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phobos/std/signals.d

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// Written in the D programming language.
/**
* Signals and Slots are an implementation of the Observer Pattern.
* Essentially, when a Signal is emitted, a list of connected Observers
* (called slots) are called.
*
* There have been several D implementations of Signals and Slots.
* This version makes use of several new features in D, which make
* using it simpler and less error prone. In particular, it is no
* longer necessary to instrument the slots.
*
* References:
* $(LUCKY A Deeper Look at Signals and Slots)$(BR)
* $(LINK2 http://en.wikipedia.org/wiki/Observer_pattern, Observer pattern)$(BR)
* $(LINK2 http://en.wikipedia.org/wiki/Signals_and_slots, Wikipedia)$(BR)
* $(LINK2 http://boost.org/doc/html/$(SIGNALS).html, Boost Signals)$(BR)
* $(LINK2 http://qt-project.org/doc/qt-5/signalsandslots.html, Qt)$(BR)
*
* There has been a great deal of discussion in the D newsgroups
* over this, and several implementations:
*
* $(LINK2 http://www.digitalmars.com/d/archives/digitalmars/D/announce/signal_slots_library_4825.html, signal slots library)$(BR)
* $(LINK2 http://www.digitalmars.com/d/archives/digitalmars/D/Signals_and_Slots_in_D_42387.html, Signals and Slots in D)$(BR)
* $(LINK2 http://www.digitalmars.com/d/archives/digitalmars/D/Dynamic_binding_--_Qt_s_Signals_and_Slots_vs_Objective-C_42260.html, Dynamic binding -- Qt's Signals and Slots vs Objective-C)$(BR)
* $(LINK2 http://www.digitalmars.com/d/archives/digitalmars/D/Dissecting_the_SS_42377.html, Dissecting the SS)$(BR)
* $(LINK2 http://www.digitalmars.com/d/archives/digitalmars/D/dwt/about_harmonia_454.html, about harmonia)$(BR)
* $(LINK2 http://www.digitalmars.com/d/archives/digitalmars/D/announce/1502.html, Another event handling module)$(BR)
* $(LINK2 http://www.digitalmars.com/d/archives/digitalmars/D/41825.html, Suggestion: signal/slot mechanism)$(BR)
* $(LINK2 http://www.digitalmars.com/d/archives/digitalmars/D/13251.html, Signals and slots?)$(BR)
* $(LINK2 http://www.digitalmars.com/d/archives/digitalmars/D/10714.html, Signals and slots ready for evaluation)$(BR)
* $(LINK2 http://www.digitalmars.com/d/archives/digitalmars/D/1393.html, Signals & Slots for Walter)$(BR)
* $(LINK2 http://www.digitalmars.com/d/archives/28456.html, Signal/Slot mechanism?)$(BR)
* $(LINK2 http://www.digitalmars.com/d/archives/19470.html, Modern Features?)$(BR)
* $(LINK2 http://www.digitalmars.com/d/archives/16592.html, Delegates vs interfaces)$(BR)
* $(LINK2 http://www.digitalmars.com/d/archives/16583.html, The importance of component programming (properties$(COMMA) signals and slots$(COMMA) etc))$(BR)
* $(LINK2 http://www.digitalmars.com/d/archives/16368.html, signals and slots)$(BR)
*
* Bugs:
* Slots can only be delegates formed from class objects or
* interfaces to class objects. If a delegate to something else
* is passed to connect(), such as a struct member function,
* a nested function or a COM interface, undefined behavior
* will result.
*
* Not safe for multiple threads operating on the same signals
* or slots.
* Macros:
* WIKI = Phobos/StdSignals
* SIGNALS=signals
*
* Copyright: Copyright Digital Mars 2000 - 2009.
* License: $(WEB www.boost.org/LICENSE_1_0.txt, Boost License 1.0).
* Authors: $(WEB digitalmars.com, Walter Bright)
* Source: $(PHOBOSSRC std/_signals.d)
*/
/* Copyright Digital Mars 2000 - 2009.
* Distributed under the Boost Software License, Version 1.0.
