use proc_macro2::TokenStream as TokenStream2;
use quote::quote;
fn max_n(args: &[TokenStream2]) -> TokenStream2 {
match args.split_first() {
Some((head, rest)) => {
let rest = max_n(rest);
quote! {
[#head, #rest][(#head < #rest) as usize]
}
}
None => quote! { 0u64 },
}
}
fn footprint(s: &synstructure::Structure) -> TokenStream2 {
let variant_footprints = s
.variants()
.iter()
.map(|variant| {
variant
.ast()
.fields
.iter()
.map(|field| &field.ty)
.map(|ty| quote! { <#ty as ::pro_storage::traits::SpreadLayout>::FOOTPRINT })
.fold(quote! { 0u64 }, |lhs, rhs| {
quote! { (#lhs + #rhs) }
})
})
.collect::<Vec<_>>();
max_n(&variant_footprints[..])
}
fn requires_deep_clean_up(s: &synstructure::Structure) -> TokenStream2 {
s.variants()
.iter()
.map(|variant| {
variant
.ast()
.fields
.iter()
.map(|field| &field.ty)
.map(|ty| quote! { <#ty as ::pro_storage::traits::SpreadLayout>::REQUIRES_DEEP_CLEAN_UP })
.fold(quote! { false }, |lhs, rhs| {
quote! { (#lhs || #rhs) }
})
})
.fold(quote! { false }, |lhs, rhs| {
quote! { (#lhs || #rhs) }
})
}
fn spread_layout_struct_derive(s: &synstructure::Structure) -> TokenStream2 {
assert!(s.variants().len() == 1, "can only operate on structs");
let footprint_body = footprint(s);
let requires_deep_clean_up_body = requires_deep_clean_up(s);
let variant: &synstructure::VariantInfo = &s.variants()[0];
let pull_body = variant.construct(|field, _index| {
let ty = &field.ty;
quote! {
<#ty as ::pro_storage::traits::SpreadLayout>::pull_spread(__key_ptr)
}
});
let push_body = variant.each(|binding| {
quote! {
::pro_storage::traits::SpreadLayout::push_spread(#binding, __key_ptr);
}
});
let clear_body = s.each(|field| {
quote! {
::pro_storage::traits::SpreadLayout::clear_spread(#field, __key_ptr);
}
});
s.gen_impl(quote! {
gen impl ::pro_storage::traits::SpreadLayout for @Self {
#[allow(unused_comparisons)]
const FOOTPRINT: u64 = #footprint_body;
const REQUIRES_DEEP_CLEAN_UP: bool = #requires_deep_clean_up_body;
fn pull_spread(__key_ptr: &mut ::pro_storage::traits::KeyPtr) -> Self {
#pull_body
}
fn push_spread(&self, __key_ptr: &mut ::pro_storage::traits::KeyPtr) {
match self { #push_body }
}
fn clear_spread(&self, __key_ptr: &mut ::pro_storage::traits::KeyPtr) {
match self { #clear_body }
}
}
})
}
fn spread_layout_enum_derive(s: &synstructure::Structure) -> TokenStream2 {
assert!(s.variants().len() >= 2, "can only operate on enums");
let footprint_body = footprint(s);
let requires_deep_clean_up_body = requires_deep_clean_up(s);
let pull_body = s
.variants()
.iter()
.map(|variant| {
variant.construct(|field, _index| {
let ty = &field.ty;
quote! {
<#ty as ::pro_storage::traits::SpreadLayout>::pull_spread(__key_ptr)
}
})
})
.enumerate()
.fold(quote! {}, |acc, (index, variant)| {
let index = index as u8;
quote! {
#acc
#index => #variant,
}
});
let push_body = s.variants().iter().enumerate().map(|(index, variant)| {
let pat = variant.pat();
let index = index as u8;
let fields = variant.bindings().iter().map(|field| {
quote! {
::pro_storage::traits::SpreadLayout::push_spread(#field, __key_ptr);
}
});
quote! {
#pat => {
{ <u8 as ::pro_storage::traits::SpreadLayout>::push_spread(&#index, __key_ptr); }
#(
{ #fields }
)*
}
}
});
let clear_body = s.each(|field| {
quote! {
::pro_storage::traits::SpreadLayout::clear_spread(#field, __key_ptr);
}
});
s.gen_impl(quote! {
gen impl ::pro_storage::traits::SpreadLayout for @Self {
#[allow(unused_comparisons)]
const FOOTPRINT: u64 = 1 + #footprint_body;
const REQUIRES_DEEP_CLEAN_UP: bool = #requires_deep_clean_up_body;
fn pull_spread(__key_ptr: &mut ::pro_storage::traits::KeyPtr) -> Self {
match <u8 as ::pro_storage::traits::SpreadLayout>::pull_spread(__key_ptr) {
#pull_body
_ => unreachable!("encountered invalid enum discriminant"),
}
}
fn push_spread(&self, __key_ptr: &mut ::pro_storage::traits::KeyPtr) {
match self {
#(
#push_body
)*
}
}
fn clear_spread(&self, __key_ptr: &mut ::pro_storage::traits::KeyPtr) {
match self {
#clear_body
}
}
}
})
}
pub fn spread_layout_derive(mut s: synstructure::Structure) -> TokenStream2 {
s.bind_with(|_| synstructure::BindStyle::Move)
.add_bounds(synstructure::AddBounds::Generics)
.underscore_const(true);
match s.ast().data {
syn::Data::Struct(_) => spread_layout_struct_derive(&s),
syn::Data::Enum(_) => spread_layout_enum_derive(&s),
_ => {
panic!(
"cannot derive `SpreadLayout` or `PackedLayout` for Rust `union` items"
)
}
}
}