зеркало из https://github.com/mozilla/gecko-dev.git
445 строки
9.3 KiB
C
445 строки
9.3 KiB
C
/* -*- Mode: C; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*-
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*
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* The contents of this file are subject to the Netscape Public License
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* Version 1.0 (the "NPL"); you may not use this file except in
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* compliance with the NPL. You may obtain a copy of the NPL at
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* http://www.mozilla.org/NPL/
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*
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* Software distributed under the NPL is distributed on an "AS IS" basis,
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* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the NPL
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* for the specific language governing rights and limitations under the
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* NPL.
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*
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* The Initial Developer of this code under the NPL is Netscape
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* Communications Corporation. Portions created by Netscape are
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* Copyright (C) 1998 Netscape Communications Corporation. All Rights
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* Reserved.
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*/
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/*
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undo.c --- undo facilities
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*/
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#include "xp.h" /* For XP_Bool... */
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#include "undo.h"
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extern int MK_OUT_OF_MEMORY;
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typedef enum {
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BOUNDARY,
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EVENT
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} undo_event_type;
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typedef struct undo_event
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{
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undo_event_type type;
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struct undo_event* next;
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struct undo_event* prev;
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void* closure;
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int (*undoit)(void*);
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void (*freeit)(void*);
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void* tag;
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void (*freetag)(void*);
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} undo_event;
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struct UndoState {
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undo_event* events;
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undo_event* redoevents;
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int depth;
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XP_Bool undoing;
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XP_Bool redoing;
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XP_Bool loggedsomething;
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int count;
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XP_AllocStructInfo allocinfo;
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int maxdepth;
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XP_Bool discardall;
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};
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#ifdef DEBUG
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static void
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undo_check_integrity(UndoState* state)
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{
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int i;
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for (i=0 ; i<2 ; i++) {
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undo_event** start;
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undo_event* tmp;
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int count1, count2;
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if (i == 0) {
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start = &(state->redoevents);
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} else {
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start = &(state->events);
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}
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if (*start) {
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count1 = 0;
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for (tmp = (*start)->next ; tmp != *start ; tmp = tmp->next) {
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count1++;
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}
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count2 = 0;
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for (tmp = (*start)->prev ; tmp != *start ; tmp = tmp->prev) {
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count2++;
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}
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XP_ASSERT(count1 == count2);
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}
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}
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}
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#else
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#define undo_check_integrity(state) /* no-op */
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#endif
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UndoState*
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UNDO_Create(int maxdepth)
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{
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UndoState* state = XP_NEW_ZAP(UndoState);
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if (state) {
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state->maxdepth = maxdepth;
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XP_InitAllocStructInfo(&(state->allocinfo), sizeof(undo_event));
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}
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return state;
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}
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static void
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undo_free_list(UndoState* state, undo_event** list)
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{
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undo_event* tmp;
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undo_event* next;
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undo_check_integrity(state);
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if (*list) {
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(*list)->prev->next = NULL;
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for (tmp = *list ; tmp ; tmp = next) {
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next = tmp->next;
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if (tmp->freeit) (*tmp->freeit)(tmp->closure);
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if (tmp->freetag) (*tmp->freetag)(tmp->tag);
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XP_FreeStruct(&state->allocinfo, tmp);
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}
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*list = NULL;
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}
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undo_check_integrity(state);
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}
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void
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UNDO_Destroy(UndoState* state)
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{
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undo_free_list(state, &state->events);
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undo_free_list(state, &state->redoevents);
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XP_FreeAllStructs(&state->allocinfo);
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XP_FREE(state);
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}
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void
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UNDO_DiscardAll(UndoState* state)
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{
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undo_free_list(state, &state->events);
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undo_free_list(state, &state->redoevents);
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if (state->depth > 0) state->discardall = TRUE;
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state->count = 0;
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}
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static int
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undo_log(UndoState* state, undo_event* event)
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{
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undo_event** start;
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int status;
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undo_check_integrity(state);
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if (event->type != BOUNDARY && state->depth == 0) {
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UNDO_StartBatch(state);
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status = undo_log(state, event);
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if (status < 0) {
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state->depth = 0;
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return status;
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}
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return UNDO_EndBatch(state, event->freetag, event->tag);
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}
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if (state->undoing) {
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start = &(state->redoevents);
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} else {
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start = &(state->events);
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}
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if (!*start) {
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event->next = event;
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event->prev = event;
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} else {
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event->next = *start;
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event->prev = event->next->prev;
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event->next->prev = event;
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event->prev->next = event;
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}
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*start = event;
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undo_check_integrity(state);
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return 0;
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}
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int
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UNDO_LogEvent(UndoState* state, int (*undoit)(void*),
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void (*freeit)(void*), void* closure,
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void (*freetag)(void*), void* tag)
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{
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undo_event* tmp;
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if (state->discardall) {
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(*freeit)(closure);
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if (freetag) (*freetag)(tag);
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return 0;
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}
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tmp = (undo_event*) XP_AllocStructZero(&state->allocinfo);
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if (!tmp) {
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UNDO_DiscardAll(state);
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(*freeit)(closure);
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if (freetag) (*freetag)(tag);
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return MK_OUT_OF_MEMORY;
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}
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state->loggedsomething = TRUE;
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tmp->type = EVENT;
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tmp->undoit = undoit;
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tmp->freeit = freeit;
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tmp->closure = closure;
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tmp->tag = tag;
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tmp->freetag = freetag;
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return undo_log(state, tmp);
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}
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int
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UNDO_StartBatch(UndoState* state)
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{
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#if 0 /* This is bad. The redo stack is not purged when a new event is logged. */
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if (state->depth == 0) {
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#else /* A better way: Only reset loggedsomething if we're in the midst of an undo or redo. */
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if( state->undoing || state->redoing ) {
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#endif
