DeriveDisplay macro for enum #1726
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,116 @@ | ||
| use proc_macro2::TokenStream; | ||
| use quote::{quote, quote_spanned, ToTokens}; | ||
| use syn::{LitInt, LitStr}; | ||
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| enum Error { | ||
| InputNotEnum, | ||
| Syn(syn::Error), | ||
| TT(TokenStream), | ||
| } | ||
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| struct Display { | ||
| ident: syn::Ident, | ||
| variants: Vec<DisplayVariant>, | ||
| } | ||
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| struct DisplayVariant { | ||
| ident: syn::Ident, | ||
| display_value: TokenStream, | ||
| } | ||
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| impl Display { | ||
| fn new(input: syn::DeriveInput) -> Result<Self, Error> { | ||
| let ident = input.ident; | ||
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| let variant_vec = match input.data { | ||
| syn::Data::Enum(syn::DataEnum { variants, .. }) => variants, | ||
| _ => return Err(Error::InputNotEnum), | ||
| }; | ||
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| let mut variants = Vec::new(); | ||
| for variant in variant_vec { | ||
| dbg!(variant.ident.clone()); | ||
| let mut display_value = variant.ident.clone().to_string().to_token_stream(); | ||
| for attr in variant.attrs.iter() { | ||
| if !attr.path().is_ident("sea_orm") { | ||
| continue; | ||
| } | ||
| attr.parse_nested_meta(|meta| { | ||
| if meta.path.is_ident("string_value") { | ||
| Some(meta.value()?.parse::<LitStr>()?); | ||
| } else if meta.path.is_ident("num_value") { | ||
| Some(meta.value()?.parse::<LitInt>()?); | ||
| } else if meta.path.is_ident("display_value") { | ||
| display_value = meta.value()?.parse::<LitStr>()?.to_token_stream(); | ||
| } else { | ||
| return Err(meta.error(format!( | ||
| "Unknown attribute parameter found: {:?}", | ||
| meta.path.get_ident() | ||
| ))); | ||
| } | ||
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| Ok(()) | ||
| }) | ||
| .map_err(Error::Syn)?; | ||
| } | ||
| variants.push(DisplayVariant { | ||
| ident: variant.ident, | ||
| display_value, | ||
| }); | ||
| } | ||
| Ok(Display { ident, variants }) | ||
| } | ||
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| fn expand(&self) -> syn::Result<TokenStream> { | ||
| let expanded_impl_active_enum = self.impl_active_enum(); | ||
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| Ok(expanded_impl_active_enum) | ||
| } | ||
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| fn impl_active_enum(&self) -> TokenStream { | ||
| let Self { ident, variants } = self; | ||
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| let variant_idents: Vec<syn::Ident> = variants | ||
| .iter() | ||
| .map(|variant| variant.ident.clone()) | ||
| .collect(); | ||
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| let variant_display: Vec<TokenStream> = variants | ||
| .iter() | ||
| .map(|variant| variant.display_value.to_owned()) | ||
| .collect(); | ||
| // dbg!(variant_display[0].to_string()) ; | ||
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| quote!( | ||
| impl #ident { | ||
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|
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| fn to_display_value(&self) -> String { | ||
| match self { | ||
| #( Self::#variant_idents => #variant_display, )* | ||
| } | ||
| .to_owned() | ||
| } | ||
| } | ||
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| #[automatically_derived] | ||
| impl std::fmt::Display for #ident { | ||
| fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result { | ||
| let v: sea_orm::sea_query::Value = Self::to_display_value(&self).into(); | ||
| write!(f, "{}", v) | ||
| } | ||
| } | ||
| ) | ||
| } | ||
| } | ||
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| pub fn expand_derive_active_enum_display(input: syn::DeriveInput) -> syn::Result<TokenStream> { | ||
| let ident_span = input.ident.span(); | ||
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| match Display::new(input) { | ||
| Ok(model) => model.expand(), | ||
| Err(Error::InputNotEnum) => Ok(quote_spanned! { | ||
| ident_span => compile_error!("you can only derive activeenum_Display on enums"); | ||
| }), | ||
| Err(Error::TT(token_stream)) => Ok(token_stream), | ||
| Err(Error::Syn(e)) => Err(e), | ||
| } | ||
| } | ||
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I believe this is not needed?
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Since the code for DeriveActiveEnum will panic if there is some unrecognised attributes, I added this so that deriving both Display and Active Enum would not make the code panic.