Add method to query sections

libs/ardour/ardour/location.h

@@ -298,6 +298,8 @@ public:
 	timepos_t first_mark_before (timepos_t const &, bool include_special_ranges = false);
 	timepos_t first_mark_after (timepos_t const &, bool include_special_ranges = false);
 
+	Location* next_section (Location*, timepos_t&, timepos_t&) const;
+
 	void marks_either_side (timepos_t const &, timepos_t &, timepos_t &) const;
 
 	/** Return range with closest start pos to the where argument

libs/ardour/location.cc

@@ -1568,6 +1568,72 @@ Locations::marks_either_side (timepos_t const & pos, timepos_t& before, timepos_
 	before = *i;
 }
 
+Location*
+Locations::next_section (Location* l, timepos_t& start, timepos_t& end) const
+{
+	vector<LocationPair> locs;
+	Location* session_range = NULL;
+	{
+		Glib::Threads::RWLock::ReaderLock lm (_lock);
+
+		for (auto const& i: locations) {
+			if (i->is_session_range ()) {
+				session_range = i;
+			} else if (i->is_section ()) {
+				locs.push_back (make_pair (i->start(), i));
+			}
+		}
+	}
+
+	LocationStartEarlierComparison cmp;
+	sort (locs.begin(), locs.end(), cmp);
+
+	if (session_range) {
+		if (locs.empty()) {
+			//locs.push_back (make_pair (session_range->start (), session_range));
+			locs.push_back (make_pair (session_range->end (), (ARDOUR::Location*)NULL));
+		} else {
+			if (locs.back().second->start () < session_range->end ()) {
+				locs.push_back (make_pair (session_range->end (), (ARDOUR::Location*)NULL));
+			}
+			if (locs.front().second->start () > session_range->start ()) {
+				//locs.insert (locs.begin (), make_pair (session_range->start (), session_range));
+			}
+		}
+	}
+
+	if (locs.size () < 2) {
+		return NULL;
+	}
+
+	/* special case fist element */
+	if (!l) {
+		l = locs[0].second;
+		start = locs[0].first;
+		end = locs[1].first;
+		return l;
+	}
+
+	Location* rv = NULL;
+	bool found = false;
+
+	for (auto const& i: locs) {
+		if (rv && found) {
+			end = i.first;
+			return rv;
+		}
+		else if (found) {
+			start = i.first;
+			rv    = i.second;
+		}
+		else if (i.second == l) {
+			found = true;
+		}
+	}
+
+	return NULL;
+}
+
 Location*
 Locations::session_range_location () const
 {

libs/ardour/luabindings.cc

@@ -1229,6 +1229,7 @@ LuaBindings::common (lua_State* L)
 		.addFunction ("remove", &Locations::remove)
 		.addRefFunction ("marks_either_side", &Locations::marks_either_side)
 		.addRefFunction ("find_all_between", &Locations::find_all_between)
+		.addRefFunction ("next_section", &Locations::next_section)
 		.endClass ()
 
 		.beginWSPtrClass <SessionObject> ("SessionObjectPtr")

share/scripts/s_sections.lua

@@ -0,0 +1,18 @@
+ardour { ["type"] = "Snippet", name = "List Sections" }
+function factory () return function ()
+
+	local s = Temporal.timepos_t(0)
+	local e = Temporal.timepos_t(0)
+	local loc = Session:locations ()
+
+	local l = nil
+	local cnt = 0
+	repeat
+		l, rv = loc:next_section (l, s, e)
+		if l ~= nil then
+			print (l:name (), rv[2], rv[3]);
+		end
+		cnt = cnt + 1
+	until (l == nil or cnt > 10)
+
+end end