Implemented custom placeholder.

Replaced type info with default placeholder.

Author: dimpolo

Cargo.toml

@@ -8,4 +8,4 @@ repository = "https://github.com/dimpolo/partialdebug/"
 license = "MIT OR Apache-2.0"
 
 [dependencies]
-partialdebug-derive = "0.0.1"
+partialdebug-derive = {path = "partialdebug-derive"} # TODO change back

partialdebug-derive/src/lib.rs

@@ -1,6 +1,7 @@
 use proc_macro::TokenStream;
 
 use quote::{quote, ToTokens};
+use syn::parse::{Parse, ParseStream};
 use syn::*;
 
 #[proc_macro_derive(NonExhaustivePartialDebug)]
@@ -49,13 +50,20 @@ pub fn derive_non_exhaustive(input: TokenStream) -> TokenStream {
     TokenStream::from(expanded)
 }
 
-#[proc_macro_derive(TypeInfoPartialDebug)]
-pub fn derive_type_info(input: TokenStream) -> TokenStream {
+#[proc_macro_derive(PlaceholderPartialDebug, attributes(placeholder))]
+pub fn derive_placeholder(input: TokenStream) -> TokenStream {
     let input = parse_macro_input!(input as ItemStruct);
-    let name = input.ident;
+    let placeholder = match get_placeholder(&input) {
+        Ok(placeholder) => placeholder,
+        Err(err) => {
+            return err.to_compile_error().into();
+        }
+    };
+
+    let name = &input.ident;
     let (impl_generics, ty_generics, where_clause) = input.generics.split_for_impl();
 
-    let fields = match input.fields {
+    let fields = match &input.fields {
         Fields::Named(FieldsNamed { named, .. }) => named,
         Fields::Unnamed(_) => unimplemented!(),
         Fields::Unit => unimplemented!(),
@@ -66,11 +74,14 @@ pub fn derive_type_info(input: TokenStream) -> TokenStream {
         let mut type_name = field.ty.to_token_stream().to_string();
         type_name.retain(|c| !c.is_whitespace()); // remove whitespace
 
+        // type name or given placeholder string
+        let placeholder_string = placeholder.as_ref().unwrap_or(&type_name);
+
         quote! {
             .field(
                 stringify!(#name),
                 match ::partialdebug::AsDebug::as_debug(&self.#name){
-                    None => &::partialdebug::Placeholder(#type_name),
+                    None => &::partialdebug::Placeholder(#placeholder_string),
                     Some(field) => field,
                 },
             )
@@ -91,3 +102,35 @@ pub fn derive_type_info(input: TokenStream) -> TokenStream {
 
     TokenStream::from(expanded)
 }
+
+struct Placeholder(String);
+
+impl Parse for Placeholder {
+    fn parse(input: ParseStream) -> Result<Self> {
+        input.parse::<Token![=]>()?;
+        Ok(Placeholder(input.parse::<LitStr>()?.value()))
+    }
+}
+
+/// Tries to parse a placeholder string if there is one
+fn get_placeholder(input: &ItemStruct) -> Result<Option<String>> {
+    let placeholders: Vec<_> = input
+        .attrs
+        .iter()
+        .filter(|attribute| attribute.path.is_ident("placeholder"))
+        .collect();
+
+    if placeholders.len() > 1 {
+        return Err(Error::new_spanned(
+            placeholders[1],
+            "More than one placeholder attribute",
+        ));
+    }
+
+    placeholders
+        .first()
+        .map(|attribute| {
+            parse2::<Placeholder>(attribute.tokens.clone()).map(|placeholder| placeholder.0)
+        })
+        .transpose()
+}

