1//------------------------------------------------------------------------------
2//	Copyright (c) 2001-2002, Haiku
3//
4//	Permission is hereby granted, free of charge, to any person obtaining a
5//	copy of this software and associated documentation files (the "Software"),
6//	to deal in the Software without restriction, including without limitation
7//	the rights to use, copy, modify, merge, publish, distribute, sublicense,
8//	and/or sell copies of the Software, and to permit persons to whom the
9//	Software is furnished to do so, subject to the following conditions:
10//
11//	The above copyright notice and this permission notice shall be included in
12//	all copies or substantial portions of the Software.
13//
14//	THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
15//	IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
16//	FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
17//	AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
18//	LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
19//	FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
20//	DEALINGS IN THE SOFTWARE.
21//
22//	File Name:		Watcher.cpp
23//	Author:			Ingo Weinhold (bonefish@users.sf.net)
24//	Description:	A Watcher represents a target of a watching service.
25//					A WatcherFilter represents a predicate on Watchers.
26//------------------------------------------------------------------------------
27
28#include <Message.h>
29
30#include "MessageDeliverer.h"
31#include "Watcher.h"
32
33// Watcher
34
35/*!	\class Watcher
36	\brief A Watcher represents a target of a watching service.
37
38	The Watcher base class only has one attribute, a BMessenger which
39	specifies the target to which notification messages shall be sent.
40	SendMessage() actually sends the message to the target. It can be
41	overridden in case of special needs.
42*/
43
44/*!	\var Watcher::fTarget
45	\brief The watcher's message target.
46*/
47
48// constructor
49/*!	\brief Creates a new watcher with a specified target.
50
51	The supplied BMessenger is copied, that is the caller can delete the
52	object when the constructor returns.
53
54	\param target The watcher's message target.
55*/
56Watcher::Watcher(const BMessenger &target)
57	: fTarget(target)
58{
59}
60
61// destructor
62/*!	\brief Frees all resources associated with the object.
63*/
64Watcher::~Watcher()
65{
66}
67
68// Target
69/*!	\brief Returns the watcher's message target.
70	\return The watcher's message target.
71*/
72const BMessenger&
73Watcher::Target() const
74{
75	return fTarget;
76}
77
78// SendMessage
79/*!	\brief Sends the supplied message to the watcher's message target.
80
81	The method can be overridden by a derived class to e.g. add additional
82	fields to the message. Note, that in this case the message must not be
83	modified directly, but a copy has to be made.
84
85	\param message The message to be sent.
86	\return \c B_OK, if everything went fine, another error code, if an error
87			occured.
88*/
89status_t
90Watcher::SendMessage(BMessage *message)
91{
92	return MessageDeliverer::Default()->DeliverMessage(message, fTarget);
93}
94
95
96// WatcherFilter
97
98/*!	\class WatcherFilter
99	\brief A WatcherFilter represents a predicate on Watchers.
100
101	It's only method Filter() returns whether a given Watcher and a BMessage
102	satisfy the predicate. This class' Filter() implementation always returns
103	\c true. Derived classes override it.
104*/
105
106// constructor
107/*!	\brief Creates a new WatchingFilter.
108*/
109WatcherFilter::WatcherFilter()
110{
111}
112
113// destructor
114/*!	\brief Frees all resources associated with the object.
115*/
116WatcherFilter::~WatcherFilter()
117{
118}
119
120// Filter
121/*!	\brief Returns whether the watcher-message pair satisfies the predicate
122		   represented by this object.
123
124	Derived classes override this method. This version always returns \c true.
125
126	\param watcher The watcher in question.
127	\param message The message in question.
128	\return \c true.
129*/
130bool
131WatcherFilter::Filter(Watcher *watcher, BMessage *message)
132{
133	return true;
134}
135
136