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use proc_macro::TokenStream;
use quote::{quote, ToTokens};
use syn::{parse, Data, DeriveInput, Fields};
const EXTERNAL_TYPES: &[&str] = &["String", "FixedOffset", "Tz", "NaiveDateTime", "Regex"];
const SUPPORTED_ANGLE_TYPES: &[&str] = &["Vec", "Box", "Option"];
#[proc_macro_derive(MzReflect, attributes(mzreflect))]
pub fn mzreflect_derive(input: TokenStream) -> TokenStream {
let ast: DeriveInput = parse(input).unwrap();
let object_name = &ast.ident;
let object_name_as_string = object_name.to_string();
let mut referenced_types = Vec::new();
let add_object_info = if let Data::Enum(enumdata) = &ast.data {
let variants = enumdata
.variants
.iter()
.map(|v| {
let variant_name = v.ident.to_string();
let (names, types_as_string, mut types_as_syn) = get_fields_names_types(&v.fields);
referenced_types.append(&mut types_as_syn);
quote! {
result.insert(#variant_name, (vec![#(#names),*], vec![#(#types_as_string),*]));
}
})
.collect::<Vec<_>>();
quote! {
if rti.enum_dict.contains_key(#object_name_as_string) { return; }
use std::collections::HashMap;
let mut result = HashMap::new();
#(#variants)*
rti.enum_dict.insert(#object_name_as_string, result);
}
} else if let Data::Struct(structdata) = &ast.data {
let (names, types_as_string, mut types_as_syn) = get_fields_names_types(&structdata.fields);
referenced_types.append(&mut types_as_syn);
quote! {
if rti.struct_dict.contains_key(#object_name_as_string) { return; }
rti.struct_dict.insert(#object_name_as_string,
(vec![#(#names),*], vec![#(#types_as_string),*]));
}
} else {
unreachable!("Not a struct or enum")
};
let referenced_types = referenced_types
.into_iter()
.flat_map(extract_reflected_type)
.map(|typ| quote! { #typ::add_to_reflected_type_info(rti); })
.collect::<Vec<_>>();
let gen = quote! {
impl lowertest::MzReflect for #object_name {
fn add_to_reflected_type_info(
rti: &mut lowertest::ReflectedTypeInfo
)
{
#add_object_info
#(#referenced_types)*
}
}
};
gen.into()
}
fn get_fields_names_types(f: &syn::Fields) -> (Vec<String>, Vec<String>, Vec<&syn::Type>) {
match f {
Fields::Named(named_fields) => {
let (names, types): (Vec<_>, Vec<_>) = named_fields
.named
.iter()
.flat_map(get_field_name_type)
.unzip();
let (types_as_string, types_as_syn) = types.into_iter().unzip();
(names, types_as_string, types_as_syn)
}
Fields::Unnamed(unnamed_fields) => {
let (types_as_string, types_as_syn): (Vec<_>, Vec<_>) = unnamed_fields
.unnamed
.iter()
.flat_map(get_field_name_type)
.map(|(_, (type_as_string, type_as_syn))| (type_as_string, type_as_syn))
.unzip();
(Vec::new(), types_as_string, types_as_syn)
}
Fields::Unit => (Vec::new(), Vec::new(), Vec::new()),
}
}
fn get_field_name_type(f: &syn::Field) -> Option<(String, (String, &syn::Type))> {
for attr in f.attrs.iter() {
if let Ok(syn::Meta::List(meta_list)) = attr.parse_meta() {
if meta_list.path.segments.last().unwrap().ident == "mzreflect" {
for nested_meta in meta_list.nested.iter() {
if let syn::NestedMeta::Meta(syn::Meta::Path(path)) = nested_meta {
if path.segments.last().unwrap().ident == "ignore" {
return None;
}
}
}
}
}
}
let name = if let Some(name) = f.ident.as_ref() {
name.to_string()
} else {
"".to_string()
};
Some((name, (get_type_as_string(&f.ty), &f.ty)))
}
fn get_type_as_string(t: &syn::Type) -> String {
let mut token_stream = proc_macro2::TokenStream::new();
t.to_tokens(&mut token_stream);
token_stream.to_string()
}
fn extract_reflected_type(t: &syn::Type) -> Vec<&syn::Type> {
match t {
syn::Type::Path(tp) => {
let last_segment = tp.path.segments.last().unwrap();
let type_name = last_segment.ident.to_string();
match &last_segment.arguments {
syn::PathArguments::None => {
if EXTERNAL_TYPES.contains(&&type_name[..])
|| type_name.starts_with(|c: char| c.is_lowercase())
{
return Vec::new();
} else {
return vec![t];
}
}
syn::PathArguments::AngleBracketed(args) => {
if SUPPORTED_ANGLE_TYPES.contains(&&type_name[..]) {
return args
.args
.iter()
.flat_map(|arg| {
if let syn::GenericArgument::Type(typ) = arg {
extract_reflected_type(typ)
} else {
Vec::new()
}
})
.collect::<Vec<_>>();
}
}
_ => {}
}
}
syn::Type::Tuple(tt) => {
return tt
.elems
.iter()
.flat_map(extract_reflected_type)
.collect::<Vec<_>>();
}
_ => {}
}
Vec::new()
}