Add duplicate key check

go/state/state.go

@@ -41,13 +41,17 @@ func(st *State) Enter(input string) {
 	st.CacheMap = make(map[string]string)
 }
 
-func(st *State) Add(k string, v string) error {
+func(st *State) Add(key string, value string) error {
-	sz := st.checkCapacity(v)
+	checkFrame := st.frameOf(key)
+	if checkFrame > -1 {
+		return fmt.Errorf("key %v already defined in frame %v", key, checkFrame)
+	}
+	sz := st.checkCapacity(value)
 	if sz == 0 {
 		return fmt.Errorf("Cache capacity exceeded %v of %v", st.CacheUseSize + sz, st.CacheSize)
 	}
-	log.Printf("add key %s value size %v", k, sz)
+	log.Printf("add key %s value size %v", key, sz)
-	st.Cache[len(st.Cache)-1][k] = v
+	st.Cache[len(st.Cache)-1][key] = value
 	st.CacheUseSize += sz
 	return nil
 }
@@ -61,11 +65,18 @@ func(st *State) Map(k string) error {
 	return nil
 }
 
+func(st *State) Depth() uint8 {
+	return uint8(len(st.Cache))
+}
+
 func(st *State) Get() (map[string]string, error) {
+	if len(st.Cache) == 0 {
+		return nil, fmt.Errorf("get at top frame")
+	}
 	return st.Cache[len(st.Cache)-1], nil
 }
 
-func (st *State) Exit() error {
+func(st *State) Exit() error {
 	l := len(st.Cache)
 	if l == 0 {
 		return fmt.Errorf("exit called beyond top frame")
@@ -81,6 +92,28 @@ func (st *State) Exit() error {
 	return nil
 }
 
+func(st *State) Reset() error {
+	st.Cache = st.Cache[:1]
+	st.CacheUseSize = 0
+	return nil
+}
+
+func(st *State) Check(key string) bool {
+	return st.frameOf(key) == -1
+}
+
+func(st *State) frameOf(key string) int {
+	log.Printf("--- %s", key)
+	for i, m := range st.Cache {
+		for k, _ := range m {
+			if k == key {
+				return i
+			}
+		}
+	}
+	return -1
+}
+
 func(st *State) checkCapacity(v string) uint32 {
 	sz := uint32(len(v))
 	if st.CacheSize == 0 {

go/state/state_test.go

@@ -73,3 +73,39 @@ func TestStateEnterExit(t *testing.T) {
 		t.Errorf("expected out of top frame error")
 	}
 }
+
+func TestStateReset(t *testing.T) {
+	st := NewState(17)
+	st.Enter("one")
+	err := st.Add("foo", "bar")
+	if err != nil {
+		t.Error(err)
+	}
+	err = st.Add("baz", "xyzzy")
+	if err != nil {
+		t.Error(err)
+	}
+	st.Enter("two")
+	st.Enter("three")
+	st.Reset()
+	if st.CacheUseSize != 0 {
+		t.Errorf("expected cache use size 0, got %v", st.CacheUseSize)
+	}
+	if st.Depth() != 1 {
+		t.Errorf("expected depth 1, got %v", st.Depth())
+	}
+}
+
+func TestStateLoadDup(t *testing.T) {
+	st := NewState(17)
+	st.Enter("one")
+	err := st.Add("foo", "bar")
+	if err != nil {
+		t.Error(err)
+	}
+	st.Enter("two")
+	err = st.Add("foo", "baz")
+	if err == nil {
+		t.Errorf("expected fail on duplicate load")
+	}
+}

go/vm/vm.go

@@ -37,7 +37,13 @@ func Run(instruction []byte, st state.State, rs resource.Fetcher, ctx context.Co
 }
 
 func instructionSplit(b []byte) (string, []byte, error) {
+	if len(b) == 0 {
+		return "", nil, fmt.Errorf("argument is empty")
+	}
 	sz := uint8(b[0])
+	if sz == 0 {
+		return "", nil, fmt.Errorf("zero-length argument")
+	}
 	tailSz := uint8(len(b))
 	if tailSz - 1 < sz {
 		return "", nil, fmt.Errorf("corrupt instruction, len %v less than symbol length: %v", tailSz, sz)
@@ -61,10 +67,27 @@ func RunSink(instruction []byte, st state.State, rs resource.Fetcher, ctx contex
 }
 
 func RunCatch(instruction []byte, st state.State, rs resource.Fetcher, ctx context.Context) (state.State, error) {
+	head, tail, err := instructionSplit(instruction)
+	if err != nil {
+		return st, err
+	}
+	r, err := rs.Get(head)
+	if err != nil {
+		return st, err
+	}
+	_ = tail
+	st.Add(head, r)
 	return st, nil
 }
 
 func RunCroak(instruction []byte, st state.State, rs resource.Fetcher, ctx context.Context) (state.State, error) {
+	head, tail, err := instructionSplit(instruction)
+	if err != nil {
+		return st, err
+	}
+	_ = head
+	_ = tail
+	st.Reset()
 	return st, nil
 }
 
@@ -73,6 +96,9 @@ func RunLoad(instruction []byte, st state.State, rs resource.Fetcher, ctx contex
 	if err != nil {
 		return st, err
 	}
+	if !st.Check(head) {
+		return st, fmt.Errorf("key %v already loaded", head)
+	}
 	fn, err := rs.FuncFor(head)
 	if err != nil {
 		return st, err