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extern crate proc_macro; | |
extern crate syn; | |
use anyhow::{anyhow, Result}; | |
use syn::Data; | |
use syn::Fields; | |
#[macro_use] | |
extern crate quote; | |
use proc_macro::TokenStream; | |
#[proc_macro_derive(Mapper)] // #[proc_macro_derive(Mapper)] を書くことで、#[derive(Mapper)] を指定した時にderive_mapper() 関数が呼び出されるようになる | |
pub fn derive_mapper(input: TokenStream) -> TokenStream { // input: TokenStream に #[derive(Mapper)] を指定した型情報が入ってくる | |
let input = syn::parse_macro_input!(input as syn::DeriveInput); // inputをparseする | |
impl_mapper_macro(&input).unwrap() | |
} | |
fn impl_mapper_macro(input: &syn::DeriveInput) -> Result<TokenStream> { | |
let data_struct = match &input.data { // #[derive(Mapper)] を指定した型がstructであるかを判定 | |
Data::Struct(data_struct) => data_struct, | |
Data::Enum(_) => Err(anyhow!("invalid type: Enum"))?, | |
Data::Union(_) => Err(anyhow!("invalid type: Union"))?, | |
}; | |
let fields_named = match &data_struct.fields { // structのfield名一覧を取得する | |
Fields::Named(fields_named) => fields_named, | |
Fields::Unnamed(_) => Err(anyhow!("invalid type: Unnamed"))?, | |
Fields::Unit => Err(anyhow!("invalid type: Unit"))?, | |
}; | |
let to_field_value_token_streams: Vec<proc_macro2::TokenStream> = fields_named | |
.named | |
.iter() | |
.enumerate() | |
.map(|(i, field)| { | |
let name = match &field.ident { | |
Some(ident) => syn::Member::Named(ident.clone()), | |
None => syn::Member::Unnamed(i.into()), | |
}; // Converterを実装した型のto_field_valueを呼び、FieldValueに変換するためのmacroを書く | |
return quote! { | |
result.insert(stringify!(#name).to_string(), rust_map_macro::mapper::Converter::to_field_value(&self.#name)); | |
}; | |
}) | |
.collect(); | |
let to_primitive_token_streams: Vec<proc_macro2::TokenStream> = fields_named | |
.named | |
.iter() | |
.enumerate() | |
.map(|(i, field)| { | |
let name = match &field.ident { | |
Some(ident) => syn::Member::Named(ident.clone()), | |
None => syn::Member::Unnamed(i.into()), | |
}; | |
let ty = &field.ty; | |
return quote! { // Converterを実装した型のto_primitiveを呼び、primitive型に変換するためのmacroを書く | |
let mut #name: Option<#ty> = None; | |
if let Some(value) = __optional_map__.get_mut(stringify!(#name)) { | |
if let Some(value) = std::mem::replace(value, None) { | |
#name = Some(rust_map_macro::mapper::Converter::to_primitive(value)?); | |
} else { | |
return Err(anyhow::anyhow!("invalid type: {}", stringify!(#ty))); | |
} | |
} | |
let #name = #name.ok_or(anyhow::anyhow!("invalid type: {}", stringify!(#ty)))?; | |
}; | |
}) | |
.collect(); | |
let to_struct_token_streams: Vec<proc_macro2::TokenStream> = fields_named | |
.named | |
.iter() | |
.enumerate() | |
.map(|(i, field)| { | |
let name = match &field.ident { | |
Some(ident) => syn::Member::Named(ident.clone()), | |
None => syn::Member::Unnamed(i.into()), | |
}; | |
return quote! { // 変換後の変数を構造体にまとめるためのmacroを書く | |
#name, | |
}; | |
}) | |
.collect(); | |
let name = &input.ident; // 構造体名 | |
let (im_generics, ty_generics, _) = input.generics.split_for_impl(); // 構造体のgenerics引数 | |
Ok(quote! { | |
impl#im_generics Mapper for #name#ty_generics { // 構造体にMapperを実装する | |
fn to_map(&self) -> std::collections::HashMap<String, rust_map_macro::mapper::FieldValue> { | |
let mut result = std::collections::HashMap::new(); | |
#(#to_field_value_token_streams)* // 上で書いたmacro(to_field_value_token_streams)をバインドする | |
result | |
} | |
fn from_map(__map__: std::collections::HashMap<String, rust_map_macro::mapper::FieldValue>) -> anyhow::Result<Self> { | |
let mut __optional_map__ = std::collections::HashMap::with_capacity(__map__.len()); | |
for (key, val) in __map__ { | |
__optional_map__.insert(key, Some(val)); | |
} | |
#(#to_primitive_token_streams)* // 上で書いたmacro(to_primitive_token_streams)をバインドする | |
Ok(#name { #(#to_struct_token_streams)* }) // 上で書いたmacro(to_struct_token_streams)をバインドする | |
} | |
} | |
} | |
.into()) | |
} |
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