Add: Generate stage

Signed-off-by: Mark Van de Vyver <[email protected]>

minitrace-macro/src/trace/generate.rs

@@ -0,0 +1,71 @@
+use proc_macro2::TokenStream;
+use quote::{quote, ToTokens};
+use syn::{parse_quote, Stmt};
+
+use crate::trace::lower::Assertion;
+
+//pub type Rust = proc_macro2::TokenStream;
+
+use crate::trace::lower::Quotable;
+use crate::trace::lower::Quotables;
+
+// Generate TokenStream to be returned by the proc-macro
+//
+// The "Lower" stage is responsible for turning the "Model" data into a
+// syn::Item that can be reported here.
+pub fn generate(quotes: Quotables<Quotable>) -> proc_macro2::TokenStream {
+    // Have a logic check earlier to error if there is not **at least one**
+    // `syn::Item`
+    #[allow(clippy::collapsible_match)]
+    #[allow(unreachable_patterns)]
+    let it = match quotes.get(0).expect("An item") {
+        Quotable::Item(item) => match item {
+            syn::Item::Fn(itemf) => Some(itemf),
+            _ => None,
+        },
+        _ => None, //?
+    };
+    let syn::ItemFn {
+        attrs,
+        vis,
+        sig,
+        block,
+    } = it.expect("An item variant");
+
+    quote!(
+        #(#attrs)*
+        #vis #sig {
+            #block
+        }
+    )
+}
+
+impl ToTokens for Assertion {
+    fn to_tokens(&self, tokens: &mut TokenStream) {
+        let Assertion { expr, message } = self;
+        let stmt: Stmt = parse_quote!(assert!(#expr, #message););
+        stmt.to_tokens(tokens);
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn fn_in_fn_out() {
+        let models = crate::trace::analyze(
+            parse_quote!(#[trace]),
+            parse_quote!(
+                fn f(x: bool) {}
+            ),
+        );
+        println!("{:?}", models.clone());
+        let ir = crate::trace::lower(models);
+        println!("{:?}", ir.clone());
+        let rust = crate::trace::generate(ir);
+        println!("{:?}", rust.clone());
+
+        assert!(syn::parse2::<syn::ItemFn>(rust).is_ok());
+    }
+}