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use attributes::{IdentList, NestedMetaList};
use darling::FromMeta;
use from::{
generate_from_enum_trait_impl_for_ref, generate_from_variant_trait_impl,
generate_from_variant_trait_impl_for_ref,
};
use itertools::Itertools;
use macros::generate_all_map_macros;
use proc_macro::TokenStream;
use proc_macro2::{Span, TokenStream as TokenStream2};
use quote::{format_ident, quote, ToTokens};
use std::collections::HashMap;
use std::iter::{self, FromIterator};
use syn::{
parse_macro_input, Attribute, AttributeArgs, Expr, Field, GenericParam, Ident, ItemStruct,
Lifetime, LifetimeDef, Type, TypeGenerics, TypeParamBound,
};
mod attributes;
mod from;
mod macros;
mod naming;
mod utils;
#[derive(Debug, FromMeta)]
struct StructOpts {
variants: IdentList,
#[darling(default)]
variant_attributes: Option<NestedMetaList>,
#[darling(default)]
specific_variant_attributes: Option<HashMap<Ident, NestedMetaList>>,
#[darling(default)]
ref_attributes: Option<NestedMetaList>,
#[darling(default)]
ref_mut_attributes: Option<NestedMetaList>,
#[darling(default)]
cast_error: ErrorOpts,
#[darling(default)]
partial_getter_error: ErrorOpts,
#[darling(default)]
no_enum: bool,
#[darling(default)]
no_map_macros: bool,
#[darling(default)]
map_into: Option<IdentList>,
#[darling(default)]
map_ref_into: Option<IdentList>,
#[darling(default)]
map_ref_mut_into: Option<IdentList>,
}
#[derive(Debug, Default, FromMeta)]
struct FieldOpts {
#[darling(default)]
only: Option<HashMap<Ident, ()>>,
#[darling(default)]
getter: Option<GetterOpts>,
#[darling(default)]
partial_getter: Option<GetterOpts>,
}
#[derive(Debug, Default, FromMeta)]
struct GetterOpts {
#[darling(default)]
copy: bool,
#[darling(default)]
no_mut: bool,
#[darling(default)]
rename: Option<Ident>,
}
#[derive(Debug, Default, FromMeta)]
struct ErrorOpts {
#[darling(default)]
ty: Option<String>,
#[darling(default)]
expr: Option<String>,
}
impl ErrorOpts {
fn parse(&self) -> Option<(Type, Expr)> {
let err_ty_str = self.ty.as_ref()?;
let err_ty: Type = syn::parse_str(err_ty_str).expect("error type not valid");
let err_expr_str = self
.expr
.as_ref()
.expect("must provide an error expr with error ty");
let err_expr: Expr = syn::parse_str(err_expr_str).expect("error expr not valid");
Some((err_ty, err_expr))
}
fn build_result_type(
&self,
ret_ty: impl ToTokens,
) -> (proc_macro2::TokenStream, proc_macro2::TokenStream) {
if let Some((err_ty, err_expr)) = self.parse() {
(quote! { Result<#ret_ty, #err_ty> }, quote! { #err_expr })
} else {
(quote! { Result<#ret_ty, ()> }, quote! { () })
}
}
}
#[derive(Debug)]
struct FieldData {
name: Ident,
field: Field,
only: Option<Vec<Ident>>,
getter_opts: GetterOpts,
partial_getter_opts: GetterOpts,
}
impl FieldData {
fn is_common(&self) -> bool {
self.only.is_none()
}
}
#[proc_macro_attribute]
pub fn superstruct(args: TokenStream, input: TokenStream) -> TokenStream {
let attr_args = parse_macro_input!(args as AttributeArgs);
let item = parse_macro_input!(input as ItemStruct);
let type_name = &item.ident;
let visibility = item.vis;
let decl_generics = &item.generics;
let (impl_generics, ty_generics, where_clause) = &item.generics.split_for_impl();
let opts = StructOpts::from_list(&attr_args).unwrap();
