examples: update examples

Closes #1234

examples/engine/engine.go

@@ -4,19 +4,26 @@ import (
 	"github.com/nspcc-dev/neo-go/pkg/interop/runtime"
 )
 
-// Main is that famous Main() function, you know.
+// NotifyScriptContainer sends runtime notification with script container hash
-func Main() bool {
+func NotifyScriptContainer() {
 	tx := runtime.GetScriptContainer()
 	runtime.Notify("Tx", tx.Hash)
+}
 
+// NotifyCallingScriptHash sends runtime notification with calling script hash
+func NotifyCallingScriptHash() {
 	callingScriptHash := runtime.GetCallingScriptHash()
 	runtime.Notify("Calling", callingScriptHash)
+}
 
+// NotifyExecutingScriptHash sends runtime notification about executing script hash
+func NotifyExecutingScriptHash() {
 	execScriptHash := runtime.GetExecutingScriptHash()
 	runtime.Notify("Executing", execScriptHash)
+}
 
+// NotifyEntryScriptHash sends notification about entry script hash
+func NotifyEntryScriptHash() {
 	entryScriptHash := runtime.GetEntryScriptHash()
 	runtime.Notify("Entry", entryScriptHash)
-
-	return true
 }

examples/iterator/iterator.go

@@ -6,8 +6,8 @@ import (
 	"github.com/nspcc-dev/neo-go/pkg/interop/storage"
 )
 
-// Main is Main(), really.
+// NotifyKeysAndValues sends notification with `foo` storage keys and values
-func Main() bool {
+func NotifyKeysAndValues() bool {
 	iter := storage.Find(storage.GetContext(), []byte("foo"))
 	values := iterator.Values(iter)
 	keys := iterator.Keys(iter)

examples/runtime/runtime.go

@@ -5,40 +5,23 @@ import (
 	"github.com/nspcc-dev/neo-go/pkg/interop/util"
 )
 
-// Check if the invoker of the contract is the specified owner
+var (
-var owner = util.FromAddress("Nis7Cu1Qn6iBb8kbeQ5HgdZT7AsQPqywTC")
+	// Check if the invoker of the contract is the specified owner
+	owner   = util.FromAddress("NULwe3UAHckN2fzNdcVg31tDiaYtMDwANt")
+	trigger byte
+)
 
-// Main is something to be ran from outside.
+// init initializes trigger before any other contract method is called
-func Main(operation string, args []interface{}) bool {
+func init() {
-	trigger := runtime.GetTrigger()
+	trigger = runtime.GetTrigger()
-
-	// Log owner upon Verification trigger
-	if trigger == runtime.Verification {
-		return CheckWitness()
-	}
-
-	// Discerns between log and notify for this test
-	if trigger == runtime.Application {
-		return handleOperation(operation, args)
-	}
-
-	return false
-}
-
-func handleOperation(operation string, args []interface{}) bool {
-	if operation == "log" {
-		return Log(args)
-	}
-
-	if operation == "notify" {
-		return Notify(args)
-	}
-
-	return false
 }
 
 // CheckWitness checks owner's witness
 func CheckWitness() bool {
+	// Log owner upon Verification trigger
+	if trigger != runtime.Verification {
+		return false
+	}
 	if runtime.CheckWitness(owner) {
 		runtime.Log("Verified Owner")
 	}
@@ -46,14 +29,19 @@ func CheckWitness() bool {
 }
 
 // Log logs given message
-func Log(args []interface{}) bool {
+func Log(message string) bool {
-	message := args[0].(string)
+	if trigger != runtime.Application {
+		return false
+	}
 	runtime.Log(message)
 	return true
 }
 
 // Notify notifies about given message
-func Notify(args []interface{}) bool {
+func Notify(event interface{}) bool {
-	runtime.Notify("Event", args[0])
+	if trigger != runtime.Application {
+		return false
+	}
+	runtime.Notify("Event", event)
 	return true
 }

examples/storage/storage.go

@@ -5,78 +5,39 @@ import (
 	"github.com/nspcc-dev/neo-go/pkg/interop/storage"
 )
 