* (See accompanying file LICENSE_1_0.txt or copy at
* http://www.boost.org/LICENSE_1_0.txt)
*/
module std.signals;
import std.stdio;
import std.c.stdlib : calloc, realloc, free;
import core.exception : onOutOfMemoryError;
// Special function for internal use only.
// Use of this is where the slot had better be a delegate
// to an object or an interface that is part of an object.
extern (C) Object _d_toObject(void* p);
// Used in place of Object.notifyRegister and Object.notifyUnRegister.
alias DisposeEvt = void delegate(Object);
extern (C) void rt_attachDisposeEvent( Object obj, DisposeEvt evt );
extern (C) void rt_detachDisposeEvent( Object obj, DisposeEvt evt );
//debug=signal;
/************************
* Mixin to create a signal within a class object.
*
* Different signals can be added to a class by naming the mixins.
*
* Example:
---
import std.signals;
import std.stdio;
class Observer
{ // our slot
void watch(string msg, int i)
{
writefln("Observed msg '%s' and value %s", msg, i);
}
}
class Foo
{
int value() { return _value; }
int value(int v)
{
if (v != _value)
{ _value = v;
// call all the connected slots with the two parameters
emit("setting new value", v);
}
return v;
}
// Mix in all the code we need to make Foo into a signal
mixin Signal!(string, int);
private :
int _value;
}
void main()
{
Foo a = new Foo;
Observer o = new Observer;
a.value = 3; // should not call o.watch()
a.connect(&o.watch); // o.watch is the slot
a.value = 4; // should call o.watch()
a.disconnect(&o.watch); // o.watch is no longer a slot
a.value = 5; // so should not call o.watch()
a.connect(&o.watch); // connect again
a.value = 6; // should call o.watch()
destroy(o); // destroying o should automatically disconnect it
a.value = 7; // should not call o.watch()
}
---
* which should print:
* <pre>
* Observed msg 'setting new value' and value 4
* Observed msg 'setting new value' and value 6
* </pre>
*
*/
mixin template Signal(T1...)
{
static import std.c.stdlib;
static import core.exception;
/***
* A slot is implemented as a delegate.
* The slot_t is the type of the delegate.
* The delegate must be to an instance of a class or an interface
* to a class instance.
* Delegates to struct instances or nested functions must not be
* used as slots.
*/
alias slot_t = void delegate(T1);
/***
* Call each of the connected slots, passing the argument(s) i to them.
*/
final void emit( T1 i )
{
foreach (slot; slots[0 .. slots_idx])
{ if (slot)
slot(i);
}
}
/***
* Add a slot to the list of slots to be called when emit() is called.
*/
final void connect(slot_t slot)
{
/* Do this:
* slots ~= slot;
* but use malloc() and friends instead
*/
auto len = slots.length;
if (slots_idx == len)
{
if (slots.length == 0)
{
len = 4;
auto p = std.c.stdlib.calloc(slot_t.sizeof, len);
if (!p)
core.exception.onOutOfMemoryError();
slots = (cast(slot_t*)p)[0 .. len];
}
else
{
len = len * 2 + 4;
auto p = std.c.stdlib.realloc(slots.ptr, slot_t.sizeof * len);
if (!p)
core.exception.onOutOfMemoryError();
slots = (cast(slot_t*)p)[0 .. len];
slots[slots_idx + 1 .. $] = null;
}
}
slots[slots_idx++] = slot;
L1:
Object o = _d_toObject(slot.ptr);
rt_attachDisposeEvent(o, &unhook);
}
/***
* Remove a slot from the list of slots to be called when emit() is called.
*/
final void disconnect(slot_t slot)
{
debug (signal) writefln("Signal.disconnect(slot)");
for (size_t i = 0; i < slots_idx; )
{
if (slots[i] == slot)
{ slots_idx--;
slots[i] = slots[slots_idx];
slots[slots_idx] = null; // not strictly necessary
Object o = _d_toObject(slot.ptr);
rt_detachDisposeEvent(o, &unhook);
}
else
i++;
}
}
/* **
* Special function called when o is destroyed.
* It causes any slots dependent on o to be removed from the list
* of slots to be called by emit().
