Each pointer needs its own stack, merging the two packages to avoid a circular dependency

pkg/interpreter/interpreter.go

@@ -25,7 +25,8 @@ func (i *Interpreter) Run() {
 func (i *Interpreter) Step() {
 	var prev *pointer.Pointer = nil
 	for p := i.p; p != nil; p = p.Next {
-		switch p.Get(*i.f) {
+		c := p.Get(*i.f)
+		switch c {
 		case '@':
 			if prev == nil {
 				i.p = p.Next
@@ -33,8 +34,13 @@ func (i *Interpreter) Step() {
 				prev.Next = p.Next
 			}
 			break
+		case '#':
+			p.Step(*i.f)
 		default:
-			log.Fatalf("Non implemented instruction code %d : %c", p.Get(*i.f), p.Get(*i.f))
+			if !p.Redirect(c) {
+				log.Fatalf("Non implemented instruction code %d : %c", c, c)
+			}
 		}
+		p.Step(*i.f)
 	}
 }

pkg/interpreter/interpreter_test.go

@@ -0,0 +1,50 @@
+package interpreter
+
+import (
+	"os"
+	"testing"
+
+	"git.adyxax.org/adyxax/gofunge/pkg/field"
+	"git.adyxax.org/adyxax/gofunge/pkg/pointer"
+	"github.com/stretchr/testify/require"
+)
+
+func TestRun(t *testing.T) {
+	file, err := os.Open("../field/test_data/minimal.b98")
+	require.NoError(t, err)
+	defer file.Close()
+	f, err := field.Load(file)
+	require.NoError(t, err)
+	NewInterpreter(f, pointer.NewPointer()).Run()
+}
+
+func TestStep(t *testing.T) {
+	testCases := []struct {
+		name            string
+		filename        string
+		pointer         *pointer.Pointer
+		expectedField   *field.Field
+		expectedPointer *pointer.Pointer
+	}{
+		{"minimal", "../field/test_data/minimal.b98", nil, nil, nil},
+	}
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			file, err := os.Open(tc.filename)
+			require.NoError(t, err)
+			defer file.Close()
+			f, err := field.Load(file)
+			require.NoError(t, err)
+			if tc.pointer == nil {
+				tc.pointer = pointer.NewPointer()
+			}
+			NewInterpreter(f, tc.pointer).Step()
+			if tc.expectedField != nil {
+				require.Equal(t, tc.expectedField, f)
+			}
+			if tc.expectedPointer != nil {
+				require.Equal(t, tc.expectedPointer, tc.pointer)
+			}
+		})
+	}
+}

pkg/pointer/pointer.go

@@ -1,6 +1,10 @@
 package pointer
 
-import "git.adyxax.org/adyxax/gofunge/pkg/field"
+import (
+	"math/rand"
+
+	"git.adyxax.org/adyxax/gofunge/pkg/field"
+)
 
 type Pointer struct {
 	// the position
@@ -12,12 +16,14 @@ type Pointer struct {
 	// The Storage offset
 	sox int
 	soy int
+	// The stack
+	ss *StackStack
 	// The next element for the multi-"threaded" b98 interpreter
 	Next *Pointer
 }
 
 func NewPointer() *Pointer {
-	return &Pointer{dx: 1}
+	return &Pointer{dx: 1, ss: NewStackStack()}
 }
 
 func (p Pointer) Split() *Pointer {
@@ -31,3 +37,45 @@ func (p *Pointer) Step(f field.Field) {
 func (p Pointer) Get(f field.Field) int {
 	return f.Get(p.x, p.y)
 }
+
+func (p *Pointer) Set(x, y int) {
+	p.x, p.y = x, y
+}
+
+func (p *Pointer) RedirectTo(dx, dy int) {
+	p.dx, p.dy = dx, dy
+}
+
+func (p *Pointer) Reverse() {
+	p.dx, p.dy = -p.dx, -p.dy
+}
+
+func (p *Pointer) Redirect(c int) bool {
+	switch c {
+	case '^':
+		p.dx, p.dy = 0, -1
+	case '>':
+		p.dx, p.dy = 1, 0
+	case 'v':
+		p.dx, p.dy = 0, 1
+	case '<':
+		p.dx, p.dy = -1, 0
+	case '?':
+		directions := []int{0, -1, 1, 0, 0, 1, -1, 0}
+		r := 2 * rand.Intn(4)
+		p.dx, p.dy = directions[r], directions[r+1]
+	case '[':
+		p.dx, p.dy = p.dy, -p.dx
+	case ']':
+		p.dx, p.dy = -p.dy, p.dx
+	case 'r':
+		p.Reverse()
+	case 'x':
+		dy := p.ss.Pop()
+		dx := p.ss.Pop()
+		p.RedirectTo(dx, dy)
+	default:
+		return false
+	}
+	return true
+}

pkg/pointer/pointer_test.go

@@ -9,7 +9,7 @@ import (
 )
 
