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Annotation of 43BSD/ucb/dbx/lists.c, revision 1.1

1.1     ! root        1: /*
        !             2:  * Copyright (c) 1983 Regents of the University of California.
        !             3:  * All rights reserved.  The Berkeley software License Agreement
        !             4:  * specifies the terms and conditions for redistribution.
        !             5:  */
        !             6: 
        !             7: #ifndef lint
        !             8: static char sccsid[] = "@(#)lists.c    5.1 (Berkeley) 5/31/85";
        !             9: #endif not lint
        !            10: 
        !            11: static char rcsid[] = "$Header: lists.c,v 1.5 84/12/26 10:40:00 linton Exp $";
        !            12: 
        !            13: /*
        !            14:  * General list definitions.
        !            15:  *
        !            16:  * The assumption is that the elements in a list are words,
        !            17:  * usually pointers to the actual information.
        !            18:  */
        !            19: 
        !            20: #include "defs.h"
        !            21: #include "lists.h"
        !            22: 
        !            23: #ifndef public
        !            24: 
        !            25: typedef struct List *List;
        !            26: typedef struct ListItem *ListItem;
        !            27: typedef char *ListElement;
        !            28: 
        !            29: #define list_item(element) generic_list_item((ListElement) (element))
        !            30: #define list_element(type, item) ((type) (item == nil ? nil : (item)->element))
        !            31: #define list_head(list) ((list == nil) ? nil : (list)->head)
        !            32: #define list_tail(list) ((list == nil) ? nil : (list)->tail)
        !            33: #define list_next(item) ((item == nil) ? nil : (item)->next)
        !            34: #define list_prev(item) ((item == nil) ? nil : (item)->prev)
        !            35: #define list_size(list) (((list) == nil) ? 0 : (list)->nitems)
        !            36: 
        !            37: #define foreach(type, i, list) \
        !            38: { \
        !            39:     register ListItem _item; \
        !            40:  \
        !            41:     _item = list_head(list); \
        !            42:     while (_item != nil) { \
        !            43:        i = list_element(type, _item); \
        !            44:        _item = list_next(_item);
        !            45: 
        !            46: #define endfor \
        !            47:     } \
        !            48: }
        !            49: 
        !            50: /*
        !            51:  * Iterate through two equal-sized lists.
        !            52:  */
        !            53: 
        !            54: #define foreach2(type1, i, list1, type2, j, list2) \
        !            55: { \
        !            56:     register ListItem _item1, _item2; \
        !            57:  \
        !            58:     _item1 = list_head(list1); \
        !            59:     _item2 = list_head(list2); \
        !            60:     while (_item1 != nil) { \
        !            61:        i = list_element(type1, _item1); \
        !            62:        j = list_element(type2, _item2); \
        !            63:        _item1 = list_next(_item1); \
        !            64:        _item2 = list_next(_item2);
        !            65: 
        !            66: #define list_islast() (_item == nil)
        !            67: #define list_curitem(list) (_item == nil ? list_tail(list) : list_prev(_item))
        !            68: 
        !            69: /*
        !            70:  * Representation should not be used outside except through macros.
        !            71:  */
        !            72: 
        !            73: struct List {
        !            74:     Integer nitems;
        !            75:     ListItem head;
        !            76:     ListItem tail;
        !            77: };
        !            78: 
        !            79: struct ListItem {
        !            80:     ListElement element;
        !            81:     ListItem next;
        !            82:     ListItem prev;
        !            83: };
        !            84: 
        !            85: #endif
        !            86: 
        !            87: /*
        !            88:  * Allocate and initialize a list.
        !            89:  */
        !            90: 
        !            91: public List list_alloc()
        !            92: {
        !            93:     List list;
        !            94: 
        !            95:     list = new(List);
        !            96:     list->nitems = 0;
        !            97:     list->head = nil;
        !            98:     list->tail = nil;
        !            99:     return list;
        !           100: }
        !           101: 
        !           102: /*
        !           103:  * Create a list item from an object (represented as pointer or integer).
