all: simplify switches

core/blockchain_test.go

@@ -1146,8 +1146,7 @@ func TestEIP155Transition(t *testing.T) {
 				return types.SignTx(types.NewTransaction(block.TxNonce(address), common.Address{}, new(big.Int), 21000, new(big.Int), nil), signer, key)
 			}
 		)
-		switch i {
-		case 0:
+		if i == 0 {
 			tx, err = basicTx(types.NewEIP155Signer(big.NewInt(2)))
 			if err != nil {
 				t.Fatal(err)

eth/filters/filter_system.go

@@ -338,8 +338,7 @@ func (es *EventSystem) broadcast(filters filterIndex, ev interface{}) {
 			}
 		}
 	case *event.TypeMuxEvent:
-		switch muxe := e.Data.(type) {
-		case core.PendingLogsEvent:
+		if muxe, ok := e.Data.(core.PendingLogsEvent); ok {
 			for _, f := range filters[PendingLogsSubscription] {
 				if e.Time.After(f.created) {
 					if matchedLogs := filterLogs(muxe.Logs, nil, f.logsCrit.ToBlock, f.logsCrit.Addresses, f.logsCrit.Topics); len(matchedLogs) > 0 {

eth/handler.go

@@ -744,8 +744,7 @@ func (pm *ProtocolManager) BroadcastTxs(txs types.Transactions) {
 func (pm *ProtocolManager) minedBroadcastLoop() {
 	// automatically stops if unsubscribe
 	for obj := range pm.minedBlockSub.Chan() {
-		switch ev := obj.Data.(type) {
-		case core.NewMinedBlockEvent:
+		if ev, ok := obj.Data.(core.NewMinedBlockEvent); ok {
 			pm.BroadcastBlock(ev.Block, true)  // First propagate block to peers
 			pm.BroadcastBlock(ev.Block, false) // Only then announce to the rest
 		}

eth/tracers/tracer.go

@@ -486,12 +486,7 @@ func (jst *Tracer) call(method string, args ...string) (json.RawMessage, error)
 }
 
 func wrapError(context string, err error) error {
-	var message string
-	switch err := err.(type) {
-	default:
-		message = err.Error()
-	}
-	return fmt.Errorf("%v    in server-side tracer function '%v'", message, context)
+	return fmt.Errorf("%v    in server-side tracer function '%v'", err, context)
 }
 
 // CaptureStart implements the Tracer interface to initialize the tracing operation.

les/handler.go

@@ -1158,8 +1158,7 @@ func (pm *ProtocolManager) getHelperTrie(id uint, idx uint64) (common.Hash, stri
 
 // getHelperTrieAuxData returns requested auxiliary data for the given HelperTrie request
 func (pm *ProtocolManager) getHelperTrieAuxData(req HelperTrieReq) []byte {
-	switch {
-	case req.Type == htCanonical && req.AuxReq == auxHeader && len(req.Key) == 8:
+	if req.Type == htCanonical && req.AuxReq == auxHeader && len(req.Key) == 8 {
 		blockNum := binary.BigEndian.Uint64(req.Key)
 		hash := rawdb.ReadCanonicalHash(pm.chainDb, blockNum)
 		return rawdb.ReadHeaderRLP(pm.chainDb, hash, blockNum)

metrics/exp/exp.go

@@ -147,21 +147,21 @@ func (exp *exp) publishResettingTimer(name string, metric metrics.ResettingTimer
 
 func (exp *exp) syncToExpvar() {
 	exp.registry.Each(func(name string, i interface{}) {
-		switch i.(type) {
+		switch i := i.(type) {
 		case metrics.Counter:
-			exp.publishCounter(name, i.(metrics.Counter))
+			exp.publishCounter(name, i)
 		case metrics.Gauge:
-			exp.publishGauge(name, i.(metrics.Gauge))
+			exp.publishGauge(name, i)
 		case metrics.GaugeFloat64:
-			exp.publishGaugeFloat64(name, i.(metrics.GaugeFloat64))
+			exp.publishGaugeFloat64(name, i)
 		case metrics.Histogram:
-			exp.publishHistogram(name, i.(metrics.Histogram))
+			exp.publishHistogram(name, i)
 		case metrics.Meter:
-			exp.publishMeter(name, i.(metrics.Meter))
+			exp.publishMeter(name, i)
 		case metrics.Timer:
-			exp.publishTimer(name, i.(metrics.Timer))
+			exp.publishTimer(name, i)
 		case metrics.ResettingTimer:
-			exp.publishResettingTimer(name, i.(metrics.ResettingTimer))
+			exp.publishResettingTimer(name, i)
 		default:
 			panic(fmt.Sprintf("unsupported type for '%s': %T", name, i))
 		}

p2p/nat/natpmp.go

@@ -115,8 +115,7 @@ func potentialGateways() (gws []net.IP) {
 			return gws
 		}
 		for _, addr := range ifaddrs {
-			switch x := addr.(type) {
-			case *net.IPNet:
+			if x, ok := addr.(*net.IPNet); ok {
 				if lan10.Contains(x.IP) || lan176.Contains(x.IP) || lan192.Contains(x.IP) {
 					ip := x.IP.Mask(x.Mask).To4()
 					if ip != nil {

p2p/nat/natupnp.go

@@ -81,11 +81,8 @@ func (n *upnp) internalAddress() (net.IP, error) {
 			return nil, err
 		}
 		for _, addr := range addrs {
-			switch x := addr.(type) {
-			case *net.IPNet:
-				if x.Contains(devaddr.IP) {
-					return x.IP, nil
-				}
+			if x, ok := addr.(*net.IPNet); ok && x.Contains(devaddr.IP) {
+				return x.IP, nil
 			}
 		}
 	}

p2p/simulations/adapters/inproc.go

@@ -353,8 +353,7 @@ func (sn *SimNode) NodeInfo() *p2p.NodeInfo {
 }
 
 func setSocketBuffer(conn net.Conn, socketReadBuffer int, socketWriteBuffer int) error {
-	switch v := conn.(type) {
-	case *net.UnixConn:
+	if v, ok := conn.(*net.UnixConn); ok {
 		err := v.SetReadBuffer(socketReadBuffer)
 		if err != nil {
 			return err

signer/core/abihelper.go

@@ -43,11 +43,11 @@ type decodedCallData struct {
 // String implements stringer interface, tries to use the underlying value-type
 func (arg decodedArgument) String() string {
 	var value string
-	switch arg.value.(type) {
+	switch val := arg.value.(type) {
 	case fmt.Stringer:
-		value = arg.value.(fmt.Stringer).String()
+		value = val.String()
 	default:
-		value = fmt.Sprintf("%v", arg.value)
+		value = fmt.Sprintf("%v", val)
 	}
 	return fmt.Sprintf("%v: %v", arg.soltype.Type.String(), value)
 }