rpa_enum 0.1.3

RPA Enum extension.
Documentation 
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use quote::quote;
use std::collections::HashMap;

pub fn get_impl(enum_ident: &syn::Ident, variant_idents: &HashMap<String, syn::Ident>, optional_variant: &Option<syn::Ident>) -> proc_macro2::TokenStream {

    let mut variants: Vec<proc_macro2::TokenStream> = Vec::new();

    variant_idents.keys().for_each(|variant_name| {
        let variant_ident = variant_idents.get(variant_name).unwrap();
        let variant_template = quote! {
            #variant_name => Ok(#enum_ident::#variant_ident),
        };
        variants.push(variant_template.into());
    });


    if optional_variant.is_some() {
        let optional_variant = optional_variant.clone().unwrap();
        return quote! {
            impl FromSql<Text, Mysql> for #enum_ident {
                fn from_sql(bytes: Option<&<Mysql as Backend>::RawValue>) -> diesel::deserialize::Result<Self> {
                    return if bytes.is_none() {
                        Ok(#enum_ident::#optional_variant)
                    } else {
                        let mut value = bytes.unwrap();
                        let mut name = String::new();
                        let result = value.read_to_string(& mut name);
                        if result.is_err() {
                            Err(format!("Invalid value for {}", stringify!(#enum_ident)).into())
                        } else {
                            match name.as_str() {
                                #(#variants)*
                                _ => Err(format!("Invalid value for {}", stringify!(#enum_ident)).into())
                            }
                        }
                    }
                }
            }
        };
    } else {
        return quote! {
            impl FromSql<Text, Mysql> for #enum_ident {
                fn from_sql(bytes: Option<&<Mysql as Backend>::RawValue>) -> diesel::deserialize::Result<Self> {
                    if bytes.is_some() {
                        let mut value = bytes.unwrap();
                        let mut name = String::new();
                        let result = value.read_to_string(& mut name);
                        if result.is_err() {
                            return Err(format!("Invalid value for {}", stringify!(#enum_ident)).into());
                        }
                        return match name.as_str() {
                            #(#variants)*
                            _ => Err(format!("Invalid value for {}", stringify!(#enum_ident)).into())
                        }
                    }
                    return Err(format!("Invalid value for {}", stringify!(#enum_ident)).into())
                }
            }
        };
    }
}