        !           104:  */
        !           105: 
        !           106: public ListItem generic_list_item(element)
        !           107: ListElement element;
        !           108: {
        !           109:     ListItem i;
        !           110: 
        !           111:     i = new(ListItem);
        !           112:     i->element = element;
        !           113:     i->next = nil;
        !           114:     i->prev = nil;
        !           115:     return i;
        !           116: }
        !           117: 
        !           118: /*
        !           119:  * Insert an item before the item in a list.
        !           120:  */
        !           121: 
        !           122: public list_insert(item, after, list)
        !           123: ListItem item;
        !           124: ListItem after;
        !           125: List list;
        !           126: {
        !           127:     ListItem a;
        !           128: 
        !           129:     checkref(list);
        !           130:     list->nitems = list->nitems + 1;
        !           131:     if (list->head == nil) {
        !           132:        list->head = item;
        !           133:        list->tail = item;
        !           134:     } else {
        !           135:        if (after == nil) {
        !           136:            a = list->head;
        !           137:        } else {
        !           138:            a = after;
        !           139:        }
        !           140:        item->next = a;
        !           141:        item->prev = a->prev;
        !           142:        if (a->prev != nil) {
        !           143:            a->prev->next = item;
        !           144:        } else {
        !           145:            list->head = item;
        !           146:        }
        !           147:        a->prev = item;
        !           148:     }
        !           149: }
        !           150: 
        !           151: /*
        !           152:  * Append an item after the given item in a list.
        !           153:  */
        !           154: 
        !           155: public list_append(item, before, list)
        !           156: ListItem item;
        !           157: ListItem before;
        !           158: List list;
        !           159: {
        !           160:     ListItem b;
        !           161: 
        !           162:     checkref(list);
        !           163:     list->nitems = list->nitems + 1;
        !           164:     if (list->head == nil) {
        !           165:        list->head = item;
        !           166:        list->tail = item;
        !           167:     } else {
        !           168:        if (before == nil) {
        !           169:            b = list->tail;
        !           170:        } else {
        !           171:            b = before;
        !           172:        }
        !           173:        item->next = b->next;
        !           174:        item->prev = b;
        !           175:        if (b->next != nil) {
        !           176:            b->next->prev = item;
        !           177:        } else {
        !           178:            list->tail = item;
        !           179:        }
        !           180:        b->next = item;
        !           181:     }
        !           182: }
        !           183: 
        !           184: /*
        !           185:  * Delete an item from a list.
        !           186:  */
        !           187: 
        !           188: public list_delete(item, list)
        !           189: ListItem item;
        !           190: List list;
        !           191: {
        !           192:     checkref(item);
        !           193:     checkref(list);
        !           194:     assert(list->nitems > 0);
        !           195:     if (item->next == nil) {
        !           196:        list->tail = item->prev;
        !           197:     } else {
        !           198:        item->next->prev = item->prev;
        !           199:     }
        !           200:     if (item->prev == nil) {
        !           201:        list->head = item->next;
        !           202:     } else {
        !           203:        item->prev->next = item->next;
        !           204:     }
        !           205:     list->nitems = list->nitems - 1;
        !           206: }
        !           207: 
        !           208: /*
        !           209:  * Concatenate one list onto the end of another.
        !           210:  */
        !           211: 
        !           212: public List list_concat(first, second)
        !           213: List first, second;
        !           214: {
        !           215:     List r;
        !           216: 
        !           217:     if (first == nil) {
        !           218:        r = second;
        !           219:     } else if (second == nil) {
        !           220:        r = first;
        !           221:     } else {
        !           222:        second->head->prev = first->tail;
        !           223:        first->tail->next = second->head;
        !           224:        first->tail = second->tail;
        !           225:        first->nitems = first->nitems + second->nitems;
        !           226:        r = first;
        !           227:     }
        !           228:     return r;
        !           229: }

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