Initial support for FRP behaviors

1 files changed, 133 insertions, 0 deletions

diff --git a/src/frp.cpp b/src/frp.cpp
new file mode 100644
index 0000000..142fcd4
--- /dev/null
+++ b/src/frp.cpp
@@ -0,0 +1,133 @@
+#include <erebos/frp.h>
+
+#include <condition_variable>
+#include <mutex>
+
+using namespace erebos;
+
+using std::condition_variable;
+using std::move;
+using std::mutex;
+using std::nullopt;
+using std::unique_lock;
+using std::weak_ptr;
+
+mutex bhvTimeMutex;
+condition_variable bhvTimeCond;
+bool bhvTimeRunning = false;
+uint64_t bhvTimeLast = 0;
+
+BhvCurTime::BhvCurTime()
+{
+	unique_lock lock(bhvTimeMutex);
+	bhvTimeCond.wait(lock, []{ return !bhvTimeRunning; });
+
+	bhvTimeRunning = true;
+	t = BhvTime(++bhvTimeLast);
+}
+
+BhvCurTime::~BhvCurTime()
+{
+	if (t) {
+		unique_lock lock(bhvTimeMutex);
+		bhvTimeRunning = false;
+		lock.unlock();
+		bhvTimeCond.notify_one();
+	}
+}
+
+BhvCurTime::BhvCurTime(BhvCurTime && other)
+{
+	t = other.t;
+	other.t = nullopt;
+}
+
+BhvCurTime & BhvCurTime::operator=(BhvCurTime && other)
+{
+	t = other.t;
+	other.t = nullopt;
+	return *this;
+}
+
+
+BhvImplBase::~BhvImplBase() = default;
+
+void BhvImplBase::dependsOn(shared_ptr<BhvImplBase> other)
+{
+	depends.push_back(other);
+	other->rdepends.push_back(shared_from_this());
+}
+
+void BhvImplBase::updated(const BhvCurTime & ctime)
+{
+	vector<shared_ptr<BhvImplBase>> toUpdate;
+	markDirty(ctime, toUpdate);
+
+	for (auto & bhv : toUpdate)
+		bhv->updateDirty(ctime);
+}
+
+void BhvImplBase::markDirty(const BhvCurTime & ctime, vector<shared_ptr<BhvImplBase>> & toUpdate)
+{
+	if (dirty)
+		return;
+
+	if (!needsUpdate(ctime))
+		return;
+
+	dirty = true;
+	toUpdate.push_back(shared_from_this());
+
+	bool prune = false;
+	for (const auto & w : rdepends) {
+		if (auto b = w.lock())
+			b->markDirty(ctime, toUpdate);
+		else
+			prune = true;
+	}
+
+	if (prune) {
+		decltype(rdepends) pruned;
+		for (const auto & w : rdepends)
+			if (!w.expired())
+				pruned.push_back(move(w));
+		rdepends = move(pruned);
+	}
+}
+
+void BhvImplBase::updateDirty(const BhvCurTime & ctime)
+{
+	if (!dirty)
+		return;
+
+	for (auto & d : depends)
+		d->updateDirty(ctime);
+
+	doUpdate(ctime);
+	dirty = false;
+
+	bool prune = false;
+	for (const auto & wcb : watchers) {
+		if (auto cb = wcb.lock())
+			(*cb)(ctime);
+		else
+			prune = true;
+	}
+
+	if (prune) {
+		decltype(watchers) pruned;
+		for (const auto & w : watchers)
+			if (!w.expired())
+				pruned.push_back(move(w));
+		watchers = move(pruned);
+	}
+}
+
+bool BhvImplBase::needsUpdate(const BhvCurTime &) const
+{
+	return true;
+}
+
+void BhvImplBase::doUpdate(const BhvCurTime &)
+{
+}