Implement UNPACK_SEQUENCE

Author: ncw

vm/eval.go

@@ -74,6 +74,11 @@ func (vm *Vm) PUSH(obj py.Object){
 vm.frame.Stack=append(vm.frame.Stack, obj)
 }
 
+// Push items to top of vm stack
+func (vm*Vm) EXTEND(items py.Tuple){
+vm.frame.Stack=append(vm.frame.Stack, items...)
+}
+
 // Adds a traceback to the exc passed in for the current vm state
 func (vm*Vm) AddTraceback(exc*py.ExceptionInfo){
 exc.Traceback=&py.Traceback{
@@ -725,7 +730,20 @@ func do_DELETE_NAME(vm *Vm, namei int32){
 // stack right-to-left.
 funcdo_UNPACK_SEQUENCE(vm*Vm, countint32){
 defervm.CheckException()
-vm.NotImplemented("UNPACK_SEQUENCE", count)
+it:=vm.POP()
+i:=count
+items:=make(py.Tuple, count)
+py.Iterate(it, func(item py.Object){
+i--
+ifi<0{
+panic(py.ExceptionNewf(py.ValueError, "Too many values to unpack (expected %d)", count))
+ }
+items[i] =item
+ })
+ifi!=0{
+panic(py.ExceptionNewf(py.ValueError, "Need more than %d values to unpack (expected %d)", count-i, count))
+ }
+vm.EXTEND(items)
 }
 
 // Implements TOS.name = TOS1, where namei is the index of name in