating that the Tracker's "updated" signal should be fired.
public interface TrackerAccumulator : Object {
public abstract bool include(DataObject object);
public abstract bool uninclude(DataObject object);
public abstract bool altered(DataObject object, Alteration alteration);
}
// A Tracker monitors a DataCollection and reports to an installed TrackerAccumulator when objects
// are available and unavailable. This simplifies connecting to the DataCollection manually to
// monitoring availability (or subclassing for similar reasons, which may not always be available).
public class Tracker {
protected delegate bool IncludeUnincludeObject(DataObject object);
private DataCollection collection;
private Gee.Collection<DataObject>? initial;
private TrackerAccumulator? acc = null;
public virtual signal void updated() {
}
public Tracker(DataCollection collection, Gee.Collection<DataObject>? initial = null) {
this.collection = collection;
this.initial = initial;
}
~Tracker() {
if (acc != null) {
collection.items_added.disconnect(on_items_added);
collection.items_removed.disconnect(on_items_removed);
collection.items_altered.disconnect(on_items_altered);
}
}
public void start(TrackerAccumulator acc) {
// can only be started once
assert(this.acc == null);
this.acc = acc;
collection.items_added.connect(on_items_added);
collection.items_removed.connect(on_items_removed);
collection.items_altered.connect(on_items_altered);
if (initial != null && initial.size > 0)
on_items_added(initial);
else if (initial == null)
on_items_added(collection.get_all());
initial = null;
}
public DataCollection get_collection() {
return collection;
}
private void on_items_added(Gee.Iterable<DataObject> added) {
include_uninclude(added, acc.include);
}
private void on_items_removed(Gee.Iterable<DataObject> removed) {
include_uninclude(removed, acc.uninclude);
}
// Subclasses can use this as a utility method.
protected void include_uninclude(Gee.Iterable<DataObject> objects, IncludeUnincludeObject cb) {
bool fire_updated = false;
foreach (DataObject object in objects)
fire_updated = cb(object) || fire_updated;
if (fire_updated)
updated();
}
private void on_items_altered(Gee.Map<DataObject, Alteration> map) {
bool fire_updated = false;
foreach (DataObject object in map.keys)
fire_updated = acc.altered(object, map.get(object)) || fire_updated;
if (fire_updated)
updated();
}
}
// A ViewTracker is Tracker designed for ViewCollections. It uses an internal mux to route
// Tracker's calls to three TrackerAccumulators: all (all objects in the ViewCollection), selected
// (only for selected objects) and visible (only for items not hidden or filtered out).
public class ViewTracker : Tracker {
private class Mux : Object, TrackerAccumulator {
public TrackerAccumulator? all;
public TrackerAccumulator? visible;
public TrackerAccumulator? selected;
public Mux(TrackerAccumulator? all, TrackerAccumulator? visible, TrackerAccumulator? selected) {
this.all = all;
this.visible = visible;
this.selected = selected;
}
public bool include(DataObject object) {
DataView view = (DataView) object;
bool fire_updated = false;
if (all != null)
fire_updated = all.include(view) || fire_updated;
if (visible != null && view.is_visible())
fire_updated = visible.include(view) || fire_updated;
if (selected != null && view.is_selected())
fire_updated = selected.include(view) || fire_updated;
return fire_updated;
}
public bool uninclude(DataObject object) {
DataView view = (DataView) object;
bool fire_updated = false;
if (all != null)
fire_updated = all.uninclude(view) || fire_updated;
if (visible != null && view.is_visible())
fire_updated = visible.uninclude(view) || fire_updated;
if (selected != null && view.is_selected())
fire_updated = selected.uninclude(view) || fire_updated;
return fire_updated;
}
public bool altered(DataObject object, Alteration alteration) {
DataView view = (DataView) object;
bool fire_updated = false;
if (all != null)
fire_updated = all.altered(view, alteration) || fire_updated;
if (visible != null && view.is_visible())
fire_updated = visible.altered(view, alteration) || fire_updated;
if (selected != null && view.is_selected())
fire_updated = selected.altered(view, alteration) || fire_updated;
return fire_updated;
}
}
private Mux? mux = null;
public ViewTracker(ViewCollection collection) {
base (collection, collection.get_all_unfiltered());
}
~ViewTracker() {
if (mux != null) {
ViewCollection? collection = get_collection() as ViewCollection;
assert(collection != null);
collection.items_shown.disconnect(on_items_shown);
collection.items_hidden.disconnect(on_items_hidden);
collection.items_selected.disconnect(on_items_selected);
collection.items_unselected.disconnect(on_items_unselected);
}
}
public new void start(TrackerAccumulator? all, TrackerAccumulator? visible, TrackerAccumulator? selected) {
assert(mux == null);
mux = new Mux(all, visible, selected);
ViewCollection? collection = get_collection() as ViewCollection;
assert(collection != null);
collection.items_shown.connect(on_items_shown);
collection.items_hidden.connect(on_items_hidden);
collection.items_selected.connect(on_items_selected);
collection.items_unselected.connect(on_items_unselected);
base.start(mux);
}
private void on_items_shown(Gee.Collection<DataView> shown) {
if (mux.visible != null)
include_uninclude(shown, mux.visible.include);
}
private void on_items_hidden(Gee.Collection<DataView> hidden) {
if (mux.visible != null)
include_uninclude(hidden, mux.visible.uninclude);
}
private void on_items_selected(Gee.Iterable<DataView> selected) {
if (mux.selected != null)
include_uninclude(selected, mux.selected.include);
}
private void on_items_unselected(Gee.Iterable<DataView> unselected) {
if (mux.selected != null)
include_uninclude(unselected, mux.selected.uninclude);
}
}
}
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