-// Main is a very useful function.
+// ctx holds storage context for contract methods
-func Main(operation string, args []interface{}) interface{} {
+var ctx storage.Context
-	if operation == "put" {
-		return Put(args)
-	}
 
-	if operation == "get" {
+// init inits storage context before any other contract method is called
-		return Get(args)
+func init() {
-	}
+	ctx = storage.GetContext()
-
-	if operation == "delete" {
-		return Delete(args)
-	}
-
-	if operation == "find" {
-		return Find(args)
-	}
-
-	return false
 }
 
 // Put puts value at key.
-func Put(args []interface{}) interface{} {
+func Put(key, value []byte) []byte {
-	ctx := storage.GetContext()
+	storage.Put(ctx, key, value)
-	if checkArgs(args, 2) {
+	return key
-		key := args[0].([]byte)
-		value := args[1].([]byte)
-		storage.Put(ctx, key, value)
-		return key
-	}
-	return false
 }
 
 // Get returns the value at passed key.
-func Get(args []interface{}) interface{} {
+func Get(key []byte) interface{} {
-	ctx := storage.GetContext()
+	return storage.Get(ctx, key)
-	if checkArgs(args, 1) {
-		key := args[0].([]byte)
-		return storage.Get(ctx, key)
-	}
-	return false
 }
 
 // Delete deletes the value at passed key.
-func Delete(args []interface{}) interface{} {
+func Delete(key []byte) bool {
-	ctx := storage.GetContext()
-	key := args[0].([]byte)
 	storage.Delete(ctx, key)
 	return true
 }
 
-// Find returns an array of key-value pairs with key that matched the passed value.
+// Find returns an array of key-value pairs with key that matched the passed value
-func Find(args []interface{}) interface{} {
+func Find(value []byte) []string {
-	ctx := storage.GetContext()
+	iter := storage.Find(ctx, value)
-	if checkArgs(args, 1) {
+	result := []string{}
-		value := args[0].([]byte)
+	for iterator.Next(iter) {
-		iter := storage.Find(ctx, value)
+		val := iterator.Value(iter)
-		result := []string{}
+		key := iterator.Key(iter)
-		for iterator.Next(iter) {
+		result = append(result, key.(string)+":"+val.(string))
-			val := iterator.Value(iter)
-			key := iterator.Key(iter)
-			result = append(result, key.(string)+":"+val.(string))
-		}
-		return result
 	}
-	return false
+	return result
-}
-
-func checkArgs(args []interface{}, length int) bool {
-	if len(args) == length {
-		return true
-	}
-
-	return false
 }

examples/token-sale/token_sale.go

@@ -11,7 +11,12 @@ const (
 	multiplier = decimals * 10
 )
 
-var owner = util.FromAddress("NNf7GXcNMFHU8pLvU84afYZCfzXDopy71M")
+var (
+	owner   = util.FromAddress("NULwe3UAHckN2fzNdcVg31tDiaYtMDwANt")
+	trigger byte
+	token   TokenConfig
+	ctx     storage.Context
+)
 
 // TokenConfig holds information about the token we want to use for the sale.
 type TokenConfig struct {
@@ -51,8 +56,8 @@ type TokenConfig struct {
 	KYCKey []byte
 }
 
-// NewTokenConfig returns the initialized TokenConfig.
+// newTokenConfig returns the initialized TokenConfig.
-func NewTokenConfig() TokenConfig {
+func newTokenConfig() TokenConfig {
 	return TokenConfig{
 		Name:                  "My awesome token",
 		Symbol:                "MAT",
@@ -82,108 +87,91 @@ func getIntFromDB(ctx storage.Context, key []byte) int {
 	return res
 }
 