let mut output_items: Vec<TokenStream> = vec![];
let mk_struct_name = |variant_name: &Ident| format_ident!("{}{}", type_name, variant_name);
let variant_names = &opts.variants.idents;
let struct_names = variant_names.iter().map(mk_struct_name).collect_vec();
let mut fields = vec![];
let mut variant_fields =
HashMap::<_, _>::from_iter(variant_names.iter().zip(iter::repeat(vec![])));
for field in item.fields.iter() {
let name = field.ident.clone().expect("named fields only");
let field_opts = field
.attrs
.iter()
.filter(|attr| is_superstruct_attr(attr))
.find_map(|attr| {
let meta = attr.parse_meta().unwrap();
Some(FieldOpts::from_meta(&meta).unwrap())
})
.unwrap_or_default();
let mut output_field = field.clone();
output_field.attrs = discard_superstruct_attrs(&output_field.attrs);
let field_variants = field_opts.only.as_ref().map_or_else(
|| variant_names.clone(),
|only| only.keys().cloned().collect_vec(),
);
for variant_name in field_variants {
variant_fields
.get_mut(&variant_name)
.expect("invalid variant name in `only`")
.push(output_field.clone());
}
if field_opts.only.is_some() && field_opts.getter.is_some() {
panic!("can't configure `only` and `getter` on the same field");
} else if field_opts.only.is_none() && field_opts.partial_getter.is_some() {
panic!("can't set `partial_getter` options on common field");
}
let only = field_opts.only.map(|only| only.keys().cloned().collect());
let getter_opts = field_opts.getter.unwrap_or_default();
let partial_getter_opts = field_opts.partial_getter.unwrap_or_default();
fields.push(FieldData {
name,
field: output_field,
only,
getter_opts,
partial_getter_opts,
});
}
let universal_struct_attributes = opts
.variant_attributes
.as_ref()
.map_or(&[][..], |attrs| &attrs.metas);
for (variant_name, struct_name) in variant_names.iter().zip(struct_names.iter()) {
let fields = &variant_fields[variant_name];
let specific_struct_attributes = opts
.specific_variant_attributes
.as_ref()
.and_then(|sv| sv.get(&variant_name))
.map_or(&[][..], |attrs| &attrs.metas);
let variant_code = quote! {
#(
#[#universal_struct_attributes]
)*
#(
#[#specific_struct_attributes]
)*
#visibility struct #struct_name #decl_generics #where_clause {
#(
#fields,
)*
}
};
output_items.push(variant_code.into());
}
if opts.no_enum {
return TokenStream::from_iter(output_items);
}
let top_level_attrs = discard_superstruct_attrs(&item.attrs);
let enum_item = quote! {
#(
#top_level_attrs
)*
#visibility enum #type_name #decl_generics #where_clause {
#(
#variant_names(#struct_names #ty_generics),
)*
}
};
output_items.push(enum_item.into());
let ref_ty_name = format_ident!("{}Ref", type_name);
let ref_ty_lifetime = Lifetime::new("'__superstruct", Span::call_site());
let mut ref_ty_decl_generics = decl_generics.clone();
ref_ty_decl_generics.params.insert(
0,
GenericParam::Lifetime(LifetimeDef::new(ref_ty_lifetime.clone())),
);
for param in ref_ty_decl_generics.params.iter_mut() {
if let GenericParam::Type(type_param) = param {
let result = type_param
.bounds
.iter()
.find(|bound| matches!(bound, TypeParamBound::Lifetime(_)));
if result.is_none() {
type_param
.bounds
.insert(0, TypeParamBound::Lifetime(ref_ty_lifetime.clone()))
}
}
}
let (ref_impl_generics, ref_ty_generics, _) = &ref_ty_decl_generics.split_for_impl();
