From 759ee2aa10323d1960405c93f7cd4cf6d383ae7a Mon Sep 17 00:00:00 2001
From: Julien Dessaux
Date: Thu, 23 Sep 2021 11:45:49 +0200
Subject: Each pointer needs its own stack, merging the two packages to avoid a
 circular dependency

---
 pkg/pointer/stack-stack.go | 95 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 95 insertions(+)
 create mode 100644 pkg/pointer/stack-stack.go

(limited to 'pkg/pointer/stack-stack.go')

diff --git a/pkg/pointer/stack-stack.go b/pkg/pointer/stack-stack.go
new file mode 100644
index 0000000..6d22f51
--- /dev/null
+++ b/pkg/pointer/stack-stack.go
@@ -0,0 +1,95 @@
+package pointer
+
+type StackStack struct {
+	head   *Stack
+	height int
+}
+
+func NewStackStack() *StackStack {
+	return &StackStack{
+		head:   NewStack(),
+		height: 1,
+	}
+}
+
+func (ss *StackStack) Begin(p *Pointer) {
+	ss.height++
+	soss := ss.head
+	n := soss.Pop()
+	np := n
+	if np < 0 {
+		np = -np
+	}
+	toss := &Stack{
+		size:   np,
+		height: np,
+		data:   make([]int, np),
+		next:   soss,
+	}
+	ss.head = toss
+	max := n - soss.height
+	if max < 0 {
+		max = 0
+	}
+	for i := n - 1; i >= max; i-- {
+		toss.data[i] = soss.data[soss.height-n+i]
+	}
+	x, y := p.GetStorageOffset()
+	soss.Push(x)
+	soss.Push(y)
+	p.CalculateNewStorageOffset()
+}
+
+func (ss *StackStack) End(p *Pointer) (reflect bool) {
+	if ss.height == 1 {
+		return true
+	}
+	soss := ss.head.next
+	n := ss.head.Pop()
+	y := soss.Pop()
+	x := soss.Pop()
+	p.SetStorageOffset(x, y)
+	if n > 0 {
+		soss.height += n
+		if soss.size < soss.height {
+			soss.data = append(soss.data, make([]int, soss.height-soss.size)...)
+			soss.size = soss.height
+		}
+		for i := n; i > 0; i-- {
+			soss.data[soss.height-i] = ss.head.data[ss.head.height-i]
+		}
+	} else {
+		soss.height += n
+		if soss.height < 0 {
+			soss.height = 0
+		}
+	}
+	ss.height--
+	ss.head = ss.head.next
+	return false
+}
+
+func (ss *StackStack) Under() (reflect bool) {
+	if ss.height == 1 {
+		return true
+	}
+	n := ss.head.Pop()
+	if n > 0 {
+		for i := 0; i < n; i++ {
+			ss.head.Push(ss.head.next.Pop())
+		}
+	} else {
+		for i := 0; i < -n; i++ {
+			ss.head.next.Push(ss.head.Pop())
+		}
+	}
+	return false
+}
+
+func (ss StackStack) Pop() int {
+	return ss.head.Pop()
+}
+
+func (ss StackStack) Push(v int) {
+	ss.head.Push(v)
+}
-- 
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