-// InCirculation return the amount of total tokens that are in circulation.
+// InCirculation returns the amount of total tokens that are in circulation.
-func (t TokenConfig) InCirculation(ctx storage.Context) int {
+func InCirculation() int {
-	return getIntFromDB(ctx, t.CirculationKey)
+	return getIntFromDB(ctx, token.CirculationKey)
 }
 
 // AddToCirculation sets the given amount as "in circulation" in the storage.
-func (t TokenConfig) AddToCirculation(ctx storage.Context, amount int) bool {
+func AddToCirculation(amount int) bool {
-	supply := getIntFromDB(ctx, t.CirculationKey)
+	supply := getIntFromDB(ctx, token.CirculationKey)
 	supply += amount
-	storage.Put(ctx, t.CirculationKey, supply)
+	storage.Put(ctx, token.CirculationKey, supply)
 	return true
 }
 
-// TokenSaleAvailableAmount returns the total amount of available tokens left
+// AvailableAmount returns the total amount of available tokens left
 // to be distributed.
-func (t TokenConfig) TokenSaleAvailableAmount(ctx storage.Context) int {
+func AvailableAmount() int {
-	inCirc := getIntFromDB(ctx, t.CirculationKey)
+	inCirc := getIntFromDB(ctx, token.CirculationKey)
-	return t.TotalSupply - inCirc
+	return token.TotalSupply - inCirc
 }
 
-// Main smart contract entry point.
+// init initializes runtime trigger, TokenConfig and storage context before any
-func Main(operation string, args []interface{}) interface{} {
+// other contract method is called
-	var (
+func init() {
-		trigger = runtime.GetTrigger()
+	trigger = runtime.GetTrigger()
-		cfg     = NewTokenConfig()
+	token = newTokenConfig()
-		ctx     = storage.GetContext()
+	ctx = storage.GetContext()
-	)
+}
 
+// checkOwnerWitness is a helper function which checks whether the invoker is the
+// owner of the contract.
+func checkOwnerWitness() bool {
 	// This is used to verify if a transfer of system assets (NEO and Gas)
 	// involving this contract's address can proceed.
-	if trigger == runtime.Verification {
-		// Check if the invoker is the owner of the contract.
-		if runtime.CheckWitness(cfg.Owner) {
-			return true
-		}
-		// Otherwise TODO
-		return false
-	}
 	if trigger == runtime.Application {
-		return handleOperation(operation, args, ctx, cfg)
+		// Check if the invoker is the owner of the contract.
-	}
+		return runtime.CheckWitness(token.Owner)
-	return true
-}
-
-func handleOperation(op string, args []interface{}, ctx storage.Context, cfg TokenConfig) interface{} {
-	// NEP-5 handlers
-	if op == "name" {
-		return cfg.Name
-	}
-	if op == "decimals" {
-		return cfg.Decimals
-	}
-	if op == "symbol" {
-		return cfg.Symbol
-	}
-	if op == "totalSupply" {
-		return getIntFromDB(ctx, cfg.CirculationKey)
-	}
-	if op == "balanceOf" {
-		if len(args) == 1 {
-			return getIntFromDB(ctx, args[0].([]byte))
-		}
-	}
-	if op == "transfer" {
-		if len(args) != 3 {
-			return false
-		}
-		from := args[0].([]byte)
-		to := args[1].([]byte)
-		amount := args[2].(int)
-		return transfer(cfg, ctx, from, to, amount)
-	}
-	if op == "transferFrom" {
-		if len(args) != 3 {
-			return false
-		}
-		from := args[0].([]byte)
-		to := args[1].([]byte)
-		amount := args[2].(int)
-		return transferFrom(cfg, ctx, from, to, amount)
-	}
-	if op == "approve" {
-		if len(args) != 3 {
-			return false
-		}
-		from := args[0].([]byte)
-		to := args[1].([]byte)
-		amount := args[2].(int)
-		return approve(ctx, from, to, amount)
-	}
-	if op == "allowance" {
-		if len(args) != 2 {
-			return false
-		}
-		from := args[0].([]byte)
-		to := args[1].([]byte)
-		return allowance(ctx, from, to)
 	}
 	return false
 }
 
