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HISTORY.C
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1980-01-05
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/*
* Copyright (c) 1987, 1988, 1989 Stanford University
*
* Permission to use, copy, modify, distribute, and sell this software and its
* documentation for any purpose is hereby granted without fee, provided
* that the above copyright notice appear in all copies and that both that
* copyright notice and this permission notice appear in supporting
* documentation, and that the name of Stanford not be used in advertising or
* publicity pertaining to distribution of the software without specific,
* written prior permission. Stanford makes no representations about
* the suitability of this software for any purpose. It is provided "as is"
* without express or implied warranty.
*
* STANFORD DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
* INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS.
* IN NO EVENT SHALL STANFORD BE LIABLE FOR ANY SPECIAL, INDIRECT OR
* CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
* DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
* OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
* WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
// $Header: history.c,v 1.8 89/10/09 14:48:05 linton Exp $
// implements class History.
#include "history.h"
#include "istring.h"
#include "listchange.h"
#include <InterViews/interactor.h>
#include <stdio.h>
// History sets its maximum number of changes and creates the history.
History::History (Interactor* i) {
const char* def = i->GetAttribute("history");
char* definition = strdup(def); // some sscanfs write to their format...
if (sscanf(definition, "%d", &maxhistory) != 1) {
maxhistory = 20; // default if we can't parse definition
fprintf(stderr, "can't parse attribute for history, ");
fprintf(stderr, "value set to %d\n", maxhistory);
}
delete definition;
changelist = new ChangeList;
}
// ~History frees storage allocated for the changes.
History::~History () {
delete changelist;
}
// IsEmpty returns true if there are no changes stored in the list.
boolean History::IsEmpty () {
return changelist->Size() == 0;
}
// Clear deletes all of the stored changes. Calling Clear prevents
// dangling pointers from being referenced if the user tries to undo a
// stored change that was made before a New, Revert, or Open command.
void History::Clear () {
changelist->DeleteAll();
}
// Do truncates the history at its current point, trims the history to
// its last maxhistory-1 changes, performs the change, appends the
// change, and leaves the current point at the end of the history.
void History::Do (ChangeNode* changenode) {
while (!changelist->AtEnd()) {
changelist->DeleteCur();
}
changelist->First();
while (changelist->Size() >= maxhistory) {
changelist->DeleteCur();
}
changenode->Do();
changelist->Append(changenode);
changelist->Last();
changelist->Next();
}
// Redo redoes a stored change in the history and steps over it unless
// the current point is already at the end of the history.
void History::Redo () {
if (!changelist->AtEnd()) {
ChangeNode* changenode = changelist->GetCur();
changenode->Do();
changelist->Next();
}
}
// Undo steps back in the history and undoes a stored change unless
// the current point is already at the beginning of the history.
void History::Undo () {
changelist->Prev();
if (!changelist->AtEnd()) {
ChangeNode* changenode = changelist->GetCur();
changenode->Undo();
} else {
changelist->Next();
}
}