let ref_attributes = opts
.ref_attributes
.as_ref()
.map_or(&[][..], |attrs| &attrs.metas);
let ref_ty = quote! {
#(
#[#ref_attributes]
)*
#visibility enum #ref_ty_name #ref_ty_decl_generics #where_clause {
#(
#variant_names(&#ref_ty_lifetime #struct_names #ty_generics),
)*
}
};
output_items.push(ref_ty.into());
let ref_mut_ty_name = format_ident!("{}RefMut", type_name);
let ref_mut_ty_lifetime = Lifetime::new("'__superstruct", Span::call_site());
let mut ref_mut_ty_decl_generics = decl_generics.clone();
ref_mut_ty_decl_generics.params.insert(
0,
GenericParam::Lifetime(LifetimeDef::new(ref_mut_ty_lifetime.clone())),
);
let (ref_mut_impl_generics, ref_mut_ty_generics, _) =
&ref_mut_ty_decl_generics.split_for_impl();
let ref_mut_attributes = opts
.ref_mut_attributes
.as_ref()
.map_or(&[][..], |attrs| &attrs.metas);
let ref_mut_ty = quote! {
#(
#[#ref_mut_attributes]
)*
#visibility enum #ref_mut_ty_name #ref_mut_ty_decl_generics #where_clause {
#(
#variant_names(&#ref_mut_ty_lifetime mut #struct_names #ty_generics),
)*
}
};
output_items.push(ref_mut_ty.into());
let getters = fields
.iter()
.filter(|f| f.is_common())
.map(|field_data| make_field_getter(type_name, &variant_names, &field_data, None));
let mut_getters = fields
.iter()
.filter(|f| f.is_common() && !f.getter_opts.no_mut)
.map(|field_data| make_mut_field_getter(type_name, &variant_names, &field_data, None));
let partial_getters = fields
.iter()
.filter(|f| !f.is_common())
.cartesian_product(&[false, true])
.flat_map(|(field_data, mutability)| {
let field_variants = field_data.only.as_ref()?;
Some(make_partial_getter(
type_name,
&field_data,
&field_variants,
&opts.partial_getter_error,
*mutability,
None,
))
});
let cast_methods = variant_names
.iter()
.flat_map(|variant_name| {
let caster = make_as_variant_method(
type_name,
variant_name,
ty_generics,
&opts.cast_error,
false,
);
let caster_mut = make_as_variant_method(
type_name,
variant_name,
ty_generics,
&opts.cast_error,
true,
);
vec![caster, caster_mut]
})
.collect_vec();
let impl_block = quote! {
impl #impl_generics #type_name #ty_generics #where_clause {
pub fn to_ref<#ref_ty_lifetime>(&#ref_ty_lifetime self) -> #ref_ty_name #ref_ty_generics {
match self {
#(
#type_name::#variant_names(ref inner)
=> #ref_ty_name::#variant_names(inner),
)*
}
}
pub fn to_mut<#ref_mut_ty_lifetime>(&#ref_mut_ty_lifetime mut self) -> #ref_mut_ty_name #ref_mut_ty_generics {
match self {
#(
#type_name::#variant_names(ref mut inner)
=> #ref_mut_ty_name::#variant_names(inner),
)*
}
}
#(
#cast_methods
)*
#(
#getters
)*
#(
#mut_getters
)*
#(
#partial_getters
)*
}
};
output_items.push(impl_block.into());
let ref_getters = fields.iter().filter(|f| f.is_common()).map(|field_data| {
make_field_getter(
&ref_ty_name,
&variant_names,
&field_data,
Some(&ref_ty_lifetime),
)
});
let ref_partial_getters = fields
.iter()
.filter(|f| !f.is_common())
.flat_map(|field_data| {
let field_variants = field_data.only.as_ref()?;
Some(make_partial_getter(
&ref_ty_name,
&field_data,
&field_variants,
&opts.partial_getter_error,
false,
Some(&ref_ty_lifetime),
))
});
let ref_impl_block = quote! {
impl #ref_impl_generics #ref_ty_name #ref_ty_generics #where_clause {
#(
#ref_getters
)*
#(
#ref_partial_getters
)*
}