-func transfer(cfg TokenConfig, ctx storage.Context, from, to []byte, amount int) bool {
+// Name returns the token name
+func Name() interface{} {
+	if trigger != runtime.Application {
+		return false
+	}
+	return token.Name
+}
+
+// Decimals returns the token decimals
+func Decimals() interface{} {
+	if trigger != runtime.Application {
+		return false
+	}
+	return token.Decimals
+}
+
+// Symbol returns the token symbol
+func Symbol() interface{} {
+	if trigger != runtime.Application {
+		return false
+	}
+	return token.Symbol
+}
+
+// TotalSupply returns the token total supply value
+func TotalSupply() interface{} {
+	if trigger != runtime.Application {
+		return false
+	}
+	return getIntFromDB(ctx, token.CirculationKey)
+}
+
+// BalanceOf returns the amount of token on the specified address
+func BalanceOf(holder []byte) interface{} {
+	if trigger != runtime.Application {
+		return false
+	}
+	return getIntFromDB(ctx, holder)
+}
+
+// Transfer transfers specified amount of token from one user to another
+func Transfer(from, to []byte, amount int) bool {
+	if trigger != runtime.Application {
+		return false
+	}
 	if amount <= 0 || len(to) != 20 || !runtime.CheckWitness(from) {
 		return false
 	}
@@ -203,7 +191,13 @@ func transfer(cfg TokenConfig, ctx storage.Context, from, to []byte, amount int)
 	return true
 }
 
-func transferFrom(cfg TokenConfig, ctx storage.Context, from, to []byte, amount int) bool {
+// TransferFrom transfers specified amount of token from one user to another.
+// It differs from Transfer in that it use allowance value to store the amount
+// of token available to transfer.
+func TransferFrom(from, to []byte, amount int) bool {
+	if trigger != runtime.Application {
+		return false
+	}
 	if amount <= 0 {
 		return false
 	}
@@ -234,8 +228,9 @@ func transferFrom(cfg TokenConfig, ctx storage.Context, from, to []byte, amount
 	return true
 }
 
-func approve(ctx storage.Context, owner, spender []byte, amount int) bool {
+// Approve stores token transfer data if the owner has enough token to send.
-	if !runtime.CheckWitness(owner) || amount < 0 {
+func Approve(owner, spender []byte, amount int) bool {
+	if !checkOwnerWitness() || amount < 0 {
 		return false
 	}
 	if len(spender) != 20 {
@@ -254,7 +249,11 @@ func approve(ctx storage.Context, owner, spender []byte, amount int) bool {
 	return true
 }
 
-func allowance(ctx storage.Context, from, to []byte) int {
+// Allowance returns allowance value for specified sender and receiver.
+func Allowance(from, to []byte) interface{} {
+	if trigger != runtime.Application {
+		return false
+	}
 	key := append(from, to...)
 	return getIntFromDB(ctx, key)
 }

examples/token/nep5/nep5.go

@@ -34,12 +34,12 @@ func getIntFromDB(ctx storage.Context, key []byte) int {
 }
 
 // GetSupply gets the token totalSupply value from VM storage
-func (t Token) GetSupply(ctx storage.Context) interface{} {
+func (t Token) GetSupply(ctx storage.Context) int {
 	return getIntFromDB(ctx, []byte(t.CirculationKey))
 }
 
 // BalanceOf gets the token balance of a specific address
-func (t Token) BalanceOf(ctx storage.Context, holder []byte) interface{} {
+func (t Token) BalanceOf(ctx storage.Context, holder []byte) int {
 	return getIntFromDB(ctx, holder)
 }
 
