1 /* llist.c - Linked list functions
2 *
3 * Linked list structures have a next pointer as their first element.
4 */
5
6 #include "toys.h"
7
8 // Callback function to free data pointer of double_list or arg_list
9
llist_free_arg(void * node)10 void llist_free_arg(void *node)
11 {
12 struct arg_list *d = node;
13
14 free(d->arg);
15 free(d);
16 }
17
llist_free_double(void * node)18 void llist_free_double(void *node)
19 {
20 struct double_list *d = node;
21
22 free(d->data);
23 free(d);
24 }
25
26 // Call a function (such as free()) on each element of a linked list.
llist_traverse(void * list,void (* using)(void * node))27 void llist_traverse(void *list, void (*using)(void *node))
28 {
29 void *old = list;
30
31 while (list) {
32 void *pop = llist_pop(&list);
33 using(pop);
34
35 // End doubly linked list too.
36 if (old == list) break;
37 }
38 }
39
40 // Return the first item from the list, advancing the list (which must be called
41 // as &list)
llist_pop(void * list)42 void *llist_pop(void *list)
43 {
44 // I'd use a void ** for the argument, and even accept the typecast in all
45 // callers as documentation you need the &, except the stupid compiler
46 // would then scream about type-punned pointers. Screw it.
47 void **llist = (void **)list;
48 void **next = (void **)*llist;
49 *llist = *next;
50
51 return (void *)next;
52 }
53
54 // Remove first item from &list and return it
dlist_pop(void * list)55 void *dlist_pop(void *list)
56 {
57 struct double_list **pdlist = (struct double_list **)list, *dlist = *pdlist;
58
59 if (!dlist) return 0;
60 if (dlist->next == dlist) *pdlist = 0;
61 else {
62 if (dlist->next) dlist->next->prev = dlist->prev;
63 if (dlist->prev) dlist->prev->next = dlist->next;
64 *pdlist = dlist->next;
65 }
66
67 return dlist;
68 }
69
70 // remove last item from &list and return it (stack pop)
dlist_lpop(void * list)71 void *dlist_lpop(void *list)
72 {
73 struct double_list *dl = *(struct double_list **)list;
74 void *v = 0;
75
76 if (dl) {
77 dl = dl->prev;
78 v = dlist_pop(&dl);
79 if (!dl) *(void **)list = 0;
80 }
81
82 return v;
83 }
84
85 // Append to list in-order (*list unchanged unless empty, ->prev is new node)
dlist_add_nomalloc(struct double_list ** list,struct double_list * new)86 void dlist_add_nomalloc(struct double_list **list, struct double_list *new)
87 {
88 if (*list) {
89 new->next = *list;
90 new->prev = (*list)->prev;
91 (*list)->prev->next = new;
92 (*list)->prev = new;
93 } else *list = new->next = new->prev = new;
94 }
95
96 // Add an entry to the end of a doubly linked list
dlist_add(struct double_list ** list,char * data)97 struct double_list *dlist_add(struct double_list **list, char *data)
98 {
99 struct double_list *new = xmalloc(sizeof(struct double_list));
100
101 new->data = data;
102 dlist_add_nomalloc(list, new);
103
104 return new;
105 }
106
107 // Terminate circular list for traversal in either direction. Returns end *.
dlist_terminate(void * list)108 void *dlist_terminate(void *list)
109 {
110 struct double_list *end = list;
111
112 if (!end || !end->prev) return 0;
113
114 end = end->prev;
115 end->next->prev = 0;
116 end->next = 0;
117
118 return end;
119 }
120
121 // Find num in cache
get_num_cache(struct num_cache * cache,long long num)122 struct num_cache *get_num_cache(struct num_cache *cache, long long num)
123 {
124 while (cache) {
125 if (num==cache->num) return cache;
126 cache = cache->next;
127 }
128
129 return 0;
130 }
131
132 // Uniquely add num+data to cache. Updates *cache, returns pointer to existing
133 // entry if it was already there.
add_num_cache(struct num_cache ** cache,long long num,void * data,int len)134 struct num_cache *add_num_cache(struct num_cache **cache, long long num,
135 void *data, int len)
136 {
137 struct num_cache *old = get_num_cache(*cache, num);
138
139 if (old) return old;
140
141 old = xzalloc(sizeof(struct num_cache)+len);
142 old->next = *cache;
143 old->num = num;
144 memcpy(old->data, data, len);
145 *cache = old;
146
147 return 0;
148 }
149