Extend and test minimal example.

chunk.go

@@ -18,8 +18,12 @@ type chunk struct {
  index int
 }
 
-func newChunk() *chunk {
- return &chunk{[]Entry{}, 0}
+func newChunk(entries ...Entry) *chunk {
+ c := &chunk{}
+ if len(entries) > 0 {
+ c.entries = entries
+ }
+ return c
 }
 
 func (c *chunk) add(e Entry) {

chunk_test.go

@@ -34,3 +34,15 @@ func TestChunk(t *testing.T) {
  t.Error("chunk should have more")
  }
 }
+
+func TestChunkVariadic(t *testing.T) {
+ c := newChunk(opEntry(op_ret), constantEntry(1))
+ if !c.hasMore() {
+ t.Error("chunk should have more")
+ }
+ c.next()
+ c.next()
+ if c.hasMore() {
+ t.Error("chunk should not have more")
+ }
+}

main.go

@@ -3,20 +3,15 @@ package main
 import "fmt"
 
 func main() {
+ C := func(i value) Entry { return constantEntry(i) }
+ Op := func(o opcode) Entry { return opEntry(o) }
  // Make our stack
  s := newStack()
- // Create a chunk of code
- c := newChunk()
  // Create code to push 1 and 2 on the stack, add them, print the
  // result, and return:
- c.add(constantEntry(1))
- c.add(constantEntry(2))
- c.add(opEntry(op_add))
- c.add(opEntry(op_print))
- c.add(opEntry(op_ret))
- // Create a VM
+ c := newChunk(C(1), C(2), Op(op_add), Op(op_ret))
+ // Run the code in a new VM:
  vm := newVM(c)
  // Run the VM
- vm.run(s)
- fmt.Println("OK")
+ fmt.Println(vm.run(s))
 }

vm.go

@@ -9,7 +9,7 @@ func newVM(c *chunk) *vm {
  return &vm{code: c, ip: 0}
 }
 
-func (v *vm) execOpcode(o opcode, s *stack) {
+func (v *vm) execOpcode(o opcode, s *stack) *value {
  switch o {
  case op_add:
  b, err := s.pop()
@@ -28,17 +28,28 @@ func (v *vm) execOpcode(o opcode, s *stack) {
  }
  println(v)
  case op_ret:
- return
+ v, err := s.pop()
+ if err != nil {
+ panic(err) // fixme
+ }
+ // End of processing may be signalled by returning a value:
+ return &v
  }
+ return nil
 }
-func (v *vm) run(s *stack) {
+
+func (v *vm) run(s *stack) value {
  for v.code.hasMore() {
  e := v.code.next()
  switch e.typ {
  case typ_opcode:
- v.execOpcode(e.opcode, s)
+ ret := v.execOpcode(e.opcode, s)
+ if ret != nil {
+ return *ret
+ }
  case typ_constant:
  s.push(e.value)
  }
  }
+ return 0
 }