[Fix] (#25) Fix compile error when no regex feature is enabled

* fix: fix error when there's no regex support

Author: Embers-of-the-Fire

src/valust-derive/src/config/struct_config.rs

@@ -215,6 +215,7 @@ impl StructOperation {
                 message: fallible.message,
                 fallible: true,
             }),
+            #[cfg(feature = "regex")]
             ValidatorItem::Regex(regex) => Ok(Self {
                 expr: func_only(regex.text)?,
                 message: regex.message,

src/valust-derive/src/parse/parse_field_validator.rs

@@ -89,6 +89,7 @@ impl ValidatorItem {
                     fallible: true,
                 }
             }
+            #[cfg(feature = "regex")]
             Self::Regex(RegexValidator { text, message, .. }) => FieldManualOperation {
                 ty: FieldOperationType::Validate,
                 expr: text,

src/valust-derive/src/utils/parser.rs

@@ -1,13 +1,13 @@
 use syn::parse::{Parse, ParseStream};
-use syn::{Expr, Ident, LitStr, Token, parenthesized, parse_quote};
+use syn::{Expr, Ident, Token, parenthesized, parse_quote};
 
 use super::regex_comp::CompatibleExpr;
 
 pub enum Expression {
     Expr(Expr),
     Func(Expr),
     #[cfg(feature = "regex")]
-    Regex(LitStr),
+    Regex(syn::LitStr),
 }
 
 impl Parse for Expression {

src/valust-derive/src/utils/regex_comp.rs

@@ -1,18 +1,21 @@
 use proc_macro2::TokenStream;
-use quote::{ToTokens, format_ident, quote};
-use syn::{Expr, Ident, LitStr};
+use quote::ToTokens;
+#[cfg(feature = "regex")]
+use quote::{format_ident, quote};
+use syn::Expr;
 
 pub enum CompatibleExpr {
     Expr(Expr),
     #[cfg(feature = "regex")]
     #[allow(dead_code)]
-    Regex(LitStr, Ident),
+    Regex(syn::LitStr, syn::Ident),
 }
 
 impl CompatibleExpr {
     pub fn as_expr(&self) -> TokenStream {
         match self {
             Self::Expr(e) => e.to_token_stream(),
+            #[cfg(feature = "regex")]
             Self::Regex(text, input) => {
                 let lock_init = quote! {
                     ::std::sync::LazyLock::new(|| {