Refactor unsafe pointer usage to use reflect.Type and pointers

Remove internal/danger package and replace unsafe pointer arithmetic with direct pointer manipulation. Update AST node references to use pointers instead of integer offsets. This improves code safety and maintainability.

Co-authored-by: thomas.pelletier <thomas.pelletier@bedrockrobotics.com>

unstable/builder.go

@@ -29,8 +29,10 @@ func (r reference) Valid() bool {
 }
 
 type builder struct {
-	tree    root
-	lastIdx int
+	tree         root
+	lastIdx      int
+	nextOffsets  []int
+	childOffsets []int
 }
 
 func (b *builder) Tree() *root {
@@ -43,29 +45,47 @@ func (b *builder) NodeAt(ref reference) *Node {
 
 func (b *builder) Reset() {
 	b.tree.nodes = b.tree.nodes[:0]
+	b.nextOffsets = b.nextOffsets[:0]
+	b.childOffsets = b.childOffsets[:0]
 	b.lastIdx = 0
 }
 
 func (b *builder) Push(n Node) reference {
 	b.lastIdx = len(b.tree.nodes)
 	b.tree.nodes = append(b.tree.nodes, n)
+	b.nextOffsets = append(b.nextOffsets, 0)
+	b.childOffsets = append(b.childOffsets, 0)
 	return reference(b.lastIdx)
 }
 
 func (b *builder) PushAndChain(n Node) reference {
 	newIdx := len(b.tree.nodes)
 	b.tree.nodes = append(b.tree.nodes, n)
+	b.nextOffsets = append(b.nextOffsets, 0)
+	b.childOffsets = append(b.childOffsets, 0)
+
 	if b.lastIdx >= 0 {
-		b.tree.nodes[b.lastIdx].next = newIdx - b.lastIdx
+		b.nextOffsets[b.lastIdx] = newIdx - b.lastIdx
 	}
 	b.lastIdx = newIdx
 	return reference(b.lastIdx)
 }
 
 func (b *builder) AttachChild(parent reference, child reference) {
-	b.tree.nodes[parent].child = int(child) - int(parent)
+	b.childOffsets[parent] = int(child) - int(parent)
 }
 
 func (b *builder) Chain(from reference, to reference) {
-	b.tree.nodes[from].next = int(to) - int(from)
+	b.nextOffsets[from] = int(to) - int(from)
+}
+
+func (b *builder) Link() {
+	for i := range b.tree.nodes {
+		if next := b.nextOffsets[i]; next != 0 {
+			b.tree.nodes[i].next = &b.tree.nodes[i+next]
+		}
+		if child := b.childOffsets[i]; child != 0 {
+			b.tree.nodes[i].child = &b.tree.nodes[i+child]
+		}
+	}
 }