use proc_macro2::{Span, TokenStream};
use quote::{quote, quote_spanned, ToTokens};
use syn::spanned::Spanned;
use syn::{DeriveInput, Generics, Path, Type};
use crate::internal::attrs::Default;
use crate::internal::inputs::RemoteInput;
use crate::internal::{attrs, Container, Context, Data, Field, Remote, Style, Variant};
pub fn expand_nix_deserialize(
crate_path: Path,
input: &mut DeriveInput,
) -> syn::Result<TokenStream> {
let cx = Context::new();
let cont = Container::from_ast(&cx, crate_path, input);
cx.check()?;
let cont = cont.unwrap();
let ty = cont.ident_type();
let body = nix_deserialize_body(&cont);
let crate_path = cont.crate_path();
Ok(nix_deserialize_impl(
crate_path,
&ty,
&cont.original.generics,
body,
))
}
pub fn expand_nix_deserialize_remote(
crate_path: Path,
input: &RemoteInput,
) -> syn::Result<TokenStream> {
let cx = Context::new();
let remote = Remote::from_ast(&cx, crate_path, input);
cx.check()?;
let remote = remote.unwrap();
let crate_path = remote.crate_path();
let body = nix_deserialize_body_from(crate_path, &remote.attrs).expect("From tokenstream");
let generics = Generics::default();
Ok(nix_deserialize_impl(crate_path, remote.ty, &generics, body))
}
fn nix_deserialize_impl(
crate_path: &Path,
ty: &Type,
generics: &Generics,
body: TokenStream,
) -> TokenStream {
let (impl_generics, ty_generics, where_clause) = generics.split_for_impl();
quote! {
#[automatically_derived]
impl #impl_generics #crate_path::nix_daemon::de::NixDeserialize for #ty #ty_generics
#where_clause
{
#[allow(clippy::manual_async_fn)]
fn try_deserialize<R>(reader: &mut R) -> impl ::std::future::Future<Output=Result<Option<Self>, R::Error>> + Send + '_
where R: ?Sized + #crate_path::nix_daemon::de::NixRead + Send,
{
#body
}
}
}
}
fn nix_deserialize_body_from(
crate_path: &syn::Path,
attrs: &attrs::Container,
) -> Option<TokenStream> {
if let Some(span) = attrs.from_str.as_ref() {
Some(nix_deserialize_from_str(crate_path, span.span()))
} else if let Some(type_from) = attrs.type_from.as_ref() {
Some(nix_deserialize_from(type_from))
} else {
attrs
.type_try_from
.as_ref()
.map(|type_try_from| nix_deserialize_try_from(crate_path, type_try_from))
}
}
fn nix_deserialize_body(cont: &Container) -> TokenStream {
if let Some(tokens) = nix_deserialize_body_from(cont.crate_path(), &cont.attrs) {
tokens
} else {
match &cont.data {
Data::Struct(style, fields) => nix_deserialize_struct(*style, fields),
Data::Enum(variants) => nix_deserialize_enum(variants),
}
}
}
fn nix_deserialize_struct(style: Style, fields: &[Field<'_>]) -> TokenStream {
let read_fields = fields.iter().map(|f| {
let field = f.var_ident();
let ty = f.ty;
let read_value = quote_spanned! {
ty.span()=> if first__ {
first__ = false;
if let Some(v) = reader.try_read_value::<#ty>().await? {
v
} else {
return Ok(None);
}
} else {
reader.read_value::<#ty>().await?
}
};
if let Some(version) = f.attrs.version.as_ref() {
let default = match &f.attrs.default {
Default::Default => quote_spanned!(ty.span()=>::std::default::Default::default),
Default::Path(path) => path.to_token_stream(),
_ => panic!("No default for versioned field"),
};
quote! {
let #field : #ty = if (#version).contains(&reader.version().minor()) {
#read_value
} else {
#default()
};
}
} else {
quote! {
let #field : #ty = #read_value;
}
}
});
let field_names = fields.iter().map(|f| f.var_ident());
let construct = match style {
Style::Struct => {
quote! {
Self { #(#field_names),* }
}
}
Style::Tuple => {
quote! {
Self(#(#field_names),*)
}
}
Style::Unit => quote!(Self),
};
quote! {
#[allow(unused_assignments)]
async move {
let mut first__ = true;
#(#read_fields)*
Ok(Some(#construct))
}
}
}
fn nix_deserialize_variant(variant: &Variant<'_>) -> TokenStream {
let ident = variant.ident;
let read_fields = variant.fields.iter().map(|f| {
let field = f.var_ident();
let ty = f.ty;
let read_value = quote_spanned! {
ty.span()=> if first__ {
first__ = false;
if let Some(v) = reader.try_read_value::<#ty>().await? {
v
} else {
return Ok(None);
}
} else {
reader.read_value::<#ty>().await?
}
};
if let Some(version) = f.attrs.version.as_ref() {
let default = match &f.attrs.default {
Default::Default => quote_spanned!(ty.span()=>::std::default::Default::default),
Default::Path(path) => path.to_token_stream(),
_ => panic!("No default for versioned field"),
};
quote! {
let #field : #ty = if (#version).contains(&reader.version().minor()) {
#read_value
} else {
#default()
};
}
} else {
quote! {
let #field : #ty = #read_value;
}
}
});
let field_names = variant.fields.iter().map(|f| f.var_ident());
let construct = match variant.style {
Style::Struct => {
quote! {
Self::#ident { #(#field_names),* }
}
}
Style::Tuple => {
quote! {
Self::#ident(#(#field_names),*)
}
}
Style::Unit => quote!(Self::#ident),
};
let version = &variant.attrs.version;
quote! {
#version => {
#(#read_fields)*
Ok(Some(#construct))
}
}
}
fn nix_deserialize_enum(variants: &[Variant<'_>]) -> TokenStream {
let match_variant = variants
.iter()
.map(|variant| nix_deserialize_variant(variant));
quote! {
#[allow(unused_assignments)]
async move {
let mut first__ = true;
match reader.version().minor() {
#(#match_variant)*
}
}
}
}
fn nix_deserialize_from(ty: &Type) -> TokenStream {
quote_spanned! {
ty.span() =>
async move {
if let Some(value) = reader.try_read_value::<#ty>().await? {
Ok(Some(<Self as ::std::convert::From<#ty>>::from(value)))
} else {
Ok(None)
}
}
}
}
fn nix_deserialize_try_from(crate_path: &Path, ty: &Type) -> TokenStream {
quote_spanned! {
ty.span() =>
async move {
use #crate_path::nix_daemon::de::Error;
if let Some(item) = reader.try_read_value::<#ty>().await? {
<Self as ::std::convert::TryFrom<#ty>>::try_from(item)
.map_err(Error::invalid_data)
.map(Some)
} else {
Ok(None)
}
}
}
}
fn nix_deserialize_from_str(crate_path: &Path, span: Span) -> TokenStream {
quote_spanned! {
span =>
async move {
use #crate_path::nix_daemon::de::Error;
if let Some(buf) = reader.try_read_bytes().await? {
let s = ::std::str::from_utf8(&buf)
.map_err(Error::invalid_data)?;
<Self as ::std::str::FromStr>::from_str(s)
.map_err(Error::invalid_data)
.map(Some)
} else {
Ok(None)
}
}
}
}
