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examples: drop token-sale contract

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It makes zero sense, it's not what it says it
is. AmountPerNEO/MaxExchangeLimitRound are not used at all to affect minting
and allowance/transferFrom features are largely obsolete. We have proper
minting implemented in NFT contracts and there is a nice NEP-17 available
also.
This commit is contained in:
Roman Khimov 2022-03-23 18:18:03 +03:00
parent a5979f6d64
commit 26c3a6c161
5 changed files with 0 additions and 300 deletions
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1
examples/README.md
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@ -33,7 +33,6 @@ See the table below for the detailed examples description.
| [storage](storage) | The contract implements API for basic operations with a contract storage. It shows hos to use `storage` interop package. See the `storage` [package documentation](../pkg/interop/storage/storage.go). |
| [timer](timer) | The idea of the contract is to count `tick` method invocations and destroy itself after the third invocation. It shows how to use `contract.Call` interop function to call, update (migrate) and destroy the contract. Please, refer to the `contract.Call` [function documentation](../pkg/interop/contract/contract.go) |
| [token](token) | This contract implements NEP-17 token standard (like NEO and GAS tokens) with all required methods and operations. See the NEP-17 token standard [specification](https://github.com/neo-project/proposals/pull/126) for details. |
| [token-sale](token-sale) | The contract represents a token with `allowance`. It means that the token owner should approve token withdrawing before the transfer. The contract demonstrates how interop packages can be combined to work together. |
## Compile

5
examples/token-sale/go.mod
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@ -1,5 +0,0 @@
module github.com/nspcc-dev/neo-go/examples/token-sale
go 1.16
require github.com/nspcc-dev/neo-go/pkg/interop v0.0.0-20220321144137-d5a9af5860af

2
examples/token-sale/go.sum
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@ -1,2 +0,0 @@
github.com/nspcc-dev/neo-go/pkg/interop v0.0.0-20220321144137-d5a9af5860af h1:QO3pU/jSYyX3EHBX8BPO01oRkVhGBXPrQaQEhn+4fv8=
github.com/nspcc-dev/neo-go/pkg/interop v0.0.0-20220321144137-d5a9af5860af/go.mod h1:QBE0I30F2kOAISNpT5oks82yF4wkkUq3SCfI3Hqgx/Y=

