Support custom fields and methods

1 files changed, 25 insertions, 14 deletions

diff --git a/src/lib.rs b/src/lib.rs
index 315dd73..314f813 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -8,7 +8,7 @@
 //! use feluments::*;
 //!
 //! #[derive(Debug, PartialEq, Eq, Builder)]
-//! #[builder(vis = pub)]
+//! #[builder(vis = pub, makro)]
 //! struct Foo {
 //!     #[builder(default = 45)]
 //!     x: i32,
@@ -20,13 +20,13 @@
 //!
 //! # fn main() {
 //! assert_eq!(
-//!     build!(Foo { x: 32, y: "baz" }),
+//!     Foo! { x: 32, y: "baz" },
 //!     Foo { x: 32, y: "baz".into(), z: () },
 //! );
 //! # }
 //! ```
 //!
-//! The above call to the [`build`] macro expands to the following:
+//! The above call to the `Foo` macro expands to the following:
 //!
 //! ```
 //! # use feluments::*;
@@ -92,6 +92,7 @@ struct BuilderFieldOptions {
 #[from_attr(ident = builder)]
 struct BuilderOptions {
 	vis: Option<Visibility>,
+	name: Option<String>,
 	makro: bool,
 }
 
@@ -101,6 +102,7 @@ struct BuilderOptions {
 /// When the `builder` attribute is applied to the struct, it may take the
 /// following arguments:
 /// - `vis`: The visibility of the `builder` method.
+/// - `name`: Sets the name of the builder struct.
 /// - `makro`: Creates a macro to construct an instance of the struct.
 ///
 /// When the `builder` attribute is applied to a field of the struct, there are
@@ -111,7 +113,8 @@ struct BuilderOptions {
 ///   provided, then the default value will be the one provided. Otherwise, it
 ///   will be [`Default::default`].
 /// - `default`: The default value of the field. Setting this parameter also
-///   implies `optional`
+///   implies `optional`. The value may be an expression, and it may even
+///   reference previous fields.
 /// - `into`: Arguments to the setter may be of any type that implements `Into`
 ///   for the type of the field.
 ///
@@ -125,7 +128,7 @@ struct BuilderOptions {
 /// struct Foo {
 ///     #[builder(default = 45)]
 ///     x: i32,
-///     #[builder(into)]
+///     #[builder(into, default = x.to_string())]
 ///     y: String,
 ///     #[builder(optional)]
 ///     z: ()
@@ -133,11 +136,11 @@ struct BuilderOptions {
 ///
 /// # fn main() {
 /// assert_eq!(
-///     Foo::builder().y("bar").z(()).build(),
-///     Foo { x: 45, y: "bar".into(), z: () },
+///     Foo::builder().x(2).z(()).build(),
+///     Foo { x: 2, y: "2".into(), z: () },
 /// );
 /// assert_eq!(
-///     Foo! { y: "bar", z: () },
+///     Foo! { y: "bar" },
 ///     Foo { x: 45, y: "bar".into(), z: () },
 /// )
 /// # }
@@ -148,7 +151,6 @@ struct BuilderOptions {
 pub fn derive_builder(input: TokenStream) -> TokenStream {
 	let structure = parse_macro_input!(input as ItemStruct);
 	let struct_name = &structure.ident;
-	let builder_name = format_ident!("{}Builder", structure.ident);
 	let fields = structure
 		.fields
 		.into_iter()
@@ -173,6 +175,11 @@ pub fn derive_builder(input: TokenStream) -> TokenStream {
 		|| fields
 			.iter()
 			.all(|field| matches!(field.visibility, Visibility::Public(_)));
+	let builder_name = if let Some(builder_name) = builder_options.name {
+		format_ident!("{builder_name}")
+	} else {
+		format_ident!("{}Builder", structure.ident)
+	};
 	let builder_macro_vis = is_builder_visible.then(|| quote! { #[macro_export]});
 	let builder_macro = builder_options.makro.then(|| {
 		quote! {
@@ -266,14 +273,16 @@ pub fn derive_builder(input: TokenStream) -> TokenStream {
 			}
 		})
 		.collect::<Box<_>>();
-	let build_fields = fields.iter().map(|field| {
+	let build_field_assignments = fields.iter().map(|field| {
 		let field_name = &field.name;
 		match &field.default {
 			Default::Value(default_value) => {
-				quote! { #field_name: self.#field_name.unwrap_or_else(|| #default_value) }
+				quote! { let #field_name = self.#field_name.unwrap_or_else(|| #default_value); }
+			}
+			Default::Impl => quote! { let #field_name = self.#field_name.unwrap_or_default(); },
+			Default::None => {
+				quote! { let #field_name = unsafe { self.#field_name.unwrap_unchecked() }; }
 			}
-			Default::Impl => quote! { #field_name: self.#field_name.unwrap_or_default() },
-			Default::None => quote! { #field_name: unsafe { self.#field_name.unwrap_unchecked() } },
 		}
 	});
 
@@ -302,10 +311,12 @@ pub fn derive_builder(input: TokenStream) -> TokenStream {
 			#(#setters)*
 		}
 
+		#[allow(all)]
 		impl #builder_name<#(#trues),*> {
 			#builder_visibility fn build(self) -> #struct_name {
+				#(#build_field_assignments)*
 				#struct_name {
-					#(#build_fields,)*
+					#(#field_names,)*
 				}
 			}
 		}