From 11dac6494d90c73545f0a9e03732c6ef7bad88b7 Mon Sep 17 00:00:00 2001
From: Julien Dessaux
Date: Tue, 21 Sep 2021 00:28:31 +0200
Subject: Began implementing the stack and the stack stack

---
 pkg/stack/stack-stack.go | 44 +++++++++++++++++++++++++
 pkg/stack/stack.go       | 51 +++++++++++++++++++++++++++++
 pkg/stack/stack_test.go  | 83 ++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 178 insertions(+)
 create mode 100644 pkg/stack/stack-stack.go
 create mode 100644 pkg/stack/stack.go
 create mode 100644 pkg/stack/stack_test.go

diff --git a/pkg/stack/stack-stack.go b/pkg/stack/stack-stack.go
new file mode 100644
index 0000000..db5a405
--- /dev/null
+++ b/pkg/stack/stack-stack.go
@@ -0,0 +1,44 @@
+package stack
+
+import (
+	"git.adyxax.org/adyxax/gofunge/pkg/pointer"
+)
+
+type StackStack struct {
+	head   *Stack
+	height int
+}
+
+func NewStackStack() *StackStack {
+	return &StackStack{
+		head:   NewStack(),
+		height: 1,
+	}
+}
+
+func (ss *StackStack) Begin(p *pointer.Pointer) {
+	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()
+}
diff --git a/pkg/stack/stack.go b/pkg/stack/stack.go
new file mode 100644
index 0000000..4dbb72c
--- /dev/null
+++ b/pkg/stack/stack.go
@@ -0,0 +1,51 @@
+package stack
+
+type Stack struct {
+	size   int
+	height int
+	data   []int
+	next   *Stack // Pointer to the next element in the stack stack
+}
+
+func NewStack() *Stack {
+	return &Stack{
+		size:   32,
+		height: 0,
+		data:   make([]int, 32),
+		next:   nil,
+	}
+}
+
+func (s *Stack) Clear() {
+	s.height = 0
+}
+
+func (s *Stack) Duplicate() {
+	if s.height > 0 {
+		s.Push(s.data[s.height-1])
+	}
+}
+
+func (s *Stack) Pop() int {
+	if s.height > 0 {
+		s.height--
+		return s.data[s.height]
+	}
+	return 0
+}
+
+func (s *Stack) Push(value int) {
+	if s.height >= s.size {
+		s.size += 32
+		s.data = append(s.data, make([]int, 32)...)
+	}
+	s.data[s.height] = value
+	s.height++
+}
+
+func (s *Stack) Swap() {
+	a := s.Pop()
+	b := s.Pop()
+	s.Push(a)
+	s.Push(b)
+}
diff --git a/pkg/stack/stack_test.go b/pkg/stack/stack_test.go
new file mode 100644
index 0000000..d9e0cca
--- /dev/null
+++ b/pkg/stack/stack_test.go
@@ -0,0 +1,83 @@
+package stack
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestNewStack(t *testing.T) {
+	require.Equal(t, NewStack(), &Stack{
+		size:   32,
+		height: 0,
+		data:   make([]int, 32),
+		next:   nil,
+	})
+}
+
+func TestClear(t *testing.T) {
+	s := NewStack()
+	s.Clear()
+	require.Equal(t, s.height, 0)
+}
+
+func TestDupicate(t *testing.T) {
+	s := NewStack()
+	s2 := NewStack()
+	s.Duplicate()
+	require.Equal(t, s.height, s2.height)
+	s.Push(12)
+	s.Duplicate()
+	s2.Push(12)
+	s2.Push(12)
+	require.Equal(t, s.height, s2.height)
+	require.Equal(t, s.data, s2.data)
+}
+
+func TestPop(t *testing.T) {
+	s := NewStack()
+	v := s.Pop()
+	require.Equal(t, v, 0)
+	s.Push(12)
+	s.Push(14)
+	v = s.Pop()
+	require.Equal(t, v, 14)
+	v = s.Pop()
+	require.Equal(t, v, 12)
+	v = s.Pop()
+	require.Equal(t, v, 0)
+}
+
+func TestPush(t *testing.T) {
+	s := NewStack()
+	for i := 0; i < 32; i++ {
+		s.Push(i)
+	}
+	require.Equal(t, s.size, 32)
+	s.Push(-1)
+	require.Equal(t, s.size, 64)
+}
+
+func TestSwap(t *testing.T) {
+	s := NewStack()
+	s2 := NewStack()
+	s.Swap()
+	s2.Push(0)
+	s2.Push(0)
+	require.Equal(t, s, s2)
+	s.Clear()
+	s.Push(1)
+	s.Swap()
+	s2.Clear()
+	s2.Push(1)
+	s2.Push(0)
+	require.Equal(t, s, s2)
+	s.Clear()
+	s.Push(1)
+	s.Push(2)
+	s2.Clear()
+	s2.Push(2)
+	s2.Push(1)
+	s.Swap()
+	require.Equal(t, s, s2)
+}
-- 
cgit v1.2.3