diff --git a/crates/algorithm_lr1/src/builder.rs b/crates/algorithm_lr1/src/builder.rs
index 5635f8f..488b96f 100644
--- a/crates/algorithm_lr1/src/builder.rs
+++ b/crates/algorithm_lr1/src/builder.rs
@@ -37,11 +37,8 @@ where
 {
     pub fn setup() -> anyhow::Result<Self> {
         // 1. Pre-process
-        let rules = S::try_into()?
-            .into_iter()
-            .map(|(rule, _)| rule)
-            .collect::<Vec<_>>();
-        let ruleset = RuleSet::from(rules);
+        let rules = S::into_iter().collect::<Vec<_>>();
+        let ruleset = S::into_ruleset();
         let first_set = ruleset.first_set();
 
         // 2. Generate dummy nonterm
@@ -76,7 +73,7 @@ where
         let mut goto_table: Vec<Vec<usize>> = Vec::with_capacity(dfa.0.len());
         for _ in 0..dfa.0.len() {
             action_table.push(HashMap::from_iter(
-                T::enum_iter()
+                T::into_iter()
                     .map(|token| (token, LRAction::None))
                     .collect::<Vec<(T, LRAction<S>)>>(),
             ));
@@ -85,7 +82,6 @@ where
         }
 
         // 5. Setup tables
-        let rule_table: Vec<S> = S::enum_iter().collect();
         for lritem_set in &dfa.0 {
             for (token, next) in &lritem_set.next {
                 match &token {
@@ -113,7 +109,7 @@ where
                             let id = lritem_set.id as usize;
                             let label = action_table[id].get_mut(&t.0).unwrap();
                             *label = LRAction::Reduce(
-                                rule_table[item.rule.id as usize],
+                                rules[item.rule.id as usize],
                                 *nonterm_table.get(lhs).unwrap(),
                                 item.rule.rhs.len(),
                             );
@@ -124,7 +120,7 @@ where
                                 LRAction::Accept
                             } else {
                                 LRAction::Reduce(
-                                    rule_table[item.rule.id as usize],
+                                    rules[item.rule.id as usize],
                                     *nonterm_table.get(lhs).unwrap(),
                                     item.rule.rhs.len(),
                                 )
diff --git a/crates/algorithm_lr1/src/lib.rs b/crates/algorithm_lr1/src/lib.rs
index a5db5a4..88cd782 100644
--- a/crates/algorithm_lr1/src/lib.rs
+++ b/crates/algorithm_lr1/src/lib.rs
@@ -68,19 +68,14 @@ mod test {
     #[derive(Debug, Clone, Copy, Syntax)]
     enum TestSyntax {
         #[rule("<expr> ::= <expr> Plus <term>")]
-        ExprPlus,
         #[rule("<expr> ::= <expr> Minus <term>")]
-        ExprMinus,
         #[rule("<expr> ::= <term>")]
-        ExprTerm,
+        Expr,
         #[rule("<term> ::= <term> Mul <num>")]
-        TermMul,
         #[rule("<term> ::= <term> Div <num>")]
-        TermDiv,
         #[rule("<term> ::= <num>")]
-        TermNum,
+        Term,
         #[rule("<num> ::= BracketL <expr> BracketR")]
-        NestedNum,
         #[rule("<num> ::= Num")]
         Num,
     }
diff --git a/crates/core/src/cfg/syntax.rs b/crates/core/src/cfg/syntax.rs
index 0b631ab..a41d085 100644
--- a/crates/core/src/cfg/syntax.rs
+++ b/crates/core/src/cfg/syntax.rs
@@ -7,17 +7,26 @@ use super::token::TokenSet;
 
 pub trait Syntax<'a>
 where
-    Self: Debug + Clone + Copy + Sized,
+    Self: Debug + Clone + Copy,
 {
     type TokenSet: TokenSet<'a>;
 
