From 709eb44ccb8d08ad7f26cdac2932eadc7ccd48e7 Mon Sep 17 00:00:00 2001
From: Melody Horn / boringcactus <melody@boringcactus.com>
Date: Fri, 18 Jun 2021 10:12:16 -0600
Subject: make model metadata available in AppConfig

---
 tosin-macros/src/lib.rs | 41 ++++++++++++++++++++++++++++++++++++++---
 1 file changed, 38 insertions(+), 3 deletions(-)

(limited to 'tosin-macros/src')

diff --git a/tosin-macros/src/lib.rs b/tosin-macros/src/lib.rs
index 7efbac6..408378f 100644
--- a/tosin-macros/src/lib.rs
+++ b/tosin-macros/src/lib.rs
@@ -2,6 +2,8 @@
 
 extern crate proc_macro;
 
+use std::fs;
+
 use proc_macro::TokenStream;
 use quote::quote;
 
@@ -19,9 +21,9 @@ fn impl_model(ast: &syn::DeriveInput) -> TokenStream {
     let name = &ast.ident;
     let gen = quote! {
         impl #name {
-            fn hello_macro() {
-                println!("Hello, Macro! My name is {}!", stringify!(#name));
-            }
+            pub const META: tosin::db::models::ModelMeta = tosin::db::models::ModelMeta {
+                name: stringify!(#name),
+            };
         }
     };
     gen.into()
@@ -55,3 +57,36 @@ pub fn gather_migrations(_input: TokenStream) -> TokenStream {
 
     gen.into()
 }
+
+#[proc_macro]
+pub fn gather_models(_input: TokenStream) -> TokenStream {
+    let call_site = proc_macro::Span::call_site();
+    let call_site_file = call_site.source_file();
+    let call_site_path = call_site_file.path();
+    if !call_site_file.is_real() {
+        panic!("call site does not have a real path");
+    }
+
+    let call_site_ast = syn::parse_file(&fs::read_to_string(call_site_path).unwrap()).unwrap();
+    let models = call_site_ast.items.iter()
+        .filter_map(|item| if let syn::Item::Struct(item) = item { Some(item) } else { None })
+        .filter(|item| item.attrs.iter().any(|attr| {
+            let attr = if let Ok(syn::Meta::List(attr)) = attr.parse_meta() { attr } else { return false; };
+            if attr.path.get_ident().map_or(false, |hopefully_derive| hopefully_derive == "derive") {
+                let mut derived = attr.nested.iter()
+                    .filter_map(|derived| if let syn::NestedMeta::Meta(derived) = derived { Some(derived) } else { None });
+                derived.any(|derived| derived.path().get_ident().map_or(false, |hopefully_model| hopefully_model == "Model"))
+            } else {
+                false
+            }
+        }))
+        .map(|item| &item.ident);
+
+    let gen = quote! {
+        pub const ALL: &[tosin::db::models::ModelMeta] = &[
+            #(#models::META),*
+        ];
+    };
+
+    gen.into()
+}
-- 
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