 func TestNewPointer(t *testing.T) {
-	require.Equal(t, NewPointer(), &Pointer{dx: 1})
+	require.Equal(t, NewPointer(), &Pointer{dx: 1, ss: NewStackStack()})
 }
 
 func TestSplit(t *testing.T) {
@@ -23,8 +23,8 @@ func TestSplit(t *testing.T) {
 	// We check that p2 is a real copy
 	p.Step(*f)
 	p2.Step(*f)
-	require.Equal(t, &Pointer{x: 1, y: 0, dx: 1}, p)
+	require.Equal(t, &Pointer{x: 1, y: 0, dx: 1, ss: NewStackStack()}, p)
-	require.Equal(t, &Pointer{x: 1, y: 0, dx: 1}, p2)
+	require.Equal(t, &Pointer{x: 1, y: 0, dx: 1, ss: NewStackStack()}, p2)
 }
 
 func TestStep(t *testing.T) { // Step is thoroughly tested in the field package
@@ -50,3 +50,61 @@ func TestGet(t *testing.T) {
 	v := p.Get(*f)
 	require.Equal(t, int('@'), v)
 }
+
+func TestSet(t *testing.T) {
+	p := NewPointer()
+	p.Set(3, 14)
+	require.Equal(t, 3, p.x)
+	require.Equal(t, 14, p.y)
+}
+
+func TestRedirectTo(t *testing.T) {
+	p := NewPointer()
+	p.RedirectTo(3, 14)
+	require.Equal(t, 3, p.dx)
+	require.Equal(t, 14, p.dy)
+}
+
+func TestReverse(t *testing.T) {
+	p := NewPointer()
+	p.RedirectTo(3, 14)
+	p.Reverse()
+	require.Equal(t, -3, p.dx)
+	require.Equal(t, -14, p.dy)
+}
+
+func TestRedirect(t *testing.T) {
+	testCases := []struct {
+		name       string
+		input      byte
+		expectedDx int
+		expectedDy int
+	}{
+		{"up", '^', 0, -1},
+		{"right", '>', 1, 0},
+		{"down", 'v', 0, 1},
+		{"left", '<', -1, 0},
+		{"turn left", '[', 14, -3},
+		{"turn right", ']', -14, 3},
+		{"reverse", 'r', -3, -14},
+		{"redirectTo", 'x', 2, 7},
+	}
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			p := NewPointer()
+			p.RedirectTo(3, 14)
+			p.ss.Push(2)
+			p.ss.Push(7)
+			v := p.Redirect(int(tc.input))
+			require.Equal(t, true, v)
+			require.Equal(t, tc.expectedDx, p.dx, "Invalid dx value")
+			require.Equal(t, tc.expectedDy, p.dy, "Invalid dy value")
+		})
+	}
+	// We cannot really test random, can we? This just gives coverage
+	p := NewPointer()
+	v := p.Redirect(int('?'))
+	require.Equal(t, true, v)
+	// A character that does not redirect should return false
+	require.Equal(t, false, p.Redirect(int('@')))
+}

pkg/pointer/stack-stack.go

@@ -1,8 +1,4 @@
-package stack
+package pointer
-
-import (
-	"git.adyxax.org/adyxax/gofunge/pkg/pointer"
-)
 
 type StackStack struct {
 	head   *Stack
@@ -16,7 +12,7 @@ func NewStackStack() *StackStack {
 	}
 }
 
-func (ss *StackStack) Begin(p *pointer.Pointer) {
+func (ss *StackStack) Begin(p *Pointer) {
 	ss.height++
 	soss := ss.head
 	n := soss.Pop()
@@ -44,7 +40,7 @@ func (ss *StackStack) Begin(p *pointer.Pointer) {
 	p.CalculateNewStorageOffset()
 }
 
-func (ss *StackStack) End(p *pointer.Pointer) (reflect bool) {
+func (ss *StackStack) End(p *Pointer) (reflect bool) {
 	if ss.height == 1 {
 		return true
 	}
@@ -89,3 +85,11 @@ func (ss *StackStack) Under() (reflect bool) {
 	}
 	return false
 }
+
+func (ss StackStack) Pop() int {
+	return ss.head.Pop()
+}
+
+func (ss StackStack) Push(v int) {
+	ss.head.Push(v)
+}

pkg/pointer/stack-stack_test.go

@@ -1,11 +1,10 @@
-package stack
+package pointer
 
 import (
 	"os"
 	"testing"
 
 	"git.adyxax.org/adyxax/gofunge/pkg/field"
-	"git.adyxax.org/adyxax/gofunge/pkg/pointer"
 	"github.com/stretchr/testify/require"
 )
 