src/lib.rs

@@ -1,57 +1,106 @@
+//! ```
+//! # #[allow(dead_code)]
+//! struct DNA {
+//!     sequence: &'static str,
+//! }
+//! ```
+//!
 //! # Non Exhaustive
 //!
 //! ```
 //! #![feature(debug_non_exhaustive)]
-//!
 //! use partialdebug::non_exhaustive::PartialDebug;
 //!
-//! #[allow(dead_code)]
-//! struct DNA {
-//!     sequence: &'static str,
-//! }
-//!
+//! # #[allow(dead_code)]
+//! # struct DNA {
+//! #     sequence: &'static str,
+//! # }
+//! #
 //! #[derive(PartialDebug)]
 //! struct Dog {
 //!     legs: usize,
 //!     eyes: usize,
 //!     dna: DNA,
 //! }
 //!
-//! let dog = Dog {
-//!     legs: 4,
-//!     eyes: 2,
-//!     dna: DNA {
-//!         sequence: "GACCCCGATTTGA",
-//!     },
-//! };
-//! assert_eq!(format!("{:?}", dog), "Dog { legs: 4, eyes: 2, .. }");
+//! # impl Dog {
+//! #     fn new() -> Dog {
+//! #         Dog {
+//! #             legs: 4,
+//! #             eyes: 2,
+//! #             dna: DNA {
+//! #                 sequence: "",
+//! #             },
+//! #         }
+//! #     }
+//! # }
+//! #
+//! assert_eq!(format!("{:?}", Dog::new()), "Dog { legs: 4, eyes: 2, .. }");
 //! ```
 //!
-//! # Type Info
+//! # Placeholder with Type Info
 //!
 //! ```
-//! use partialdebug::type_info::PartialDebug;
+//! use partialdebug::placeholder::PartialDebug;
 //!
-//! #[allow(dead_code)]
-//! struct DNA {
-//!     sequence: &'static str,
+//! # #[allow(dead_code)]
+//! # struct DNA {
+//! #     sequence: &'static str,
+//! # }
+//! #
+//! #[derive(PartialDebug)]
+//! struct Dog {
+//!     legs: usize,
+//!     eyes: usize,
+//!     dna: DNA,
 //! }
 //!
+//! # impl Dog {
+//! #     fn new() -> Dog {
+//! #         Dog {
+//! #             legs: 4,
+//! #             eyes: 2,
+//! #             dna: DNA {
+//! #                 sequence: "",
+//! #             },
+//! #         }
+//! #     }
+//! # }
+//! #
+//! assert_eq!(format!("{:?}", Dog::new()), "Dog { legs: 4, eyes: 2, dna: DNA }");
+//! ```
+//!
+//! # Placeholder with Custom Text
+//!
+//! ```
+//! use partialdebug::placeholder::PartialDebug;
+//!
+//! # #[allow(dead_code)]
+//! # struct DNA {
+//! #     sequence: &'static str,
+//! # }
+//! #
 //! #[derive(PartialDebug)]
+//! #[placeholder = "Unknown"]
 //! struct Dog {
 //!     legs: usize,
 //!     eyes: usize,
 //!     dna: DNA,
 //! }
 //!
-//! let dog = Dog {
-//!     legs: 4,
-//!     eyes: 2,
-//!     dna: DNA {
-//!         sequence: "GACCCCGATTTGA",
-//!     },
-//! };
-//! assert_eq!(format!("{:?}", dog), "Dog { legs: 4, eyes: 2, dna: DNA }");
+//! # impl Dog {
+//! #     fn new() -> Dog {
+//! #         Dog {
+//! #             legs: 4,
+//! #             eyes: 2,
+//! #             dna: DNA {
+//! #                 sequence: "",
+//! #             },
+//! #         }
+//! #     }
+//! # }
+//! #
+//! assert_eq!(format!("{:?}", Dog::new()), "Dog { legs: 4, eyes: 2, dna: Unknown }");
 //! ```
 
 #![allow(incomplete_features)]
@@ -87,6 +136,6 @@ pub mod non_exhaustive {
     pub use partialdebug_derive::NonExhaustivePartialDebug as PartialDebug;
 }
 
-pub mod type_info {
-    pub use partialdebug_derive::TypeInfoPartialDebug as PartialDebug;
+pub mod placeholder {
+    pub use partialdebug_derive::PlaceholderPartialDebug as PartialDebug;
 }