Refactored code heavily to be able to use a state stack - main function now does the basic init, looping, and shutdown, and each state is a pointer to an object that has its own event handling, rendering, etc

Makefile

@@ -4,7 +4,7 @@ PROJECT=graphgame
 CXX=g++
 CXXFLAGS=-DDEBUG -g `sdl-config --cflags`
 LDFLAGS=`sdl-config --libs`
-OBJECTS=drawutils.o gamecore.o graph.o main.o mainevent.o mathutils.o gamedata.o sdlrenderer.o
+OBJECTS=drawutils.o game.o graph.o main.o mainevent.o mathutils.o gamedata.o sdlrenderer.o
 
 all: $(PROJECT)
 

game.cpp

@@ -0,0 +1,52 @@
+#include "game.h"
+#include "mathutils.h"
+#include "debug.h"
+#include <SDL.h>
+
+int Game::NODE_RADIUS = 12;
+
+Game::~Game()
+{
+    renderer.cleanup();
+}
+
+
+void Game::execute(stack<GameState*> &state_stack) throw(StateExit)
+{
+    SDL_Event event;
+    while(SDL_PollEvent(&event))
+	handle_event(&event);
+    renderer.render(data);
+}
+
+
+bool Game::init()
+{
+    return renderer.init();
+}
+
+
+void Game::on_exit()
+{
+    throw StateExit();
+}
+
+
+void Game::on_lbutton_down(int x, int y)
+{
+    data.do_vertex(x, y, NODE_RADIUS);
+}
+
+
+void Game::on_rbutton_down(int mX, int mY)
+{
+    data.clear_current_vertex();
+}
+
+
+void Game::on_key_down(SDLKey sym, SDLMod mod, Uint16 unicode)
+{
+    if (sym == SDLK_q && mod & KMOD_CTRL) throw StateExit();
+    if (sym == SDLK_a) data.set_mode(MODE_ATTACK);
+    if (sym == SDLK_m) data.set_mode(MODE_MOVE);
+}

game.h

@@ -1,23 +1,28 @@
-/* This is the heart of the application.
-   This contains the basic game looping code, sets up event handlers, etc.
+/* This is the heart of the application - the main game state where we are
+   actually playing.
 
-   All the hard work will eventually get farmed out to other objects, for now,
-   we're doing almost everything in here.
+   This contains the basic game logic.
  */
 
+#ifndef _GAME_H_
+#define _GAME_H_
 
-#ifndef _GAME_CORE_H_
-#define _GAME_CORE_H_
-
-#include "mainevent.h"
 #include "gamedata.h"
 #include "sdlrenderer.h"
+#include "gamestate.h"
+#include <stack>
 
-class GameCore : public MainEvent
+using std::stack;
+
+
+class Game : public GameState
 {
  public:
-    GameCore();
-    int execute();
+    Game() {}
+    ~Game();
+
+    bool init();
+    void execute(stack<GameState*> &state_stack) throw(StateExit);
 
  protected:
     // event handlers
@@ -26,14 +31,8 @@ class GameCore : public MainEvent
     void on_rbutton_down(int mX, int mY);
     void on_key_down(SDLKey sym, SDLMod mod, Uint16 unicode);
 
-
  private:
-    bool init();
-
     void render();
-    void cleanup();
-
-    bool is_running;
 
     SDLRenderer renderer;
 
@@ -44,5 +43,4 @@ class GameCore : public MainEvent
     static int MAX_MOVE_DISTANCE;
 };
 
-
 #endif

gamecore.cpp

@@ -1,71 +0,0 @@
-#include "gamecore.h"
-#include "mathutils.h"
-#include "debug.h"
-#include <SDL.h>
-
-int GameCore::NODE_RADIUS = 12;
-
-GameCore::GameCore()
-{
-    is_running = true;
-}
-
-int GameCore::execute()
-{
-    if (!init()) return 1;
-
-    SDL_Event event;
-
-    while (is_running)
-    {
-	while(SDL_PollEvent(&event))
-	    handle_event(&event);
-	//	iterate();
-	renderer.render(data);
-    }
-
-    cleanup();
-
-    return 0;
-}
-
-
-bool GameCore::init()
-{
-    if (SDL_Init(SDL_INIT_EVERYTHING) < 0) return false;
-    SDL_WM_SetCaption("TreeWars","TreeWars");
-    return renderer.init();
-}
-
-
-void GameCore::cleanup()
-{
-    renderer.cleanup();
-    SDL_Quit();
-}
-
-
-void GameCore::on_exit()
-{
-    is_running = false;
-}
-
-
-void GameCore::on_lbutton_down(int x, int y)
-{
-    data.do_vertex(x, y, NODE_RADIUS);
-}
-
-
-void GameCore::on_rbutton_down(int mX, int mY)
-{
-    data.clear_current_vertex();
-}
-
-
-void GameCore::on_key_down(SDLKey sym, SDLMod mod, Uint16 unicode)
-{
-    if (sym == SDLK_q && mod & KMOD_CTRL) is_running = false;
-    if (sym == SDLK_a) data.set_mode(MODE_ATTACK);
-    if (sym == SDLK_m) data.set_mode(MODE_MOVE);
-}

gamestate.h

@@ -0,0 +1,29 @@
+/* Abstract instance of a game state.
+   This contains the basic functions for game looping code,
+   and has a fully-functional event handler we can overload later
+ */
+
+#ifndef _GAME_STATE_H_
+#define _GAME_STATE_H_
+
+#include "mainevent.h"
+#include <exception>
+#include <stack>
+
+using std::exception;
+using std::stack;
+
+class StateExit : public exception {};
+
+class GameState : public MainEvent
+{
+ public:
+    GameState() {}
+    ~GameState() {}
+
+    virtual bool init() = 0;
+    virtual void execute(stack<GameState*> &game_state) throw(StateExit) = 0;
+};
+
+
+#endif

main.cpp

@@ -1,9 +1,43 @@
 /* Do basic initialization, get the loop going */
 
-#include "gamecore.h"
+#include "gamestate.h"
+#include "game.h"
+#include <SDL.h>
 
-int main()
+int main(int argc, char** argv)
 {
-    GameCore game_core;
-    return game_core.execute();
+    // Barebones setup for our game
+    if (SDL_Init(SDL_INIT_EVERYTHING) < 0) return false;
+    SDL_WM_SetCaption("TreeWars","TreeWars");
+
+    stack<GameState*> state_stack;
+
+    // initialize the stack by initting and pushing the initial state(s)
+    GameState* tmpstate = new Game();
+    if (!tmpstate->init()) exit(1);
+    state_stack.push(tmpstate);
+
+    while (!state_stack.empty())
+    {
+	GameState* state = state_stack.top();
+	try {
+	    state->execute(state_stack);
+	} catch (StateExit& e) {
+
+	    // remove the old state
+	    state_stack.pop();
+	    delete state;
+	    
+	    // init the new state, discarding it if we fail
+	    while (!(state_stack.empty() || state_stack.top()->init()))
+	    {
+		state_stack.pop();
+		delete state;
+	    }
+	}
+    }
+
+    SDL_Quit();
+
+    return 0;
 }