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Don't crash when a slot is deregistered in the middle of signal processing

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this was possible (and used) with FbTk::Subject, but the implemetation of FbTk::Signal didn't
support it, which made it impossible to continue with conversion.
This commit is contained in:
Pavel Labath 2011-05-02 23:01:24 +02:00
parent 144d716a42
commit bef2039d2c
1 changed files with 46 additions and 15 deletions
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61
src/FbTk/Signal.hh
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@ -24,9 +24,9 @@
#include "RefCount.hh"
#include "Slot.hh"
#include <algorithm>
#include <list>
#include <map>
#include <vector>
#include <set>
namespace FbTk {
@ -40,6 +40,10 @@ namespace SigImpl {
* handled by the child class so it can do the type checking.
*/
class SignalHolder {
protected:
typedef RefCount<SlotBase> SlotPtr;
typedef std::list<SlotPtr> SlotList;
public:
/// Special tracker interface used by SignalTracker.
class Tracker {
@ -49,13 +53,12 @@ public:
virtual void disconnect(SignalHolder& signal) = 0;
};
/// Do not use this type outside this class
typedef std::list<RefCount<SlotBase> > SlotList;
typedef SlotList::iterator Iterator;
typedef Iterator SlotID;
typedef SlotList::const_iterator ConstIterator;
SignalHolder() : m_emitting(0) {}
~SignalHolder() {
// Disconnect this holder from all trackers.
for (Trackers::iterator it = m_trackers.begin(),
@ -67,13 +70,21 @@ public:
/// Remove a specific slot \c id from this signal
void disconnect(SlotID slotIt) {
m_slots.erase( slotIt );
if(m_emitting) {
// if we are emitting, we must not erase the actual element, as that would
// invalidate iterators in the emit() function
*slotIt = SlotPtr();
} else
m_slots.erase( slotIt );
}
/// Removes all slots connected to this
void clear() {
m_slots.clear();
if(m_emitting)
std::fill(m_slots.begin(), m_slots.end(), SlotPtr());
else
m_slots.clear();
}
void connectTracker(SignalHolder::Tracker& tracker) {
@ -92,14 +103,22 @@ protected:
Iterator end() { return m_slots.end(); }
/// Connect a slot to this signal. Must only be called by child classes.
SlotID connect(const RefCount<SlotBase>& slot) {
SlotID connect(const SlotPtr& slot) {
return m_slots.insert(m_slots.end(), slot);
}
void begin_emitting() { ++m_emitting; }
void end_emitting() {
if(--m_emitting == 0) {
// remove elements which belonged slots that detached themselves
m_slots.erase(std::remove(m_slots.begin(), m_slots.end(), SlotPtr()), m_slots.end());
}
}
private:
typedef std::set<Tracker*> Trackers;
SlotList m_slots; ///< all slots connected to a signal
Trackers m_trackers; ///< all instances that tracks this signal.
unsigned m_emitting;
};
struct EmptyArg {};
@ -113,14 +132,17 @@ template <typename ReturnType,
class Signal: public SigImpl::SignalHolder {
public:
void emit(Arg1 arg1, Arg2 arg2, Arg3 arg3) {
begin_emitting();
for ( Iterator it = begin(); it != end(); ++it ) {
static_cast<SigImpl::SlotBase3<ReturnType, Arg1, Arg2, Arg3> &>(**it)(arg1, arg2, arg3);
if(*it)
static_cast<SigImpl::SlotBase3<ReturnType, Arg1, Arg2, Arg3> &>(**it)(arg1, arg2, arg3);
}
end_emitting();
}
template<typename Functor>
SlotID connect(const Functor& functor) {
return SignalHolder::connect(FbTk::RefCount<SigImpl::SlotBase>(
return SignalHolder::connect(SlotPtr(
new SigImpl::Slot3<ReturnType, Arg1, Arg2, Arg3, Functor>(functor)
));
}
@ -131,14 +153,17 @@ template <typename ReturnType, typename Arg1, typename Arg2>
class Signal<ReturnType, Arg1, Arg2, SigImpl::EmptyArg>: public SigImpl::SignalHolder {
public:
void emit(Arg1 arg1, Arg2 arg2) {
begin_emitting();
for ( Iterator it = begin(); it != end(); ++it ) {
static_cast<SigImpl::SlotBase2<ReturnType, Arg1, Arg2> &>(**it)(arg1, arg2);
if(*it)
static_cast<SigImpl::SlotBase2<ReturnType, Arg1, Arg2> &>(**it)(arg1, arg2);
}
end_emitting();
}
template<typename Functor>
SlotID connect(const Functor& functor) {
return SignalHolder::connect(FbTk::RefCount<SigImpl::SlotBase>(
return SignalHolder::connect(SlotPtr(
new SigImpl::Slot2<ReturnType, Arg1, Arg2, Functor>(functor)
));
}
@ -149,14 +174,17 @@ template <typename ReturnType, typename Arg1>
class Signal<ReturnType, Arg1, SigImpl::EmptyArg, SigImpl::EmptyArg>: public SigImpl::SignalHolder {
public:
void emit(Arg1 arg) {
begin_emitting();
for ( Iterator it = begin(); it != end(); ++it ) {
static_cast<SigImpl::SlotBase1<ReturnType, Arg1> &>(**it)(arg);
if(*it)
static_cast<SigImpl::SlotBase1<ReturnType, Arg1> &>(**it)(arg);
}
end_emitting();
}
template<typename Functor>
SlotID connect(const Functor& functor) {
return SignalHolder::connect(FbTk::RefCount<SigImpl::SlotBase>(
return SignalHolder::connect(SlotPtr(
new SigImpl::Slot1<ReturnType, Arg1, Functor>(functor)
));
}
@ -167,14 +195,17 @@ template <typename ReturnType>
class Signal<ReturnType, SigImpl::EmptyArg, SigImpl::EmptyArg, SigImpl::EmptyArg>: public SigImpl::SignalHolder {
public:
void emit() {
begin_emitting();
for ( Iterator it = begin(); it != end(); ++it ) {
static_cast<SigImpl::SlotBase0<ReturnType> &>(**it)();
if(*it)
static_cast<SigImpl::SlotBase0<ReturnType> &>(**it)();
}
end_emitting();
}
template<typename Functor>
SlotID connect(const Functor& functor) {
return SignalHolder::connect(FbTk::RefCount<SigImpl::SlotBase>(
return SignalHolder::connect(SlotPtr(
new SigImpl::Slot0<ReturnType, Functor>(functor)
));
}