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Annotation of 42BSD/ucb/dbx/lists.c, revision 1.1

1.1     ! root        1: /* Copyright (c) 1982 Regents of the University of California */
        !             2: 
        !             3: static char sccsid[] = "@(#)lists.c 1.2 12/15/82";
        !             4: 
        !             5: /*
        !             6:  * General list definitions.
        !             7:  *
        !             8:  * The assumption is that the elements in a list are words,
        !             9:  * usually pointers to the actual information.
        !            10:  */
        !            11: 
        !            12: #include "defs.h"
        !            13: #include "lists.h"
        !            14: 
        !            15: #ifndef public
        !            16: 
        !            17: typedef struct List *List;
        !            18: typedef struct ListItem *ListItem;
        !            19: typedef char *ListElement;
        !            20: 
        !            21: #define list_item(element) generic_list_item((ListElement) (element))
        !            22: #define list_element(type, item) ((type) (item == nil ? nil : (item)->element))
        !            23: #define list_head(list) ((list == nil) ? nil : (list)->head)
        !            24: #define list_tail(list) ((list == nil) ? nil : (list)->tail)
        !            25: #define list_next(item) ((item == nil) ? nil : (item)->next)
        !            26: #define list_prev(item) ((item == nil) ? nil : (item)->prev)
        !            27: #define list_size(list) (((list) == nil) ? 0 : (list)->nitems)
        !            28: 
        !            29: #define foreach(type, i, list) \
        !            30: { \
        !            31:     register ListItem _item; \
        !            32:  \
        !            33:     _item = list_head(list); \
        !            34:     while (_item != nil) { \
        !            35:        i = list_element(type, _item); \
        !            36:        _item = list_next(_item);
        !            37: 
        !            38: #define endfor \
        !            39:     } \
        !            40: }
        !            41: 
        !            42: /*
        !            43:  * Iterate through two equal-sized lists.
        !            44:  */
        !            45: 
        !            46: #define foreach2(type1, i, list1, type2, j, list2) \
        !            47: { \
        !            48:     register ListItem _item1, _item2; \
        !            49:  \
        !            50:     _item1 = list_head(list1); \
        !            51:     _item2 = list_head(list2); \
        !            52:     while (_item1 != nil) { \
        !            53:        i = list_element(type1, _item1); \
        !            54:        j = list_element(type2, _item2); \
        !            55:        _item1 = list_next(_item1); \
        !            56:        _item2 = list_next(_item2);
        !            57: 
        !            58: #define list_islast() (_item == nil)
        !            59: #define list_curitem(list) (_item == nil ? list_tail(list) : list_prev(_item))
        !            60: 
        !            61: /*
        !            62:  * Representation should not be used outside except through macros.
        !            63:  */
        !            64: 
        !            65: struct List {
        !            66:     Integer nitems;
        !            67:     ListItem head;
        !            68:     ListItem tail;
        !            69: };
        !            70: 
        !            71: struct ListItem {
        !            72:     ListElement element;
        !            73:     ListItem next;
        !            74:     ListItem prev;
        !            75: };
        !            76: 
        !            77: #endif
        !            78: 
        !            79: /*
        !            80:  * Allocate and initialize a list.
        !            81:  */
        !            82: 
        !            83: public List list_alloc()
        !            84: {
        !            85:     List list;
        !            86: 
        !            87:     list = new(List);
        !            88:     list->nitems = 0;
        !            89:     list->head = nil;
        !            90:     list->tail = nil;
        !            91:     return list;
        !            92: }
        !            93: 
        !            94: /*
        !            95:  * Create a list item from an object (represented as pointer or integer).
        !            96:  */
        !            97: 
        !            98: public ListItem generic_list_item(element)
        !            99: ListElement element;
        !           100: {
        !           101:     ListItem i;
        !           102: 
        !           103:     i = new(ListItem);
        !           104:     i->element = element;
        !           105:     i->next = nil;
        !           106:     i->prev = nil;
        !           107:     return i;
        !           108: }
        !           109: 
        !           110: /*
        !           111:  * Insert an item before the item in a list.
        !           112:  */
        !           113: 
        !           114: public list_insert(item, after, list)
        !           115: ListItem item;
        !           116: ListItem after;
        !           117: List list;
        !           118: {
        !           119:     ListItem a;
        !           120: 
        !           121:     checkref(list);
        !           122:     list->nitems = list->nitems + 1;
        !           123:     if (list->head == nil) {
        !           124:        list->head = item;
        !           125:        list->tail = item;
        !           126:     } else {
        !           127:        if (after == nil) {
        !           128:            a = list->head;
        !           129:        } else {
        !           130:            a = after;
        !           131:        }
        !           132:        item->next = a;
        !           133:        item->prev = a->prev;
        !           134:        if (a->prev != nil) {
        !           135:            a->prev->next = item;
        !           136:        } else {
        !           137:            list->head = item;
        !           138:        }
        !           139:        a->prev = item;
        !           140:     }
        !           141: }
        !           142: 
        !           143: /*
        !           144:  * Append an item after the given item in a list.
        !           145:  */
        !           146: 
        !           147: public list_append(item, before, list)
        !           148: ListItem item;
        !           149: ListItem before;
        !           150: List list;
        !           151: {
        !           152:     ListItem b;
        !           153: 
        !           154:     checkref(list);
        !           155:     list->nitems = list->nitems + 1;
        !           156:     if (list->head == nil) {
        !           157:        list->head = item;
        !           158:        list->tail = item;
        !           159:     } else {
        !           160:        if (before == nil) {
        !           161:            b = list->tail;
        !           162:        } else {
        !           163:            b = before;
        !           164:        }
        !           165:        item->next = b->next;
        !           166:        item->prev = b;
        !           167:        if (b->next != nil) {
        !           168:            b->next->prev = item;
        !           169:        } else {
        !           170:            list->tail = item;
        !           171:        }
        !           172:        b->next = item;
        !           173:     }
        !           174: }
        !           175: 
        !           176: /*
        !           177:  * Delete an item from a list.
        !           178:  */
        !           179: 
        !           180: public list_delete(item, list)
        !           181: ListItem item;
        !           182: List list;
        !           183: {
        !           184:     checkref(item);
        !           185:     checkref(list);
        !           186:     assert(list->nitems > 0);
        !           187:     if (item->next == nil) {
        !           188:        list->tail = item->prev;
        !           189:     } else {
        !           190:        item->next->prev = item->prev;
        !           191:     }
        !           192:     if (item->prev == nil) {
        !           193:        list->head = item->next;
        !           194:     } else {
        !           195:        item->prev->next = item->next;
        !           196:     }
        !           197:     list->nitems = list->nitems - 1;
        !           198: }
        !           199: 
        !           200: /*
        !           201:  * Concatenate one list onto the end of another.
        !           202:  */
        !           203: 
        !           204: public List list_concat(first, second)
        !           205: List first, second;
        !           206: {
        !           207:     List r;
        !           208: 
        !           209:     if (first == nil) {
        !           210:        r = second;
        !           211:     } else if (second == nil) {
        !           212:        r = first;
        !           213:     } else {
        !           214:        second->head->prev = first->tail;
        !           215:        first->tail->next = second->head;
        !           216:        first->tail = second->tail;
        !           217:        first->nitems = first->nitems + second->nitems;
        !           218:        r = first;
        !           219:     }
        !           220:     return r;
        !           221: }

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