-    fn enum_iter() -> impl Iterator<Item = Self>;
-    fn to_rule(&self) -> Rule<'a, Self::TokenSet>;
+    fn into_iter() -> impl Iterator<Item = Self>;
+    fn into_rules(&self) -> Vec<Rule<'a, Self::TokenSet>>;
 
-    fn try_into() -> anyhow::Result<Vec<(Rule<'a, Self::TokenSet>, Self)>> {
-        Self::enum_iter()
-            .map(|elem| Ok((Self::to_rule(&elem), elem)))
-            .collect::<anyhow::Result<Vec<_>>>()
+    fn into_ruleset() -> RuleSet<'a, Self::TokenSet> {
+        let rules = Self::into_iter()
+            .enumerate()
+            .flat_map(|(idx, elem)| {
+                let mut rules = Self::into_rules(&elem);
+                for rule in &mut rules {
+                    rule.id = idx;
+                }
+                rules
+            })
+            .collect::<Vec<_>>();
+
+        RuleSet::from(rules)
     }
 }
 
@@ -108,16 +117,12 @@ pub struct RuleSet<'a, T: TokenSet<'a>> {
 }
 
 impl<'a, T: TokenSet<'a>> From<Vec<Rule<'a, T>>> for RuleSet<'a, T> {
-    fn from(mut rules: Vec<Rule<'a, T>>) -> Self {
+    fn from(rules: Vec<Rule<'a, T>>) -> Self {
         let top = match &rules[0].lhs {
             RuleElem::NonTerm(s) => s.clone(),
             _ => unreachable!(),
         };
 
-        for (idx, rule) in rules.iter_mut().enumerate() {
-            rule.id = idx;
-        }
-
         RuleSet {
             top,
             rules,
@@ -228,7 +233,7 @@ impl<'a, T: TokenSet<'a>> RuleSet<'a, T> {
 mod test {
     use std::collections::HashMap;
 
-    use super::{TokenSet, Syntax, Rule, RuleElem, RuleSet};
+    use super::{TokenSet, Syntax, Rule, RuleElem};
 
     #[derive(Clone, Copy, Hash, PartialEq, Eq, Debug)]
     enum TestToken {
@@ -242,7 +247,7 @@ mod test {
     }
 
     impl TokenSet<'_> for TestToken {
-        fn enum_iter() -> impl Iterator<Item = Self> {
+        fn into_iter() -> impl Iterator<Item = Self> {
             Box::new(
                 vec![
                     TestToken::Num,
@@ -257,7 +262,7 @@ mod test {
             )
         }
 
-        fn to_regex(&self) -> &'static str {
+        fn into_regex_str(&self) -> &'static str {
             match self {
                 TestToken::Num => r"^[1-9][0-9]*",
                 TestToken::Plus => r"^\+",
@@ -289,7 +294,7 @@ mod test {
     impl<'a> Syntax<'a> for TestSyntax {
         type TokenSet = TestToken;
 
-        fn enum_iter() -> impl Iterator<Item = Self> {
+        fn into_iter() -> impl Iterator<Item = Self> {
             Box::new(
                 vec![
                     TestSyntax::ExprPlus,
@@ -305,7 +310,7 @@ mod test {
             )
         }
 
-        fn to_rule(&self) -> Rule<'a, Self::TokenSet> {
+        fn into_rules(&self) -> Vec<Rule<'a, Self::TokenSet>> {
             let expr_plus = Rule::from((
                 RuleElem::new_nonterm("expr"),
                 vec![
@@ -364,14 +369,14 @@ mod test {
             let fact_2_num = Rule::from((RuleElem::new_nonterm("fact"), vec![]));
 
