1 /*-------------------------------------------------------------------------
4 * interface for PostgreSQL generic linked list package
6 * This package implements singly-linked homogeneous lists.
8 * It is important to have constant-time length, append, and prepend
9 * operations. To achieve this, we deal with two distinct data
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.
18 * We support three types of lists:
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
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.)
30 * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
31 * Portions Copyright (c) 1994, Regents of the University of California
33 * $PostgreSQL: pgsql/src/include/nodes/pg_list.h,v 1.58 2008/03/17 02:18:55 tgl Exp $
35 *-------------------------------------------------------------------------
40 #include "nodes/nodes.h"
43 typedef struct ListCell ListCell;
47 NodeTag type; /* T_List, T_IntList, or T_OidList */
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
69 #define NIL ((List *) NULL)
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. Therefore, we implement them using GCC inline functions,
75 * and as regular functions with non-GCC compilers.
79 static __inline__ ListCell *
82 return l ? l->head : NULL;
85 static __inline__ ListCell *
88 return l ? l->tail : NULL;
94 return l ? l->length : 0;
98 extern ListCell *list_head(List *l);
99 extern ListCell *list_tail(List *l);
100 extern int list_length(List *l);
101 #endif /* __GNUC__ */
104 * NB: There is an unfortunate legacy from a previous incarnation of
105 * the List API: the macro lfirst() was used to mean "the data in this
106 * cons cell". To avoid changing every usage of lfirst(), that meaning
107 * has been kept. As a result, lfirst() takes a ListCell and returns
108 * the data it contains; to get the data in the first cell of a
109 * List, use linitial(). Worse, lsecond() is more closely related to
110 * linitial() than lfirst(): given a List, lsecond() returns the data
111 * in the second cons cell.
114 #define lnext(lc) ((lc)->next)
115 #define lfirst(lc) ((lc)->data.ptr_value)
116 #define lfirst_int(lc) ((lc)->data.int_value)
117 #define lfirst_oid(lc) ((lc)->data.oid_value)
119 #define linitial(l) lfirst(list_head(l))
120 #define linitial_int(l) lfirst_int(list_head(l))
121 #define linitial_oid(l) lfirst_oid(list_head(l))
123 #define lsecond(l) lfirst(lnext(list_head(l)))
124 #define lsecond_int(l) lfirst_int(lnext(list_head(l)))
125 #define lsecond_oid(l) lfirst_oid(lnext(list_head(l)))
127 #define lthird(l) lfirst(lnext(lnext(list_head(l))))
128 #define lthird_int(l) lfirst_int(lnext(lnext(list_head(l))))
129 #define lthird_oid(l) lfirst_oid(lnext(lnext(list_head(l))))
131 #define lfourth(l) lfirst(lnext(lnext(lnext(list_head(l)))))
132 #define lfourth_int(l) lfirst_int(lnext(lnext(lnext(list_head(l)))))
133 #define lfourth_oid(l) lfirst_oid(lnext(lnext(lnext(list_head(l)))))
135 #define llast(l) lfirst(list_tail(l))
136 #define llast_int(l) lfirst_int(list_tail(l))
137 #define llast_oid(l) lfirst_oid(list_tail(l))
140 * Convenience macros for building fixed-length lists
142 #define list_make1(x1) lcons(x1, NIL)
143 #define list_make2(x1,x2) lcons(x1, list_make1(x2))
144 #define list_make3(x1,x2,x3) lcons(x1, list_make2(x2, x3))
145 #define list_make4(x1,x2,x3,x4) lcons(x1, list_make3(x2, x3, x4))
147 #define list_make1_int(x1) lcons_int(x1, NIL)
148 #define list_make2_int(x1,x2) lcons_int(x1, list_make1_int(x2))
149 #define list_make3_int(x1,x2,x3) lcons_int(x1, list_make2_int(x2, x3))
150 #define list_make4_int(x1,x2,x3,x4) lcons_int(x1, list_make3_int(x2, x3, x4))
152 #define list_make1_oid(x1) lcons_oid(x1, NIL)
153 #define list_make2_oid(x1,x2) lcons_oid(x1, list_make1_oid(x2))
154 #define list_make3_oid(x1,x2,x3) lcons_oid(x1, list_make2_oid(x2, x3))
155 #define list_make4_oid(x1,x2,x3,x4) lcons_oid(x1, list_make3_oid(x2, x3, x4))
159 * a convenience macro which loops through the list
161 #define foreach(cell, l) \
162 for ((cell) = list_head(l); (cell) != NULL; (cell) = lnext(cell))
166 * a convenience macro which loops through a list starting from a
169 #define for_each_cell(cell, initcell) \
170 for ((cell) = (initcell); (cell) != NULL; (cell) = lnext(cell))
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.
