implement mementos snapshots

12 files changed, 163 insertions, 13 deletions

diff --git a/ArtistData.h b/ArtistData.h
index 1c3c88c..1a75842 100644
--- a/ArtistData.h
+++ b/ArtistData.h
@@ -1,5 +1,7 @@
 #pragma once
 
+#include "Memento.h"
+
 struct ArtistData {
 	float x = 0.0;
 	float y = 0.0;
@@ -7,3 +9,12 @@ struct ArtistData {
 	float vy = 0.0;
 };
 
+class ArtistDataMemento : public Memento {
+	friend class People;
+
+public:
+	ArtistDataMemento(const ArtistData & data) : data(data) {}
+private:
+	ArtistData data;
+};
+
diff --git a/Canvas.cpp b/Canvas.cpp
index b7cc8a5..86b5bec 100644
--- a/Canvas.cpp
+++ b/Canvas.cpp
@@ -109,3 +109,26 @@ void Canvas::update_tiles() {
 	}
 }
 
+Memories Canvas::save() {
+	Memories data;
+	data.push_back(make_unique<CanvasDataMemento>(this->data));
+	for (Tile * tile : this->tiles) {
+		data.push_back(make_unique<TileDataMemento>(tile->data));
+	}
+	return data;
+}
+
+void Canvas::restore(const Memories & memories) {
+	for (const unique_ptr<Memento> & memory : memories) {
+		auto canvas = dynamic_cast<CanvasDataMemento *>(memory.get());
+		if (canvas != nullptr) {
+			this->set_data(canvas->data);
+		}
+
+		auto tile = dynamic_cast<TileDataMemento *>(memory.get());
+		if (tile != nullptr) {
+			this->set_tile(tile->data);
+		}
+	}
+}
+
diff --git a/Canvas.h b/Canvas.h
index b602fb2..294b335 100644
--- a/Canvas.h
+++ b/Canvas.h
@@ -28,6 +28,10 @@ public:
 	void set_data(CanvasData data);
 
 public:
+	Memories save();
+	void restore(const Memories &);
+
+public:
 	TileColorFactory tile_color;
 	TileBehaviorFactory tile_behavior;
 
diff --git a/CanvasData.h b/CanvasData.h
index d2b0666..69e8c8c 100644
--- a/CanvasData.h
+++ b/CanvasData.h
@@ -1,7 +1,18 @@
 #pragma once
 
+#include "Memento.h"
+
 struct CanvasData {
 	unsigned rows = 0;
 	unsigned columns = 0;
 };
 
+class CanvasDataMemento : public Memento {
+	friend class Canvas;
+
+public:
+	CanvasDataMemento(const CanvasData & data) : data(data) {}
+private:
+	CanvasData data;
+};
+
diff --git a/Memento.h b/Memento.h
new file mode 100644
index 0000000..0bc6c92
--- /dev/null
+++ b/Memento.h
@@ -0,0 +1,13 @@
+#pragma once
+
+#include <vector>
+#include <memory>
+
+class Memento {
+public:
+	Memento() = default;
+	virtual ~Memento() = default;
+};
+
+typedef std::vector<std::unique_ptr<Memento>> Memories;
+
diff --git a/Museum.cpp b/Museum.cpp
index 4a12038..d389602 100644
--- a/Museum.cpp
+++ b/Museum.cpp
@@ -20,22 +20,39 @@ void Museum::update() {
 	this->canvas.update();
 	this->collision.update();
 	this->tick++;
+
+	unsigned long long next_snapshot = this->snapshot_ticks;
+	if (!this->history.empty()) next_snapshot += this->history.top().tick;
+	if (next_snapshot > this->tick) return;
+	this->history.push(this->save_snapshot());
+	printf("saved snapshot at tick %llu\n", this->tick);
 }
 
 void Museum::skip_forward() {
-	this->jump += this->snapshot_ticks;
+	this->jump++;
 }
-
 void Museum::skip_backward() {
-
+	this->jump--;
 }
 
 void Museum::work() {
 	while (this->working) {
-		// immediately process forward jumps, even if paused
+		// immediately process jumps, even if paused
 		if (this->jump > 0) {
-			for (; this->jump != 0; this->jump--)
-				this->update();
+			// forward jump
+			for (; this->jump != 0; this->jump--) {
+				printf("jumping forward %u ticks\n", this->snapshot_ticks);
+				for (size_t i = 0; i < this->snapshot_ticks; i++)
+					this->update();
+			}
+		} else if (this->jump < 0) {
+			// backward jump
+			for (; this->jump != 0; this->jump++) {
+				if (this->history.empty()) continue;
+				printf("restoring snapshot from tick %llu\n", this->history.top().tick);
+				this->restore_snapshot(this->history.top());
+				this->history.pop();
+			}
 		}
 
 		// wait with regular update if paused
@@ -48,3 +65,23 @@ void Museum::work() {
 	}
 }
 