impl #ref_impl_generics Copy for #ref_ty_name #ref_ty_generics #where_clause { }
impl #ref_impl_generics Clone for #ref_ty_name #ref_ty_generics #where_clause {
fn clone(&self) -> Self { *self }
}
};
output_items.push(ref_impl_block.into());
let ref_mut_getters = fields
.iter()
.filter(|f| f.is_common() && !f.getter_opts.no_mut)
.map(|field_data| {
make_mut_field_getter(
&ref_mut_ty_name,
&variant_names,
&field_data,
Some(&ref_mut_ty_lifetime),
)
});
let ref_mut_partial_getters = fields
.iter()
.filter(|f| !f.is_common() && !f.partial_getter_opts.no_mut)
.flat_map(|field_data| {
let field_variants = field_data.only.as_ref()?;
Some(make_partial_getter(
&ref_mut_ty_name,
&field_data,
&field_variants,
&opts.partial_getter_error,
true,
Some(&ref_mut_ty_lifetime),
))
});
let ref_mut_impl_block = quote! {
impl #ref_mut_impl_generics #ref_mut_ty_name #ref_mut_ty_generics #where_clause {
#(
#ref_mut_getters
)*
#(
#ref_mut_partial_getters
)*
}
};
output_items.push(ref_mut_impl_block.into());
if !opts.no_map_macros && !opts.no_enum {
let num_generics = decl_generics.params.len();
generate_all_map_macros(
&type_name,
&ref_ty_name,
&ref_mut_ty_name,
num_generics,
&struct_names,
variant_names,
&opts,
&mut output_items,
);
} else {
assert!(
opts.map_into.is_none(),
"`map_into` is set but map macros are disabled"
);
assert!(
opts.map_ref_into.is_none(),
"`map_ref_into` is set but map macros are disabled"
);
assert!(
opts.map_ref_mut_into.is_none(),
"`map_ref_mut_into` is set but map macros are disabled"
);
}
for (variant_name, struct_name) in variant_names.iter().zip_eq(&struct_names) {
let from_impl = generate_from_variant_trait_impl(
type_name,
impl_generics,
ty_generics,
where_clause,
variant_name,
struct_name,
);
output_items.push(from_impl.into());
let from_impl_for_ref = generate_from_variant_trait_impl_for_ref(
&ref_ty_name,
&ref_ty_lifetime,
ref_impl_generics,
ref_ty_generics,
ty_generics,
where_clause,
variant_name,
struct_name,
);
output_items.push(from_impl_for_ref.into());
}
let ref_from_top_level_impl = generate_from_enum_trait_impl_for_ref(
type_name,
ty_generics,
&ref_ty_name,
&ref_ty_lifetime,
ref_impl_generics,
ref_ty_generics,
where_clause,
);
output_items.push(ref_from_top_level_impl.into());
TokenStream::from_iter(output_items)
}
fn make_field_getter(
type_name: &Ident,
variant_names: &[Ident],
field_data: &FieldData,
lifetime: Option<&Lifetime>,
) -> proc_macro2::TokenStream {
let field_name = &field_data.name;
let field_type = &field_data.field.ty;
let getter_opts = &field_data.getter_opts;
let fn_name = getter_opts.rename.as_ref().unwrap_or(field_name);
let return_type = if getter_opts.copy {
quote! { #field_type }
} else {
quote! { &#lifetime #field_type}
};
let return_expr = if getter_opts.copy {
quote! { inner.#field_name }
} else {
quote! { &inner.#field_name }
};
let cfg_attrs = get_cfg_attrs(&field_data.field.attrs);
quote! {
#(
#cfg_attrs
)*
pub fn #fn_name(&self) -> #return_type {
match self {
#(
#type_name::#variant_names(ref inner) => {
#return_expr
}
)*
}
}
}
}
fn make_mut_field_getter(
type_name: &Ident,
variant_names: &[Ident],
field_data: &FieldData,
lifetime: Option<&Lifetime>,
) -> proc_macro2::TokenStream {
let field_name = &field_data.name;
let field_type = &field_data.field.ty;
