fix: use loop instead of ragel

CHANGELOG.md

@@ -42,7 +42,6 @@ Every module contains its own CHANGELOG.md. Please refer to the module you are i
 
 ### Features
 
-* (types) [#19511](https://github.com/cosmos/cosmos-sdk/pull/19511) Replace regex parsing of denom validation to direct matching methods.
 * (runtime) [#19571](https://github.com/cosmos/cosmos-sdk/pull/19571) Implement `core/router.Service` it in runtime. This service is present in all modules (when using depinject).
 * (types) [#19164](https://github.com/cosmos/cosmos-sdk/pull/19164) Add a ValueCodec for the math.Uint type that can be used in collections maps.
 * (types) [#19281](https://github.com/cosmos/cosmos-sdk/pull/19281) Added a new method, `IsGT`, for `types.Coin`. This method is used to check if a `types.Coin` is greater than another `types.Coin`.
@@ -142,8 +141,8 @@ Every module contains its own CHANGELOG.md. Please refer to the module you are i
 * (server) [#18909](https://github.com/cosmos/cosmos-sdk/pull/18909) Remove configuration endpoint on grpc reflection endpoint in favour of auth module bech32prefix endpoint already exposed.
 * (crypto) [#19541](https://github.com/cosmos/cosmos-sdk/pull/19541) The deprecated `FromTmProtoPublicKey`, `ToTmProtoPublicKey`, `FromTmPubKeyInterface` and `ToTmPubKeyInterface` functions have been removed. Use their replacements (`Cmt` instead of `Tm`) instead.
 * (types) [#19652](https://github.com/cosmos/cosmos-sdk/pull/19652) 
-  * Moved`types/module.HasRegisterInterfaces` to `cosmossdk.io/core`.
-  * Moved `RegisterInterfaces` and `RegisterImplementations` from `InterfaceRegistry` to `cosmossdk.io/core/registry.LegacyRegistry` interface.
+    * Moved`types/module.HasRegisterInterfaces` to `cosmossdk.io/core`.
+    * Moved `RegisterInterfaces` and `RegisterImplementations` from `InterfaceRegistry` to `cosmossdk.io/core/registry.LegacyRegistry` interface.
 
 ### Client Breaking Changes
 

types/coin.go

@@ -7,6 +7,7 @@ import (
 	"regexp"
 	"sort"
 	"strings"
+	"unicode"
 
 	"cosmossdk.io/math"
 )
@@ -865,10 +866,9 @@ func SetCoinDenomRegex(reFn func() string) {
 func ValidateDenom(denom string) error {
 	if reDnm == nil || reDecCoin == nil {
 		// Convert the string to a byte slice as required by the Ragel-generated function.
-		denomBytes := []byte(denom)
 
 		// Call the Ragel-generated function.
-		if !MatchDenom(denomBytes) {
+		if !MatchDenom(denom) {
 			return fmt.Errorf("invalid denom: %s", denom)
 		}
 	} else if !reDnm.MatchString(denom) { // If reDnm has been initialized, use it for matching.
@@ -878,6 +878,35 @@ func ValidateDenom(denom string) error {
 	return nil
 }
 
+// isValidRune checks if a given rune is a valid character for a rune.
+// It returns true if the rune is a letter, digit, '/', ':', '.', '_', or '-'.
+func isValidRune(r rune) bool {
+	return unicode.IsLetter(r) || unicode.IsDigit(r) || r == '/' || r == ':' || r == '.' || r == '_' || r == '-'
+}
+
+// MatchDenom checks if the given string is a valid denomination.
+// A valid denomination must have a length between 3 and 128 characters,
+// start with a letter, and only contain valid runes.
+func MatchDenom(s string) bool {
+	length := len(s)
+	if length < 3 || length > 128 {
+		return false
+	}
+
+	firstRune := rune(s[0])
+	if !unicode.IsLetter(firstRune) {
+		return false
+	}
+
+	for _, r := range s[1:] {
+		if !isValidRune(r) {
+			return false
+		}
+	}
+
+	return true
+}
+
 func mustValidateDenom(denom string) {
 	if err := ValidateDenom(denom); err != nil {
 		panic(err)