new

.gitignore

@@ -0,0 +1,3 @@
+/target
+**/*.rs.bk
+Cargo.lock

Cargo.toml

@@ -0,0 +1,15 @@
+[package]
+name = "funtime"
+version = "0.1.0"
+authors = ["Jacob Brown <[email protected]>"]
+edition = "2018"
+license = "MIT OR Apache-2.0"
+
+[dependencies]
+syn = { version = "1", features = ["full", "extra-traits"] }
+quote = "1"
+proc-macro2 = "1"
+
+
+[lib]
+proc-macro = true

examples/simple.rs

@@ -0,0 +1,15 @@
+#[funtime::timed]
+fn foo() -> i32 {
+
+    let mut x = 1;
+
+    x += 1;
+
+    10
+
+}   
+
+
+fn main() {
+    foo();
+}

src/lib.rs

@@ -0,0 +1,74 @@
+extern crate proc_macro;
+
+use proc_macro::TokenStream;
+use proc_macro2::Span;
+use quote::quote;
+use syn::*;
+
+#[proc_macro_attribute]
+pub fn timed(attrs: TokenStream, item: TokenStream) -> TokenStream {
+
+    if let Ok(mut fun) = parse::<ItemFn>(item) {
+        let new_stmts = rewrite_stmts(fun.sig.ident.to_string(), &fun.block.stmts);
+        fun.block.stmts = new_stmts;
+        return quote!(#fun).into();
+        // return panic!("{}", quote!(#fun));
+    }
+
+    unimplemented!()
+}
+
+fn rewrite_stmts(name: String, stmts: &[Stmt]) -> Vec<Stmt> {
+
+    let setup: Block = parse_quote! {{
+        struct FuntimeTimer(std::time::Instant, String);
+
+        impl Drop for FuntimeTimer {
+            fn drop(&mut self) {
+                println!("Took {:?}: `{}` complete", self.0.elapsed(), &self.1);
+            }
+        }
+
+        impl FuntimeTimer {
+            fn print_elapsed(&self, short: &str) {
+                println!("Took {:?}: `{}`", self.0.elapsed(), short);
+            }
+        }
+
+        let funtime_timer = FuntimeTimer(std::time::Instant::now(), String::from(#name));
+
+    }};
+
+    let mut new_stmts = setup.stmts;
+
+    for stmt in stmts {
+        new_stmts.push(stmt.clone());
+
+        if let Stmt::Expr(..) = stmt {
+            continue;
+        }
+
+        let mut short = format!("{}", quote::ToTokens::to_token_stream(stmt)).chars().collect::<Vec<_>>();
+
+        let short = if short.len() > 40 {
+            let mut short = short[..37].into_iter().collect::<String>();
+            short.push_str("...");
+            short
+        } else {
+            short.into_iter().collect::<String>()
+        };
+
+        new_stmts.push(parse_quote!(funtime_timer.print_elapsed(#short);));
+    }
+
+    new_stmts
+}
+
+
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn it_works() {
+        assert_eq!(2 + 2, 4);
+    }
+}