1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143

use proc_macro2::TokenStream;
use quote::quote;
use syn::{Data, DeriveInput, Fields};

use crate::helpers::{
    non_enum_error, occurrence_error, HasStrumVariantProperties, HasTypeProperties,
};

pub fn from_string_inner(ast: &DeriveInput) -> syn::Result<TokenStream> {
    let name = &ast.ident;
    let (impl_generics, ty_generics, where_clause) = ast.generics.split_for_impl();
    let variants = match &ast.data {
        Data::Enum(v) => &v.variants,
        _ => return Err(non_enum_error()),
    };

    let type_properties = ast.get_type_properties()?;
    let strum_module_path = type_properties.crate_module_path();

    let mut default_kw = None;
    let mut default = quote! { _ => ::core::result::Result::Err(#strum_module_path::ParseError::VariantNotFound) };
    let mut arms = Vec::new();
    for variant in variants {
        let ident = &variant.ident;
        let variant_properties = variant.get_variant_properties()?;

        if variant_properties.disabled.is_some() {
            continue;
        }

        if let Some(kw) = variant_properties.default {
            if let Some(fst_kw) = default_kw {
                return Err(occurrence_error(fst_kw, kw, "default"));
            }

            match &variant.fields {
                Fields::Unnamed(fields) if fields.unnamed.len() == 1 => {}
                _ => {
                    return Err(syn::Error::new_spanned(
                        variant,
                        "Default only works on newtype structs with a single String field",
                    ))
                }
            }

            default_kw = Some(kw);
            default = quote! {
                default => ::core::result::Result::Ok(#name::#ident(default.into()))
            };
            continue;
        }

        let is_ascii_case_insensitive = variant_properties
            .ascii_case_insensitive
            .unwrap_or(type_properties.ascii_case_insensitive);
        // If we don't have any custom variants, add the default serialized name.
        let attrs = variant_properties
            .get_serializations(type_properties.case_style)
            .into_iter()
            .map(|serialization| {
                if is_ascii_case_insensitive {
                    quote! { s if s.eq_ignore_ascii_case(#serialization) }
                } else {
                    quote! { #serialization }
                }
            });

        let params = match &variant.fields {
            Fields::Unit => quote! {},
            Fields::Unnamed(fields) => {
                let defaults =
                    ::std::iter::repeat(quote!(Default::default())).take(fields.unnamed.len());
                quote! { (#(#defaults),*) }
            }
            Fields::Named(fields) => {
                let fields = fields
                    .named
                    .iter()
                    .map(|field| field.ident.as_ref().unwrap());
                quote! { {#(#fields: Default::default()),*} }
            }
        };

        arms.push(quote! { #(#attrs => ::core::result::Result::Ok(#name::#ident #params)),* });
    }

    arms.push(default);

    let from_str = quote! {
        #[allow(clippy::use_self)]
        impl #impl_generics ::core::str::FromStr for #name #ty_generics #where_clause {
            type Err = #strum_module_path::ParseError;
            fn from_str(s: &str) -> ::core::result::Result< #name #ty_generics , <Self as ::core::str::FromStr>::Err> {
                match s {
                    #(#arms),*
                }
            }
        }
    };

    let try_from_str = try_from_str(
        name,
        impl_generics,
        ty_generics,
        where_clause,
        strum_module_path,
    );

    Ok(quote! {
        #from_str
        #try_from_str
    })
}

#[rustversion::before(1.34)]
fn try_from_str(
    _name: &proc_macro2::Ident,
    _impl_generics: syn::ImplGenerics,
    _ty_generics: syn::TypeGenerics,
    _where_clause: Option<&syn::WhereClause>,
    _strum_module_path: syn::Path,
) -> TokenStream {
    Default::default()
}

#[rustversion::since(1.34)]
fn try_from_str(
    name: &proc_macro2::Ident,
    impl_generics: syn::ImplGenerics,
    ty_generics: syn::TypeGenerics,
    where_clause: Option<&syn::WhereClause>,
    strum_module_path: syn::Path,
) -> TokenStream {
    quote! {
        #[allow(clippy::use_self)]
        impl #impl_generics ::core::convert::TryFrom<&str> for #name #ty_generics #where_clause {
            type Error = #strum_module_path::ParseError;
            fn try_from(s: &str) -> ::core::result::Result< #name #ty_generics , <Self as ::core::convert::TryFrom<&str>>::Error> {
                ::core::str::FromStr::from_str(s)
            }
        }
    }
}