use macros to create monsters

macros/Cargo.toml

@@ -0,0 +1,17 @@
+[package]
+name = "macros"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+[lib]
+name = "macros"
+path = "src/lib.rs"
+proc-macro = true
+
+
+[dependencies]
+syn = "2.0.85"
+quote = "1.0.37"
+proc-macro2 = "1.0.89"
+darling= "0.20.10"

macros/src/lib.rs

@@ -0,0 +1,58 @@
+extern crate proc_macro;
+
+use proc_macro::TokenStream;
+use quote::quote;
+
+
+#[proc_macro_derive(CreateMonsters)]
+pub fn create_monsters(input: TokenStream) -> TokenStream {
+    let input = syn::parse_macro_input!(input as syn::File);
+    let (enum_item, _) = match &input.items[0] {
+        syn::Item::Enum(enum_item) => (enum_item, &enum_item.attrs),
+        _ => panic!("must be an enum"),
+    };
+
+    let structs = enum_item.variants.iter().map(|variant| {
+        let variant_name = &variant.ident;
+
+        let t = quote! {
+        pub struct #variant_name {
+            name: String,
+            life: usize,
+            position: Position,
+            symbol: String,
+            color: Color,
+            experience_gain: usize,
+            ticks_between_steps: u128,
+            damage_range: RangeInclusive<usize>,
+        }
+        impl Monster for #variant_name {
+            fn get_name(&self) -> &str { &self.name }
+            fn is_dead(&self) -> bool { self.life <= 0 }
+            fn get_experience_gain(&self) -> usize { self.experience_gain }
+            fn get_representation(&self) -> (&str, Color) { (&self.symbol, self.color) }
+            fn decrease_life(&mut self, by: usize) {
+                self.life = self.life.saturating_sub(by);
+            }
+            fn get_ticks_between_steps(&self) -> u128 { self.ticks_between_steps }
+            fn damage(&self) -> usize { rand::thread_rng().gen_range(self.damage_range.clone()) }
+
+            #[cfg(test)]
+            fn get_life(&self) -> usize { self.life }
+        }
+        impl HasPosition for #variant_name {
+            fn get_position(&mut self) -> &mut Position {
+                &mut self.position
+            }
+            fn get_immutable_position(&self) -> &Position {
+                &self.position
+            }
+        }
+        };
+        t
+    });
+    let output = quote::quote! {
+        #(#structs)*
+    };
+    output.into()
+}