279
examples/token-sale/token_sale.go
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@ -1,279 +0,0 @@
package tokensale
import (
"github.com/nspcc-dev/neo-go/pkg/interop"
"github.com/nspcc-dev/neo-go/pkg/interop/runtime"
"github.com/nspcc-dev/neo-go/pkg/interop/storage"
"github.com/nspcc-dev/neo-go/pkg/interop/util"
)
const (
decimals = 8
multiplier = decimals * 10
)
var (
owner = util.FromAddress("NbrUYaZgyhSkNoRo9ugRyEMdUZxrhkNaWB")
trigger byte
token TokenConfig
ctx storage.Context
)
// TokenConfig holds information about the token we want to use for the sale.
type TokenConfig struct {
// Name of the token.
Name string
// 3 letter abbreviation of the token.
Symbol string
// How decimals this token will have.
Decimals int
// Address of the token owner. This is the Uint160 hash.
Owner []byte
// The total amount of tokens created. Notice that we need to multiply the
// amount by 100000000. (10^8)
TotalSupply int
// Initial amount is number of tokens that are available for the token sale.
InitialAmount int
// How many NEO will be worth 1 token. For example:
// Lets say 1 euro per token, where 1 NEO is 60 euro. This means buyers
// will get (60 * 10^8) tokens for 1 NEO.
AmountPerNEO int
// How many Gas will be worth 1 token. This is the same calculation as
// for the AmountPerNEO, except Gas price will have a different value.
AmountPerGas int
// The maximum amount you can mint in the limited round. For example:
// 500 NEO/buyer * 60 tokens/NEO * 10^8
MaxExchangeLimitRound int
// When to start the token sale.
SaleStart int
// When to end the initial limited round if there is one. For example:
// SaleStart + 10000
LimitRoundEnd int
// The prefix used to store how many tokens there are in circulation.
CirculationKey []byte
// The prefix used to store how many tokens there are in the limited round.
LimitRoundKey []byte
// The prefix used to store the addresses that are registered with KYC.
KYCKey []byte
}
// newTokenConfig returns the initialized TokenConfig.
func newTokenConfig() TokenConfig {
return TokenConfig{
Name: "My awesome token",
Symbol: "MAT",
Decimals: decimals,
Owner: owner,
TotalSupply: 10000000 * multiplier,
InitialAmount: 5000000 * multiplier,
AmountPerNEO: 60 * multiplier,
AmountPerGas: 40 * multiplier,
MaxExchangeLimitRound: 500 * 60 * multiplier,
SaleStart: 75500,
LimitRoundEnd: 75500 + 10000,
CirculationKey: []byte("in_circulation"),
LimitRoundKey: []byte("r1"),
KYCKey: []byte("kyc_ok"),
}
}
// getIntFromDB is a helper that checks for nil result of storage.Get and returns
// zero as the default value.
func getIntFromDB(ctx storage.Context, key []byte) int {
var res int
val := storage.Get(ctx, key)
if val != nil {
res = val.(int)
}
return res
}
// InCirculation returns the amount of total tokens that are in circulation.
func InCirculation() int {
return getIntFromDB(ctx, token.CirculationKey)
}
// addToCirculation sets the given amount as "in circulation" in the storage.
func addToCirculation(amount int) bool {
if amount < 0 {
return false
}
supply := getIntFromDB(ctx, token.CirculationKey)
supply += amount
if supply > token.TotalSupply {
return false
}
storage.Put(ctx, token.CirculationKey, supply)
return true
}
// AvailableAmount returns the total amount of available tokens left
// to be distributed.
func AvailableAmount() int {
inCirc := getIntFromDB(ctx, token.CirculationKey)
return token.TotalSupply - inCirc
}
// init initializes runtime trigger, TokenConfig and storage context before any
// other contract method is called
func init() {
trigger = runtime.GetTrigger()
token = newTokenConfig()
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.Application {
// Check if the invoker is the owner of the contract.
return runtime.CheckWitness(token.Owner)
}
return false
}
// Decimals returns the token decimals
func Decimals() int {
if trigger != runtime.Application {
panic("invalid trigger")
}
return token.Decimals
}
// Symbol returns the token symbol
func Symbol() string {
if trigger != runtime.Application {
panic("invalid trigger")
}
return token.Symbol
}
// TotalSupply returns the token total supply value
func TotalSupply() int {
if trigger != runtime.Application {
panic("invalid trigger")
}
return getIntFromDB(ctx, token.CirculationKey)
}
// BalanceOf returns the amount of token on the specified address
func BalanceOf(holder interop.Hash160) int {
if trigger != runtime.Application {
panic("invalid trigger")
}
return getIntFromDB(ctx, holder)
}
// Transfer transfers specified amount of token from one user to another
func Transfer(from, to interop.Hash160, amount int, _ interface{}) bool {
if trigger != runtime.Application {
return false
}
if amount <= 0 || len(to) != 20 || !runtime.CheckWitness(from) {
return false
}
amountFrom := getIntFromDB(ctx, from)
if amountFrom < amount {
return false
}
if amountFrom == amount {
storage.Delete(ctx, from)
} else {
diff := amountFrom - amount
storage.Put(ctx, from, diff)
}
amountTo := getIntFromDB(ctx, to)
totalAmountTo := amountTo + amount
if totalAmountTo != 0 {
storage.Put(ctx, to, totalAmountTo)
}
return true
}
// 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
}
availableKey := append(from, to...)
if len(availableKey) != 40 {
return false
}
availableTo := getIntFromDB(ctx, availableKey)
if availableTo < amount {
return false
}
fromBalance := getIntFromDB(ctx, from)
if fromBalance < amount {
return false
}
toBalance := getIntFromDB(ctx, to)
newFromBalance := fromBalance - amount
newToBalance := toBalance + amount
storage.Put(ctx, to, newToBalance)
storage.Put(ctx, from, newFromBalance)
newAllowance := availableTo - amount
if newAllowance == 0 {
storage.Delete(ctx, availableKey)
} else {
storage.Put(ctx, availableKey, newAllowance)
}
return true
}
// Approve stores token transfer data if the owner has enough token to send.
func Approve(owner, spender []byte, amount int) bool {
if !checkOwnerWitness() || amount < 0 {
return false
}
if len(spender) != 20 {
return false
}
toSpend := getIntFromDB(ctx, owner)
if toSpend < amount {
return false
}
approvalKey := append(owner, spender...)
if amount == 0 {
storage.Delete(ctx, approvalKey)
} else {
storage.Put(ctx, approvalKey, amount)
}
return true
}
// 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)
}
// Mint initial supply of tokens
func Mint(to []byte) bool {
if trigger != runtime.Application {
return false
}
if !checkOwnerWitness() {
return false
}
minted := storage.Get(ctx, []byte("minted"))
if minted != nil && minted.(bool) == true {
return false
}
storage.Put(ctx, to, token.TotalSupply)
storage.Put(ctx, []byte("minted"), true)
addToCirculation(token.TotalSupply)
return true
}

13
examples/token-sale/token_sale.yml
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@ -1,13 +0,0 @@
name: "My awesome token"
sourceurl: https://github.com/nspcc-dev/neo-go/
supportedstandards: ["NEP-17"]
safemethods: ["balanceOf", "decimals", "symbol", "totalSupply"]
events:
- name: Transfer
parameters:
- name: from
type: Hash160
- name: to
type: Hash160
- name: amount
type: Integer