use crate::{macros::tokens, runtime::paths::Paths};
mod field;
pub(super) mod mode;
mod plan;
mod scalar;
mod segment;
mod sources;
use plan::{Scope, encoding};
use segment::task;
pub(super) fn build(
paths: &Paths,
mode: mode::Mode,
mut st: syn::ItemStruct,
) -> syn::Result<proc_macro2::TokenStream> {
let ns_json = &paths.json;
let ns_http = &paths.http;
let [v_raw, v_idx, v_depth] = ["__raw", "__idx", "__depth"].map(tokens::local);
let [v_bytes, v_decode, v_done, v_error] =
["__bytes", "__decoder", "__decoded", "__error"].map(tokens::local);
use std::collections::BTreeMap;
use proc_macro2::TokenStream;
use syn::{Fields, ext::IdentExt, visit::Visit};
if matches!(mode.purpose, mode::Purpose::Decode) && !st.generics.params.is_empty() {
return Err(syn::Error::new_spanned(
&st.generics,
"generic JSON declarations require `encode` or `try_encode`",
));
}
let mut symbols = crate::types::Generics::new(st.generics.clone());
symbols.reserve().visit_item_struct(&st);
let marker = symbols.ident("__sark_json_marker");
let name = st.ident.clone();
let vis = st.vis.clone();
let fields = match &mut st.fields {
Fields::Named(named) => {
use crate::json::field::FieldMode;
let parsed = named
.named
.iter()
.map(|field| FieldMode::from_field(field, mode.plain))
.collect::<syn::Result<Vec<_>>>()?;
for field in &mut named.named {
field.attrs.retain(|attr| {
!attr.path().is_ident("raw")
&& !attr.path().is_ident("plain")
&& !attr.path().is_ident("field")
});
}
named
.named
.iter()
.zip(parsed)
.enumerate()
.map(|(idx, (field, (kind, rename)))| {
let ident = field.ident.clone().ok_or_else(|| {
syn::Error::new(proc_macro2::Span::call_site(), "named field required")
})?;
let label = match rename {
Some(name) => name,
None => ident.unraw().to_string(),
};
Ok(plan::JsonField {
bind: tokens::local(&format!("__f{idx}")),
ident,
ty: field.ty.clone(),
vis: field.vis.clone(),
name: label,
mode: kind,
})
})
.collect::<syn::Result<Vec<_>>>()?
}
Fields::Unnamed(unnamed) => {
return Err(syn::Error::new_spanned(
unnamed,
"#[sark_gen::json] requires a named-field struct",
));
}
Fields::Unit => {
return Err(syn::Error::new_spanned(
&name,
"#[sark_gen::json] requires a named-field struct",
));
}
};
let mut names = BTreeMap::new();
for field in fields.iter().filter(|field| !field.mode.flatten) {
if let Some(first) = names.insert(field.name.as_str(), &field.ident) {
let mut error = syn::Error::new_spanned(&field.ident, "duplicate JSON wire field name");
error.combine(syn::Error::new_spanned(
first,
"first field with this wire name",
));
return Err(error);
}
}
let plan = plan::Plan {
mode: &mode,
fields,
};
if !matches!(mode.purpose, mode::Purpose::Encode)
&& let Some(field) = plan.fields.iter().find(|field| field.mode.flatten)
{
return Err(syn::Error::new_spanned(
&field.ident,
"`flatten` requires encoding-only `#[json(encode)]`",
));
}
if mode.exact
&& plan
.fields
.iter()
.any(|field| field.mode.nested || field.mode.seq)
{
return Err(syn::Error::new(
proc_macro2::Span::call_site(),
"#[field(nested)] and #[field(seq)] are not supported with `exact`",
));
}
let names = encoding::Names::new(&st.generics);
let plan::Emission { lengths, writes } = plan.encoding(paths, Scope::Object, &names)?;
let (_, enc_ty, _) = st.generics.split_for_impl();
let encoder = encoding::emit(
paths,
&st.generics,
quote::quote!(#name #enc_ty),
&names,
&lengths,
&writes,
);
if let syn::Fields::Named(named) = &mut st.fields {
for (decl, field) in named.named.iter_mut().zip(&plan.fields) {
decl.ty = field::proof_type(paths, &field.ty, field.mode)?;
}
}
let members = if matches!(mode.purpose, mode::Purpose::TryEncode) {
TokenStream::new()
} else {
plan.members(paths, &st)?
};
if !matches!(mode.purpose, mode::Purpose::Decode) {
st.attrs.retain(|attr| !attr.path().is_ident("json"));
return scope(
&st,
quote::quote! {
#st
#encoder
#members
},
);
}
let scoped = task::expand(
paths,
&name,
&vis,
&st.generics,
&plan.fields,
&mode,
&marker,
)?;
let borrow = plan.borrowed(paths);
let stream = {
let order = match mode.kind {
mode::JsonKind::Ordered => quote::quote!(#ns_json::segment::Order::Ordered),
mode::JsonKind::Unordered => quote::quote!(#ns_json::segment::Order::Unordered),
};
let schema = plan
.fields
.iter()
.map(|field| {
let name =
syn::LitByteStr::new(field.name.as_bytes(), proc_macro2::Span::call_site());
let view = if field.mode.nested || field.mode.seq {
quote::quote!(#ns_json::segment::Projection::Segments)
} else {
let class = scalar::Classified::of(&field.ty)?;
match class.scalar {
scalar::Scalar::Shared if !field.mode.raw && !field.mode.plain => {
quote::quote!(#ns_json::segment::Projection::Frame)
}
scalar::Scalar::Shared | scalar::Scalar::Token => {
quote::quote!(#ns_json::segment::Projection::Bytes)
}
_ => {
quote::quote!(#ns_json::segment::Projection::Scalar)
}
}
};
Ok(quote::quote!(#ns_json::segment::Field::new(
#name,
#view,
)))
})
.collect::<syn::Result<Vec<_>>>()?;
segment::decode(paths, &name, &vis, &plan.fields, order, schema, &marker)?
