feat: add lifetime support

Closes #1

crates/smart-cache-macro/Cargo.toml

@@ -21,4 +21,6 @@ proc-macro2 = "1.0"
 sha2 = "0.11.0-pre.4"
 
 [dev-dependencies]
-trybuild = "1.0"
+trybuild = "1.0.89"
+smart-cache = { path = "../smart-cache" }
+rkyv = { version = "0.8.9" }

crates/smart-cache-macro/src/lib.rs

@@ -42,6 +42,14 @@ fn check_for_mutable_refs(
     Ok(())
 }
 
+fn get_param_type(ty: &Type) -> &Type {
+    if let Type::Reference(type_ref) = ty {
+        &type_ref.elem
+    } else {
+        ty
+    }
+}
+
 #[proc_macro_attribute]
 pub fn cached(_attr: TokenStream, item: TokenStream) -> TokenStream {
     let input_fn = parse_macro_input!(item as ItemFn);
@@ -99,7 +107,7 @@ pub fn cached(_attr: TokenStream, item: TokenStream) -> TokenStream {
     let param_types: Vec<_> = fn_inputs
         .iter()
         .filter_map(|arg| match arg {
-            FnArg::Typed(pat_type) => Some(&pat_type.ty),
+            FnArg::Typed(pat_type) => Some(get_param_type(&pat_type.ty)),
             _ => None,
         })
         .collect();

crates/smart-cache-macro/tests/success/ref.rs

@@ -1,12 +1,10 @@
 use smart_cache_macro::cached;
 
 #[cached]
-fn pure_function(x: &i32) -> i32 {
-    *x + 1
+fn takes_ref(s: String) -> String {
+    s
 }
 
 fn main() {
-    let x = 42;
-    assert_eq!(pure_function(&x), 43);
-    assert_eq!(pure_function(&x), 43); // Should hit cache
+    takes_ref("hello".to_string());
 }

crates/smart-cache-macro/tests/success/unit_string.rs

@@ -0,0 +1,11 @@
+use smart_cache_macro::cached;
+
+#[cached]
+fn unit(s: String) -> String {
+    s
+}
+
+fn main() {
+    let result = unit("hello".to_string());
+    assert_eq!(result, "hello");
+}

crates/smart-cache-macro/tests/tests.rs

@@ -4,5 +4,5 @@ fn compile_tests() {
     t.compile_fail("tests/compile-fail/*.rs");
 
     // skip for now as refs are broken (#1)
-    // t.pass("tests/success/*.rs");
+    t.pass("tests/success/*.rs");
 }

crates/smart-cache/tests/something.rs

@@ -1,7 +1,7 @@
 use smart_cache_macro::cached;
 
 #[cached]
-fn expensive_computation(x: String, y: i32) -> String {
+fn expensive_computation(x: &str, y: i32) -> String {
     use std::{thread, time::Duration};
 
     thread::sleep(Duration::from_secs(3));
@@ -11,6 +11,6 @@ fn expensive_computation(x: String, y: i32) -> String {
 
 #[test]
 fn test_cached() {
-    let x = expensive_computation("hello".to_string(), 2);
+    let x = expensive_computation("hello", 2);
     println!("{x}");
 }