1 /*-------------------------------------------------------------------------
2 *
3 * pg_list.h
4 * interface for PostgreSQL generic linked list package
5 *
6 * This package implements singly-linked homogeneous lists.
7 *
8 * It is important to have constant-time length, append, and prepend
9 * operations. To achieve this, we deal with two distinct data
10 * structures:
11 *
12 * 1. A set of "list cells": each cell contains a data field and
13 * a link to the next cell in the list or NULL.
14 * 2. A single structure containing metadata about the list: the
15 * type of the list, pointers to the head and tail cells, and
16 * the length of the list.
17 *
18 * We support three types of lists:
19 *
20 * T_List: lists of pointers
21 * (in practice usually pointers to Nodes, but not always;
22 * declared as "void *" to minimize casting annoyances)
23 * T_IntList: lists of integers
24 * T_OidList: lists of Oids
25 *
26 * (At the moment, ints and Oids are the same size, but they may not
27 * always be so; try to be careful to maintain the distinction.)
28 *
29 *
30 * Portions Copyright (c) 1996-2018, PostgreSQL Global Development Group
31 * Portions Copyright (c) 1994, Regents of the University of California
32 *
33 * src/include/nodes/pg_list.h
34 *
35 *-------------------------------------------------------------------------
36 */
37 #ifndef PG_LIST_H
38 #define PG_LIST_H
39
40 #include "nodes/nodes.h"
41
42
43 typedef struct ListCell ListCell;
44
45 typedef struct List
46 {
47 NodeTag type; /* T_List, T_IntList, or T_OidList */
48 int length;
49 ListCell *head;
50 ListCell *tail;
51 } List;
52
53 struct ListCell
54 {
55 union
56 {
57 void *ptr_value;
58 int int_value;
59 Oid oid_value;
60 } data;
61 ListCell *next;
62 };
63
64 /*
65 * The *only* valid representation of an empty list is NIL; in other
66 * words, a non-NIL list is guaranteed to have length >= 1 and
67 * head/tail != NULL
68 */
69 #define NIL ((List *) NULL)
70
71 /*
72 * These routines are used frequently. However, we can't implement
73 * them as macros, since we want to avoid double-evaluation of macro
74 * arguments.
75 */
76 static inline ListCell *
list_head(const List * l)77 list_head(const List *l)
78 {
79 return l ? l->head : NULL;
80 }
81
82 static inline ListCell *
list_tail(List * l)83 list_tail(List *l)
84 {
85 return l ? l->tail : NULL;
86 }
87
88 static inline int
list_length(const List * l)89 list_length(const List *l)
90 {
91 return l ? l->length : 0;
92 }
93
94 /*
95 * NB: There is an unfortunate legacy from a previous incarnation of
96 * the List API: the macro lfirst() was used to mean "the data in this
97 * cons cell". To avoid changing every usage of lfirst(), that meaning
98 * has been kept. As a result, lfirst() takes a ListCell and returns
99 * the data it contains; to get the data in the first cell of a
100 * List, use linitial(). Worse, lsecond() is more closely related to
101 * linitial() than lfirst(): given a List, lsecond() returns the data
102 * in the second cons cell.
103 */
104
105 #define lnext(lc) ((lc)->next)
106 #define lfirst(lc) ((lc)->data.ptr_value)
107 #define lfirst_int(lc) ((lc)->data.int_value)
108 #define lfirst_oid(lc) ((lc)->data.oid_value)
109 #define lfirst_node(type,lc) castNode(type, lfirst(lc))
110
111 #define linitial(l) lfirst(list_head(l))
112 #define linitial_int(l) lfirst_int(list_head(l))
113 #define linitial_oid(l) lfirst_oid(list_head(l))
114 #define linitial_node(type,l) castNode(type, linitial(l))
115
116 #define lsecond(l) lfirst(lnext(list_head(l)))
117 #define lsecond_int(l) lfirst_int(lnext(list_head(l)))
118 #define lsecond_oid(l) lfirst_oid(lnext(list_head(l)))
119 #define lsecond_node(type,l) castNode(type, lsecond(l))
120
121 #define lthird(l) lfirst(lnext(lnext(list_head(l))))
122 #define lthird_int(l) lfirst_int(lnext(lnext(list_head(l))))
123 #define lthird_oid(l) lfirst_oid(lnext(lnext(list_head(l))))
124 #define lthird_node(type,l) castNode(type, lthird(l))
125
126 #define lfourth(l) lfirst(lnext(lnext(lnext(list_head(l)))))
127 #define lfourth_int(l) lfirst_int(lnext(lnext(lnext(list_head(l)))))
128 #define lfourth_oid(l) lfirst_oid(lnext(lnext(lnext(list_head(l)))))
129 #define lfourth_node(type,l) castNode(type, lfourth(l))
130
131 #define llast(l) lfirst(list_tail(l))
132 #define llast_int(l) lfirst_int(list_tail(l))
133 #define llast_oid(l) lfirst_oid(list_tail(l))
134 #define llast_node(type,l) castNode(type, llast(l))
135
136 /*
137 * Convenience macros for building fixed-length lists
138 */
