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Add basic IRC2 token implementation
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‎tokens/build.gradle

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@@ -6,3 +6,7 @@ java {
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sourceCompatibility = JavaVersion.VERSION_11
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targetCompatibility = JavaVersion.VERSION_11
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}
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dependencies {
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compileOnly 'foundation.icon:javaee-api:0.8.6'
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}

‎tokens/src/main/java/com/iconloop/score/token/irc2/IRC2.java

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/*
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* Copyright 2020 ICONLOOP Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.iconloop.score.token.irc2;
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import score.Address;
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import score.annotation.Optional;
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import java.math.BigInteger;
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public interface IRC2 {
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/**
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* Returns the name of the token. (e.g. "MySampleToken")
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*/
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String name();
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/**
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* Returns the symbol of the token. (e.g. "MST")
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*/
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String symbol();
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/**
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* Returns the number of decimals the token uses. (e.g. 18)
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*/
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int decimals();
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/**
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* Returns the total token supply.
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*/
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BigInteger totalSupply();
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/**
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* Returns the account balance of another account with address {@code _owner}.
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*/
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BigInteger balanceOf(Address _owner);
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/**
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* Transfers {@code _value} amount of tokens to address {@code _to}, and MUST fire the {@code Transfer} event.
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* This function SHOULD throw if the caller account balance does not have enough tokens to spend.
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* If {@code _to} is a contract, this function MUST invoke the function {@code tokenFallback(Address, int, bytes)}
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* in {@code _to}. If the {@code tokenFallback} function is not implemented in {@code _to} (receiver contract),
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* then the transaction must fail and the transfer of tokens should not occur.
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* If {@code _to} is an externally owned address, then the transaction must be sent without trying to execute
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* {@code tokenFallback} in {@code _to}. {@code _data} can be attached to this token transaction.
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* {@code _data} can be empty.
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*/
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void transfer(Address _to, BigInteger _value, @Optional byte[] _data);
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/**
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* (EventLog) Must trigger on any successful token transfers.
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*/
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void Transfer(Address _from, Address _to, BigInteger _value, byte[] _data);
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}

‎tokens/src/main/java/com/iconloop/score/token/irc2/IRC2Basic.java

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/*
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* Copyright 2020 ICONLOOP Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.iconloop.score.token.irc2;
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import score.Address;
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import score.Context;
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import score.DictDB;
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import score.annotation.EventLog;
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import score.annotation.External;
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import score.annotation.Optional;
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import java.math.BigInteger;
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public abstract class IRC2Basic implements IRC2 {
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private final String name;
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private final String symbol;
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private final int decimals;
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private final BigInteger totalSupply;
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private final DictDB<Address, BigInteger> balances;
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public IRC2Basic(String _name, String _symbol, BigInteger _decimals, BigInteger _initialSupply) {
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this.name = _name;
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this.symbol = _symbol;
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this.decimals = _decimals.intValue();
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// decimals must be larger than 0 and less than 21
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Context.require(this.decimals >= 0);
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Context.require(this.decimals <= 21);
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// initialSupply must be larger than 0
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Context.require(_initialSupply.compareTo(BigInteger.ZERO) >= 0);
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// calculate totalSupply
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if (_initialSupply.compareTo(BigInteger.ZERO) > 0) {
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BigInteger oneToken = pow10(this.decimals);
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this.totalSupply = oneToken.multiply(_initialSupply);
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} else {
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this.totalSupply = BigInteger.ZERO;
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}
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// set the initial balance of the owner
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this.balances = Context.newDictDB("balances", BigInteger.class);
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this.balances.set(Context.getOrigin(), this.totalSupply);
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}
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// BigInteger#pow() is not implemented in the shadow BigInteger.
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// we need to use our implementation for that.
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private static BigInteger pow10(int exponent) {
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BigInteger result = BigInteger.ONE;
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for (int i = 0; i < exponent; i++) {
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result = result.multiply(BigInteger.TEN);
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}
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return result;
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}
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@External(readonly=true)
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public String name() {
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return name;
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}
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@External(readonly=true)
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public String symbol() {
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return symbol;
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}
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@External(readonly=true)
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public int decimals() {
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return decimals;
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}
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@External(readonly=true)
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public BigInteger totalSupply() {
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return totalSupply;
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}
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@External(readonly=true)
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public BigInteger balanceOf(Address _owner) {
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return safeGetBalance(_owner);
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}
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@External
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public void transfer(Address _to, BigInteger _value, @Optional byte[] _data) {
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Address _from = Context.getCaller();
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// check some basic requirements
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Context.require(_value.compareTo(BigInteger.ZERO) >= 0);
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Context.require(safeGetBalance(_from).compareTo(_value) >= 0);
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// adjust the balances
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safeSetBalance(_from, safeGetBalance(_from).subtract(_value));
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safeSetBalance(_to, safeGetBalance(_to).add(_value));
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// if the recipient is SCORE, call 'tokenFallback' to handle further operation
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byte[] dataBytes = (_data == null) ? new byte[0] : _data;
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if (_to.isContract()) {
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Context.call(_to, "tokenFallback", _from, _value, dataBytes);
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}
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// emit Transfer event
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Transfer(_from, _to, _value, dataBytes);
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}
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protected void _burn(Address owner, BigInteger amount) {
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// TODO: burn
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}
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private BigInteger safeGetBalance(Address owner) {
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return balances.getOrDefault(owner, BigInteger.ZERO);
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}
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private void safeSetBalance(Address owner, BigInteger amount) {
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balances.set(owner, amount);
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}
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@EventLog(indexed=3)
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public void Transfer(Address _from, Address _to, BigInteger _value, byte[] _data) {}
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}

‎tokens/src/main/java/com/iconloop/score/token/irc2/IRC2Burnable.java

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/*
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* Copyright 2020 ICONLOOP Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.iconloop.score.token.irc2;
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import score.Context;
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import score.annotation.External;
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import java.math.BigInteger;
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public abstract class IRC2Burnable extends IRC2Basic {
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public IRC2Burnable(String _name, String _symbol, BigInteger _decimals, BigInteger _initialSupply) {
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super(_name, _symbol, _decimals, _initialSupply);
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}
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@External
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public void burn(BigInteger _amount) {
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_burn(Context.getCaller(), _amount);
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}
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}

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