🎉 [pagetop-macros] Macros para facilitar la vida

pagetop-macros/src/lib.rs

@@ -0,0 +1,47 @@
+use concat_string::concat_string;
+use proc_macro::TokenStream;
+use quote::{quote, quote_spanned, ToTokens};
+use syn::{parse_macro_input, parse_str, ItemFn};
+
+#[proc_macro_attribute]
+pub fn fn_with(_attr: TokenStream, item: TokenStream) -> TokenStream {
+    let fn_item = parse_macro_input!(item as ItemFn);
+    let fn_name = fn_item.sig.ident.to_string();
+
+    if !fn_name.starts_with("alter_") {
+        let expanded = quote_spanned! {
+            fn_item.sig.ident.span() =>
+                compile_error!("expected a \"pub fn alter_...() -> &mut Self\" method");
+        };
+        return expanded.into();
+    }
+
+    let args: Vec<String> = fn_item
+        .sig
+        .inputs
+        .iter()
+        .skip(1)
+        .map(|arg| arg.to_token_stream().to_string())
+        .collect();
+
+    let param: Vec<String> = args
+        .iter()
+        .map(|arg| arg.split_whitespace().next().unwrap().to_string())
+        .collect();
+
+    #[rustfmt::skip]
+    let fn_builder = parse_str::<ItemFn>(concat_string!("
+        pub fn ", fn_name.replace("alter_", "with_"), "(mut self, ", args.join(", "), ") -> Self {
+            self.", fn_name, "(", param.join(", "), ");
+            self
+        }
+    ").as_str()).unwrap();
+
+    let fn_original = fn_item.into_token_stream();
+
+    let expanded = quote! {
+        #fn_builder
+        #fn_original
+    };
+    expanded.into()
+}