139 #define list_make1(x1) lcons(x1, NIL)
140 #define list_make2(x1,x2) lcons(x1, list_make1(x2))
141 #define list_make3(x1,x2,x3) lcons(x1, list_make2(x2, x3))
142 #define list_make4(x1,x2,x3,x4) lcons(x1, list_make3(x2, x3, x4))
143 #define list_make5(x1,x2,x3,x4,x5) lcons(x1, list_make4(x2, x3, x4, x5))
144
145 #define list_make1_int(x1) lcons_int(x1, NIL)
146 #define list_make2_int(x1,x2) lcons_int(x1, list_make1_int(x2))
147 #define list_make3_int(x1,x2,x3) lcons_int(x1, list_make2_int(x2, x3))
148 #define list_make4_int(x1,x2,x3,x4) lcons_int(x1, list_make3_int(x2, x3, x4))
149 #define list_make5_int(x1,x2,x3,x4,x5) lcons_int(x1, list_make4_int(x2, x3, x4, x5))
150
151 #define list_make1_oid(x1) lcons_oid(x1, NIL)
152 #define list_make2_oid(x1,x2) lcons_oid(x1, list_make1_oid(x2))
153 #define list_make3_oid(x1,x2,x3) lcons_oid(x1, list_make2_oid(x2, x3))
154 #define list_make4_oid(x1,x2,x3,x4) lcons_oid(x1, list_make3_oid(x2, x3, x4))
155 #define list_make5_oid(x1,x2,x3,x4,x5) lcons_oid(x1, list_make4_oid(x2, x3, x4, x5))
156
157 /*
158 * foreach -
159 * a convenience macro which loops through the list
160 */
161 #define foreach(cell, l) \
162 for ((cell) = list_head(l); (cell) != NULL; (cell) = lnext(cell))
163
164 /*
165 * for_each_cell -
166 * a convenience macro which loops through a list starting from a
167 * specified cell
168 */
169 #define for_each_cell(cell, initcell) \
170 for ((cell) = (initcell); (cell) != NULL; (cell) = lnext(cell))
171
172 /*
173 * forboth -
174 * a convenience macro for advancing through two linked lists
175 * simultaneously. This macro loops through both lists at the same
176 * time, stopping when either list runs out of elements. Depending
177 * on the requirements of the call site, it may also be wise to
178 * assert that the lengths of the two lists are equal.
179 */
180 #define forboth(cell1, list1, cell2, list2) \
181 for ((cell1) = list_head(list1), (cell2) = list_head(list2); \
182 (cell1) != NULL && (cell2) != NULL; \
183 (cell1) = lnext(cell1), (cell2) = lnext(cell2))
184
185 /*
186 * for_both_cell -
187 * a convenience macro which loops through two lists starting from the
188 * specified cells of each. This macro loops through both lists at the same
189 * time, stopping when either list runs out of elements. Depending on the
190 * requirements of the call site, it may also be wise to assert that the
191 * lengths of the two lists are equal, and initcell1 and initcell2 are at
192 * the same position in the respective lists.
193 */
194 #define for_both_cell(cell1, initcell1, cell2, initcell2) \
195 for ((cell1) = (initcell1), (cell2) = (initcell2); \
196 (cell1) != NULL && (cell2) != NULL; \
197 (cell1) = lnext(cell1), (cell2) = lnext(cell2))
198
199 /*
200 * forthree -
201 * the same for three lists
202 */
203 #define forthree(cell1, list1, cell2, list2, cell3, list3) \
204 for ((cell1) = list_head(list1), (cell2) = list_head(list2), (cell3) = list_head(list3); \
205 (cell1) != NULL && (cell2) != NULL && (cell3) != NULL; \
206 (cell1) = lnext(cell1), (cell2) = lnext(cell2), (cell3) = lnext(cell3))
207
208 extern List *lappend(List *list, void *datum);
209 extern List *lappend_int(List *list, int datum);
210 extern List *lappend_oid(List *list, Oid datum);
211
212 extern ListCell *lappend_cell(List *list, ListCell *prev, void *datum);
213 extern ListCell *lappend_cell_int(List *list, ListCell *prev, int datum);
214 extern ListCell *lappend_cell_oid(List *list, ListCell *prev, Oid datum);
215
216 extern List *lcons(void *datum, List *list);
217 extern List *lcons_int(int datum, List *list);
218 extern List *lcons_oid(Oid datum, List *list);
219
220 extern List *list_concat(List *list1, List *list2);
221 extern List *list_truncate(List *list, int new_size);
222
223 extern ListCell *list_nth_cell(const List *list, int n);
224 extern void *list_nth(const List *list, int n);
225 extern int list_nth_int(const List *list, int n);
226 extern Oid list_nth_oid(const List *list, int n);
227 #define list_nth_node(type,list,n) castNode(type, list_nth(list, n))
228
229 extern bool list_member(const List *list, const void *datum);
230 extern bool list_member_ptr(const List *list, const void *datum);
231 extern bool list_member_int(const List *list, int datum);
232 extern bool list_member_oid(const List *list, Oid datum);
233
234 extern List *list_delete(List *list, void *datum);
235 extern List *list_delete_ptr(List *list, void *datum);
236 extern List *list_delete_int(List *list, int datum);
237 extern List *list_delete_oid(List *list, Oid datum);
