From a9955719da79ae1154adc019cf9c9c9d1eb0d479 Mon Sep 17 00:00:00 2001
From: Roman Khimov <roman@nspcc.ru>
Date: Thu, 4 Jun 2020 15:41:54 +0300
Subject: [PATCH] native: make mint/burn for 0 no-ops

Prevent emitting useless transfer events and doing useless gets/puts.
---
 pkg/core/native/native_nep5.go | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/pkg/core/native/native_nep5.go b/pkg/core/native/native_nep5.go
index e969805cb..eb8c0ef23 100644
--- a/pkg/core/native/native_nep5.go
+++ b/pkg/core/native/native_nep5.go
@@ -208,11 +208,17 @@ func (c *nep5TokenNative) balanceOf(ic *interop.Context, args []vm.StackItem) vm
 }
 
 func (c *nep5TokenNative) mint(ic *interop.Context, h util.Uint160, amount *big.Int) {
+	if amount.Sign() == 0 {
+		return
+	}
 	c.addTokens(ic, h, amount)
 	c.emitTransfer(ic, nil, &h, amount)
 }
 
 func (c *nep5TokenNative) burn(ic *interop.Context, h util.Uint160, amount *big.Int) {
+	if amount.Sign() == 0 {
+		return
+	}
 	amount = new(big.Int).Neg(amount)
 	c.addTokens(ic, h, amount)
 	c.emitTransfer(ic, &h, nil, amount)