From 5f33598fcfe071b617efdcc7ff7d5d0aa183cc1a Mon Sep 17 00:00:00 2001
From: David Cole <david.cole1340@gmail.com>
Date: Thu, 10 Nov 2022 13:51:05 +1300
Subject: [PATCH] add `before` flag to `#[php_startup]` (#170)

* add `before` flag to `#[php_startup]`

this calls the user-provided startup function _before_ the classes and
constants registered by the macro system are registered with PHP. by
default the behaviour is to run this function after, which means you
cannot define an interface and use it on a struct.

* cargo fmt
---
 crates/macros/src/lib.rs              |  5 +++--
 crates/macros/src/module.rs           |  2 +-
 crates/macros/src/startup_function.rs | 28 ++++++++++++++++++++++-----
 src/lib.rs                            |  5 +++++
 4 files changed, 32 insertions(+), 8 deletions(-)

diff --git a/crates/macros/src/lib.rs b/crates/macros/src/lib.rs
index e744703..2e6deaf 100644
--- a/crates/macros/src/lib.rs
+++ b/crates/macros/src/lib.rs
@@ -87,10 +87,11 @@ pub fn php_module(_: TokenStream, input: TokenStream) -> TokenStream {
 }
 
 #[proc_macro_attribute]
-pub fn php_startup(_: TokenStream, input: TokenStream) -> TokenStream {
+pub fn php_startup(args: TokenStream, input: TokenStream) -> TokenStream {
+    let args = parse_macro_input!(args as AttributeArgs);
     let input = parse_macro_input!(input as ItemFn);
 
-    match startup_function::parser(input) {
+    match startup_function::parser(Some(args), input) {
         Ok(parsed) => parsed,
         Err(e) => syn::Error::new(Span::call_site(), e).to_compile_error(),
     }
diff --git a/crates/macros/src/module.rs b/crates/macros/src/module.rs
index 9eb2df3..2c118c0 100644
--- a/crates/macros/src/module.rs
+++ b/crates/macros/src/module.rs
@@ -34,7 +34,7 @@ pub fn parser(input: ItemFn) -> Result<TokenStream> {
             fn php_module_startup() {}
         })
         .map_err(|_| anyhow!("Unable to generate PHP module startup function."))?;
-        let startup = startup_function::parser(parsed)?;
+        let startup = startup_function::parser(None, parsed)?;
 
         state = STATE.lock();
         Some(startup)
diff --git a/crates/macros/src/startup_function.rs b/crates/macros/src/startup_function.rs
index 47fcfeb..76b9877 100644
--- a/crates/macros/src/startup_function.rs
+++ b/crates/macros/src/startup_function.rs
@@ -1,13 +1,27 @@
 use std::collections::HashMap;
 
 use anyhow::{anyhow, Result};
+use darling::FromMeta;
 use proc_macro2::{Ident, Span, TokenStream};
 use quote::quote;
-use syn::{Expr, ItemFn, Signature};
+use syn::{AttributeArgs, Expr, ItemFn, Signature};
 
 use crate::{class::Class, constant::Constant, STATE};
 
-pub fn parser(input: ItemFn) -> Result<TokenStream> {
+#[derive(Default, Debug, FromMeta)]
+#[darling(default)]
+struct StartupArgs {
+    before: bool,
+}
+
+pub fn parser(args: Option<AttributeArgs>, input: ItemFn) -> Result<TokenStream> {
+    let args = if let Some(args) = args {
+        StartupArgs::from_list(&args)
+            .map_err(|e| anyhow!("Unable to parse attribute arguments: {:?}", e))?
+    } else {
+        StartupArgs::default()
+    };
+
     let ItemFn { sig, block, .. } = input;
     let Signature { ident, .. } = sig;
     let stmts = &block.stmts;
@@ -17,6 +31,11 @@ pub fn parser(input: ItemFn) -> Result<TokenStream> {
 
     let classes = build_classes(&state.classes)?;
     let constants = build_constants(&state.constants);
+    let (before, after) = if args.before {
+        (Some(quote! { internal(); }), None)
+    } else {
+        (None, Some(quote! { internal(); }))
+    };
 
     let func = quote! {
         #[doc(hidden)]
@@ -30,11 +49,10 @@ pub fn parser(input: ItemFn) -> Result<TokenStream> {
 
             ::ext_php_rs::internal::ext_php_rs_startup();
 
+            #before
             #(#classes)*
             #(#constants)*
-
-            // TODO return result?
-            internal();
+            #after
 
             0
         }
diff --git a/src/lib.rs b/src/lib.rs
index 41216a3..7d9f5b2 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -518,6 +518,11 @@ pub use ext_php_rs_derive::php_class;
 /// this macro if you have registered any classes or constants when using the
 /// [`macro@php_module`] macro.
 ///
+/// The attribute accepts one optional flag -- `#[php_startup(before)]` --
+/// which forces the annotated function to be called _before_ the other classes
+/// and constants are registered. By default the annotated function is called
+/// after these classes and constants are registered.
+///
 /// # Example
 ///
 /// ```