+static void memories_concat(Memories & a, Memories b) {
+	a.insert(a.end(), make_move_iterator(b.begin()), make_move_iterator(b.end()));
+}
+
+Museum::Snapshot Museum::save_snapshot() {
+	Snapshot snapshot = {
+		.tick = this->tick,
+		.memories = {},
+	};
+	memories_concat(snapshot.memories, this->canvas.save());
+	memories_concat(snapshot.memories, this->people.save());
+	return snapshot;
+}
+
+void Museum::restore_snapshot(const Snapshot & snapshot) {
+	this->tick = snapshot.tick;
+	this->canvas.restore(snapshot.memories);
+	this->people.restore(snapshot.memories);
+}
+
diff --git a/Museum.h b/Museum.h
index 27e7915..bc5b590 100644
--- a/Museum.h
+++ b/Museum.h
@@ -2,6 +2,7 @@
 
 #include <thread>
 #include <chrono>
+#include <stack>
 
 #include "People.h"
 #include "Canvas.h"
@@ -28,7 +29,7 @@ public:
 	void skip_backward();
 
 private:
-	unsigned long jump = 0;
+	int jump = 0;
 
 private:
 	bool working = true;
@@ -37,7 +38,16 @@ private:
 
 private:
 	unsigned long long tick = 0;
-	static constexpr unsigned snapshot_ticks = 50;
 	static constexpr std::chrono::milliseconds tick_interval = 15ms;
+
+private:
+	static constexpr unsigned snapshot_ticks = 50;
+	struct Snapshot {
+		unsigned long long tick;
+		Memories memories;
+	};
+	std::stack<Snapshot, std::vector<Snapshot>> history;
+	Snapshot save_snapshot();
+	void restore_snapshot(const Snapshot &);
 };
 
diff --git a/People.cpp b/People.cpp
index 39d44db..d11434d 100644
--- a/People.cpp
+++ b/People.cpp
@@ -1,6 +1,8 @@
 #include <algorithm>
+#include <memory>
 
 #include "People.h"
+#include "ArtistData.h"
 #include "util.h"
 
 using namespace std;
@@ -50,3 +52,21 @@ void People::update(bool tick) {
 	}
 }
 
+Memories People::save() {
+	Memories data;
+	for (Artist * artist : this->artists) {
+		data.push_back(make_unique<ArtistDataMemento>(artist->data));
+	}
+	return data;
+}
+
+void People::restore(const Memories & memories) {
+	this->artists.clear();
+	this->artist_count = 0;
+	for (const unique_ptr<Memento> & memory : memories) {
+		auto data = dynamic_cast<ArtistDataMemento *>(memory.get());
+		if (data == nullptr) continue;
+		this->add_artist(data->data);
+	}
+}
+
diff --git a/People.h b/People.h
index 940a6d5..83516c9 100644
--- a/People.h
+++ b/People.h
@@ -22,6 +22,10 @@ public:
 
 	void update(bool tick = true);
 
+public:
+	Memories save();
+	void restore(const Memories &);
+
 private:
 	std::forward_list<Artist *> artists;
 	size_t artist_count = 0;
diff --git a/TileData.h b/TileData.h
index 87d9003..314466c 100644
--- a/TileData.h
+++ b/TileData.h
@@ -2,9 +2,20 @@
 
 #include <string>
 
+#include "Memento.h"
+
 struct TileData {
 	unsigned int x = 0;
 	unsigned int y = 0;
 	std::string type = "";
 };
 
+class TileDataMemento : public Memento {
+	friend class Canvas;
+
+public:
+	TileDataMemento(const TileData & data) : data(data) {}
+private:
+	TileData data;
+};
+
diff --git a/docs/class-diag.puml b/docs/class-diag.puml
index 9ce43eb..f695ed3 100644
--- a/docs/class-diag.puml
+++ b/docs/class-diag.puml
@@ -111,7 +111,7 @@ rectangle Group_Collisions as "Collisions" <<group>> {
 		--
 		- museum : Museum &
 	}
-	class CollisionChecker <<abstract>> {
+	abstract class CollisionChecker {
 		+ CollisionChecker(Museum &)
 		+ check() <<pure virtual>>
 		--
@@ -169,7 +169,7 @@ rectangle Group_Pathfinding as "Pathfinding" <<group>> {
 		--
 		- museum : Museum &
 	}
-  class Pathfinder <<abstract>> {
+	abstract class Pathfinder {
 		+ Pathfinder(Museum &)
 		+ find_between(const XY &, const XY &) <<pure virtual>
 		--
@@ -260,6 +260,9 @@ rectangle Group_Model as "Model" <<group>> {
 		- artist_count : size_t
 		- museum : Museum &
 	}
+	interface Memento {
+	}
+	People -r[hidden] Canvas
 	}
 	together {
 	class Tile {
@@ -383,6 +386,10 @@ rectangle Group_Model as "Model" <<group>> {
 	Tile --> "state" TileBehavior
 	Tile .[norank].> TileBehaviorFactory
 
+	Memento <|.[norank]. TileData
+	Memento <|.[norank]. ArtistData
+	Memento <|.[norank]. CanvasData
+
 	' LAYOUT
 	Artist -r[hidden] Tile
 }
diff --git a/readme.md b/readme.md
index 309abed..42c9aaf 100644
--- a/readme.md
+++ b/readme.md
@@ -1,6 +1,5 @@
 # TODO
 
-DPA:
-
-- state snapshots (memento)
+- update class diagram
+- triple check class diagram