Save exists functionality.

chapter-11-loadsave/src/components.rs

@@ -123,8 +123,6 @@ pub struct WantsToDropItem {
 
 pub struct SerializeMe;
 
-
-
 // WantsToMelee wrapper
 #[derive(Serialize, Deserialize, Clone)]
 pub struct WantsToMeleeData<M>(M);

chapter-11-loadsave/src/gui.rs

@@ -221,6 +221,7 @@ pub enum MainMenuSelection { NewGame, LoadGame, Quit }
 pub enum MainMenuResult { NoSelection{ selected : MainMenuSelection }, Selected{ selected: MainMenuSelection } }
 
 pub fn main_menu(gs : &mut State, ctx : &mut Rltk) -> MainMenuResult {
+    let save_exists = super::saveload_system::does_save_exist();
     let runstate = gs.ecs.fetch::<RunState>();
 
     ctx.print_color_centered(15, RGB::named(rltk::YELLOW), RGB::named(rltk::BLACK), "Rust Roguelike Tutorial");
@@ -232,10 +233,12 @@ pub fn main_menu(gs : &mut State, ctx : &mut Rltk) -> MainMenuResult {
             ctx.print_color_centered(24, RGB::named(rltk::WHITE), RGB::named(rltk::BLACK), "Begin New Game");
         }
 
-        if selection == MainMenuSelection::LoadGame {
-            ctx.print_color_centered(25, RGB::named(rltk::MAGENTA), RGB::named(rltk::BLACK), "Load Game");
-        } else {
-            ctx.print_color_centered(25, RGB::named(rltk::WHITE), RGB::named(rltk::BLACK), "Load Game");
+        if save_exists {
+            if selection == MainMenuSelection::LoadGame {
+                ctx.print_color_centered(25, RGB::named(rltk::MAGENTA), RGB::named(rltk::BLACK), "Load Game");
+            } else {
+                ctx.print_color_centered(25, RGB::named(rltk::WHITE), RGB::named(rltk::BLACK), "Load Game");
+            }
         }
 
         if selection == MainMenuSelection::Quit {
@@ -250,21 +253,27 @@ pub fn main_menu(gs : &mut State, ctx : &mut Rltk) -> MainMenuResult {
                 match key {
                     VirtualKeyCode::Escape => { return MainMenuResult::NoSelection{ selected: MainMenuSelection::Quit } }
                     VirtualKeyCode::Up => {
-                        let newselection;
+                        let mut newselection;
                         match selection {
                             MainMenuSelection::NewGame => newselection = MainMenuSelection::Quit,
                             MainMenuSelection::LoadGame => newselection = MainMenuSelection::NewGame,
                             MainMenuSelection::Quit => newselection = MainMenuSelection::LoadGame
                         }
+                        if newselection == MainMenuSelection::LoadGame && !save_exists {
+                            newselection = MainMenuSelection::NewGame;
+                        }
                         return MainMenuResult::NoSelection{ selected: newselection }
                     }
                     VirtualKeyCode::Down => {
-                        let newselection;
+                        let mut newselection;
                         match selection {
                             MainMenuSelection::NewGame => newselection = MainMenuSelection::LoadGame,
                             MainMenuSelection::LoadGame => newselection = MainMenuSelection::Quit,
                             MainMenuSelection::Quit => newselection = MainMenuSelection::NewGame
                         }
+                        if newselection == MainMenuSelection::LoadGame && !save_exists {
+                            newselection = MainMenuSelection::Quit;
+                        }
                         return MainMenuResult::NoSelection{ selected: newselection }
                     }
                     VirtualKeyCode::Return => return MainMenuResult::Selected{ selected : selection },

chapter-11-loadsave/src/main.rs

@@ -29,7 +29,7 @@ mod gamelog;
 mod spawner;
 mod inventory_system;
 use inventory_system::{ ItemCollectionSystem, ItemUseSystem, ItemDropSystem };
-mod saveload_system;
+pub mod saveload_system;
 
 #[derive(PartialEq, Copy, Clone)]
 pub enum RunState { AwaitingInput, 

chapter-11-loadsave/src/saveload_system.rs

@@ -4,6 +4,7 @@ use specs::error::NoError;
 use super::components::*;
 use std::fs::File;
 use std::io::Write;
+use std::path::Path;
 
 macro_rules! serialize_individually {
     ($ecs:expr, $ser:expr, $data:expr, $( $type:ty),*) => {
@@ -29,4 +30,8 @@ pub fn save_game(ecs : &World) {
         AreaOfEffect, Confusion, ProvidesHealing, InBackpack, WantsToPickupItem, WantsToUseItem,
         WantsToDropItem
     );
+}
+
+pub fn does_save_exist() -> bool {
+    Path::new("./savegame.json").exists()
 }