validators-derive 0.26.0

The provided crate offers a procedural macro for defining validators, including optional parameters.
use quote::quote;
use syn::{Data, DeriveInput, Fields, Meta, Path};

use super::ValidatorHandler;
use crate::{
    common::{attributes::basic_attribute::BasicAttribute, type_enum::TypeEnum},
    panic,
};

pub(crate) struct SemverReqHandler;

#[allow(dead_code)]
#[derive(Debug)]
pub struct Struct(TypeEnum);

const ITEM: Struct = Struct(TypeEnum::VersionReq);

impl ValidatorHandler for SemverReqHandler {
    fn meta_handler(ast: DeriveInput, meta: Meta) -> syn::Result<proc_macro2::TokenStream> {
        #[allow(unused_variables)]
        let type_attribute = BasicAttribute::build_from_meta(&meta)?;

        if let Data::Struct(data) = ast.data
            && let Fields::Unnamed(_) = &data.fields
            && data.fields.len() == 1
        {
            let mut token_stream = proc_macro2::TokenStream::new();

            let name = ast.ident;

            let error_path: Path = syn::parse2(quote! { validators_prelude::SemverError }).unwrap();

            token_stream.extend(quote! {
                        impl #name {
                            #[inline]
                            fn v_parse_str(s: &str) -> Result<validators_prelude::semver::VersionReq, #error_path> {
                                Ok(validators_prelude::semver::VersionReq::parse(s)?)
                            }
                        }
                    });

            token_stream.extend(quote! {
                        impl ValidateString for #name {
                            type Error = #error_path;

                            #[inline]
                            fn parse_string<S: Into<validators_prelude::String>>(s: S) -> Result<Self, Self::Error> {
                                Ok(Self(Self::v_parse_str(s.into().as_str())?))
                            }

                            #[inline]
                            fn parse_str<S: AsRef<str>>(s: S) -> Result<Self, Self::Error> {
                                Ok(Self(Self::v_parse_str(s.as_ref())?))
                            }

                            #[inline]
                            fn validate_str<S: AsRef<str>>(s: S) -> Result<(), Self::Error> {
                                Self::v_parse_str(s.as_ref())?;

                                Ok(())
                            }
                        }
                    });

            #[cfg(feature = "serde")]
            {
                if type_attribute.serde_options.serialize {
                    token_stream.extend(quote! {
                        impl validators_prelude::serde::Serialize for #name {
                            #[inline]
                            fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
                                where
                                    S: validators_prelude::serde::Serializer, {
                                validators_prelude::serde::Serialize::serialize(&self.0, serializer)
                            }
                        }
                    });
                }

                if type_attribute.serde_options.deserialize {
                    token_stream.extend(quote! {
                        impl<'de> validators_prelude::serde::Deserialize<'de> for #name {
                            #[inline]
                            fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
                            where
                                D: validators_prelude::serde::Deserializer<'de>, {
                                validators_prelude::serde::Deserialize::deserialize(deserializer)
                            }
                        }
                    });
                }
            }

            #[cfg(feature = "rocket")]
            {
                if type_attribute.rocket_options.from_form_field {
                    crate::common::rocket::impl_from_form_field(&mut token_stream, &name);
                }

                if type_attribute.rocket_options.from_param {
                    crate::common::rocket::impl_from_param(&mut token_stream, &name, &error_path);
                }
            }

            return Ok(token_stream);
        }

        Err(panic::validator_for_specific_item(meta.path(), ITEM))
    }
}