@@ -104,7 +104,7 @@ func IsUsableAddress(addr []byte) bool {
 	return false
 }
 
-// Mint initial supply of tokens.
+// Mint initial supply of tokens
 func (t Token) Mint(ctx storage.Context, to []byte) bool {
 	if !IsUsableAddress(t.Owner) {
 		return false

examples/token/token.go

@@ -11,11 +11,16 @@ const (
 	multiplier = 100000000
 )
 
-var owner = util.FromAddress("NMipL5VsNoLUBUJKPKLhxaEbPQVCZnyJyB")
+var (
+	owner = util.FromAddress("NULwe3UAHckN2fzNdcVg31tDiaYtMDwANt")
+	token nep5.Token
+	ctx   storage.Context
+)
 
-// createToken initializes the Token Interface for the Smart Contract to operate with
+// init initializes the Token Interface and storage context for the Smart
-func createToken() nep5.Token {
+// Contract to operate with
-	return nep5.Token{
+func init() {
+	token = nep5.Token{
 		Name:           "Awesome NEO Token",
 		Symbol:         "ANT",
 		Decimals:       decimals,
@@ -23,95 +28,40 @@ func createToken() nep5.Token {
 		TotalSupply:    11000000 * multiplier,
 		CirculationKey: "TokenCirculation",
 	}
-}
+	ctx = storage.GetContext()
-
-// Main function = contract entry
-func Main(operation string, args []interface{}) interface{} {
-	if operation == "name" {
-		return Name()
-	}
-	if operation == "symbol" {
-		return Symbol()
-	}
-	if operation == "decimals" {
-		return Decimals()
-	}
-
-	if operation == "totalSupply" {
-		return TotalSupply()
-	}
-
-	if operation == "balanceOf" {
-		hodler := args[0].([]byte)
-		return BalanceOf(hodler)
-	}
-
-	if operation == "transfer" && checkArgs(args, 3) {
-		from := args[0].([]byte)
-		to := args[1].([]byte)
-		amount := args[2].(int)
-		return Transfer(from, to, amount)
-	}
-
-	if operation == "mint" && checkArgs(args, 1) {
-		addr := args[0].([]byte)
-		return Mint(addr)
-	}
-
-	return true
-}
-
-// checkArgs checks args array against a length indicator
-func checkArgs(args []interface{}, length int) bool {
-	if len(args) == length {
-		return true
-	}
-
-	return false
 }
 
 // Name returns the token name
 func Name() string {
-	t := createToken()
+	return token.Name
-	return t.Name
 }
 
 // Symbol returns the token symbol
 func Symbol() string {
-	t := createToken()
+	return token.Symbol
-	return t.Symbol
 }
 
 // Decimals returns the token decimals
 func Decimals() int {
-	t := createToken()
+	return token.Decimals
-	return t.Decimals
 }
 
 // TotalSupply returns the token total supply value
-func TotalSupply() interface{} {
+func TotalSupply() int {
-	t := createToken()
+	return token.GetSupply(ctx)
-	ctx := storage.GetContext()
-	return t.GetSupply(ctx)
 }
 
 // BalanceOf returns the amount of token on the specified address
 func BalanceOf(holder []byte) interface{} {
-	t := createToken()
+	return token.BalanceOf(ctx, holder)
-	ctx := storage.GetContext()
-	return t.BalanceOf(ctx, holder)
 }
 
 // Transfer token from one user to another
 func Transfer(from []byte, to []byte, amount int) bool {
-	t := createToken()
+	return token.Transfer(ctx, from, to, amount)
-	ctx := storage.GetContext()
-	return t.Transfer(ctx, from, to, amount)
 }
 
 // Mint initial supply of tokens
 func Mint(to []byte) bool {
-	t := createToken()
+	return token.Mint(ctx, to)
-	ctx := storage.GetContext()
-	return t.Mint(ctx, to)
 }