From 683c9b112d754569d0c75ea48b588fa8b08f0ba9 Mon Sep 17 00:00:00 2001
From: Aotokitsuruya <contact@aotoki.me>
Date: Wed, 22 Nov 2023 21:03:02 +0800
Subject: [PATCH] Implement stack struct to keep callinfo

---
 context.go     |  7 ++++---
 mruby.go       |  5 +++--
 stack/stack.go | 35 +++++++++++++++++++++++++++++++++++
 vm.go          | 12 ++----------
 4 files changed, 44 insertions(+), 15 deletions(-)
 create mode 100644 stack/stack.go

diff --git a/context.go b/context.go
index 8b13207..c68dfa0 100644
--- a/context.go
+++ b/context.go
@@ -1,10 +1,11 @@
 package mruby
 
+import "github.com/elct9620/mruby-go/stack"
+
 type context struct {
-	ciCursor  int
-	callinfos []*callinfo
+	callinfo *stack.Stack[*callinfo]
 }
 
 func (ctx *context) GetCallinfo() *callinfo {
-	return ctx.callinfos[len(ctx.callinfos)-1]
+	return ctx.callinfo.Peek()
 }
diff --git a/mruby.go b/mruby.go
index a84dcce..428b7cc 100644
--- a/mruby.go
+++ b/mruby.go
@@ -1,5 +1,7 @@
 package mruby
 
+import "github.com/elct9620/mruby-go/stack"
+
 type (
 	Value  = any
 	Symbol = string
@@ -27,8 +29,7 @@ type State struct {
 func New() *State {
 	return &State{
 		context: &context{
-			ciCursor:  -1,
-			callinfos: []*callinfo{},
+			callinfo: stack.New[*callinfo](),
 		},
 		falseClass: &RClass{},
 	}
diff --git a/stack/stack.go b/stack/stack.go
new file mode 100644
index 0000000..15df023
--- /dev/null
+++ b/stack/stack.go
@@ -0,0 +1,35 @@
+package stack
+
+type Stack[T any] struct {
+	container []T
+}
+
+func New[T any]() *Stack[T] {
+	return &Stack[T]{container: []T{}}
+}
+
+func (s *Stack[T]) Push(v T) {
+	s.container = append(s.container, v)
+}
+
+func (s *Stack[T]) Pop() T {
+	v := s.container[len(s.container)-1]
+	s.container = s.container[:len(s.container)-1]
+	return v
+}
+
+func (s *Stack[T]) Peek() T {
+	return s.container[len(s.container)-1]
+}
+
+func (s *Stack[T]) Len() int {
+	return len(s.container)
+}
+
+func (s *Stack[T]) Get(idx int) T {
+	return s.container[idx]
+}
+
+func (s *Stack[T]) Set(idx int, v T) {
+	s.container[idx] = v
+}
diff --git a/vm.go b/vm.go
index fc9f55f..99cf32b 100644
--- a/vm.go
+++ b/vm.go
@@ -9,20 +9,12 @@ func (state *State) PushCallinfo(mid string, argc byte, targetClass *RClass) *ca
 		stack:       []Value{nil},
 		targetClass: targetClass,
 	}
-
-	ctx.ciCursor++
-
-	if ctx.ciCursor >= len(state.context.callinfos) {
-		ctx.callinfos = append(state.context.callinfos, callinfo)
-	} else {
-		ctx.callinfos[ctx.ciCursor] = callinfo
-	}
+	ctx.callinfo.Push(callinfo)
 
 	return callinfo
 }
 
 func (state *State) PopCallinfo() {
 	ctx := state.context
-	ctx.callinfos[ctx.ciCursor] = nil
-	ctx.ciCursor--
+	ctx.callinfo.Pop()
 }