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use darling::FromAttributes;
use proc_macro::TokenStream;
use quote::quote;
use std::error::Error;
use syn::{DataEnum, Fields, Ident, ext::IdentExt};
use crate::jsjson::{
attributes::{ContainerOpts, FieldOpts},
is_vec_u8, js_json_object, object_ident,
};
// {
// "Somestring": "foobar"
// }
//
// {
// "Point": { "x": 10, "y": "one" }
// }
//
// {
// "Tuple": ["two", 20]
// }
//
// "Nothing"
pub(super) fn impl_js_json_enum(
name: &Ident,
data: &DataEnum,
container_opts: ContainerOpts,
) -> Result<TokenStream, Box<dyn Error>> {
let object = object_ident();
// Encoding code for every variant
let mut variant_encodes = vec![];
// Encoding code for every simple variant (data-less)
let mut variant_string_decodes = vec![];
// Envoding code for every compound variant (with data)
let mut variant_object_decodes = vec![];
for variant in &data.variants {
let field_opts = FieldOpts::from_attributes(&variant.attrs)?;
let variant_ident = &variant.ident;
let variant_name = variant.ident.unraw().to_string();
let json_key = match field_opts.rename {
Some(json_key) => json_key,
None => match container_opts.rename_all {
Some(rule) => rule.rename(&variant_name),
None => variant_name.clone(),
},
};
match &variant.fields {
// Simple variant
// Enum::Variant <-> "Variant"
Fields::Unit => {
variant_encodes.push(quote! { Self::#variant_ident => #json_key.to_json(), });
variant_string_decodes.push(quote! { #json_key => Ok(Self::#variant_ident), });
}
// Compound variant with unnamed field(s) (tuple)
// Enum::Variant(...) <-> "Variant": ...
Fields::Unnamed(fields) => {
// Enum::Variant(T) <-> "Variant": T
if fields.unnamed.len() == 1 {
// Encode
let encoded = js_json_object(&[quote! {
vertigo::object_insert(&mut #object, #json_key, value.to_json());
}]);
variant_encodes.push(quote! {
Self::#variant_ident(value) => #encoded,
});
// Decode
variant_object_decodes.push(quote! {
if let Some(value) = compound_variant.get_mut(#json_key) {
return Ok(Self::#variant_ident(
vertigo::JsJsonDeserialize::from_json(ctx.clone(), value.to_owned())?
))
}
});
// Enum::Variant(T1, T2...) <-> "Variant": [T1, T2, ...]
} else {
// Encode
let (field_idents, field_encodes) =
super::tuple_fields::get_encodes(fields.unnamed.iter());
let encoded = js_json_object(&[quote! {
vertigo::object_insert(
&mut #object,
#json_key,
vertigo::JsJson::List(::std::vec![#(#field_encodes)*]),
);
}]);
variant_encodes.push(quote! {
Self::#variant_ident(#(#field_idents,)*) => #encoded,
});
// Decode
let fields_number = field_idents.len();
let field_decodes = super::tuple_fields::get_decodes(field_idents);
variant_object_decodes.push(quote! {
if let Some(value) = compound_variant.get_mut(#json_key) {
match value.to_owned() {
vertigo::JsJson::List(fields) => {
if fields.len() != #fields_number {
return Err(ctx.add(
format!("Wrong unmber of fields in tuple for variant {}. Expected {}, got {}", #variant_name, #fields_number, fields.len())
));
}
let mut fields_rev = fields.into_iter().rev().collect::<Vec<_>>();
return Ok(Self::#variant_ident (
#(#field_decodes)*
))
},
x => return Err(ctx.add(
format!("Invalid type {} while decoding enum tuple, expected list", x.typename())
)),
}
}
});
}
}
// Compound variant with named field(s) (anonymous struct)
// Enum::Variant { x: X, y: Y, ...) <-> "Variant": { x: X, y: Y, ... }
Fields::Named(fields) => {
// Encode
let field_idents = fields
.named
.iter()
.filter_map(|field| field.ident.clone())
.collect::<Vec<_>>();
let mut field_encodes = fields
.named
.iter()
.filter_map(|field| Some((field.ident.clone()?, &field.ty)))
.map(|(field_ident, field_ty)| {
let field_name = field_ident.unraw().to_string();
// Same treatment a struct field of this type gets - see `is_vec_u8`.
let insert = if is_vec_u8(field_ty) {
quote! {
vertigo::object_insert(&mut #object, #field_name, vertigo::JsJson::Vec(#field_ident));
}
} else {
quote! {
vertigo::object_insert(&mut #object, #field_name, #field_ident.to_json());
}
};
(field_name, insert)
})
.collect::<Vec<_>>();
// Ascending key order, for the same reason the struct encoder sorts: an
// insert that lands past everything already in the map shifts nothing.
field_encodes.sort_by(|(left, _), (right, _)| left.cmp(right));
let field_encodes = field_encodes
.into_iter()
.map(|(_, tokens)| tokens)
.collect::<Vec<_>>();
let inner = js_json_object(&field_encodes);
let encoded = js_json_object(&[quote! {
vertigo::object_insert(&mut #object, #json_key, #inner);
}]);
variant_encodes.push(quote! {
Self::#variant_ident {#(#field_idents,)*} => #encoded,
});
// Decode
let field_decodes = fields
.named
.iter()
.filter_map(|field| Some((field.ident.clone()?, &field.ty)))
.map(|(field_ident, field_ty)| {
let field_name = field_ident.unraw().to_string();
if is_vec_u8(field_ty) {
return quote! {
#field_ident: value
.get_property_jsjson(&ctx, #field_name)
.and_then(|item| match item {
vertigo::JsJson::Vec(data) => Ok(data),
other => {
let message = [
"Vec<u8> expected, received ",
other.typename(),
].concat();
Err(ctx.add(message))
}
})?,
};
}
quote! {
#field_ident: value.get_property(&ctx, #field_name)?,
}
})
.collect::<Vec<_>>();
variant_object_decodes.push(quote! {
if let Some(value) = compound_variant.get_mut(#json_key) {
return Ok(Self::#variant_ident {
#(#field_decodes)*
})
}
});
}
}
}
let result = quote! {
impl vertigo::JsJsonSerialize for #name {
fn to_json(self) -> vertigo::JsJson {
match self {
#(#variant_encodes)*
}
}
}
impl vertigo::JsJsonDeserialize for #name {
fn from_json(
ctx: vertigo::JsJsonContext,
json: vertigo::JsJson,
) -> Result<Self, vertigo::JsJsonContext> {
match json {
vertigo::JsJson::String(simple_variant) => {
match simple_variant.as_str() {
#(#variant_string_decodes)*
x => Err(ctx.add(format!("Invalid simple variant {x}"))),
}
}
vertigo::JsJson::Object(mut compound_variant) => {
#(#variant_object_decodes)*
Err(ctx.add("Value not matched with any variant".to_string()))
}
x => Err(ctx.add(
format!("Invalid type {} while decoding enum, expected string or object", x.typename())
)),
}
}
}
};
Ok(result.into())
}