Merge pull request #20 from sfackler/inline

Allow inlined types

staged-builder-internals/src/lib.rs

@@ -28,6 +28,8 @@ use syn::{
 ///     crate. Defaults to `::staged_builder`.
 /// * `mod` - The name of the submodule that will contain the generated builder types. Defaults to the struct's name
 ///     converted to `snake_case`.
+/// * `inline` - Causes the generated builder types to be defined in the same module as the struct, rather than a
+///     submodule.
 ///
 /// # Field options
 ///
@@ -235,37 +237,55 @@ fn expand(input: DeriveInput) -> Result<TokenStream, Error> {
     let overrides = StructOverrides::new(&input.attrs)?;
     let fields = resolve_fields(&overrides, fields)?;
 
-    let vis = &input.vis;
-    let module_name = module_name(&overrides, &input);
-
     let builder_impl = builder_impl(&input, &overrides, &fields);
+    let module = module(&input, &overrides, &fields);
 
-    let module_docs = format!("Builder types for [`{}`].", &input.ident);
+    let tokens = quote! {
+        #builder_impl
+        #module
+    };
 
-    let builder = builder(&input);
-    let default = default_impl(&overrides, &fields);
+    Ok(tokens)
+}
+
+fn module(
+    input: &DeriveInput,
+    overrides: &StructOverrides,
+    fields: &[ResolvedField<'_>],
+) -> TokenStream {
+    let builder = builder(input, overrides);
+    let default = default_impl(overrides, fields);
     let stages = fields
         .iter()
         .enumerate()
         .filter(|(_, f)| f.default.is_none())
-        .map(|(i, _)| stage(&input, i, &fields));
-    let final_stage = final_stage(&input, &overrides, &fields);
+        .map(|(i, _)| stage(input, overrides, i, fields));
+    let final_stage = final_stage(input, overrides, fields);
+
+    let parts = quote! {
+        #builder
+        #default
+        #(#stages)*
+        #final_stage
+    };
 
-    let tokens = quote! {
-        #builder_impl
+    if overrides.inline {
+        return parts;
+    }
+
+    let vis = &input.vis;
+    let module_name = module_name(overrides, input);
+
+    let module_docs = format!("Builder types for [`{}`].", &input.ident);
 
+    quote! {
         #[doc = #module_docs]
         #vis mod #module_name {
             use super::*;
 
-            #builder
-            #default
-            #(#stages)*
-            #final_stage
+            #parts
         }
-    };
-
-    Ok(tokens)
+    }
 }
 
 fn module_name(overrides: &StructOverrides, input: &DeriveInput) -> Ident {
@@ -283,15 +303,20 @@ fn builder_impl(
     let name = &input.ident;
     let vis = &input.vis;
 
-    let module_name = module_name(overrides, input);
-    let builder_name = initial_stage(fields).unwrap_or_else(final_name);
+    let module_path = if overrides.inline {
+        quote!()
+    } else {
+        let module_name = module_name(overrides, input);
+        quote!(#module_name::)
+    };
+    let stage_name = initial_stage(fields).unwrap_or_else(final_name);
     let private = overrides.private();
 
     quote! {
         impl #name {
             /// Returns a new builder.
             #[inline]
-            #vis fn builder() -> #module_name::Builder<#module_name::#builder_name> {
+            #vis fn builder() -> #module_path Builder<#module_path #stage_name> {
                 #private::Default::default()
             }
         }
@@ -305,12 +330,20 @@ fn initial_stage(fields: &[ResolvedField<'_>]) -> Option<Ident> {
         .map(|f| stage_name(f))
 }
 
-fn builder(input: &DeriveInput) -> TokenStream {
-    let docs = format!("A builder for [{0}](super::{0}).", input.ident);
+fn builder(input: &DeriveInput, overrides: &StructOverrides) -> TokenStream {
+    let link = if overrides.inline {
+        format!("[{}]", input.ident)
+    } else {
+        format!("[{0}](super::{0})", input.ident)
+    };
+
+    let docs = format!("A builder for {link}");
+
+    let vis = stage_vis(&input.vis, overrides);
 
     quote! {
         #[doc = #docs]
-        pub struct Builder<T>(T);
+        #vis struct Builder<T>(T);
     }
 }
 
@@ -345,8 +378,13 @@ fn default_field_initializers(fields: &[ResolvedField<'_>]) -> TokenStream {
     quote!(#(#fields,)*)
 }
 
