add Iterable interface

objects/array.go

@@ -115,3 +115,11 @@ func (o *Array) IndexSet(index, value Object) (err error) {
 
 	return nil
 }
+
+// Iterate creates an array iterator.
+func (o *Array) Iterate() Iterator {
+	return &ArrayIterator{
+		v: o.Value,
+		l: len(o.Value),
+	}
+}

objects/array_iterator.go

@@ -9,14 +9,6 @@ type ArrayIterator struct {
 	l int
 }
 
-// NewArrayIterator creates an ArrayIterator.
-func NewArrayIterator(v *Array) Iterator {
-	return &ArrayIterator{
-		v: v.Value,
-		l: len(v.Value),
-	}
-}
-
 // TypeName returns the name of the type.
 func (i *ArrayIterator) TypeName() string {
 	return "array-iterator"

objects/immutable_map.go

@@ -84,3 +84,17 @@ func (o *ImmutableMap) Equals(x Object) bool {
 
 	return true
 }
+
+// Iterate creates an immutable map iterator.
+func (o *ImmutableMap) Iterate() Iterator {
+	var keys []string
+	for k := range o.Value {
+		keys = append(keys, k)
+	}
+
+	return &ImmutableMapIterator{
+		v: o.Value,
+		k: keys,
+		l: len(keys),
+	}
+}

objects/immutable_map_iterator.go

@@ -10,20 +10,6 @@ type ImmutableMapIterator struct {
 	l int
 }
 
-// NewModuleMapIterator creates a module iterator.
-func NewModuleMapIterator(v *ImmutableMap) Iterator {
-	var keys []string
-	for k := range v.Value {
-		keys = append(keys, k)
-	}
-
-	return &ImmutableMapIterator{
-		v: v.Value,
-		k: keys,
-		l: len(keys),
-	}
-}
-
 // TypeName returns the name of the type.
 func (i *ImmutableMapIterator) TypeName() string {
 	return "module-iterator"

objects/iterable.go

@@ -0,0 +1,7 @@
+package objects
+
+// Iterable represents an object that has iterator.
+type Iterable interface {
+	// Iterate should return an Iterator for the type.
+	Iterate() Iterator
+}

objects/map.go

@@ -97,3 +97,17 @@ func (o *Map) IndexSet(index, value Object) (err error) {
 
 	return nil
 }
+
+// Iterate creates a map iterator.
+func (o *Map) Iterate() Iterator {
+	var keys []string
+	for k := range o.Value {
+		keys = append(keys, k)
+	}
+
+	return &MapIterator{
+		v: o.Value,
+		k: keys,
+		l: len(keys),
+	}
+}

objects/map_iterator.go

@@ -10,20 +10,6 @@ type MapIterator struct {
 	l int
 }
 
-// NewMapIterator creates a map iterator.
-func NewMapIterator(v *Map) Iterator {
-	var keys []string
-	for k := range v.Value {
-		keys = append(keys, k)
-	}
-
-	return &MapIterator{
-		v: v.Value,
-		k: keys,
-		l: len(keys),
-	}
-}
-
 // TypeName returns the name of the type.
 func (i *MapIterator) TypeName() string {
 	return "map-iterator"

objects/string.go

@@ -81,3 +81,15 @@ func (o *String) IndexGet(index Object) (res Object, err error) {
 
 	return
 }
+
+// Iterate creates a string iterator.
+func (o *String) Iterate() Iterator {
+	if o.runeStr == nil {
+		o.runeStr = []rune(o.Value)
+	}
+
+	return &StringIterator{
+		v: o.runeStr,
+		l: len(o.runeStr),
+	}
+}

objects/string_iterator.go

@@ -9,16 +9,6 @@ type StringIterator struct {
 	l int
 }
 
-// NewStringIterator creates a string iterator.
-func NewStringIterator(v *String) Iterator {
-	r := []rune(v.Value)
-
-	return &StringIterator{
-		v: r,
-		l: len(r),
-	}
-}
-
 // TypeName returns the name of the type.
 func (i *StringIterator) TypeName() string {
 	return "string-iterator"

runtime/vm.go

@@ -921,19 +921,13 @@ func (v *VM) Run() error {
 			dst := v.stack[v.sp-1]
 			v.sp--
 
-			switch dst := (*dst).(type) {
-			case *objects.Array:
-				iterator = objects.NewArrayIterator(dst)
-			case *objects.Map:
-				iterator = objects.NewMapIterator(dst)
-			case *objects.ImmutableMap:
-				iterator = objects.NewModuleMapIterator(dst)
-			case *objects.String:
-				iterator = objects.NewStringIterator(dst)
-			default:
-				return fmt.Errorf("non-iterable type: %s", dst.TypeName())
+			iterable, ok := (*dst).(objects.Iterable)
+			if !ok {
+				return fmt.Errorf("non-iterable type: %s", (*dst).TypeName())
 			}
 
+			iterator = iterable.Iterate()
+
 			if v.sp >= StackSize {
 				return ErrStackOverflow
 			}
@@ -945,12 +939,13 @@ func (v *VM) Run() error {
 			iterator := v.stack[v.sp-1]
 			v.sp--
 
-			b := (*iterator).(objects.Iterator).Next()
+			hasMore := (*iterator).(objects.Iterator).Next()
+
 			if v.sp >= StackSize {
 				return ErrStackOverflow
 			}
 
-			if b {
+			if hasMore {
 				v.stack[v.sp] = truePtr
 			} else {
 				v.stack[v.sp] = falsePtr

runtime/vm_iterable_test.go

@@ -0,0 +1,44 @@
+package runtime_test
+
+import (
+	"testing"
+
+	"github.com/d5/tengo/objects"
+)
+
+type StringArrayIterator struct {
+	objectImpl
+	strArr *StringArray
+	idx    int
+}
+
+func (i *StringArrayIterator) TypeName() string {
+	return "string-array-iterator"
+}
+
+func (i *StringArrayIterator) Next() bool {
+	i.idx++
+	return i.idx <= len(i.strArr.Value)
+}
+
+func (i *StringArrayIterator) Key() objects.Object {
+	return &objects.Int{Value: int64(i.idx - 1)}
+}
+
+func (i *StringArrayIterator) Value() objects.Object {
+	return &objects.String{Value: i.strArr.Value[i.idx-1]}
+}
+
+func (o *StringArray) Iterate() objects.Iterator {
+	return &StringArrayIterator{
+		strArr: o,
+	}
+}
+
+func TestIterable(t *testing.T) {
+	strArr := func() *StringArray { return &StringArray{Value: []string{"one", "two", "three"}} }
+
+	expectWithSymbols(t, `for i, s in arr { out += i }`, 3, SYM{"arr": strArr()})
+	expectWithSymbols(t, `for i, s in arr { out += s }`, "onetwothree", SYM{"arr": strArr()})
+	expectWithSymbols(t, `for i, s in arr { out += s + i }`, "one0two1three2", SYM{"arr": strArr()})
+}