From 9318464daaee62481f7f80105bc2ec14c9c01e16 Mon Sep 17 00:00:00 2001
From: Daniel Silverstone <dsilvers@digital-scurf.org>
Date: Sat, 22 Oct 2022 10:49:32 +0100
Subject: (derive): Support steps with &Path arguments

Signed-off-by: Daniel Silverstone <dsilvers@digital-scurf.org>
---
 subplotlib-derive/src/lib.rs | 30 +++++++++++++++++++++++++++++-
 1 file changed, 29 insertions(+), 1 deletion(-)

diff --git a/subplotlib-derive/src/lib.rs b/subplotlib-derive/src/lib.rs
index 86f5c5e..7aef0dc 100644
--- a/subplotlib-derive/src/lib.rs
+++ b/subplotlib-derive/src/lib.rs
@@ -29,6 +29,25 @@ fn ty_is_borrow_str(ty: &Type) -> bool {
     }
 }
 
+fn ty_is_borrow_path(ty: &Type) -> bool {
+    if let Type::Reference(ty) = ty {
+        if ty.mutability.is_none() && ty.lifetime.is_none() {
+            if let Type::Path(pp) = &*ty.elem {
+                pp.path.is_ident("Path")
+            } else {
+                // not a path, so not &Path
+                false
+            }
+        } else {
+            // mutable, or a lifetime stated, so not &Path
+            false
+        }
+    } else {
+        // Not & so not &Path
+        false
+    }
+}
+
 fn ty_is_datafile(ty: &Type) -> bool {
     if let Type::Path(ty) = ty {
         ty.path.is_ident("SubplotDataFile")
@@ -242,6 +261,8 @@ fn process_step(mut input: ItemFn) -> proc_macro2::TokenStream {
             .map(|(id, ty)| {
                 let ty = if ty_is_borrow_str(ty) {
                     parse_quote!(::std::string::String)
+                } else if ty_is_borrow_path(ty) {
+                    parse_quote!(::std::path::PathBuf)
                 } else {
                     ty.clone()
                 };
@@ -278,6 +299,13 @@ fn process_step(mut input: ItemFn) -> proc_macro2::TokenStream {
                             self
                         }
                     }
+                } else if ty_is_borrow_path(ty) {
+                    quote! {
+                        pub fn #id<P: Into<std::path::PathBuf>>(mut self, value: P) -> Self {
+                            self.#id = value.into();
+                            self
+                        }
+                    }
                 } else {
                     quote! {
                         pub fn #id(mut self, value: #ty) -> Self {
@@ -292,7 +320,7 @@ fn process_step(mut input: ItemFn) -> proc_macro2::TokenStream {
         let buildargs: Vec<_> = fields
             .iter()
             .map(|(id, ty)| {
-                if ty_is_borrow_str(ty) {
+                if ty_is_borrow_str(ty) || ty_is_borrow_path(ty) {
                     quote! {
                        &self.#id
                     }
-- 
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