# HG changeset patch
# User Hasan Yavuz ÖZDERYA <hy@ozderya.net>
# Date 2017-12-19 10:13:34
# Node ID 46213689acd3a1869f9261e3d74d0ef86461c71f
# Parent  90a919d06a7705a38d8c01391c7b7b3e6e9e67ba

sink stores pointer to connected source

diff --git a/src/sink.cpp b/src/sink.cpp
--- a/src/sink.cpp
+++ b/src/sink.cpp
@@ -50,3 +50,14 @@ void Sink::setNumChannels(unsigned nc, b
         sink->setNumChannels(nc, x);
     }
 }
+
+void Sink::setSource(const Source* s)
+{
+    Q_ASSERT((source == NULL) != (s == NULL));
+    source = s;
+}
+
+const Source* Sink::connectedSource() const
+{
+    return source;
+}
diff --git a/src/sink.h b/src/sink.h
--- a/src/sink.h
+++ b/src/sink.h
@@ -34,6 +34,8 @@ public:
     /// Disconnects a follower. Disconnecting an unconnected sink is
     /// an error.
     void disconnectFollower(Sink* sink);
+    /// Returns the connected source. `NULL` if it's not connected.
+    const Source* connectedSource() const;
 
 protected:
     /// Entry point for incoming data. Re-implementations should
@@ -46,11 +48,18 @@ protected:
     virtual bool hasX() const = 0;
     /// Returns number of channels
     virtual unsigned numChannels() const = 0;
+    /// Set by the connected source when its connected. When
+    /// disconnecting it's set to `NULL`.
+    ///
+    /// @important Trying to connect a source while its already
+    /// connected is an error.
+    void setSource(const Source* s);
 
     friend Source;
 
 private:
     QList<Sink*> followers;
+    const Source* source = NULL;   ///< source that this sink is connected to
 };
 
 #endif // SINK_H
diff --git a/src/source.cpp b/src/source.cpp
--- a/src/source.cpp
+++ b/src/source.cpp
@@ -24,15 +24,19 @@
 void Source::connect(Sink* sink)
 {
     Q_ASSERT(!sinks.contains(sink));
+    Q_ASSERT(sink->connectedSource() == NULL);
 
     sinks.append(sink);
+    sink->setSource(this);
     sink->setNumChannels(numChannels(), hasX());
 }
 
 void Source::disconnect(Sink* sink)
 {
     Q_ASSERT(sinks.contains(sink));
+    Q_ASSERT(sink->connectedSource() == this);
 
+    sink->setSource(NULL);
     sinks.removeOne(sink);
 }
 
diff --git a/tests/test.cpp b/tests/test.cpp
--- a/tests/test.cpp
+++ b/tests/test.cpp
@@ -123,6 +123,12 @@ TEST_CASE("sink", "[memory, stream]")
     REQUIRE(follower.hasX() == true);
 }
 
+TEST_CASE("sink must be created unconnected", "[memory, stream]")
+{
+    TestSink sink;
+    REQUIRE(sink.connectedSource() == NULL);
+}
+
 class TestSource : public Source
 {
 public:
@@ -185,6 +191,18 @@ TEST_CASE("source", "[memory, stream]")
     REQUIRE(sink.totalFed == 100);
 }
 
+TEST_CASE("source must set/unset sink 'source'", "[memory, stream]")
+{
+    TestSink sink;
+    TestSource source(3, false);
+
+    source.connect(&sink);
+    REQUIRE(sink.connectedSource() == &source);
+
+    source.disconnect(&sink);
+    REQUIRE(sink.connectedSource() == NULL);
+}
+
 TEST_CASE("IndexBuffer", "[memory, buffer]")
 {
     IndexBuffer buf(10);