array literals

code/code.go

@@ -29,6 +29,7 @@ const (
 	OpNull
 	OpGetGlobal
 	OpSetGlobal
+	OpArray
 )
 
 type Definition struct {
@@ -55,6 +56,7 @@ var definitions = map[Opcode]*Definition{
 	OpNull:          {"OpNull", []int{}},
 	OpGetGlobal:     {"OpGetGlobal", []int{2}},
 	OpSetGlobal:     {"OpSetGlobal", []int{2}},
+	OpArray:         {"OpArray", []int{2}},
 }
 
 func Lookup(op byte) (*Definition, error) {

compiler/compiler.go

@@ -194,6 +194,16 @@ func (c *Compiler) Compile(node ast.Node) error {
 		str := &object.String{Value: node.Value}
 		c.emit(code.OpConstant, c.addConstant(str))
 
+	case *ast.ArrayLiteral:
+		for _, el := range node.Elements {
+			err := c.Compile(el)
+			if err != nil {
+				return err
+			}
+		}
+
+		c.emit(code.OpArray, len(node.Elements))
+
 	}
 
 	return nil

compiler/compiler_test.go

@@ -302,6 +302,49 @@ func TestStringExpressions(t *testing.T) {
 	runCompilerTests(t, tests)
 }
 
+func TestArrayLiterals(t *testing.T) {
+	tests := []compilerTestCase{
+		{
+			input:             "[]",
+			expectedConstants: []interface{}{},
+			expectedInstructions: []code.Instructions{
+				code.Make(code.OpArray, 0),
+				code.Make(code.OpPop),
+			},
+		},
+		{
+			input:             "[1, 2, 3]",
+			expectedConstants: []interface{}{1, 2, 3},
+			expectedInstructions: []code.Instructions{
+				code.Make(code.OpConstant, 0),
+				code.Make(code.OpConstant, 1),
+				code.Make(code.OpConstant, 2),
+				code.Make(code.OpArray, 3),
+				code.Make(code.OpPop),
+			},
+		},
+		{
+			input:             "[1 + 2, 3 - 4, 5 * 6]",
+			expectedConstants: []interface{}{1, 2, 3, 4, 5, 6},
+			expectedInstructions: []code.Instructions{
+				code.Make(code.OpConstant, 0),
+				code.Make(code.OpConstant, 1),
+				code.Make(code.OpAdd),
+				code.Make(code.OpConstant, 2),
+				code.Make(code.OpConstant, 3),
+				code.Make(code.OpSub),
+				code.Make(code.OpConstant, 4),
+				code.Make(code.OpConstant, 5),
+				code.Make(code.OpMul),
+				code.Make(code.OpArray, 3),
+				code.Make(code.OpPop),
+			},
+		},
+	}
+
+	runCompilerTests(t, tests)
+}
+
 func runCompilerTests(t *testing.T, tests []compilerTestCase) {
 	t.Helper()
 

vm/vm.go

@@ -133,12 +133,34 @@ func (vm *VM) Run() error {
 				return err
 			}
 
+		case code.OpArray:
+			numElements := int(code.ReadUint16(vm.instructions[ip+1:]))
+			ip += 2
+
+			array := vm.buildArray(vm.sp-numElements, vm.sp)
+			vm.sp = vm.sp - numElements
+
+			err := vm.push(array)
+			if err != nil {
+				return err
+			}
+
 		}
 	}
 
 	return nil
 }
 
+func (vm *VM) buildArray(startIndex, endIndex int) object.Object {
+	elements := make([]object.Object, endIndex-startIndex)
+
+	for i := startIndex; i < endIndex; i++ {
+		elements[i-startIndex] = vm.stack[i]
+	}
+
+	return &object.Array{Elements: elements}
+}
+
 func isTruthy(obj object.Object) bool {
 	switch obj := obj.(type) {
 

vm/vm_test.go

@@ -61,6 +61,24 @@ func testExpectedObject(t *testing.T, expected interface{}, actual object.Object
 			t.Errorf("testStringObject failed: %s", err)
 		}
 
+	case []int:
+		array, ok := actual.(*object.Array)
+		if !ok {
+			t.Errorf("object not Array: %T (%+v)", actual, actual)
+		}
+
+		if len(array.Elements) != len(expected) {
+			t.Errorf("wrong num of elements. want=%d, got=%d", len(expected), len(array.Elements))
+			return
+		}
+
+		for i, expectedElem := range expected {
+			err := testIntegerObject(int64(expectedElem), array.Elements[i])
+			if err != nil {
+				t.Errorf("testIntgerObject failed: %s", err)
+			}
+		}
+
 	case *object.Null:
 		if actual != Null {
 			t.Errorf("object is not Null: %T (%+v)", actual, actual)
@@ -204,3 +222,13 @@ func TestStringExpressions(t *testing.T) {
 
 	runVmTests(t, tests)
 }
+
+func TestArrayLiterals(t *testing.T) {
+	tests := []vmTestCase{
+		{"[]", []int{}},
+		{"[1, 2, 3]", []int{1, 2, 3}},
+		{"[1 + 2, 3 * 4, 5 + 6]", []int{3, 12, 11}},
+	}
+
+	runVmTests(t, tests)
+}