@@ -17,7 +16,7 @@ func TestBegin(t *testing.T) {
 		expected.head.next.Push(0)
 		expected.height++
 		ss := NewStackStack()
-		p := pointer.NewPointer()
+		p := NewPointer()
 		ss.Begin(p)
 		require.Equal(t, expected, ss)
 		x, y := p.GetStorageOffset()
@@ -40,7 +39,7 @@ func TestBegin(t *testing.T) {
 		expected.head.next.Push(0)
 		expected.head.next.Push(0)
 		expected.height++
-		p := pointer.NewPointer()
+		p := NewPointer()
 		file, err := os.Open("../field/test_data/hello.b98")
 		require.NoError(t, err, "Failed to open file")
 		f, err := field.Load(file)
@@ -61,7 +60,7 @@ func TestBegin(t *testing.T) {
 		expected.head.next.Push(2)
 		expected.head.next.Push(3)
 		expected.height++
-		p := pointer.NewPointer()
+		p := NewPointer()
 		p.SetStorageOffset(2, 3)
 		file, err := os.Open("../field/test_data/hello.b98")
 		require.NoError(t, err, "Failed to open file")
@@ -87,7 +86,7 @@ func TestBegin(t *testing.T) {
 		expected.head.next.Push(36)
 		expected.head.next.Push(42)
 		expected.height++
-		p := pointer.NewPointer()
+		p := NewPointer()
 		p.SetStorageOffset(36, 42)
 		ss := NewStackStack()
 		ss.head.Push(7)
@@ -104,7 +103,7 @@ func TestBegin(t *testing.T) {
 func TestEnd(t *testing.T) {
 	t.Run("empty", func(t *testing.T) {
 		expected := NewStackStack()
-		p := pointer.NewPointer()
+		p := NewPointer()
 		ss := NewStackStack()
 		ss.Begin(p)
 		reflect := ss.End(p)
@@ -121,7 +120,7 @@ func TestEnd(t *testing.T) {
 		expected.head.Pop()
 		expected.head.Pop()
 		expected.head.Pop()
-		p := pointer.NewPointer()
+		p := NewPointer()
 		ss := NewStackStack()
 		ss.head.Push(7)
 		ss.head.Push(12)
@@ -139,7 +138,7 @@ func TestEnd(t *testing.T) {
 	})
 	t.Run("drop too much", func(t *testing.T) {
 		expected := NewStackStack()
-		p := pointer.NewPointer()
+		p := NewPointer()
 		ss := NewStackStack()
 		ss.Begin(p)
 		ss.head.Push(-3)
@@ -149,7 +148,7 @@ func TestEnd(t *testing.T) {
 	})
 	t.Run("reflect", func(t *testing.T) {
 		expected := NewStackStack()
-		p := pointer.NewPointer()
+		p := NewPointer()
 		ss := NewStackStack()
 		reflect := ss.End(p)
 		require.Equal(t, true, reflect)
@@ -164,7 +163,7 @@ func TestEnd(t *testing.T) {
 		expected.head.Push(14)
 		expected.head.Push(-2)
 		expected.head.Push(5)
-		p := pointer.NewPointer()
+		p := NewPointer()
 		ss := NewStackStack()
 		ss.head.size = 4
 		ss.head.data = make([]int, 4)
@@ -195,7 +194,7 @@ func TestUnder(t *testing.T) {
 		require.Equal(t, expected, ss)
 	})
 	t.Run("positive", func(t *testing.T) {
-		pe := pointer.NewPointer()
+		pe := NewPointer()
 		expected := NewStackStack()
 		expected.head.Push(1)
 		expected.head.Push(2)
@@ -209,7 +208,7 @@ func TestUnder(t *testing.T) {
 		expected.head.next.Pop()
 		expected.head.next.Pop()
 		expected.head.next.Pop()
-		p := pointer.NewPointer()
+		p := NewPointer()
 		ss := NewStackStack()
 		ss.head.Push(1)
 		ss.head.Push(2)
@@ -223,7 +222,7 @@ func TestUnder(t *testing.T) {
 		require.Equal(t, expected, ss)
 	})
 	t.Run("negative", func(t *testing.T) {
-		pe := pointer.NewPointer()
+		pe := NewPointer()
 		expected := NewStackStack()
 		expected.Begin(pe)
 		expected.head.next.Push(12)
@@ -237,7 +236,7 @@ func TestUnder(t *testing.T) {
 		expected.head.Pop()
 		expected.head.Pop()
 		expected.head.Pop()
-		p := pointer.NewPointer()
+		p := NewPointer()
 		ss := NewStackStack()
 		ss.Begin(p)
 		ss.head.Push(8)
@@ -249,3 +248,13 @@ func TestUnder(t *testing.T) {
 		require.Equal(t, expected, ss)
 	})
 }
+
+func TestPushPop(t *testing.T) {
+	ss := NewStackStack()
+	ss.Push(12)
+	ss.Push(5)
+	v := ss.Pop()
+	require.Equal(t, 5, v)
+	v = ss.Pop()
+	require.Equal(t, 12, v)
+}

pkg/pointer/stack.go

@@ -1,4 +1,4 @@
-package stack
+package pointer
 
 type Stack struct {
 	size   int

pkg/pointer/stack_test.go

@@ -1,4 +1,4 @@
-package stack
+package pointer
 
 import (
 	"testing"