From f2a418d79d97ac8618ad04e22e388c3a871c79e8 Mon Sep 17 00:00:00 2001
From: Glenn Maynard <gmaynard@users.sourceforge.net>
Date: Sun, 3 Jul 2005 03:05:54 +0000
Subject: [PATCH] implement HiddenPtr smart pointer type; use it for Steps. 
 This avoids having to write a whole copy constructor for a class just to hide
 a couple types from the header.

---
 stepmania/src/NoteData.cpp       |  2 +
 stepmania/src/RageUtil_AutoPtr.h | 97 ++++++++++++++++++++++++++++++++
 stepmania/src/Steps.cpp          |  2 +-
 stepmania/src/Steps.h            |  3 +-
 4 files changed, 102 insertions(+), 2 deletions(-)

diff --git a/stepmania/src/NoteData.cpp b/stepmania/src/NoteData.cpp
index 390df26af7..4a584f8a62 100644
--- a/stepmania/src/NoteData.cpp
+++ b/stepmania/src/NoteData.cpp
@@ -9,6 +9,8 @@
 #include "RageUtil.h"
 #include "RageLog.h"
 
+#include "RageUtil_AutoPtr.h"
+REGISTER_CLASS_TRAITS( NoteData, new NoteData(*pCopy) )
 
 NoteData::NoteData()
 {
diff --git a/stepmania/src/RageUtil_AutoPtr.h b/stepmania/src/RageUtil_AutoPtr.h
index c841dff828..3c821e1b18 100644
--- a/stepmania/src/RageUtil_AutoPtr.h
+++ b/stepmania/src/RageUtil_AutoPtr.h
@@ -96,6 +96,103 @@ inline void swap( AutoPtrCopyOnWrite<T> &a, AutoPtrCopyOnWrite<T> &b )
 	a.Swap(b);
 }
 
+/*
+ * This smart pointer template is used to safely hide implementations from
+ * headers, to reduce dependencies.  This is the same as declaring a pointer
+ * to a class, and allocating/deallocating it in the implementation: only
+ * the implementation needs to include that class.  This makes copying
+ * and deletion automatic, so you don't need to include a copy ctor or
+ * remember to delete it.
+ *
+ * There's one subtlety: in order to copy or delete an object, we need its
+ * definition.  This is intended to avoid pulling in the definition.  So,
+ * we use a traits class to hide it.  Use REGISTER_CLASS_TRAITS for each
+ * class used with this template.
+ *
+ * Concepts from http://www.gotw.ca/gotw/062.htm.
+ */
+template<class T>
+struct HiddenPtrTraits
+{
+	static T *Copy( const T *pCopy );
+	static void Delete( T *p );
+};
+#define REGISTER_CLASS_TRAITS(T, CopyExpr) \
+	template<> T *HiddenPtrTraits<T>::Copy( const T *pCopy ) { return CopyExpr; } \
+	template<> void HiddenPtrTraits<T>::Delete( T *p ) { delete p; }
+
+template<class T>
+class HiddenPtr
+{
+public:
+	const T& operator*() const { return *m_pPtr; }
+	const T* operator->() const { return m_pPtr; }
+	T& operator*() { return *m_pPtr; }
+	T* operator->() { return m_pPtr; }
+
+	explicit HiddenPtr( T *p = NULL )
+	{
+		m_pPtr = p;
+	}
+
+	HiddenPtr( const HiddenPtr<T> &cpy )
+	{
+		if( cpy.m_pPtr == NULL )
+			m_pPtr = NULL;
+		else
+			m_pPtr = HiddenPtrTraits<T>::Copy( cpy.m_pPtr );
+	}
+
+	template<class U>
+	HiddenPtr( const HiddenPtr<U> &cpy )
+	{
+		if( cpy.m_pPtr == NULL )
+			m_pPtr = NULL;
+		else
+			m_pPtr = HiddenPtrTraits<U>::Copy( cpy.m_pPtr );
+	}
+
+	~HiddenPtr()
+	{
+		HiddenPtrTraits<T>::Delete( m_pPtr );
+	}
+	void Swap( HiddenPtr<T> &rhs ) { swap( m_pPtr, rhs.m_pPtr ); }
+
+	HiddenPtr<T> &operator=( T *p )
+	{
+		HiddenPtr<T> t( p );
+		Swap( t );
+		return *this;
+	}
+
+	HiddenPtr<T> &operator=( const HiddenPtr &cpy )
+	{
+		HiddenPtr<T> t( cpy );
+		Swap( t );
+		return *this;
+	}
+
+	template<class U>
+	HiddenPtr<T> &operator=( const HiddenPtr<U> &cpy )
+	{
+		HiddenPtr<T> t( cpy );
+		Swap( t );
+		return *this;
+	}
+
+private:
+	T *m_pPtr;
+
+	template<class U>
+	friend class HiddenPtr;
+};
+
+template<class T>
+inline void swap( HiddenPtr<T> &a, HiddenPtr<T> &b )
+{
+	a.Swap(b);
+}
+
 #endif
 
 /*
diff --git a/stepmania/src/Steps.cpp b/stepmania/src/Steps.cpp
index 35406da56d..0b32522a88 100644
--- a/stepmania/src/Steps.cpp
+++ b/stepmania/src/Steps.cpp
@@ -16,6 +16,7 @@
 #include "global.h"
 #include "Steps.h"
 #include "StepsUtil.h"
+#include "song.h"
 #include "RageUtil.h"
 #include "RageLog.h"
 #include "NoteData.h"
@@ -41,7 +42,6 @@ Steps::Steps()
 
 Steps::~Steps()
 {
-	delete m_pNoteData;
 }
 
 void Steps::SetNoteData( const NoteData& noteDataNew )
diff --git a/stepmania/src/Steps.h b/stepmania/src/Steps.h
index f55fe5a311..3e9d0aa5d6 100644
--- a/stepmania/src/Steps.h
+++ b/stepmania/src/Steps.h
@@ -8,6 +8,7 @@
 #include "Grade.h"
 #include "RadarValues.h"
 #include "Difficulty.h"
+#include "RageUtil_AutoPtr.h"
 class Profile;
 class NoteData;
 struct lua_State;
@@ -76,7 +77,7 @@ protected:
 	/* We can have one or both of these; if we have both, they're always identical.
 	 * Call Compress() to force us to only have m_sNoteDataCompressed; otherwise, creation of 
 	 * these is transparent. */
-	mutable NoteData *m_pNoteData;
+	mutable HiddenPtr<NoteData> m_pNoteData;
 	mutable bool m_bNoteDataIsFilled;
 	mutable CString m_sNoteDataCompressed;