* Fixed crash on closing MIDI automation tracks, because ARDOUR::Parameter::operator< violated strict weak ordering,

  which is necessary for std::set to work correctly
* few small style guide corrections


git-svn-id: svn://localhost/ardour2/branches/3.0@3363 d708f5d6-7413-0410-9779-e7cbd77b26cf

2 files changed, 66 insertions, 12 deletions

diff --git a/libs/ardour/ardour/midi_ring_buffer.h b/libs/ardour/ardour/midi_ring_buffer.h
index baa8e9d948..76cefd57a1 100644
--- a/libs/ardour/ardour/midi_ring_buffer.h
+++ b/libs/ardour/ardour/midi_ring_buffer.h
@@ -141,13 +141,15 @@ template<typename T>
 bool
 MidiRingBufferBase<T>::full_peek(size_t size, T* dst)
 {
-	if (read_space() < size)
+	if (read_space() < size) {
 		return false;
+	}
 
 	const size_t read_size = peek(size, dst);
 	
-	if (read_size < size)
+	if (read_size < size) {
 		peek(size - read_size, dst + read_size);
+	}
 
 	return true;
 }
@@ -181,13 +183,15 @@ template<typename T>
 bool
 MidiRingBufferBase<T>::full_read(size_t size, T* dst)
 {
-	if (read_space() < size)
+	if (read_space() < size) {
 		return false;
+	}
 
 	const size_t read_size = read(size, dst);
 	
-	if (read_size < size)
+	if (read_size < size) {
 		read(size - read_size, dst + read_size);
+	}
 
 	return true;
 }
@@ -292,11 +296,14 @@ inline bool
 MidiRingBuffer::read(double* time, size_t* size, Byte* buf)
 {
 	bool success = MidiRingBufferBase<Byte>::full_read(sizeof(double), (Byte*)time);
-	if (success)
+	
+	if (success) {
 		success = MidiRingBufferBase<Byte>::full_read(sizeof(size_t), (Byte*)size);
-	if (success)
+	}
+	if (success) {
 		success = MidiRingBufferBase<Byte>::full_read(*size, buf);
-
+	}
+	
 	return success;
 }
 
@@ -308,8 +315,9 @@ inline bool
 MidiRingBuffer::read_prefix(double* time, size_t* size)
 {
 	bool success = MidiRingBufferBase<Byte>::full_read(sizeof(double), (Byte*)time);
-	if (success)
+	if (success) {
 		success = MidiRingBufferBase<Byte>::full_read(sizeof(size_t), (Byte*)size);
+	}
 
 	return success;
 }
@@ -338,8 +346,9 @@ MidiRingBuffer::write(double time, size_t size, const Byte* buf)
 	// Don't write event if it doesn't match channel filter
 	if (is_channel_event(buf[0]) && get_channel_mode() == FilterChannels) {
 		Byte channel = buf[0] & 0x0F;
-		if ( !(get_channel_mask() & (1L << channel)) )
+		if ( !(get_channel_mask() & (1L << channel)) ) {
 			return 0;
+		}
 	}
 
 	if (write_space() < (sizeof(double) + sizeof(size_t) + size)) {
@@ -388,8 +397,9 @@ MidiRingBuffer::read(MidiBuffer& dst, nframes_t start, nframes_t end, nframes_t
 	
 		full_peek(sizeof(double), (Byte*)&ev_time);
 	
-		if (ev_time > end)
+		if (ev_time > end) {
 			break;
+		}
 		
 		bool success = MidiRingBufferBase<Byte>::full_read(sizeof(double), (Byte*)&ev_time);
 		if (success) {
diff --git a/libs/ardour/ardour/parameter.h b/libs/ardour/ardour/parameter.h
index a795ee0eaa..b86174aa0a 100644
--- a/libs/ardour/ardour/parameter.h
+++ b/libs/ardour/ardour/parameter.h
@@ -58,17 +58,61 @@ public:
 	inline uint32_t       id()      const { return _id; }
 	inline uint8_t        channel() const { return _channel; }
 
+	/**
+	 * Equivalence operator
+	 * It is obvious from the definition that this operator
+	 * is transitive, as required by stict weak ordering
+	 * (see: http://www.sgi.com/tech/stl/StrictWeakOrdering.html)
+	 */
 	inline bool operator==(const Parameter& id) const {
 		return (_type == id._type && _id == id._id && _channel == id._channel);
 	}
 	
-	/** Arbitrary but fixed ordering (for use in e.g. std::map) */
+	/** Strict weak ordering 
+	 * (see: http://www.sgi.com/tech/stl/StrictWeakOrdering.html)  
+	 * This is necessary so that std::set works): 
+	 * Sort Parameters first according to type then to id and lastly to channel.
+	 *  
+	 * Proof:
+	 * <ol>
+	 * <li>Irreflexivity: f(x, x) is false because of the irreflexivity of \c < in each branch.</li>
+	 * 
+	 * <li>Antisymmetry: given x != y, f(x, y) implies !f(y, x) because of the same 
+	 *     property of \c < in each branch and the symmetry of operator==. </li>
+	 * 
+	 * <li>Transitivity: let f(x, y) and f(y, z) be true. We prove by assuming the contrary,
+	 *     that f(x, z) does not hold. 
+	 *    That would imply exactly one of the following:
+	 * 	  <ol>
+	 *      <li> x == z which contradicts the assumption f(x, y) and f(y, x)
+	 *                 because of antisymmetry.
+	 *      </li>
+	 *      <li> f(z, x) is true. That would imply that one of the ivars (we call it i) 
+	 *           of x is greater than the same ivar in z while all "previous" ivars
+	 *           are equal. That would imply that also in y all those "previous"
+	 *           ivars are equal and because if x.i > z.i it is impossible
+	 *           that there is an y that satisfies x.i < y.i < z.i at the same
+	 *           time which contradicts the assumption.
+	 *      </li>
+	 *    </ol> 
+	 * </li>
+	 * </ol>
+	 */
+	
 	inline bool operator<(const Parameter& id) const {
 #ifndef NDEBUG
 		if (_type == NullAutomation)
 			PBD::warning << "Uninitialized Parameter compared." << endmsg;
 #endif
-		return (_channel < id._channel || _type < id._type || _id < id._id);
+		if (_type < id._type) {
+			return true;
+		} else if (_type == id._type && _id < id._id) {
+			return true;
+		} else if (_id == id._id && _channel < id._channel) {
+			return true;
+		}
+		
+		return false;
 	}
 	
 	inline operator bool() const { return (_type != 0); }