*/
final void unhook(Object o)
{
debug (signal) writefln("Signal.unhook(o = %s)", cast(void*)o);
for (size_t i = 0; i < slots_idx; )
{
if (_d_toObject(slots[i].ptr) is o)
{ slots_idx--;
slots[i] = slots[slots_idx];
slots[slots_idx] = null; // not strictly necessary
}
else
i++;
}
}
/* **
* There can be multiple destructors inserted by mixins.
*/
~this()
{
/* **
* When this object is destroyed, need to let every slot
* know that this object is destroyed so they are not left
* with dangling references to it.
*/
if (slots)
{
foreach (slot; slots[0 .. slots_idx])
{
if (slot)
{ Object o = _d_toObject(slot.ptr);
rt_detachDisposeEvent(o, &unhook);
}
}
std.c.stdlib.free(slots.ptr);
slots = null;
}
}
private:
slot_t[] slots; // the slots to call from emit()
size_t slots_idx; // used length of slots[]
}
// A function whose sole purpose is to get this module linked in
// so the unittest will run.
void linkin() { }
unittest
{
class Observer
{
void watch(string msg, int i)
{
//writefln("Observed msg '%s' and value %s", msg, i);
captured_value = i;
captured_msg = msg;
}
int captured_value;
string captured_msg;
}
class Foo
{
@property int value() { return _value; }
@property int value(int v)
{
if (v != _value)
{ _value = v;
emit("setting new value", v);
}
return v;
}
mixin Signal!(string, int);
private:
int _value;
}
Foo a = new Foo;
Observer o = new Observer;
// check initial condition
assert(o.captured_value == 0);
assert(o.captured_msg == "");
// set a value while no observation is in place
a.value = 3;
assert(o.captured_value == 0);
assert(o.captured_msg == "");
// connect the watcher and trigger it
a.connect(&o.watch);
a.value = 4;
assert(o.captured_value == 4);
assert(o.captured_msg == "setting new value");
// disconnect the watcher and make sure it doesn't trigger
a.disconnect(&o.watch);
a.value = 5;
assert(o.captured_value == 4);
assert(o.captured_msg == "setting new value");
// reconnect the watcher and make sure it triggers
a.connect(&o.watch);
a.value = 6;
assert(o.captured_value == 6);
assert(o.captured_msg == "setting new value");
// destroy the underlying object and make sure it doesn't cause
// a crash or other problems
destroy(o);
a.value = 7;
}
unittest {
class Observer
{
int i;
long l;
string str;
void watchInt(string str, int i)
{
this.str = str;
this.i = i;
}
void watchLong(string str, long l)
{
this.str = str;
this.l = l;
}
}
class Bar
{
@property void value1(int v) { s1.emit("str1", v); }
@property void value2(int v) { s2.emit("str2", v); }
@property void value3(long v) { s3.emit("str3", v); }
mixin Signal!(string, int) s1;
mixin Signal!(string, int) s2;
mixin Signal!(string, long) s3;
}
void test(T)(T a) {
auto o1 = new Observer;
auto o2 = new Observer;
auto o3 = new Observer;
// connect the watcher and trigger it
a.s1.connect(&o1.watchInt);
a.s2.connect(&o2.watchInt);
a.s3.connect(&o3.watchLong);
assert(!o1.i && !o1.l && !o1.str);
assert(!o2.i && !o2.l && !o2.str);
assert(!o3.i && !o3.l && !o3.str);
a.value1 = 11;
assert(o1.i == 11 && !o1.l && o1.str == "str1");
assert(!o2.i && !o2.l && !o2.str);
assert(!o3.i && !o3.l && !o3.str);
o1.i = -11; o1.str = "x1";
a.value2 = 12;
assert(o1.i == -11 && !o1.l && o1.str == "x1");
assert(o2.i == 12 && !o2.l && o2.str == "str2");