238 extern List *list_delete_first(List *list);
239 extern List *list_delete_cell(List *list, ListCell *cell, ListCell *prev);
240
241 extern List *list_union(const List *list1, const List *list2);
242 extern List *list_union_ptr(const List *list1, const List *list2);
243 extern List *list_union_int(const List *list1, const List *list2);
244 extern List *list_union_oid(const List *list1, const List *list2);
245
246 extern List *list_intersection(const List *list1, const List *list2);
247 extern List *list_intersection_int(const List *list1, const List *list2);
248
249 /* currently, there's no need for list_intersection_ptr etc */
250
251 extern List *list_difference(const List *list1, const List *list2);
252 extern List *list_difference_ptr(const List *list1, const List *list2);
253 extern List *list_difference_int(const List *list1, const List *list2);
254 extern List *list_difference_oid(const List *list1, const List *list2);
255
256 extern List *list_append_unique(List *list, void *datum);
257 extern List *list_append_unique_ptr(List *list, void *datum);
258 extern List *list_append_unique_int(List *list, int datum);
259 extern List *list_append_unique_oid(List *list, Oid datum);
260
261 extern List *list_concat_unique(List *list1, List *list2);
262 extern List *list_concat_unique_ptr(List *list1, List *list2);
263 extern List *list_concat_unique_int(List *list1, List *list2);
264 extern List *list_concat_unique_oid(List *list1, List *list2);
265
266 extern void list_free(List *list);
267 extern void list_free_deep(List *list);
268
269 extern List *list_copy(const List *list);
270 extern List *list_copy_tail(const List *list, int nskip);
271
272 typedef int (*list_qsort_comparator) (const void *a, const void *b);
273 extern List *list_qsort(const List *list, list_qsort_comparator cmp);
274
275 /*
276 * To ease migration to the new list API, a set of compatibility
277 * macros are provided that reduce the impact of the list API changes
278 * as far as possible. Until client code has been rewritten to use the
279 * new list API, the ENABLE_LIST_COMPAT symbol can be defined before
280 * including pg_list.h
281 */
282 #ifdef ENABLE_LIST_COMPAT
283
284 #define lfirsti(lc) lfirst_int(lc)
285 #define lfirsto(lc) lfirst_oid(lc)
286
287 #define makeList1(x1) list_make1(x1)
288 #define makeList2(x1, x2) list_make2(x1, x2)
289 #define makeList3(x1, x2, x3) list_make3(x1, x2, x3)
290 #define makeList4(x1, x2, x3, x4) list_make4(x1, x2, x3, x4)
291
292 #define makeListi1(x1) list_make1_int(x1)
293 #define makeListi2(x1, x2) list_make2_int(x1, x2)
294
295 #define makeListo1(x1) list_make1_oid(x1)
296 #define makeListo2(x1, x2) list_make2_oid(x1, x2)
297
298 #define lconsi(datum, list) lcons_int(datum, list)
299 #define lconso(datum, list) lcons_oid(datum, list)
300
301 #define lappendi(list, datum) lappend_int(list, datum)
302 #define lappendo(list, datum) lappend_oid(list, datum)
303
304 #define nconc(l1, l2) list_concat(l1, l2)
305
306 #define nth(n, list) list_nth(list, n)
307
308 #define member(datum, list) list_member(list, datum)
309 #define ptrMember(datum, list) list_member_ptr(list, datum)
310 #define intMember(datum, list) list_member_int(list, datum)
311 #define oidMember(datum, list) list_member_oid(list, datum)
312
313 /*
314 * Note that the old lremove() determined equality via pointer
315 * comparison, whereas the new list_delete() uses equal(); in order to
316 * keep the same behavior, we therefore need to map lremove() calls to
317 * list_delete_ptr() rather than list_delete()
318 */
319 #define lremove(elem, list) list_delete_ptr(list, elem)
320 #define LispRemove(elem, list) list_delete(list, elem)
321 #define lremovei(elem, list) list_delete_int(list, elem)
322 #define lremoveo(elem, list) list_delete_oid(list, elem)
323
324 #define ltruncate(n, list) list_truncate(list, n)
325
326 #define set_union(l1, l2) list_union(l1, l2)
327 #define set_uniono(l1, l2) list_union_oid(l1, l2)
328 #define set_ptrUnion(l1, l2) list_union_ptr(l1, l2)
329
330 #define set_difference(l1, l2) list_difference(l1, l2)
331 #define set_differenceo(l1, l2) list_difference_oid(l1, l2)
332 #define set_ptrDifference(l1, l2) list_difference_ptr(l1, l2)
333
334 #define equali(l1, l2) equal(l1, l2)
335 #define equalo(l1, l2) equal(l1, l2)
336
337 #define freeList(list) list_free(list)
338
339 #define listCopy(list) list_copy(list)
340
341 extern int length(List *list);
342 #endif /* ENABLE_LIST_COMPAT */
343
344 #endif /* PG_LIST_H */
345