mariano-aguero

const Big = require('big.js')
const BN = require('bn.js')

const MathBN = {
  sub: (a, b) => {
    const aBN = new Big(a || '0')
    const bBN = new Big(b || '0')
    return aBN.sub(bBN).toString(10)
  },
  add: (a, b) => {

mariano-aguero

// This is an implementation of the FA1.2 specification in PascaLIGO

type amount is nat;

type account is record
    balance : amount;
    allowances: map(address, amount);
end

type action is

mariano-aguero

(address :from, (address :to, nat :value)) %transfer
view (address :owner) nat                  %getBalance
view unit nat                              %getTotalSupply

mariano-aguero

function natToTz(const val: nat): tez is val * 1tz

function natToMutez(const val: nat): tez is val * 1mutez

function tezToNatWithMutez(const val: tez): nat is val / 1mutez

function tezToNatWithTz(const val: tez): nat is val / 1tz

function natToInt(const val: nat): int is val + 0

mariano-aguero

function main (const action : tokenAction ; const store : store) : return is 
  block {
    if amount =/= 0tz then failwith ("This contract do not accept token amount");
    else skip;
  } with case action of
    GetAllowance(n) -> allowance(n.0, n.1, n.2, store)
    | Transfer(n) -> transfer(n.0, n.1, n.2, store)
    | Approve(n) -> approve(n.0, n.1, store)
    | GetBalance(n) -> balanceOf(n.0, n.1, store)
    | GetTotalSupply(n) -> totalSupply(n.1, store)

mariano-aguero

type tokenAction is
| GetAllowance of (address * address * contract(nat))
| Transfer of (address * address * nat)
| Approve of (address * nat)
| GetBalance of (address * contract(nat))
| GetTotalSupply of (unit * contract(nat))
| Mint of (nat)
| Burn of (nat)
| Symbol of (unit * contract(string))
| Name of (unit * contract(string))

mariano-aguero

type account is record
  balance: nat;
  allowances: map(address, nat);
end

type store is record
  owners: set(address);
  decimals: nat; // Added this property used in the erc20 ethereum specification
  symbol: string; // Added this property used in the erc20 ethereum specification
  name: string; // Added this property used in the erc20 ethereum specification

mariano-aguero

function mint (const value : nat ; var store : store) : return is
 block {
  // Fail if is not an owner
  if not isOwner(sender, store) then failwith("You must be an owner of the contract to mint tokens");
  else block {
    var ownerAccount: account := record 
        balance = 0n;
        allowances = (map end : map(address, nat));
    end;
    case store.accounts[sender] of

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function approve (const addressSpender : address; const value : nat; var store : store) : return is
  block {
    // If sender is the spender approving is not necessary
    if sender = addressSpender then skip;
    else block {
        const senderAccount: account = getAccount(sender, store.accounts);
        var allowed: nat :=  getAllowance(addressSpender, senderAccount.allowances); 

        // Changing allowance value from non-zero value to a non-zero value is forbidden to prevent the corresponding attack vector.
        if allowed =/= 0n then failwith("UnsafeAllowanceChange");

mariano-aguero

function transfer (const addressFrom : address; const addressTo : address; const value : nat; var store : store) : return is
  block {
    if addressFrom = addressTo then skip;
    else block {
      case isAllowed(addressFrom, addressTo, value, store) of 
      | False -> block {
          failwith ("NotEnoughAllowance");
        }
      | True -> skip
      end;