let getter_opts = &field_data.getter_opts;
let fn_name = format_ident!("{}_mut", getter_opts.rename.as_ref().unwrap_or(field_name));
let return_type = quote! { &#lifetime mut #field_type };
let param = make_self_arg(true, lifetime);
let return_expr = quote! { &mut inner.#field_name };
let cfg_attrs = get_cfg_attrs(&field_data.field.attrs);
quote! {
#(
#cfg_attrs
)*
pub fn #fn_name(#param) -> #return_type {
match self {
#(
#type_name::#variant_names(ref mut inner) => {
#return_expr
}
)*
}
}
}
}
fn make_self_arg(mutable: bool, lifetime: Option<&Lifetime>) -> proc_macro2::TokenStream {
if mutable {
quote! { &#lifetime mut self }
} else {
quote! { &self }
}
}
fn make_type_ref(
ty: &Type,
mutable: bool,
copy: bool,
lifetime: Option<&Lifetime>,
) -> proc_macro2::TokenStream {
if mutable {
quote! { &#lifetime mut #ty }
} else if copy {
quote! { #ty }
} else {
quote! { &#lifetime #ty }
}
}
fn make_partial_getter(
type_name: &Ident,
field_data: &FieldData,
field_variants: &[Ident],
error_opts: &ErrorOpts,
mutable: bool,
lifetime: Option<&Lifetime>,
) -> proc_macro2::TokenStream {
let field_name = &field_data.name;
let renamed_field = field_data
.partial_getter_opts
.rename
.as_ref()
.unwrap_or(field_name);
let fn_name = if mutable {
format_ident!("{}_mut", renamed_field)
} else {
renamed_field.clone()
};
let copy = field_data.partial_getter_opts.copy;
let self_arg = make_self_arg(mutable, lifetime);
let ret_ty = make_type_ref(&field_data.field.ty, mutable, copy, lifetime);
let ret_expr = if mutable {
quote! { &mut inner.#field_name }
} else if copy {
quote! { inner.#field_name }
} else {
quote! { &inner.#field_name }
};
let (res_ret_ty, err_expr) = error_opts.build_result_type(&ret_ty);
let cfg_attrs = get_cfg_attrs(&field_data.field.attrs);
quote! {
#(
#cfg_attrs
)*
pub fn #fn_name(#self_arg) -> #res_ret_ty {
match self {
#(
#type_name::#field_variants(inner) => Ok(#ret_expr),
)*
_ => Err(#err_expr),
}
}
}
}
fn make_as_variant_method(
type_name: &Ident,
variant_name: &Ident,
type_generics: &TypeGenerics,
cast_err_opts: &ErrorOpts,
mutable: bool,
) -> proc_macro2::TokenStream {
let variant_ty = format_ident!("{}{}", type_name, variant_name);
let (suffix, arg, ret_ty, binding) = if mutable {
(
"_mut",
quote! { &mut self },
quote! { &mut #variant_ty #type_generics },
quote! { ref mut inner },
)
} else {
(
"",
quote! { &self },
quote! { &#variant_ty #type_generics },
quote! { ref inner },
)
};
let (ret_res_ty, err_expr) = cast_err_opts.build_result_type(&ret_ty);
let fn_name = format_ident!("as_{}{}", variant_name.to_string().to_lowercase(), suffix);
quote! {
pub fn #fn_name(#arg) -> #ret_res_ty {
match self {
#type_name::#variant_name(#binding) => Ok(inner),
_ => Err(#err_expr),
}
}
}
}
fn discard_superstruct_attrs(attrs: &[Attribute]) -> Vec<Attribute> {
attrs
.iter()
.filter(|attr| !is_superstruct_attr(attr))
.cloned()
.collect()
}
fn get_cfg_attrs(attrs: &[Attribute]) -> Vec<Attribute> {
attrs
.iter()
.filter(|attr| is_attr_with_ident(attr, "cfg"))
.cloned()
.collect()
}
fn is_superstruct_attr(attr: &Attribute) -> bool {
is_attr_with_ident(attr, "superstruct")
}
fn is_attr_with_ident(attr: &Attribute, ident: &str) -> bool {
attr.path
.get_ident()
.map_or(false, |attr_ident| attr_ident.to_string() == ident)
}