core: make SpawnVM a method of context

spawnVMWithInterops is rather long too type and
it doesn't use Blockchain in any way.

pkg/core/interops.go

@@ -14,7 +14,9 @@ import (
 	"github.com/nspcc-dev/neo-go/pkg/core/dao"
 	"github.com/nspcc-dev/neo-go/pkg/core/state"
 	"github.com/nspcc-dev/neo-go/pkg/core/transaction"
+	"github.com/nspcc-dev/neo-go/pkg/smartcontract"
 	"github.com/nspcc-dev/neo-go/pkg/smartcontract/trigger"
+	"github.com/nspcc-dev/neo-go/pkg/util"
 	"github.com/nspcc-dev/neo-go/pkg/vm"
 	"go.uber.org/zap"
 )
@@ -35,6 +37,23 @@ func newInteropContext(trigger trigger.Type, bc Blockchainer, d dao.DAO, block *
 	return &interopContext{bc, trigger, block, tx, dao, nes, log}
 }
 
+// SpawnVM returns a VM with script getter and interop functions set
+// up for current blockchain.
+func (ic *interopContext) SpawnVM() *vm.VM {
+	vm := vm.New()
+	vm.SetScriptGetter(func(hash util.Uint160) ([]byte, bool) {
+		cs, err := ic.dao.GetContractState(hash)
+		if err != nil {
+			return nil, false
+		}
+		hasDynamicInvoke := (cs.Properties & smartcontract.HasDynamicInvoke) != 0
+		return cs.Script, hasDynamicInvoke
+	})
+	vm.RegisterInteropGetter(ic.getSystemInterop)
+	vm.RegisterInteropGetter(ic.getNeoInterop)
+	return vm
+}
+
 // interopedFunction binds function name, id with the function itself and price,
 // it's supposed to be inited once for all interopContexts, so it doesn't use
 // vm.InteropFuncPrice directly.