gint: add an interactive REPL

2 files changed, 10 insertions, 4 deletions

diff --git a/vm1/vm.go b/vm1/vm.go
index f7113f2..c2f4882 100644
--- a/vm1/vm.go
+++ b/vm1/vm.go
@@ -6,7 +6,7 @@ import (
 	"strconv" // for tracing only
 )
 
-const debug = false
+const debug = true
 
 // Byte-code instruction set.
 const (
@@ -155,7 +155,7 @@ func (m *Machine) Run() (err error) {
 	}
 }
 
-func (m *Machine) PushCode(code [][]int64) (p int) {
+func (m *Machine) PushCode(code ...[]int64) (p int) {
 	p = len(m.code)
 	m.code = append(m.code, code...)
 	return p
@@ -165,6 +165,12 @@ func (m *Machine) SetIP(ip int)          { m.ip = ip }
 func (m *Machine) Push(v ...any) (l int) { l = len(m.mem); m.mem = append(m.mem, v...); return }
 func (m *Machine) Pop() (v any)          { l := len(m.mem) - 1; v = m.mem[l]; m.mem = m.mem[:l]; return }
 
+func (m *Machine) PopExit() {
+	if l := len(m.code); l > 0 && m.code[l-1][1] == Exit {
+		m.code = m.code[:l-1]
+	}
+}
+
 // Disassemble returns the code as a readable string.
 func Disassemble(code [][]int64) (asm string) {
 	for _, op := range code {
diff --git a/vm1/vm_test.go b/vm1/vm_test.go
index 257ac44..272a321 100644
--- a/vm1/vm_test.go
+++ b/vm1/vm_test.go
@@ -13,7 +13,7 @@ func TestVM(t *testing.T) {
 			for _, v := range test.sym {
 				m.Push(v)
 			}
-			m.PushCode(test.code)
+			m.PushCode(test.code...)
 			if err := m.Run(); err != nil {
 				t.Errorf("run error: %v", err)
 			}
@@ -33,7 +33,7 @@ func BenchmarkVM(b *testing.B) {
 			for i := 0; i < b.N; i++ {
 				b.StopTimer()
 				m := &Machine{}
-				m.PushCode(test.code)
+				m.PushCode(test.code...)
 				b.StartTimer()
 
 				if err := m.Run(); err != nil {