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))
185 extern List *lappend(List *list, void *datum);
186 extern List *lappend_int(List *list, int datum);
187 extern List *lappend_oid(List *list, Oid datum);
189 extern ListCell *lappend_cell(List *list, ListCell *prev, void *datum);
190 extern ListCell *lappend_cell_int(List *list, ListCell *prev, int datum);
191 extern ListCell *lappend_cell_oid(List *list, ListCell *prev, Oid datum);
193 extern List *lcons(void *datum, List *list);
194 extern List *lcons_int(int datum, List *list);
195 extern List *lcons_oid(Oid datum, List *list);
197 extern List *list_concat(List *list1, List *list2);
198 extern List *list_truncate(List *list, int new_size);
200 extern void *list_nth(List *list, int n);
201 extern int list_nth_int(List *list, int n);
202 extern Oid list_nth_oid(List *list, int n);
204 extern bool list_member(List *list, void *datum);
205 extern bool list_member_ptr(List *list, void *datum);
206 extern bool list_member_int(List *list, int datum);
207 extern bool list_member_oid(List *list, Oid datum);
209 extern List *list_delete(List *list, void *datum);
210 extern List *list_delete_ptr(List *list, void *datum);
211 extern List *list_delete_int(List *list, int datum);
212 extern List *list_delete_oid(List *list, Oid datum);
213 extern List *list_delete_first(List *list);
214 extern List *list_delete_cell(List *list, ListCell *cell, ListCell *prev);
216 extern List *list_union(List *list1, List *list2);
217 extern List *list_union_ptr(List *list1, List *list2);
218 extern List *list_union_int(List *list1, List *list2);
219 extern List *list_union_oid(List *list1, List *list2);
221 extern List *list_difference(List *list1, List *list2);
222 extern List *list_difference_ptr(List *list1, List *list2);
223 extern List *list_difference_int(List *list1, List *list2);
224 extern List *list_difference_oid(List *list1, List *list2);
226 extern List *list_append_unique(List *list, void *datum);
227 extern List *list_append_unique_ptr(List *list, void *datum);
228 extern List *list_append_unique_int(List *list, int datum);
229 extern List *list_append_unique_oid(List *list, Oid datum);
231 extern List *list_concat_unique(List *list1, List *list2);
232 extern List *list_concat_unique_ptr(List *list1, List *list2);
233 extern List *list_concat_unique_int(List *list1, List *list2);
234 extern List *list_concat_unique_oid(List *list1, List *list2);
236 extern void list_free(List *list);
237 extern void list_free_deep(List *list);
239 extern List *list_copy(List *list);
240 extern List *list_copy_tail(List *list, int nskip);
243 * To ease migration to the new list API, a set of compatibility
244 * macros are provided that reduce the impact of the list API changes
245 * as far as possible. Until client code has been rewritten to use the
246 * new list API, the ENABLE_LIST_COMPAT symbol can be defined before
247 * including pg_list.h
249 #ifdef ENABLE_LIST_COMPAT
251 #define lfirsti(lc) lfirst_int(lc)
252 #define lfirsto(lc) lfirst_oid(lc)
254 #define makeList1(x1) list_make1(x1)
255 #define makeList2(x1, x2) list_make2(x1, x2)
256 #define makeList3(x1, x2, x3) list_make3(x1, x2, x3)
257 #define makeList4(x1, x2, x3, x4) list_make4(x1, x2, x3, x4)
259 #define makeListi1(x1) list_make1_int(x1)
260 #define makeListi2(x1, x2) list_make2_int(x1, x2)
262 #define makeListo1(x1) list_make1_oid(x1)
263 #define makeListo2(x1, x2) list_make2_oid(x1, x2)
265 #define lconsi(datum, list) lcons_int(datum, list)
266 #define lconso(datum, list) lcons_oid(datum, list)
268 #define lappendi(list, datum) lappend_int(list, datum)
269 #define lappendo(list, datum) lappend_oid(list, datum)
271 #define nconc(l1, l2) list_concat(l1, l2)
273 #define nth(n, list) list_nth(list, n)
275 #define member(datum, list) list_member(list, datum)
276 #define ptrMember(datum, list) list_member_ptr(list, datum)
277 #define intMember(datum, list) list_member_int(list, datum)
278 #define oidMember(datum, list) list_member_oid(list, datum)
281 * Note that the old lremove() determined equality via pointer
282 * comparison, whereas the new list_delete() uses equal(); in order to
283 * keep the same behavior, we therefore need to map lremove() calls to
284 * list_delete_ptr() rather than list_delete()
286 #define lremove(elem, list) list_delete_ptr(list, elem)
287 #define LispRemove(elem, list) list_delete(list, elem)
288 #define lremovei(elem, list) list_delete_int(list, elem)
289 #define lremoveo(elem, list) list_delete_oid(list, elem)
291 #define ltruncate(n, list) list_truncate(list, n)
293 #define set_union(l1, l2) list_union(l1, l2)
294 #define set_uniono(l1, l2) list_union_oid(l1, l2)
295 #define set_ptrUnion(l1, l2) list_union_ptr(l1, l2)
297 #define set_difference(l1, l2) list_difference(l1, l2)
298 #define set_differenceo(l1, l2) list_difference_oid(l1, l2)
299 #define set_ptrDifference(l1, l2) list_difference_ptr(l1, l2)
301 #define equali(l1, l2) equal(l1, l2)
302 #define equalo(l1, l2) equal(l1, l2)
304 #define freeList(list) list_free(list)
306 #define listCopy(list) list_copy(list)
308 extern int length(List *list);
309 #endif /* ENABLE_LIST_COMPAT */
311 #endif /* PG_LIST_H */