From d051af7264ee62d03473f1929414e262e918c30a Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Fri, 9 Aug 2013 13:30:30 +0300
Subject: [PATCH] Reserve enough blocks for the entire train when placing

---
 source/libr2c2/blockallocator.cpp | 44 +++++++++++++++++++++++++++++--
 source/libr2c2/blockallocator.h   |  2 +-
 source/libr2c2/train.cpp          | 18 +++++++++----
 source/libr2c2/train.h            |  2 +-
 4 files changed, 57 insertions(+), 9 deletions(-)

diff --git a/source/libr2c2/blockallocator.cpp b/source/libr2c2/blockallocator.cpp
index 547415a..2e81677 100644
--- a/source/libr2c2/blockallocator.cpp
+++ b/source/libr2c2/blockallocator.cpp
@@ -60,13 +60,53 @@ void BlockAllocator::set_active(bool a)
 	}
 }
 
-void BlockAllocator::start_from(const BlockIter &block)
+bool BlockAllocator::start_from(const BlockIter &block)
 {
 	if(!block)
 		throw invalid_argument("BlockAllocator::start_from");
 
+	float remaining_length = 0;
+	unsigned n_vehs = train.get_n_vehicles();
+	for(unsigned i=0; i<n_vehs; ++i)
+		remaining_length += train.get_vehicle(i).get_type().get_length();
+
 	clear();
-	reserve_block(block);
+
+	BlockList blocks_to_reserve;
+	for(BlockIter b=block; b; b=b.next())
+	{
+		if(b->get_train())
+			break;
+		blocks_to_reserve.push_back(b);
+		for(TrackIter t=b.track_iter(); (t && &t->get_block()==&*b); t=t.next())
+			remaining_length -= t->get_type().get_path_length(t->get_active_path());
+		if(remaining_length<=0)
+			break;
+	}
+
+	if(remaining_length>0)
+		return false;
+
+	for(BlockList::iterator i=blocks_to_reserve.begin(); i!=blocks_to_reserve.end(); ++i)
+	{
+		blocks.push_back(*i);
+		try
+		{
+			(*i)->reserve(&train);
+		}
+		catch(...)
+		{
+			blocks.pop_back();
+			while(i!=blocks_to_reserve.begin())
+			{
+				blocks.pop_back();
+				(*--i)->reserve(0);
+			}
+			throw;
+		}
+	}
+
+	return true;
 }
 
 void BlockAllocator::rewind_to(const Block &block)
diff --git a/source/libr2c2/blockallocator.h b/source/libr2c2/blockallocator.h
index f5af90e..fe05603 100644
--- a/source/libr2c2/blockallocator.h
+++ b/source/libr2c2/blockallocator.h
@@ -48,7 +48,7 @@ public:
 	void set_active(bool);
 	bool is_active() const { return active; }
 
-	void start_from(const BlockIter &);
+	bool start_from(const BlockIter &);
 	void rewind_to(const Block &);
 	void clear();
 	bool empty() const { return blocks.empty(); }
diff --git a/source/libr2c2/train.cpp b/source/libr2c2/train.cpp
index 95b78b5..07461b8 100644
--- a/source/libr2c2/train.cpp
+++ b/source/libr2c2/train.cpp
@@ -185,21 +185,29 @@ void Train::ai_message(const TrainAI::Message &msg)
 		(*i)->message(msg);
 }
 
-void Train::place(const BlockIter &block)
+bool Train::place(const BlockIter &block)
 {
 	if(!block)
 		throw invalid_argument("Train::place");
 	if(controller->get_speed())
 		throw logic_error("moving");
 
-	allocator.start_from(block);
 	accurate_position = false;
 	last_entry_block = BlockIter();
 
-	if(reverse)
-		vehicles.front()->place(block.reverse().track_iter(), VehiclePlacement::FRONT_BUFFER);
+	if(allocator.start_from(block))
+	{
+		if(reverse)
+			vehicles.front()->place(block.reverse().track_iter(), VehiclePlacement::FRONT_BUFFER);
+		else
+			vehicles.back()->place(block.track_iter(), VehiclePlacement::BACK_BUFFER);
+		return true;
+	}
 	else
-		vehicles.back()->place(block.track_iter(), VehiclePlacement::BACK_BUFFER);
+	{
+		unplace();
+		return false;
+	}
 }
 
 void Train::unplace()
diff --git a/source/libr2c2/train.h b/source/libr2c2/train.h
index 3aaf6b1..340537a 100644
--- a/source/libr2c2/train.h
+++ b/source/libr2c2/train.h
@@ -112,7 +112,7 @@ public:
 		return 0;
 	}
 
-	void place(const BlockIter &);
+	bool place(const BlockIter &);
 	void unplace();
 	bool is_placed() const { return !allocator.empty(); }
 	void stop_at(Block *);
-- 
2.45.2