Refactor VM and operators

internal/object/array.go

@@ -2,6 +2,7 @@ package object
 
 import (
 	"bytes"
+	"fmt"
 	"strings"
 )
 
@@ -18,30 +19,30 @@ func (ao *Array) Bool() bool {
 	return len(ao.Elements) > 0
 }
 
-func (a *Array) PopLeft() Object {
-	if len(a.Elements) > 0 {
-		e := a.Elements[0]
-		a.Elements = a.Elements[1:]
+func (ao *Array) PopLeft() Object {
+	if len(ao.Elements) > 0 {
+		e := ao.Elements[0]
+		ao.Elements = ao.Elements[1:]
 		return e
 	}
 	return &Null{}
 }
 
-func (a *Array) PopRight() Object {
-	if len(a.Elements) > 0 {
-		e := a.Elements[(len(a.Elements) - 1)]
-		a.Elements = a.Elements[:(len(a.Elements) - 1)]
+func (ao *Array) PopRight() Object {
+	if len(ao.Elements) > 0 {
+		e := ao.Elements[(len(ao.Elements) - 1)]
+		ao.Elements = ao.Elements[:(len(ao.Elements) - 1)]
 		return e
 	}
 	return &Null{}
 }
 
-func (a *Array) Prepend(obj Object) {
-	a.Elements = append([]Object{obj}, a.Elements...)
+func (ao *Array) Prepend(obj Object) {
+	ao.Elements = append([]Object{obj}, ao.Elements...)
 }
 
-func (a *Array) Append(obj Object) {
-	a.Elements = append(a.Elements, obj)
+func (ao *Array) Append(obj Object) {
+	ao.Elements = append(ao.Elements, obj)
 }
 
 func (ao *Array) Inspect() string {
@@ -69,6 +70,63 @@ func (ao *Array) Less(i, j int) bool {
 	return false
 }
 
+func (ao *Array) Add(other Object) (Object, error) {
+	if other.Type() != ao.Type() {
+		return nil, NewBinaryOpError(ao, other, "+")
+	}
+
+	var elements []Object
+	elements = append(elements, ao.Elements...)
+	elements = append(elements, other.(*Array).Elements...)
+
+	return &Array{Elements: elements}, nil
+
+}
+
+func (ao *Array) Mul(other Object) (Object, error) {
+	if other.Type() != IntegerType {
+		return nil, NewBinaryOpError(ao, other, "*")
+	}
+
+	var elements []Object
+	N := int(other.(*Integer).Value)
+	for i := 0; i < N; i++ {
+		elements = append(elements, ao.Elements...)
+	}
+
+	return &Array{Elements: elements}, nil
+}
+
+func (ao *Array) Get(index Object) (Object, error) {
+	if !AssertTypes(index, IntegerType) {
+		return nil, fmt.Errorf("invalid type for array index, expected Integer got %s", index.Type())
+	}
+
+	i := index.(*Integer).Value
+	N := int64(len(ao.Elements))
+	if i < 0 || i >= N {
+		return &Null{}, nil
+	}
+
+	return ao.Elements[i], nil
+}
+
+func (ao *Array) Set(index, other Object) error {
+	if !AssertTypes(index, IntegerType) {
+		return fmt.Errorf("invalid type for array index, expected Integer got %s", index.Type())
+	}
+
+	i := index.(*Integer).Value
+	N := int64(len(ao.Elements))
+	if i < 0 || i >= N {
+		return fmt.Errorf("index out of bounds %d with array length %d", i, N)
+	}
+
+	ao.Elements[i] = other
+
+	return nil
+}
+
 func (ao *Array) Compare(other Object) int {
 	if obj, ok := other.(*Array); ok {
 		if len(ao.Elements) != len(obj.Elements) {