             match self {
-                TestSyntax::ExprPlus => expr_plus,
-                TestSyntax::ExprMinus => expr_minus,
-                TestSyntax::Expr2Term => expr_2_term,
-                TestSyntax::TermMul => term_mul,
-                TestSyntax::TermDiv => term_div,
-                TestSyntax::Term2Fact => term_2_fact,
-                TestSyntax::Fact2Expr => fact_2_expr,
-                TestSyntax::Fact2Num => fact_2_num,
+                TestSyntax::ExprPlus => vec![expr_plus],
+                TestSyntax::ExprMinus => vec![expr_minus],
+                TestSyntax::Expr2Term => vec![expr_2_term],
+                TestSyntax::TermMul => vec![term_mul],
+                TestSyntax::TermDiv => vec![term_div],
+                TestSyntax::Term2Fact => vec![term_2_fact],
+                TestSyntax::Fact2Expr => vec![fact_2_expr],
+                TestSyntax::Fact2Num => vec![fact_2_num],
             }
         }
     }
@@ -399,12 +404,7 @@ mod test {
 
     #[test]
     fn first_set() {
-        let rules = <TestSyntax as Syntax>::try_into()
-            .unwrap()
-            .into_iter()
-            .map(|(rule, _)| rule)
-            .collect::<Vec<_>>();
-        let ruleset = RuleSet::from(rules);
+        let ruleset = <TestSyntax as Syntax>::into_ruleset();
         let first_set = ruleset.first_set();
 
         check(
diff --git a/crates/core/src/cfg/token.rs b/crates/core/src/cfg/token.rs
index 7eb1032..e3a6d3f 100644
--- a/crates/core/src/cfg/token.rs
+++ b/crates/core/src/cfg/token.rs
@@ -1,19 +1,25 @@
 use std::fmt::Debug;
 use std::hash::Hash;
 
-use regex::Regex;
+use regex::{Regex, RegexSet};
 
 pub trait TokenSet<'a>
 where
     Self: Debug + Copy + Clone + Hash + Eq,
 {
     fn ignore_str() -> &'a str;
-    fn enum_iter() -> impl Iterator<Item = Self>;
-    fn to_regex(&self) -> &'a str;
+    fn into_iter() -> impl Iterator<Item = Self>;
+    fn into_regex_str(&self) -> &'a str;
 
-    fn try_into() -> anyhow::Result<Vec<(Regex, Self)>> {
-        Self::enum_iter()
-            .map(|token| Ok((Regex::new(Self::to_regex(&token))?, token)))
-            .collect::<anyhow::Result<Vec<_>>>()
+    fn into_regex(&self) -> anyhow::Result<Regex> {
+        Ok(Regex::new(self.into_regex_str())?)
+    }
+
+    fn try_into_regexset() -> anyhow::Result<RegexSet> {
+        let regex_set = Self::into_iter()
+            .map(|token| Self::into_regex_str(&token))
+            .collect::<Vec<_>>();
+
+        Ok(RegexSet::new(regex_set)?)
     }
 }
diff --git a/crates/core/src/lex.rs b/crates/core/src/lex.rs
index 44b2484..240da9f 100644
--- a/crates/core/src/lex.rs
+++ b/crates/core/src/lex.rs
@@ -41,9 +41,9 @@ impl Lexer {
 
 struct LexDriver<'a, 'b, T: TokenSet<'a>> {
     // Regex
+    regex_istr: Regex,
     regex_set: RegexSet,
     regex_map: Vec<(Regex, T)>,
-    regex_istr: Regex,
 
     // State
     input: &'b str,
@@ -57,18 +57,16 @@ impl<'a, 'b, T: TokenSet<'a>> TryFrom<&'b str> for LexDriver<'a, 'b, T> {
     type Error = anyhow::Error;
 
     fn try_from(input: &'b str) -> anyhow::Result<Self> {
-        let regex_map = T::try_into()?;
-        let regex_set = regex_map
-            .iter()
-            .map(|(_, token)| T::to_regex(&token))
-            .collect::<Vec<_>>();
-        let regex_set = RegexSet::new(regex_set)?;
         let regex_istr = Regex::new(T::ignore_str())?;
+        let regex_set = T::try_into_regexset()?;
+        let regex_map = T::into_iter()
+            .map(|token| Ok((token.into_regex()?, token)))
+            .collect::<anyhow::Result<Vec<_>>>()?;
 
