Implement "resume reload" command.

When resuming, you can pass "reload" as the argument, which causes the
cart's code to be reloaded before resuming the game.

This allows for a much smoother iterative development style where you
can pause the game, make changes, and see the effect of those changes
without restarting the game. It does require some special handling in
the cart to support saving state to a global and avoiding that state
being reinitialized if it's already set; for instance:

    state = state or {x=25, y=100, shots={}}

This implements the reload method for the Lua and Fennel scripts, but
it will need to be implemented for other scripts independently.

Author: technomancy

src/api/fennel.c

@@ -38,6 +38,31 @@ static const char* execute_fennel_src = FENNEL_CODE(
   if(not ok) then return msg end
 );
 
+static bool loadFennelCode(tic_mem* tic, const char* code)
+{
+    tic_core* core = (tic_core*)tic;
+    lua_State* fennel = core->currentVM;
+
+    if (luaL_loadbuffer(fennel, execute_fennel_src,
+                        strlen(execute_fennel_src), "execute_fennel") != LUA_OK)
+    {
+        core->data->error(core->data->data, "failed to load fennel shim");
+        return false;
+    }
+
+    lua_pushstring(fennel, code);
+    lua_call(fennel, 1, 1);
+    const char* err = lua_tostring(fennel, -1);
+
+    if (err)
+    {
+        core->data->error(core->data->data, err);
+        return false;
+    } else {
+      return true;
+    }
+}
+
 static bool initFennel(tic_mem* tic, const char* code)
 {
     tic_core* core = (tic_core*)tic;
@@ -48,38 +73,25 @@ static bool initFennel(tic_mem* tic, const char* code)
 
     luaapi_init(core);
 
-    {
-        lua_State* fennel = core->currentVM;
-
-        lua_settop(fennel, 0);
-
-        if (luaL_loadbuffer(fennel, (const char *)loadfennel_lua,
-                            loadfennel_lua_len, "fennel.lua") != LUA_OK)
-        {
-            core->data->error(core->data->data, "failed to load fennel compiler");
-            return false;
-        }
+    lua_State* fennel = core->currentVM;
 
-        lua_call(fennel, 0, 0);
+    lua_settop(fennel, 0);
 
-        if (luaL_loadbuffer(fennel, execute_fennel_src, strlen(execute_fennel_src), "execute_fennel") != LUA_OK)
-        {
-            core->data->error(core->data->data, "failed to load fennel compiler");
-            return false;
-        }
+    if (luaL_loadbuffer(fennel, (const char *)loadfennel_lua,
+                        loadfennel_lua_len, "fennel.lua") != LUA_OK)
+    {
+        core->data->error(core->data->data, "failed to load fennel compiler");
+        return false;
+    }
 
-        lua_pushstring(fennel, code);
-        lua_call(fennel, 1, 1);
-        const char* err = lua_tostring(fennel, -1);
+    lua_call(fennel, 0, 0);
 
-        if (err)
-        {
-            core->data->error(core->data->data, err);
-            return false;
-        }
-    }
+    return loadFennelCode(tic, code);
+}
 
-    return true;
+static bool reloadFennel(tic_mem* tic)
+{
+    return loadFennelCode(tic, tic->cart.code.data);
 }
 
 static const char* const FennelKeywords [] =
@@ -195,6 +207,7 @@ TIC_EXPORT const tic_script EXPORT_SCRIPT(Fennel) =
     .projectComment     = ";;",
     {
       .init               = initFennel,
+      .reload             = reloadFennel,
       .close              = luaapi_close,
       .tick               = luaapi_tick,
       .boot               = luaapi_boot,

src/api/lua.c

@@ -55,6 +55,20 @@ static bool initLua(tic_mem* tic, const char* code)
     return true;
 }
 
+static bool reloadLua(tic_mem* tic)
+{
+    tic_core* core = (tic_core*)tic;
+    lua_State* lua = core->currentVM;
+    const char* code = tic->cart.code.data;
+
+    if(luaL_loadstring(lua, code) != LUA_OK || lua_pcall(lua, 0, LUA_MULTRET, 0) != LUA_OK)
+    {
+        core->data->error(core->data->data, lua_tostring(lua, -1));
+        return false;
+    }
+    return true;
+}
+
 static const char* const LuaKeywords [] =
 {
     "and", "break", "do", "else", "elseif",
@@ -214,6 +228,7 @@ TIC_EXPORT const tic_script EXPORT_SCRIPT(Lua) =
     .projectComment     = "--",
     {
       .init               = initLua,
+      .reload             = reloadLua,
       .close              = luaapi_close,
       .tick               = luaapi_tick,
       .boot               = luaapi_boot,

src/script.h

@@ -33,6 +33,7 @@ struct tic_script
     struct
     {
         bool(*init)(tic_mem* memory, const char* code);
+        bool(*reload)(tic_mem* memory);
         void(*close)(tic_mem* memory);
 
         tic_tick tick;

src/studio/screens/console.c

@@ -2667,6 +2667,23 @@ static void onRunCommand(Console* console)
 
 static void onResumeCommand(Console* console)
 {
+    if(console->desc->count)
+    {
+        const char* param = console->desc->params->key;
+
+        if(strcmp(param, "reload") == 0)
+        {
+            const tic_script* script_config = tic_get_script(console->tic);
+            if (script_config->reload)
+            {
+                script_config->reload(console->tic);
+            }
+            else
+            {
+                printError(console, "reload not implemented for the script");
+            }
+        }
+    }
     commandDone(console);
 
     resumeGame(console->studio);