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use proc_macro::TokenStream;
use quote::{format_ident, quote};
use syn::{parse::Parse, parse_macro_input, DeriveInput, Ident, Lit, Meta, MetaList, Token, Type};
struct SerdeCryptAttrStruct {
ident: Ident,
_punct: Token![=],
literal: Lit,
}
impl Parse for SerdeCryptAttrStruct {
fn parse(input: syn::parse::ParseStream) -> syn::Result<Self> {
Ok(SerdeCryptAttrStruct {
ident: input.parse()?,
_punct: input.parse()?,
literal: input.parse()?,
})
}
}
struct SerdeCryptTypes {
e: Type,
_punct: Token![,],
d: Type,
}
impl Parse for SerdeCryptTypes {
fn parse(input: syn::parse::ParseStream) -> syn::Result<Self> {
Ok(SerdeCryptTypes {
e: input.parse()?,
_punct: input.parse()?,
d: input.parse()?,
})
}
}
#[proc_macro_attribute]
pub fn serde_crypt_gen(_meta: TokenStream, input: TokenStream) -> TokenStream {
let ast = parse_macro_input!(input as DeriveInput);
let vis = ast.vis;
let attrs = ast.attrs.iter().map(|e| quote! { #e }).reduce(|a, e| {
quote! {
#a
#e
}
});
let encrypted_ident = format_ident!("{}Encrypted", ast.ident);
let decrypted_ident = format_ident!("{}Decrypted", ast.ident);
let encrypted_fields = match &ast.data {
syn::Data::Struct(ref data_struct) => data_struct
.fields
.iter()
.map(|field| {
let ident = &field.ident;
let field_vis = &field.vis;
let mut replace = false;
let mut custom_types = false;
let mut ty = field.ty.clone();
let field_attrs = &field
.attrs
.iter()
.filter(|attr| {
if let Meta::List(MetaList { path, tokens, .. }) = &attr.meta {
let serde_tag: Result<SerdeCryptAttrStruct, _> =
syn::parse2(tokens.clone());
let crypt_types: Result<SerdeCryptTypes, _> =
syn::parse2(tokens.clone());
if serde_tag.is_ok() {
let tokens = serde_tag.unwrap();
let ident = tokens.ident.to_string();
let lit: String = match tokens.literal {
Lit::Str(val) => val.value(),
_ => return true,
};
if path.is_ident("serde") && ident == "with" && lit == "serde_crypt"
{
replace = true;
return false;
}
}
if crypt_types.is_ok() {
let tokens = crypt_types.unwrap();
let enc = tokens.e;
if path.is_ident("serde_crypt_types") {
custom_types = true;
replace = true;
ty = enc;
return false;
}
}
}
true
})
.map(|e| quote! {#e})
.reduce(|a, e| {
quote! {
#a
#e
}
});
if replace {
if custom_types {
quote! {
#field_attrs
#field_vis #ident: #ty
}
} else {
quote! {
#field_attrs
#field_vis #ident: String
}
}
} else {
quote! { #field }
}
})
.reduce(|a, e| {
return quote! {
#a,
#e
};
}),
_ => panic!("#[serde_crypt_gen] may only be used on structs"),
};
let decrypted_fields = match &ast.data {
syn::Data::Struct(ref data_struct) => data_struct
.fields
.iter()
.map(|field| {
let ident = &field.ident;
let field_vis = &field.vis;
let mut custom_types = false;
let mut ty = field.ty.clone();
let field_attrs = &field
.attrs
.iter()
.filter(|attr| {
if let Meta::List(MetaList { path, tokens, .. }) = &attr.meta {
let crypt_types: Result<SerdeCryptTypes, _> =
syn::parse2(tokens.clone());
if crypt_types.is_ok() {
let tokens = crypt_types.unwrap();
let dec = tokens.d;
if path.is_ident("serde_crypt_types") {
custom_types = true;
ty = dec;
return false;
}
}
}
true
})
.map(|e| quote! {#e})
.reduce(|a, e| {
quote! {
#a
#e
}
});
if custom_types {
quote! {
#field_attrs
#[serde(with = "serde_crypt")]
#field_vis #ident: #ty
}
} else {
quote! { #field }
}
})
.map(|e| quote! {#e})
.reduce(|a, e| {
quote! {
#a,
#e
}
}),
_ => panic!("#[serde_crypt_gen] may only be used on structs"),
};
let types = quote! {
#attrs
#vis struct #encrypted_ident {
#encrypted_fields
}
#attrs
#vis struct #decrypted_ident {
#decrypted_fields
}
};
types.into()
}