         Ok(LexDriver {
+            regex_istr,
             regex_set,
             regex_map,
-            regex_istr,
             input,
             pos: 0,
             tokenset: PhantomData,
@@ -126,11 +124,11 @@ mod test {
             r"^[ \t\n]+"
         }
 
-        fn enum_iter() -> Box<dyn Iterator<Item = Self>> {
-            Box::new(vec![TestToken::Num, TestToken::Plus].into_iter())
+        fn into_iter() -> impl Iterator<Item = Self> {
+            vec![TestToken::Num, TestToken::Plus].into_iter()
         }
 
-        fn to_regex(&self) -> &'static str {
+        fn into_regex_str(&self) -> &'static str {
             match self {
                 TestToken::Num => r"^[1-9][0-9]*",
                 TestToken::Plus => r"^\+",
diff --git a/crates/core_derive/src/impl/syntax.rs b/crates/core_derive/src/impl/syntax.rs
index b1e8574..83324ce 100644
--- a/crates/core_derive/src/impl/syntax.rs
+++ b/crates/core_derive/src/impl/syntax.rs
@@ -31,13 +31,13 @@ pub fn syntax_proc_macro_impl(ast: DeriveInput) -> TokenStream {
         impl<'a> Syntax<'a> for #enum_name {
             type TokenSet = #enum_assoc_type;
 
-            fn enum_iter() -> impl Iterator<Item = Self> {
+            fn into_iter() -> impl Iterator<Item = Self> {
                 vec![
                     #( #enum_variants, )*
                 ].into_iter()
             }
 
-            fn to_rule(&self) -> Rule<'a, Self::TokenSet> {
+            fn into_rules(&self) -> Vec<Rule<'a, Self::TokenSet>> {
                 match self {
                     #( #enum_rule_table, )*
                     _ => unimplemented!(),
@@ -50,23 +50,23 @@ pub fn syntax_proc_macro_impl(ast: DeriveInput) -> TokenStream {
 struct VariantInfo<'a> {
     parent_ident: &'a Ident,
     self_ident: &'a Ident,
-    rule: Option<TokenStream>,
+    rules: Vec<TokenStream>,
 }
 
 impl<'a> VariantInfo<'a> {
     fn parse(parent_ident: &'a Ident, variant: &'a Variant) -> VariantInfo<'a> {
         let self_ident = &variant.ident;
 
-        let mut rule = None;
+        let mut rules = vec![];
         for attr in &variant.attrs {
             let attr = attr.parse_args::<LitStr>().unwrap().value();
-            rule = Some(Self::parse_rule(&attr));
+            rules.push(Self::parse_rule(&attr));
         }
 
         VariantInfo {
             parent_ident,
             self_ident,
-            rule,
+            rules,
         }
     }
 
@@ -102,9 +102,11 @@ impl<'a> VariantInfo<'a> {
 
     fn gen_ident_with_rule(&self) -> TokenStream {
         let ident = self.gen_ident();
-        match &self.rule {
-            Some(rule) => quote! { #ident => #rule },
-            None => quote! { unimplemented!() },
+        if self.rules.is_empty() {
+            quote! { #ident => unimplemented!() }
+        } else {
+            let rules = &self.rules;
+            quote! { #ident => vec![#(#rules),*] }
         }
     }
 }
diff --git a/crates/core_derive/src/impl/tokenset.rs b/crates/core_derive/src/impl/tokenset.rs
index 84bcef3..1cd4df7 100644
--- a/crates/core_derive/src/impl/tokenset.rs
+++ b/crates/core_derive/src/impl/tokenset.rs
@@ -36,13 +36,13 @@ pub fn proc_macro_impl(ast: DeriveInput) -> TokenStream {
                 #enum_ignored
             }
 