-fn stage(input: &DeriveInput, idx: usize, fields: &[ResolvedField<'_>]) -> TokenStream {
-    let vis = stage_vis(&input.vis);
+fn stage(
+    input: &DeriveInput,
+    overrides: &StructOverrides,
+    idx: usize,
+    fields: &[ResolvedField<'_>],
+) -> TokenStream {
+    let vis = stage_vis(&input.vis, overrides);
     let field = &fields[idx];
     let name = field.field.ident.as_ref().unwrap();
 
@@ -397,7 +435,11 @@ fn stage(input: &DeriveInput, idx: usize, fields: &[ResolvedField<'_>]) -> Token
     }
 }
 
-fn stage_vis(vis: &Visibility) -> TokenStream {
+fn stage_vis(vis: &Visibility, overrides: &StructOverrides) -> TokenStream {
+    if overrides.inline {
+        return quote!(#vis);
+    }
+
     match vis {
         Visibility::Public(_) => quote!(#vis),
         Visibility::Restricted(restricted) => {
@@ -440,7 +482,7 @@ fn final_stage(
     overrides: &StructOverrides,
     fields: &[ResolvedField<'_>],
 ) -> TokenStream {
-    let vis = stage_vis(&input.vis);
+    let vis = stage_vis(&input.vis, overrides);
     let builder_name = final_name();
     let struct_name = &input.ident;
     let names = fields.iter().map(|f| f.field.ident.as_ref().unwrap());
@@ -459,7 +501,7 @@ fn final_stage(
     let build = if overrides.validate {
         validated_build(input, overrides, fields)
     } else {
-        unvalidated_build(input, fields)
+        unvalidated_build(input, overrides, fields)
     };
 
     quote! {
@@ -610,6 +652,11 @@ fn validated_build(
     fields: &[ResolvedField<'_>],
 ) -> TokenStream {
     let struct_name = &input.ident;
+    let struct_path = if overrides.inline {
+        quote!(#struct_name)
+    } else {
+        quote!(super::#struct_name)
+    };
     let names = fields
         .iter()
         .map(|f| f.field.ident.as_ref().unwrap())
@@ -623,10 +670,10 @@ fn validated_build(
         pub fn build(
             self,
         ) -> #private::Result<
-            super::#struct_name,
-            <super::#struct_name as #crate_::Validate>::Error,
+            #struct_path,
+            <#struct_path as #crate_::Validate>::Error,
         > {
-            let value = super::#struct_name {
+            let value = #struct_path {
                 #(#names: self.0.#names,)*
             };
             #crate_::Validate::validate(&value)?;
@@ -635,17 +682,26 @@ fn validated_build(
     }
 }
 
-fn unvalidated_build(input: &DeriveInput, fields: &[ResolvedField<'_>]) -> TokenStream {
+fn unvalidated_build(
+    input: &DeriveInput,
+    overrides: &StructOverrides,
+    fields: &[ResolvedField<'_>],
+) -> TokenStream {
     let struct_name = &input.ident;
+    let struct_path = if overrides.inline {
+        quote!(#struct_name)
+    } else {
+        quote!(super::#struct_name)
+    };
     let names = fields
         .iter()
         .map(|f| f.field.ident.as_ref().unwrap())
         .collect::<Vec<_>>();
 
     quote! {
         #[inline]
-        pub fn build(self) -> super::#struct_name {
-            super::#struct_name {
+        pub fn build(self) -> #struct_path {
+            #struct_path {
                 #(#names: self.0.#names,)*
             }
         }
@@ -682,6 +738,7 @@ struct StructOverrides {
     crate_: Option<Path>,
     #[struct_meta(name = "mod")]
     mod_: Option<Ident>,
+    inline: bool,
 }
 
 impl StructOverrides {

staged-builder/tests/test.rs

@@ -188,3 +188,23 @@ fn closure_convert() {
     };
     assert_eq!(actual, expected);
 }
+
+mod inline {
+    use staged_builder::staged_builder;
+
+    #[derive(PartialEq, Debug)]
+    #[staged_builder]
+    #[builder(inline)]
+    struct Inline {
+        a: i32,
+    }
+
+    #[test]
+    fn inline() {
+        let builder: Builder<AStage> = Inline::builder();
+        let stage: Builder<Complete> = builder.a(1);
+        let actual: Inline = stage.build();
+        let expected = Inline { a: 1 };
+        assert_eq!(actual, expected);
+    }
+}