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state->loggedsomething = FALSE;
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}
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state->depth++;
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undo_check_integrity(state);
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return 0;
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}
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int
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UNDO_EndBatch(UndoState* state, void (*freetag)(void*), void* tag)
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{
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int status;
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undo_check_integrity(state);
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XP_ASSERT(state->depth > 0);
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state->depth--;
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if (state->depth == 0) {
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undo_event** start;
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if (state->discardall) {
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UNDO_DiscardAll(state);
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state->discardall = FALSE;
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return 0;
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}
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if (state->undoing) {
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start = &(state->redoevents);
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} else {
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start = &(state->events);
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if (state->loggedsomething) {
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undo_free_list(state, &state->redoevents);
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}
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}
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if (*start && (*start)->type != BOUNDARY) {
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undo_event* tmp = (undo_event*)XP_AllocStructZero(&state->allocinfo);
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if (!tmp) {
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UNDO_DiscardAll(state);
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return MK_OUT_OF_MEMORY;
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}
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tmp->type = BOUNDARY;
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tmp->tag = tag;
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tmp->freetag = freetag;
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status = undo_log(state, tmp);
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if (status < 0) {
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UNDO_DiscardAll(state);
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return status;
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}
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if (!state->undoing) {
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if (state->count >= state->maxdepth) {
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/* exceeded undo count - pull one off the bottom of the stack. */
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undo_event* prev;
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for (tmp = state->events->prev ; ; tmp = prev) {
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undo_event_type type = tmp->type;
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/* better not be at the top of the stack, */
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XP_ASSERT(tmp != state->events);
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prev = tmp->prev;
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tmp->prev->next = tmp->next;
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tmp->next->prev = tmp->prev;
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if (type == EVENT) {
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if (tmp->freeit) (*tmp->freeit)(tmp->closure);
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if (tmp->freetag) (*tmp->freetag)(tmp->tag);
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}
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XP_FreeStruct(&state->allocinfo, tmp);
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/* stop at the next boundary, which makes a whole Batch */
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if (type == BOUNDARY) break;
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}
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}
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else
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{
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state->count++;
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}
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}
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}
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undo_check_integrity(state);
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}
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return 0;
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}
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static int
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undo_doone(UndoState* state, undo_event** from)
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{
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int status = 0;
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undo_event* tmp = *from;
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undo_check_integrity(state);
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XP_ASSERT(tmp != NULL);
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switch (tmp->type) {
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case BOUNDARY:
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break;
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case EVENT:
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if (tmp->undoit) {
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status = (*tmp->undoit)(tmp->closure);
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}
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break;
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default:
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XP_ASSERT(0);
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}
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*from = tmp->next;
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if (*from == tmp) {
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*from = NULL;
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} else {
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(*from)->prev = tmp->prev;
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(*from)->prev->next = (*from);
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}
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undo_check_integrity(state);
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XP_FreeStruct(&state->allocinfo, tmp);
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return status;
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}
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static int
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undo_doit(UndoState* state, undo_event** from)
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{
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int status;
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void (*tmp_freetag)(void*);
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void *tmp_tag;
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XP_ASSERT(state->depth == 0);
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if (!*from) return 0;
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status = UNDO_StartBatch(state);
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if (status < 0) return status;
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XP_ASSERT((*from)->type == BOUNDARY);
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/* Save the tag information so it persists in the opposing undo/redo stack */
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tmp_freetag = (*from)->freetag;
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tmp_tag = (*from)->tag;
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do {
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status = undo_doone(state, from);
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if (status < 0) break;
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} while (*from && (*from)->type != BOUNDARY);
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if (status >= 0) status = UNDO_EndBatch(state, tmp_freetag, tmp_tag);
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if (status < 0) {
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UNDO_DiscardAll(state);
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}
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return status;
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}
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int
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UNDO_DoUndo(UndoState* state)
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{
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int status;
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XP_ASSERT(state->depth == 0 && !state->undoing);
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state->undoing = TRUE;
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status = undo_doit(state, &(state->events));
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state->undoing = FALSE;
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state->count--;
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return status;
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}
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int
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UNDO_DoRedo(UndoState* state)
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{
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int status;
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undo_event* tmp = state->redoevents;
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state->redoevents = NULL; /* Prevent any code from throwing away the
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remaining redo events. */
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XP_ASSERT(state->depth == 0 && !state->undoing);
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state->redoing = TRUE;
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status = undo_doit(state, &tmp);
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state->redoing = FALSE;
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XP_ASSERT(state->redoevents == NULL);
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state->redoevents = tmp;
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return status;
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}
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static XP_Bool
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undo_has_event(undo_event* event)
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{
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undo_event* tmp = event;
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if (tmp) {
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do {
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if (tmp->type == EVENT) return TRUE;
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tmp = tmp->next;
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} while (tmp != event);
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}
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return FALSE;
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}
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XP_Bool
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UNDO_CanUndo(UndoState* state)
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{
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return undo_has_event(state->events);
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}
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XP_Bool
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UNDO_CanRedo(UndoState* state)
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{
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return undo_has_event(state->redoevents);
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}
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static void *
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undo_get_tag(undo_event* event)
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{
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undo_event* tmp = event;
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if (tmp) {
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do {
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if (tmp->type == BOUNDARY)
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return tmp->tag;
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tmp = tmp->next;
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} while (tmp != event);
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}
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return NULL;
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}
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void *
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UNDO_PeekUndoTag(UndoState* state)
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{
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return state ? undo_get_tag(state->events) : NULL;
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}
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void *
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UNDO_PeekRedoTag(UndoState* state)
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{
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return state ? undo_get_tag(state->redoevents) : NULL;
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}
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