};
let decode = quote::quote! {
let mut #v_decode = #ns_json::segment::Decoder::<Self>::one(#v_bytes)?;
loop {
match #v_decode.poll(::core::num::NonZero::<::core::primitive::usize>::MAX) {
#ns_json::segment::Progress::Ready(#v_done) => return ::core::result::Result::Ok(#v_done),
#ns_json::segment::Progress::Failed(#v_error) => return ::core::result::Result::Err(#v_error),
#ns_json::segment::Progress::NeedInput => {
return ::core::result::Result::Err(#ns_json::Error::Invalid.into());
}
#ns_json::segment::Progress::Pending => {}
}
}
};
let request = {
let view = quote::format_ident!("{}JsonView", name);
let items = plan
.fields
.iter()
.map(|field| {
Ok(plan::JsonField {
ident: field.ident.clone(),
bind: field.bind.clone(),
ty: field::request_type(paths, &field.ty, field.mode)?,
vis: field.vis.clone(),
name: field.name.clone(),
mode: field.mode,
})
})
.collect::<syn::Result<Vec<_>>>()?;
let shape = plan::Plan {
mode: &mode,
fields: items,
};
let decls = shape
.fields
.iter()
.map(|field| {
let ident = &field.ident;
let ty = field::proof_type(paths, &field.ty, field.mode)?;
let vis = &field.vis;
Ok(quote::quote!(#vis #ident: #ty))
})
.collect::<syn::Result<Vec<_>>>()?;
let locals = shape.locals(paths)?;
let finals = shape.finals(paths);
let body = shape.decode_body(paths)?;
let generics = syn::parse_quote!(<'req>);
let names = encoding::Names::new(&generics);
let plan::Emission { lengths, writes } = shape.encoding(paths, Scope::Object, &names)?;
let encode = encoding::emit(
paths,
&generics,
quote::quote!(#view<'req>),
&names,
&lengths,
&writes,
);
quote::quote! {
#vis struct #view<'req> {
#( #decls, )*
#[doc(hidden)]
#marker: ::core::marker::PhantomData<&'req ()>,
}
impl #ns_json::parsing::Request for #name {
type View<'req> = #view<'req>;
fn prefix<'req>(
#v_raw: &'req [::core::primitive::u8],
mut #v_idx: ::core::primitive::usize,
#v_depth: #ns_json::parsing::Depth,
) -> ::core::result::Result<
(Self::View<'req>, ::core::primitive::usize),
#ns_json::parsing::Error<'req>,
> {
#ns_json::input::Input::ws(#v_raw, &mut #v_idx);
#ns_json::input::Input::expect_byte(#v_raw, &mut #v_idx, b'{')?;
#(#locals)*
#body
::core::result::Result::Ok((#view {
#(#finals,)*
#marker: ::core::marker::PhantomData,
}, #v_idx))
}
}
impl<'view> #ns_json::parsing::Request for #view<'view> {
type View<'req> = #view<'req>;
fn prefix<'req>(
#v_raw: &'req [::core::primitive::u8],
#v_idx: ::core::primitive::usize,
#v_depth: #ns_json::parsing::Depth,
) -> ::core::result::Result<
(Self::View<'req>, ::core::primitive::usize),
#ns_json::parsing::Error<'req>,
> {
<#name as #ns_json::parsing::Request>::prefix(#v_raw, #v_idx, #v_depth)
}
}
#encode
}
};
st.attrs.retain(|attr| !attr.path().is_ident("json"));
scope(
&st,
quote::quote! {
#st
#request
#scoped
impl #ns_json::parsing::Decode for #name {
fn decode<'__e>(#v_bytes: #ns_http::o3::buffer::storage::Shared) ->
::core::result::Result<Self, #ns_json::parsing::Error<'__e>> {
#decode
}
#borrow
}
#stream
#encoder
#members
},
)
}
fn scope(
source: &syn::ItemStruct,
output: proc_macro2::TokenStream,
) -> syn::Result<proc_macro2::TokenStream> {
use quote::ToTokens;
use syn::{visit::Visit, visit_mut::VisitMut};
let mut names = crate::types::Generics::new(source.generics.clone());
names.reserve().visit_item_struct(source);
let prefix = crate::handler::names::encoded("__SarkJson", &source.ident).to_string();
let module = quote::format_ident!("{}", prefix.to_lowercase());
let mut imports = crate::types::Imports::new(names, prefix);
let mut declarations = proc_macro2::TokenStream::new();
let mut implementations = proc_macro2::TokenStream::new();
for item in syn::parse2::<syn::File>(output)?.items {
if let syn::Item::Impl(mut item) = item {
imports.bind(&item.generics);
imports.visit_item_impl_mut(&mut item);
item.to_tokens(&mut implementations);
} else {
item.to_tokens(&mut declarations);
}
}
let (outer, inner) = imports.finish()?;
Ok(quote::quote! {
#declarations
#outer
mod #module {
#inner
#implementations
}
})
}