assert(!o3.i && !o3.l && !o3.str);
o2.i = -12; o2.str = "x2";
a.value3 = 13;
assert(o1.i == -11 && !o1.l && o1.str == "x1");
assert(o2.i == -12 && !o1.l && o2.str == "x2");
assert(!o3.i && o3.l == 13 && o3.str == "str3");
o3.l = -13; o3.str = "x3";
// disconnect the watchers and make sure it doesn't trigger
a.s1.disconnect(&o1.watchInt);
a.s2.disconnect(&o2.watchInt);
a.s3.disconnect(&o3.watchLong);
a.value1 = 21;
a.value2 = 22;
a.value3 = 23;
assert(o1.i == -11 && !o1.l && o1.str == "x1");
assert(o2.i == -12 && !o1.l && o2.str == "x2");
assert(!o3.i && o3.l == -13 && o3.str == "x3");
// reconnect the watcher and make sure it triggers
a.s1.connect(&o1.watchInt);
a.s2.connect(&o2.watchInt);
a.s3.connect(&o3.watchLong);
a.value1 = 31;
a.value2 = 32;
a.value3 = 33;
assert(o1.i == 31 && !o1.l && o1.str == "str1");
assert(o2.i == 32 && !o1.l && o2.str == "str2");
assert(!o3.i && o3.l == 33 && o3.str == "str3");
// destroy observers
destroy(o1);
destroy(o2);
destroy(o3);
a.value1 = 41;
a.value2 = 42;
a.value3 = 43;
}
test(new Bar);
class BarDerived: Bar
{
@property void value4(int v) { s4.emit("str4", v); }
@property void value5(int v) { s5.emit("str5", v); }
@property void value6(long v) { s6.emit("str6", v); }
mixin Signal!(string, int) s4;
mixin Signal!(string, int) s5;
mixin Signal!(string, long) s6;
}
auto a = new BarDerived;
test!Bar(a);
test!BarDerived(a);
auto o4 = new Observer;
auto o5 = new Observer;
auto o6 = new Observer;
// connect the watcher and trigger it
a.s4.connect(&o4.watchInt);
a.s5.connect(&o5.watchInt);
a.s6.connect(&o6.watchLong);
assert(!o4.i && !o4.l && !o4.str);
assert(!o5.i && !o5.l && !o5.str);
assert(!o6.i && !o6.l && !o6.str);
a.value4 = 44;
assert(o4.i == 44 && !o4.l && o4.str == "str4");
assert(!o5.i && !o5.l && !o5.str);
assert(!o6.i && !o6.l && !o6.str);
o4.i = -44; o4.str = "x4";
a.value5 = 45;
assert(o4.i == -44 && !o4.l && o4.str == "x4");
assert(o5.i == 45 && !o5.l && o5.str == "str5");
assert(!o6.i && !o6.l && !o6.str);
o5.i = -45; o5.str = "x5";
a.value6 = 46;
assert(o4.i == -44 && !o4.l && o4.str == "x4");
assert(o5.i == -45 && !o4.l && o5.str == "x5");
assert(!o6.i && o6.l == 46 && o6.str == "str6");
o6.l = -46; o6.str = "x6";
// disconnect the watchers and make sure it doesn't trigger
a.s4.disconnect(&o4.watchInt);
a.s5.disconnect(&o5.watchInt);
a.s6.disconnect(&o6.watchLong);
a.value4 = 54;
a.value5 = 55;
a.value6 = 56;
assert(o4.i == -44 && !o4.l && o4.str == "x4");
assert(o5.i == -45 && !o4.l && o5.str == "x5");
assert(!o6.i && o6.l == -46 && o6.str == "x6");
// reconnect the watcher and make sure it triggers
a.s4.connect(&o4.watchInt);
a.s5.connect(&o5.watchInt);
a.s6.connect(&o6.watchLong);
a.value4 = 64;
a.value5 = 65;
a.value6 = 66;
assert(o4.i == 64 && !o4.l && o4.str == "str4");
assert(o5.i == 65 && !o4.l && o5.str == "str5");
assert(!o6.i && o6.l == 66 && o6.str == "str6");
// destroy observers
destroy(o4);
destroy(o5);
destroy(o6);
a.value4 = 44;
a.value5 = 45;
a.value6 = 46;
}
version(none) // Disabled because of dmd @@@BUG5028@@@
unittest
{
class A
{
mixin Signal!(string, int) s1;
}
class B : A
{
mixin Signal!(string, int) s2;
}
}
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