-            fn enum_iter() -> impl Iterator<Item = Self> {
+            fn into_iter() -> impl Iterator<Item = Self> {
                 vec![
                     #( #enum_variants, )*
                 ].into_iter()
             }
 
-            fn to_regex(&self) -> &'static str {
+            fn into_regex_str(&self) -> &'static str {
                 match self {
                     #( #enum_regex_table, )*
                     _ => unimplemented!(),
diff --git a/examples/expr.rs b/examples/expr.rs
index 6ae7d5d..a2a33b5 100644
--- a/examples/expr.rs
+++ b/examples/expr.rs
@@ -28,19 +28,14 @@ enum ExprTokenSet {
 #[derive(Debug, Clone, Copy, Syntax)]
 enum ExprSyntax {
     #[rule("<expr> ::= <expr> Plus <term>")]
-    ExprPlus,
     #[rule("<expr> ::= <expr> Minus <term>")]
-    ExprMinus,
     #[rule("<expr> ::= <term>")]
-    ExprTerm,
+    Expr,
     #[rule("<term> ::= <term> Mul <num>")]
-    TermMul,
     #[rule("<term> ::= <term> Div <num>")]
-    TermDiv,
     #[rule("<term> ::= <num>")]
-    TermNum,
+    Term,
     #[rule("<num> ::= BracketL <expr> BracketR")]
-    NestedNum,
     #[rule("<num> ::= Num")]
     Num,
 }
diff --git a/tests/derive.rs b/tests/derive.rs
index 81e8db1..87d107f 100644
--- a/tests/derive.rs
+++ b/tests/derive.rs
@@ -23,25 +23,20 @@ enum TestTokenSet {
 #[derive(Debug, Clone, Copy, Syntax)]
 enum TestSyntax {
     #[rule("<expr> ::= <expr> Plus <term>")]
-    ExprPlus,
     #[rule("<expr> ::= <expr> Minus <term>")]
-    ExprMinus,
     #[rule("<expr> ::= <term>")]
-    ExprTerm,
+    Expr,
     #[rule("<term> ::= <term> Mul <num>")]
-    TermMul,
     #[rule("<term> ::= <term> Div <num>")]
-    TermDiv,
     #[rule("<term> ::= <num>")]
-    TermNum,
+    Term,
     #[rule("<num> ::= BracketL <expr> BracketR")]
-    NestedNum,
     #[rule("<num> ::= Num")]
     Num,
 }
 
 #[test]
 fn check_compile() {
-    let _ = TestTokenSet::to_regex(&self::TestTokenSet::Plus);
-    let _ = TestSyntax::to_rule(&self::TestSyntax::ExprPlus);
+    let _ = TestTokenSet::into_regex(&self::TestTokenSet::Plus);
+    let _ = TestSyntax::into_rules(&self::TestSyntax::Expr);
 }
diff --git a/tests/serde.rs b/tests/serde.rs
index 24ddfba..ce2a274 100644
--- a/tests/serde.rs
+++ b/tests/serde.rs
@@ -27,19 +27,14 @@ enum TestTokenSet {
 #[derive(Debug, Clone, Copy, Serialize, Deserialize, Syntax)]
 enum TestSyntax {
     #[rule("<expr> ::= <expr> Plus <term>")]
-    ExprPlus,
     #[rule("<expr> ::= <expr> Minus <term>")]
-    ExprMinus,
     #[rule("<expr> ::= <term>")]
-    ExprTerm,
+    Expr,
     #[rule("<term> ::= <term> Mul <num>")]
-    TermMul,
     #[rule("<term> ::= <term> Div <num>")]
-    TermDiv,
     #[rule("<term> ::= <num>")]
-    TermNum,
+    Term,
     #[rule("<num> ::= BracketL <expr> BracketR")]
-    NestedNum,
     #[rule("<num> ::= Num")]
     Num,
 }