From 71607c5efb3b85fe89a0ed86c21d583c28f773a8 Mon Sep 17 00:00:00 2001
From: grisenti <emanuele@grisenti.net>
Date: Sat, 17 Dec 2022 16:05:33 +0100
Subject: [PATCH] HPL1: fix const correctness in dgTree

---
 .../engine/libraries/newton/core/dgTree.cpp   | 58 ++++++++++++++++---
 .../engine/libraries/newton/core/dgTree.h     | 12 ++--
 2 files changed, 58 insertions(+), 12 deletions(-)

diff --git a/engines/hpl1/engine/libraries/newton/core/dgTree.cpp b/engines/hpl1/engine/libraries/newton/core/dgTree.cpp
index 8a9bceb36d3..094114a4db6 100644
--- a/engines/hpl1/engine/libraries/newton/core/dgTree.cpp
+++ b/engines/hpl1/engine/libraries/newton/core/dgTree.cpp
@@ -22,26 +22,26 @@
 #include "dgStdafx.h"
 #include "dgTree.h"
 
-dgRedBackNode *dgRedBackNode::Minimum() const {
-	dgRedBackNode *ptr = (dgRedBackNode *) this;
+const dgRedBackNode *dgRedBackNode::Minimum() const {
+	const dgRedBackNode *ptr = this;
 	for (; ptr->m_left; ptr = ptr->m_left) {
 	}
 	return ptr;
 }
 
-dgRedBackNode *dgRedBackNode::Maximum() const {
-	dgRedBackNode *ptr = (dgRedBackNode *) this;
+const dgRedBackNode *dgRedBackNode::Maximum() const {
+	const dgRedBackNode *ptr = this;
 	for (; ptr->m_right; ptr = ptr->m_right) {
 	}
 	return ptr;
 }
 
-dgRedBackNode *dgRedBackNode::Prev() const {
+const dgRedBackNode *dgRedBackNode::Prev() const {
 	if (m_left) {
 		return m_left->Maximum();
 	}
 
-	dgRedBackNode *node = (dgRedBackNode *) this;
+	const dgRedBackNode *node = this;
 	dgRedBackNode *ptr = m_parent;
 	for (; ptr && node == ptr->m_left; ptr = ptr->m_parent) {
 		node = ptr;
@@ -50,13 +50,55 @@ dgRedBackNode *dgRedBackNode::Prev() const {
 
 }
 
-dgRedBackNode *dgRedBackNode::Next() const {
+const dgRedBackNode *dgRedBackNode::Next() const {
 
 	if (m_right) {
 		return m_right->Minimum();
 	}
 
-	dgRedBackNode *node = (dgRedBackNode *) this;
+	const dgRedBackNode *node = this;
+	dgRedBackNode *ptr = m_parent;
+	for (; ptr && node == ptr->m_right; ptr = ptr->m_parent) {
+		node = ptr;
+	}
+	return ptr;
+}
+
+dgRedBackNode *dgRedBackNode::Minimum() {
+	dgRedBackNode *ptr = this;
+	for (; ptr->m_left; ptr = ptr->m_left) {
+	}
+	return ptr;
+}
+
+dgRedBackNode *dgRedBackNode::Maximum() {
+	dgRedBackNode *ptr = this;
+	for (; ptr->m_right; ptr = ptr->m_right) {
+	}
+	return ptr;
+}
+
+dgRedBackNode *dgRedBackNode::Prev() {
+	if (m_left) {
+		return m_left->Maximum();
+	}
+
+	dgRedBackNode *node = this;
+	dgRedBackNode *ptr = m_parent;
+	for (; ptr && node == ptr->m_left; ptr = ptr->m_parent) {
+		node = ptr;
+	}
+	return ptr;
+
+}
+
+dgRedBackNode *dgRedBackNode::Next() {
+
+	if (m_right) {
+		return m_right->Minimum();
+	}
+
+	dgRedBackNode *node = this;
 	dgRedBackNode *ptr = m_parent;
 	for (; ptr && node == ptr->m_right; ptr = ptr->m_parent) {
 		node = ptr;
diff --git a/engines/hpl1/engine/libraries/newton/core/dgTree.h b/engines/hpl1/engine/libraries/newton/core/dgTree.h
index d500563cb28..3190ce27952 100644
--- a/engines/hpl1/engine/libraries/newton/core/dgTree.h
+++ b/engines/hpl1/engine/libraries/newton/core/dgTree.h
@@ -64,10 +64,14 @@ public:
 	inline void SetInTreeFlag(dgUnsigned32 flag);
 
 	void RemoveAll();
-	dgRedBackNode *Prev() const;
-	dgRedBackNode *Next() const;
-	dgRedBackNode *Minimum() const;
-	dgRedBackNode *Maximum() const;
+	const dgRedBackNode *Prev() const;
+	const dgRedBackNode *Next() const;
+	const dgRedBackNode *Minimum() const;
+	const dgRedBackNode *Maximum() const;
+	dgRedBackNode *Prev();
+	dgRedBackNode *Next();
+	dgRedBackNode *Minimum();
+	dgRedBackNode *Maximum();
 	void Remove(dgRedBackNode **const head);
 	void Unlink(dgRedBackNode **const head);
 	void InsertFixup(dgRedBackNode **const head);