Implement storing variables

elm.go

@@ -28,6 +28,8 @@ const (
 	JMPIF Operation = 10
 	CALL Operation = 11
 	RET Operation = 12
+	STORE Operation = 13
+	GET Operation = 14
 )
 
 type Inst struct {
@@ -206,6 +208,28 @@ func (m* Machine) Execute() error {
 		currentFrame := m.stackFrame[len(m.stackFrame) - 1]
 		m.stackFrame = m.stackFrame[:len(m.stackFrame) - 1]
 		m.ip = int32(currentFrame.ReturnAddress)
+	case STORE:
+		if (m.sp < 1) {
+			return errors.New("Nothing to store on the stack")
+		}
+
+		if (instr.Operand < 0) {
+			return errors.New("Incorrect variable address")
+		}
+
+		currentFrame := m.stackFrame[len(m.stackFrame) - 1]
+		currentFrame.StoreVariable(int(instr.Operand), m.stack[m.sp - 1])
+		m.sp--
+		m.ip++
+	case GET:
+		if (instr.Operand < 0) {
+			return errors.New("Incorrect variable address")
+		}
+
+		currentFrame := m.stackFrame[len(m.stackFrame) - 1]
+		m.stack[m.sp] = currentFrame.GetVariable(int(instr.Operand))
+		m.sp++
+		m.ip++
 	}
 	return nil
 }

elm_test.go

@@ -442,6 +442,7 @@ func TestCallPass(t * testing.T) {
 	assert.True(t, m.isHalted, "Virtual Machine should be Halted");
 	assert.Equal(t, int32(1), m.stack[0], "Should skip the pushed value")
 	assert.Equal(t, int32(69), m.stack[1], "Should skip the pushed value")
+	assert.Equal(t, 2, len(m.stackFrame), "Should create the function stack frame")
 	assert.Equal(t, int32(0), m.stack[2], "Should be zero afterall")
 }
 
@@ -464,4 +465,61 @@ func TestRetPass(t * testing.T) {
 	assert.Equal(t, int32(69), m.stack[1], "Should skip the pushed value")
 	assert.Equal(t, int32(6), m.stack[2], "Should skip the pushed value")
 	assert.Equal(t, int32(0), m.stack[3], "Should be zero afterall")
+	assert.Equal(t, 1, len(m.stackFrame), "Should pop the function stack frame")
 }
+
+func TestStoreWontPassIfStackEmpty(t *testing.T) {
+	m := Constructor()
+
+	m.Push(Inst{Operation: STORE, Operand: 1})
+	m.Push(Inst{Operation: HALT})
+	
+	err := m.Run()
+
+	assert.NotNil(t, err, "Should be errored");
+}
+
+func TestStoreWontPassIfNegativeOperand(t *testing.T) {
+	m := Constructor()
+	
+	m.Push(Inst{Operation: PUSH, Operand: 6})
+	m.Push(Inst{Operation: STORE, Operand: -1})
+	m.Push(Inst{Operation: HALT})
+	
+	err := m.Run()
+
+	assert.NotNil(t, err, "Should be errored");
+}
+
+func TestStoreShouldStoreOnTheFrame(t *testing.T) {
+	m := Constructor()
+	
+	m.Push(Inst{Operation: PUSH, Operand: 6})
+	m.Push(Inst{Operation: STORE, Operand: 0})
+	m.Push(Inst{Operation: HALT})
+	
+	err := m.Run()
+
+	assert.Nil(t, err, "Should not be errored");
+	assert.Equal(t, int32(0), m.sp, "Should decrement the stack pointer")
+	assert.Equal(t, int32(6), m.stackFrame[0].Locals[0], "Should contain the value")
+	assert.Equal(t, int32(2), m.ip, "Instruction pointer should be incremented");
+}
+
+func TestGetShouldGetVariableFromFrame(t *testing.T) {
+	m := Constructor()
+	
+	m.Push(Inst{Operation: PUSH, Operand: 6})
+	m.Push(Inst{Operation: STORE, Operand: 0})
+	m.Push(Inst{Operation: PUSH, Operand: 1})
+	m.Push(Inst{Operation: GET, Operand: 0})
+	m.Push(Inst{Operation: HALT})
+	
+	err := m.Run()
+
+	assert.Nil(t, err, "Should not be errored");
+	assert.Equal(t, int32(6), m.stack[1], "Should contain the value")
+	assert.Equal(t, int32(4), m.ip, "Instruction pointer should be incremented");
+}
+
+