First commit

6 files changed, 395 insertions, 0 deletions

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..ea8c4bf
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+/target
diff --git a/Cargo.lock b/Cargo.lock
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index 0000000..331ab82
--- /dev/null
+++ b/Cargo.lock
@@ -0,0 +1,163 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 4
+
+[[package]]
+name = "attribute-derive"
+version = "0.10.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "05832cdddc8f2650cc2cc187cc2e952b8c133a48eb055f35211f61ee81502d77"
+dependencies = [
+ "attribute-derive-macro",
+ "derive-where",
+ "manyhow",
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
+[[package]]
+name = "attribute-derive-macro"
+version = "0.10.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0a7cdbbd4bd005c5d3e2e9c885e6fa575db4f4a3572335b974d8db853b6beb61"
+dependencies = [
+ "collection_literals",
+ "interpolator",
+ "manyhow",
+ "proc-macro-utils",
+ "proc-macro2",
+ "quote",
+ "quote-use",
+ "syn",
+]
+
+[[package]]
+name = "auguments"
+version = "0.1.0"
+dependencies = [
+ "attribute-derive",
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
+[[package]]
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+
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+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
+[[package]]
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+source = "registry+https://github.com/rust-lang/crates.io-index"
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+
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+checksum = "b33efb3ca6d3b07393750d4030418d594ab1139cee518f0dc88db70fec873587"
+dependencies = [
+ "manyhow-macros",
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
+[[package]]
+name = "manyhow-macros"
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+source = "registry+https://github.com/rust-lang/crates.io-index"
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+ "proc-macro-utils",
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+ "quote",
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+dependencies = [
+ "proc-macro2",
+ "quote",
+ "smallvec",
+]
+
+[[package]]
+name = "proc-macro2"
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+dependencies = [
+ "unicode-ident",
+]
+
+[[package]]
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+ "proc-macro2",
+]
+
+[[package]]
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+dependencies = [
+ "quote",
+ "quote-use-macros",
+]
+
+[[package]]
+name = "quote-use-macros"
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+source = "registry+https://github.com/rust-lang/crates.io-index"
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+dependencies = [
+ "proc-macro-utils",
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
+[[package]]
+name = "smallvec"
+version = "1.15.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
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+
+[[package]]
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+dependencies = [
+ "proc-macro2",
+ "quote",
+ "unicode-ident",
+]
+
+[[package]]
+name = "unicode-ident"
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+source = "registry+https://github.com/rust-lang/crates.io-index"
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diff --git a/Cargo.toml b/Cargo.toml
new file mode 100644
index 0000000..449a8f1
--- /dev/null
+++ b/Cargo.toml
@@ -0,0 +1,13 @@
+[package]
+name = "auguments"
+version = "0.1.0"
+edition = "2024"
+
+[lib]
+proc-macro = true
+
+[dependencies]
+syn = { version = "2", features = ["full"] }
+quote = "1"
+proc-macro2 = "1"
+attribute-derive = "0.10"
diff --git a/rustfmt.toml b/rustfmt.toml
new file mode 100644
index 0000000..d3d0d1e
--- /dev/null
+++ b/rustfmt.toml
@@ -0,0 +1,3 @@
+edition = "2024"
+hard_tabs = true
+newline_style = "Unix"
diff --git a/src/lib.rs b/src/lib.rs
new file mode 100644
index 0000000..056b6f1
--- /dev/null
+++ b/src/lib.rs
@@ -0,0 +1,198 @@
+use attribute_derive::FromAttr;
+use proc_macro::TokenStream;
+use proc_macro2::Span;
+use quote::{format_ident, quote};
+use syn::{
+	Expr, ExprStruct, Ident, ItemStruct, LitBool, Type, Visibility, parse_macro_input, token::Pub,
+};
+
+enum Default {
+	None,
+	Impl,
+	Value(Expr),
+}
+
+struct MaybeOptionalField {
+	visibility: Visibility,
+	name: Ident,
+	default: Default,
+	auto_into: bool,
+	ty: Type,
+}
+
+#[derive(FromAttr)]
+#[from_attr(ident = builder)]
+struct BuilderFieldOptions {
+	vis: Option<Visibility>,
+	optional: bool,
+	default: Option<Expr>,
+	into: bool,
+}
+
+#[proc_macro_derive(Builder, attributes(builder))]
+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()
+		.map(|field| {
+			let attrs = BuilderFieldOptions::from_attributes(field.attrs).unwrap();
+			MaybeOptionalField {
+				visibility: attrs.vis.unwrap_or(field.vis),
+				name: field.ident.unwrap(),
