1 files changed, 153 insertions, 0 deletions
diff --git a/libs/ardour/ardour/history.h b/libs/ardour/ardour/history.h
new file mode 100644
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+++ b/libs/ardour/ardour/history.h
@@ -0,0 +1,153 @@
+/*
+    Copyright (C) 2001 Paul Davis 
+
+    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, write to the Free Software
+    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+
+    $Id$
+*/
+
+#ifndef __ardour_history_h__
+#define __ardour_history_h__
+
+#include <list>
+#include <sigc++/signal.h>
+
+template<class T>
+//struct History : public SigC::Object 
+struct History : public sigc::trackable
+{
+    typedef list<T *> StateList;
+    
+    StateList states;
+    StateList::iterator current;
+
+    History() { current = states.end(); }
+    ~History() { states.erase (states.begin(), states.end()); }
+
+    sigc::signal<void> CurrentChanged;
+
+    void clear () {
+	    for (StateList::iterator i = states.begin(); i != states.end(); i++) {
+		    delete *i;
+	    }
+	    states.clear ();
+	    current = states.end();
+	    CurrentChanged();
+    }
+
+    void push (T *state) {
+	    /* remove any "undone" history above the current location
+	       in the history, before pushing new state. 
+	    */
+	    if (current != states.begin() && current != states.end()) {
+		    states.erase (states.begin(), current);
+	    }
+	    current = states.insert (states.begin(), state);
+	    CurrentChanged ();
+    }
+
+    T *top() { 
+	    if (current != states.end()) {
+		    return *current;
+	    } else {
+		    return 0;
+	    }
+    }
+
+    T *pop (bool remove) {
+	if (current == states.end()) {
+		return 0;
+	}
+	
+	if (current == states.begin()) {
+		return *current;
+	}
+	
+	current--;
+	T *state = *current;
+
+	if (remove) {
+		states.erase (current);
+	}
+
+	CurrentChanged ();
+	return state;
+    }	
+
+    T *earlier (uint32_t n) {
+	    StateList::iterator i;
+	    
+	    if (current == states.end()) {
+		    return 0;
+	    }
+	    
+	    if (n == 0) {
+		    return *current;
+	    }
+	    
+	    /* the list is in LIFO order, so move toward the end to go "earlier" */
+	    
+	    for (i = current; n && i != states.end(); i++, n--);
+	    
+	    if (i == states.end()) {
+		    return 0;
+	    } else {
+		    current = i;
+		    CurrentChanged ();
+		    return *i;
+	    }
+    }
+
+    T *later (uint32_t n) {
+	    StateList::iterator i;
+	    
+	    if (current == states.end()) {
+		    return 0;
+	    }
+	    
+	    if (n == 0) {
+		    return *current;
+	    }
+	    
+	    /* the list is in LIFO order, so move toward the beginning to go "later" */
+	    
+	    for (i = current; n && i != states.begin(); i--, n--);
+	    if (i != current) {
+		    current = i;
+		    CurrentChanged();
+	    }
+	    return *i;
+    }
+
+    T *nth (uint32_t n) {
+	    StateList::iterator i;
+	    
+	    for (i = states.begin(); n && i != states.end(); n--, i++);
+	    
+	    if (i != states.end()) {
+		    if (i != current) {
+			    current = i;
+			    CurrentChanged ();
+		    }
+		    return *i;
+	    } else {
+		    return 0;
+	    }
+    }
+    
+};
+
+#endif /* __ardour_history_h__ */
+