doubly linked list base class and template for contained specific instantations

common/dlist.cpp

+/*
+ * This program source code file is part of KICAD, a free EDA CAD application.
+ *
+ * Copyright (C) 2008 SoftPLC Corporation, Dick Hollenbeck <dick@softplc.com>
+ * Copyright (C) 1992-2008 Kicad Developers, see change_log.txt for contributors.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, you may find one here:
+ * http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
+ * or you may search the http://www.gnu.org website for the version 2 license,
+ * or you may write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA
+ */
+
+
+#include "fctsys.h"
+#include "dlist.h"
+#include "base_struct.h"
+
+
+/* Implement the class DHEAD from dlist.h */
+
+
+DHEAD::~DHEAD()
+{
+    if( meOwner )
+        DestructAll();
+}
+
+
+void DHEAD::DestructAll()
+{
+    EDA_BaseStruct* next;
+    EDA_BaseStruct* item = first;
+
+    while( item )
+    {
+        next = item->Next();
+        delete item;            // virtual destructor, class specific
+        item = next;
+    }
+
+    first = 0;
+    last  = 0;
+    count = 0;
+}
+
+
+void DHEAD::Append( EDA_BaseStruct* aNewElement )
+{
+    wxASSERT( aNewElement != NULL );
+
+    if( first )        // list is not empty, first is not touched
+    {
+        wxASSERT( last != NULL );
+
+        aNewElement->SetNext( 0 );
+        aNewElement->SetBack( last );
+
+        last->SetNext( aNewElement );
+        last = aNewElement;
+    }
+    else        // list is empty, first and last are changed
+    {
+        aNewElement->SetNext( 0 );
+        aNewElement->SetBack( 0 );
+
+        first = aNewElement;
+        last  = aNewElement;
+    }
+
+    aNewElement->SetList( this );
+
+    ++count;
+}
+
+
+void DHEAD::Insert( EDA_BaseStruct* aNewElement, EDA_BaseStruct* aAfterMe )
+{
+    wxASSERT( aNewElement != NULL );
+
+    if( !aAfterMe )
+        Append( aNewElement );
+    else
+    {
+        wxASSERT( aAfterMe->GetList() == this );
+
+        // the list cannot be empty if aAfterMe is supposedly on the list
+        wxASSERT( first && last );
+
+        if( first == aAfterMe )
+        {
+            aAfterMe->SetBack( aNewElement );
+
+            aNewElement->SetBack( 0 );  // first in list does not point back
+            aNewElement->SetNext( aAfterMe );
+
+            first = aNewElement;
+        }
+        else
+        {
+            EDA_BaseStruct* oldBack = aAfterMe->Back();
+
+            aAfterMe->SetBack( aNewElement );
+
+            aNewElement->SetBack( oldBack );
+            aNewElement->SetNext( aAfterMe );
+
+            oldBack->SetNext( aNewElement );
+        }
+
+        aNewElement->SetList( this );
+
+        ++count;
+    }
+}
+
+
+void DHEAD::Remove( EDA_BaseStruct* aElement )
+{
+    wxASSERT( aElement )
+    wxASSERT( aElement->GetList() == this );
+
+    if( aElement->Next() )
+    {
+        aElement->Next()->SetBack( aElement->Back() );
+    }
+    else
+    {
+        wxASSERT( last == aElement );
+        last = aElement->Back();
+    }
+
+    if( aElement->Back() )
+    {
+        aElement->Back()->SetNext( aElement->Back() );
+    }
+    else
+    {
+        wxASSERT( first == aElement );
+        first = aElement->Next();
+    }
+
+    aElement->SetBack( 0 );
+    aElement->SetNext( 0 );
+    aElement->SetList( 0 );
+
+    --count;
+}
+

include/dlist.h

+/*
+ * This program source code file is part of KICAD, a free EDA CAD application.
+ *
+ * Copyright (C) 2008 SoftPLC Corporation, Dick Hollenbeck <dick@softplc.com>
+ * Copyright (C) 1992-2008 Kicad Developers, see change_log.txt for contributors.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, you may find one here:
+ * http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
+ * or you may search the http://www.gnu.org website for the version 2 license,
+ * or you may write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA
+ */
+
+
+#ifndef DLIST_H_
+#define DLIST_H_
+
+
+class EDA_BaseStruct;
+
+
+/**
+ * Class DHEAD
+ * is only for use by template class DLIST, use that instead.
+ */
+class DHEAD
+{
+protected:
+    EDA_BaseStruct*     first;          ///< first element in list, or NULL if list empty
+    EDA_BaseStruct*     last;           ///< last elment in list, or NULL if empty
+    unsigned            count;          ///< how many elements are in the list
+    bool                meOwner;        ///< I must delete the objects in my destructor
+
+    /**
+     * Constructor DHEAD
+     * is protected so that a DHEAD can only be instantiated from within a
+     * DLIST template.
+     */
+    DHEAD() :
+        first(0),
+        last(0),
+        count(0),
+        meOwner(true)
+    {
+    }
+
+    ~DHEAD();
+
+public:
+
+    /**
+     * Function DestructAll
+     * deletes all items on the list and leaves the list empty.
+     */
+    void DestructAll();
+
+    /**
+     * Function SetOwnership
+     * controls whether the list owns the objects and is responsible for
+     * deleteing their memory at time of this object's destruction.
+     */
+    void SetOwnership( bool Iown ) { meOwner = Iown; }
+
+    /**
+     * Function Append
+     * adds \a aNewElement to the end of the list.
+     */
+    void Append( EDA_BaseStruct* aNewElement );
+
+    /**
+     * Function Insert
+     * puts aNewElement just in front of aElementAfterMe in the list sequence.
+     * If aElementAfterMe is NULL, then simply Append()
+     */
+    void Insert( EDA_BaseStruct* aNewElement, EDA_BaseStruct* aElementAfterMe );
+
+    /**
+     * Function Insert
+     * puts aNewElement in front of list sequence.
+     */
+    void Insert( EDA_BaseStruct* aNewElement )
+    {
+        Insert( aNewElement, first );
+    }
+
+    /**
+     * Function Remove
+     * removes \a aElement from the list, but does not delete it.
+     */
+    void Remove( EDA_BaseStruct* aElement );
+
+    /**
+     * Function GetCount
+     * returns the number of elements in the list.
+     */
+    unsigned GetCount() { return count; }
+};
+
+
+/**
+ * Class DLIST
+ * is the head of a doubly linked list.  It contains pointers to the first
+ * and last elements in a doubly linked list.  The elements in the list must
+ * be of class T or derived from T, and T must be derived from EDA_BaseStruct.
+ */
+template <class T>
+class DLIST : public DHEAD
+{
+public:
+
+    /**
+     * operator T*
+     * is a casting operator that returns \a first casted to a T*
+     */
+    operator T* () const { return GetFirst(); }
+
+    /**
+     * Function GetFirst
+     * returns the first T* in the list, or NULL if the list is empty.
+     */
+    T*  GetFirst() const { return (T*) first; }
+
+    /**
+     * Function GetLast
+     * returns the last T* in the list, or NULL if the list is empty.
+     */
+    T*  GetLast() const { return (T*) last; }
+};
+
+#endif      // DLIST_H_