+				default: match (attrs.optional, attrs.default) {
+					(true, None) => Default::Impl,
+					(_, Some(expr)) => Default::Value(expr),
+					(false, None) => Default::None,
+				},
+				auto_into: attrs.into,
+				ty: field.ty,
+			}
+		})
+		.collect::<Box<_>>();
+
+	let builder_visibility = fields
+		.iter()
+		.all(|field| matches!(field.visibility, Visibility::Public(_)))
+		.then_some(Visibility::Public(Pub {
+			span: Span::call_site(),
+		}));
+	let field_names = fields
+		.iter()
+		.map(|field| field.name.clone())
+		.collect::<Box<_>>();
+	let field_types = fields
+		.iter()
+		.map(|field| field.ty.clone())
+		.collect::<Box<_>>();
+	let const_generics = fields
+		.iter()
+		.filter(|field| matches!(field.default, Default::None))
+		.map(|field| Ident::new(&field.name.to_string().to_uppercase(), field.name.span()))
+		.collect::<Box<_>>();
+	let trues = (0..const_generics.len())
+		.map(|_| LitBool::new(true, Span::call_site()))
+		.collect::<Box<_>>();
+	let falses = (0..const_generics.len())
+		.map(|_| LitBool::new(false, Span::call_site()))
+		.collect::<Box<_>>();
+
+	let mut j = 0;
+	let setters = fields
+		.iter()
+		.enumerate()
+		.map(|(i, field)| {
+            let visibility = &field.visibility;
+			let setter_name = &field.name;
+			let ty = &field.ty;
+			let param_ty = if field.auto_into { quote! {#ty} } else { quote! { impl ::core::convert::Into<#ty> } };
+			let field_name = &field.name;
+			let fields_head = &field_names[0..i];
+			let fields_tail = &field_names[i+1..];
+			if matches!(field.default, Default::None) {
+				let generics_head = &const_generics[0..j];
+				let generics_tail = &const_generics[j+1..];
+				j += 1;
+				quote! {
+					#visibility fn #setter_name(self, value: #param_ty>) -> #builder_name<#(#generics_head,)* true, #(#generics_tail),*> {
+						#builder_name {
+							#(#fields_head: self.#fields_head,)*
+							#field_name: Some(value.into()),
+							#(#fields_tail: self.#fields_tail,)*
+						}
+					}
+				}
+			} else {
+				let maybe_setter_name = format_ident!("maybe_{}", &field.name);
+				let clear_name = format_ident!("clear_{}", &field.name);
+				quote! {
+					#visibility fn #setter_name(self, value: #param_ty) -> #builder_name<#(#const_generics),*> {
+						#builder_name {
+							#(#fields_head: self.#fields_head,)*
+							#field_name: Some(value.into()),
+							#(#fields_tail: self.#fields_tail,)*
+						}
+					}
+
+					#visibility fn #maybe_setter_name(self, value: core::option::Option<#param_ty>) -> #builder_name<#(#const_generics),*> {
+						#builder_name {
+							#(#fields_head: self.#fields_head,)*
+							#field_name: value.map(Into::into),
+							#(#fields_tail: self.#fields_tail,)*
+						}
+					}
+
+					#visibility fn #clear_name(self) -> #builder_name<#(#const_generics),*> {
+						#builder_name {
+							#(#fields_head: self.#fields_head,)*
+							#field_name: None,
+							#(#fields_tail: self.#fields_tail,)*
+						}
+					}
+				}
+			}
+		})
+		.collect::<Box<_>>();
+	let build_fields = 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) }
+			}
+			Default::Impl => quote! { #field_name: self.#field_name.unwrap_or_default() },
+			Default::None => quote! { #field_name: unsafe { self.#field_name.unwrap_unchecked() } },
+		}
+	});
+
+	quote! {
+		#builder_visibility struct #builder_name<#(const #const_generics: bool),*> {
+			#(#field_names: Option<#field_types>,)*
+		}
+
+		impl<#(const #const_generics: bool),*> core::default::Default for #builder_name<#(#const_generics),*> {
+			fn default() -> Self {
+				Self {
+					#(#field_names: None,)*
+				}
+			}
+		}
+
+		impl #struct_name {
+			#builder_visibility fn builder() -> #builder_name<#(#falses),*> {
+				#builder_name::default()
+			}
+		}
+
+		impl<#(const #const_generics: bool),*> #builder_name<#(#const_generics),*> {
+			#(#setters)*
+		}
+
+		impl #builder_name<#(#trues),*> {
+			#builder_visibility fn build(self) -> #struct_name {
+				#struct_name {
+					#(#build_fields,)*
+				}
+			}
+		}
+	}
+	.into()
+}
+
+#[proc_macro]
+pub fn build(input: TokenStream) -> TokenStream {
+	let structure = parse_macro_input!(input as ExprStruct);
+	let struct_name = &structure.path;
+
+	let field_names = structure.fields.iter().map(|field| &field.member);
+	let field_values = structure.fields.iter().map(|field| &field.expr);
+
+	quote! {
+		#struct_name
+			::builder()
+			#(.#field_names(#field_values))*
+			.build()
+	}
+	.into()
+}
diff --git a/tests/basic.rs b/tests/basic.rs
new file mode 100644
index 0000000..68cefb7
--- /dev/null
+++ b/tests/basic.rs
@@ -0,0 +1,17 @@
+use auguments::{Builder, build};
+
+#[derive(Builder)]
+#[allow(dead_code)]
+struct Foo {
+	#[builder(into, vis = pub)]
+	bar: String,
+	#[builder(default = 32)]
+	baz: i32,
+	bat: (),
+}
+
+fn main() {
+	let _: Foo = Foo::builder().baz(32).bar("hello").bat(()).build();
+	let bar = "hello";
+	let _: Foo = build!(Foo { bar, bat: () });
+}