R4R: Add custom validation for denom (#6755)

Allow ValidateDenom to be customized per application.

closes: #6744

CHANGELOG.md

@@ -163,6 +163,7 @@ be used to retrieve the actual proposal `Content`. Also the `NewMsgSubmitProposa
 
 ### Features
 
+* [\#6755](https://github.com/cosmos/cosmos-sdk/pull/6755) Add custom regex validation for `Coin` denom by overwriting `CoinDenomRegex` when using `/types/coin.go`.
 * [\#7265](https://github.com/cosmos/cosmos-sdk/pull/7265) Support Tendermint block pruning through a new `min-retain-blocks` configuration that can be set in either `app.toml` or via the CLI. This parameter is used in conjunction with other criteria to determine the height at which Tendermint should prune blocks.
 * (vesting) [\#7209](https://github.com/cosmos/cosmos-sdk/pull/7209) Create new `MsgCreateVestingAccount` message type along with CLI handler that allows for the creation of delayed and continuous vesting types.
 * (events) [\#7121](https://github.com/cosmos/cosmos-sdk/pull/7121) The application now drives what events are indexed by Tendermint via the `index-events` configuration in `app.toml`, which is a list of events taking the form `{eventType}.{attributeKey}`.

types/coin.go

@@ -602,15 +602,32 @@ var (
 	reAmt       = `[[:digit:]]+`
 	reDecAmt    = `[[:digit:]]*\.[[:digit:]]+`
 	reSpc       = `[[:space:]]*`
-	reDnm       = regexp.MustCompile(fmt.Sprintf(`^%s$`, reDnmString))
-	reCoin      = regexp.MustCompile(fmt.Sprintf(`^(%s)%s(%s)$`, reAmt, reSpc, reDnmString))
-	reDecCoin   = regexp.MustCompile(fmt.Sprintf(`^(%s)%s(%s)$`, reDecAmt, reSpc, reDnmString))
+	reDnm       = returnReDnm
+	reCoin      = returnReCoin
+	reDecCoin   = returnDecCoin
 )
 
-// ValidateDenom validates a denomination string returning an error if it is
-// invalid.
+func returnDecCoin() *regexp.Regexp {
+	return regexp.MustCompile(fmt.Sprintf(`^(%s)%s(%s)$`, reDecAmt, reSpc, CoinDenomRegex()))
+}
+func returnReCoin() *regexp.Regexp {
+	return regexp.MustCompile(fmt.Sprintf(`^(%s)%s(%s)$`, reAmt, reSpc, CoinDenomRegex()))
+}
+func returnReDnm() *regexp.Regexp {
+	return regexp.MustCompile(fmt.Sprintf(`^%s$`, CoinDenomRegex()))
+}
+
+// DefaultCoinDenomRegex returns the default regex string
+func DefaultCoinDenomRegex() string {
+	return reDnmString
+}
+
+// CoinDenomRegex returns the current regex string and can be overwritten for custom validation
+var CoinDenomRegex = DefaultCoinDenomRegex
+
+// ValidateDenom is the default validation function for Coin.Denom.
 func ValidateDenom(denom string) error {
-	if !reDnm.MatchString(denom) {
+	if !reDnm().MatchString(denom) {
 		return fmt.Errorf("invalid denom: %s", denom)
 	}
 	return nil
@@ -628,7 +645,7 @@ func mustValidateDenom(denom string) {
 func ParseCoin(coinStr string) (coin Coin, err error) {
 	coinStr = strings.TrimSpace(coinStr)
 
-	matches := reCoin.FindStringSubmatch(coinStr)
+	matches := reCoin().FindStringSubmatch(coinStr)
 	if matches == nil {
 		return Coin{}, fmt.Errorf("invalid coin expression: %s", coinStr)
 	}

types/coin_test.go

@@ -98,6 +98,30 @@ func (s *coinTestSuite) TestCoinIsValid() {
 	}
 }
 
+func (s *coinTestSuite) TestCustomValidation() {
+
+	newDnmRegex := `[\x{1F600}-\x{1F6FF}]`
+	sdk.CoinDenomRegex = func() string {
+		return newDnmRegex
+	}
+
+	cases := []struct {
+		coin       sdk.Coin
+		expectPass bool
+	}{
+		{sdk.Coin{"🙂", sdk.NewInt(1)}, true},
+		{sdk.Coin{"🙁", sdk.NewInt(1)}, true},
+		{sdk.Coin{"🌶", sdk.NewInt(1)}, false}, // outside the unicode range listed above
+		{sdk.Coin{"asdf", sdk.NewInt(1)}, false},
+		{sdk.Coin{"", sdk.NewInt(1)}, false},
+	}
+
+	for i, tc := range cases {
+		s.Require().Equal(tc.expectPass, tc.coin.IsValid(), "unexpected result for IsValid, tc #%d", i)
+	}
+	sdk.CoinDenomRegex = sdk.DefaultCoinDenomRegex
+}
+
 func (s *coinTestSuite) TestAddCoin() {
 	cases := []struct {
 		inputOne    sdk.Coin

types/dec_coin.go

@@ -615,7 +615,7 @@ func (coins DecCoins) Sort() DecCoins {
 func ParseDecCoin(coinStr string) (coin DecCoin, err error) {
 	coinStr = strings.TrimSpace(coinStr)
 
-	matches := reDecCoin.FindStringSubmatch(coinStr)
+	matches := reDecCoin().FindStringSubmatch(coinStr)
 	if matches == nil {
 		return DecCoin{}, fmt.Errorf("invalid decimal coin expression: %s", coinStr)
 	}