Current File : //backups/router/usr/local/include/postgresql/server/nodes/pg_list.h
/*-------------------------------------------------------------------------
*
* pg_list.h
* interface for PostgreSQL generic list package
*
* Once upon a time, parts of Postgres were written in Lisp and used real
* cons-cell lists for major data structures. When that code was rewritten
* in C, we initially had a faithful emulation of cons-cell lists, which
* unsurprisingly was a performance bottleneck. A couple of major rewrites
* later, these data structures are actually simple expansible arrays;
* but the "List" name and a lot of the notation survives.
*
* One important concession to the original implementation is that an empty
* list is always represented by a null pointer (preferentially written NIL).
* Non-empty lists have a header, which will not be relocated as long as the
* list remains non-empty, and an expansible data array.
*
* We support four types of lists:
*
* T_List: lists of pointers
* (in practice usually pointers to Nodes, but not always;
* declared as "void *" to minimize casting annoyances)
* T_IntList: lists of integers
* T_OidList: lists of Oids
* T_XidList: lists of TransactionIds
* (the XidList infrastructure is less complete than the other cases)
*
* (At the moment, ints, Oids, and XIDs are the same size, but they may not
* always be so; be careful to use the appropriate list type for your data.)
*
*
* Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* src/include/nodes/pg_list.h
*
*-------------------------------------------------------------------------
*/
#ifndef PG_LIST_H
#define PG_LIST_H
#include "nodes/nodes.h"
typedef union ListCell
{
void *ptr_value;
int int_value;
Oid oid_value;
TransactionId xid_value;
} ListCell;
typedef struct List
{
NodeTag type; /* T_List, T_IntList, T_OidList, or T_XidList */
int length; /* number of elements currently present */
int max_length; /* allocated length of elements[] */
ListCell *elements; /* re-allocatable array of cells */
/* We may allocate some cells along with the List header: */
ListCell initial_elements[FLEXIBLE_ARRAY_MEMBER];
/* If elements == initial_elements, it's not a separate allocation */
} List;
/*
* The *only* valid representation of an empty list is NIL; in other
* words, a non-NIL list is guaranteed to have length >= 1.
*/
#define NIL ((List *) NULL)
/*
* State structs for various looping macros below.
*/
typedef struct ForEachState
{
const List *l; /* list we're looping through */
int i; /* current element index */
} ForEachState;
typedef struct ForBothState
{
const List *l1; /* lists we're looping through */
const List *l2;
int i; /* common element index */
} ForBothState;
typedef struct ForBothCellState
{
const List *l1; /* lists we're looping through */
const List *l2;
int i1; /* current element indexes */
int i2;
} ForBothCellState;
typedef struct ForThreeState
{
const List *l1; /* lists we're looping through */
const List *l2;
const List *l3;
int i; /* common element index */
} ForThreeState;
typedef struct ForFourState
{
const List *l1; /* lists we're looping through */
const List *l2;
const List *l3;
const List *l4;
int i; /* common element index */
} ForFourState;
typedef struct ForFiveState
{
const List *l1; /* lists we're looping through */
const List *l2;
const List *l3;
const List *l4;
const List *l5;
int i; /* common element index */
} ForFiveState;
/*
* These routines are small enough, and used often enough, to justify being
* inline.
*/
/* Fetch address of list's first cell; NULL if empty list */
static inline ListCell *
list_head(const List *l)
{
return l ? &l->elements[0] : NULL;
}
/* Fetch address of list's last cell; NULL if empty list */
static inline ListCell *
list_tail(const List *l)
{
return l ? &l->elements[l->length - 1] : NULL;
}
/* Fetch address of list's second cell, if it has one, else NULL */
static inline ListCell *
list_second_cell(const List *l)
{
if (l && l->length >= 2)
return &l->elements[1];
else
return NULL;
}
/* Fetch list's length */
static inline int
list_length(const List *l)
{
return l ? l->length : 0;
}
/*
* Macros to access the data values within List cells.
*
* Note that with the exception of the "xxx_node" macros, these are
* lvalues and can be assigned to.
*
* NB: There is an unfortunate legacy from a previous incarnation of
* the List API: the macro lfirst() was used to mean "the data in this
* cons cell". To avoid changing every usage of lfirst(), that meaning
* has been kept. As a result, lfirst() takes a ListCell and returns
* the data it contains; to get the data in the first cell of a
* List, use linitial(). Worse, lsecond() is more closely related to
* linitial() than lfirst(): given a List, lsecond() returns the data
* in the second list cell.
*/
#define lfirst(lc) ((lc)->ptr_value)
#define lfirst_int(lc) ((lc)->int_value)
#define lfirst_oid(lc) ((lc)->oid_value)
#define lfirst_xid(lc) ((lc)->xid_value)
#define lfirst_node(type,lc) castNode(type, lfirst(lc))
#define linitial(l) lfirst(list_nth_cell(l, 0))
#define linitial_int(l) lfirst_int(list_nth_cell(l, 0))
#define linitial_oid(l) lfirst_oid(list_nth_cell(l, 0))
#define linitial_node(type,l) castNode(type, linitial(l))
#define lsecond(l) lfirst(list_nth_cell(l, 1))
#define lsecond_int(l) lfirst_int(list_nth_cell(l, 1))
#define lsecond_oid(l) lfirst_oid(list_nth_cell(l, 1))
#define lsecond_node(type,l) castNode(type, lsecond(l))
#define lthird(l) lfirst(list_nth_cell(l, 2))
#define lthird_int(l) lfirst_int(list_nth_cell(l, 2))
#define lthird_oid(l) lfirst_oid(list_nth_cell(l, 2))
#define lthird_node(type,l) castNode(type, lthird(l))
#define lfourth(l) lfirst(list_nth_cell(l, 3))
#define lfourth_int(l) lfirst_int(list_nth_cell(l, 3))
#define lfourth_oid(l) lfirst_oid(list_nth_cell(l, 3))
#define lfourth_node(type,l) castNode(type, lfourth(l))
#define llast(l) lfirst(list_last_cell(l))
#define llast_int(l) lfirst_int(list_last_cell(l))
#define llast_oid(l) lfirst_oid(list_last_cell(l))
#define llast_xid(l) lfirst_xid(list_last_cell(l))
#define llast_node(type,l) castNode(type, llast(l))
/*
* Convenience macros for building fixed-length lists
*/
#define list_make_ptr_cell(v) ((ListCell) {.ptr_value = (v)})
#define list_make_int_cell(v) ((ListCell) {.int_value = (v)})
#define list_make_oid_cell(v) ((ListCell) {.oid_value = (v)})
#define list_make_xid_cell(v) ((ListCell) {.xid_value = (v)})
#define list_make1(x1) \
list_make1_impl(T_List, list_make_ptr_cell(x1))
#define list_make2(x1,x2) \
list_make2_impl(T_List, list_make_ptr_cell(x1), list_make_ptr_cell(x2))
#define list_make3(x1,x2,x3) \
list_make3_impl(T_List, list_make_ptr_cell(x1), list_make_ptr_cell(x2), \
list_make_ptr_cell(x3))
#define list_make4(x1,x2,x3,x4) \
list_make4_impl(T_List, list_make_ptr_cell(x1), list_make_ptr_cell(x2), \
list_make_ptr_cell(x3), list_make_ptr_cell(x4))
#define list_make5(x1,x2,x3,x4,x5) \
list_make5_impl(T_List, list_make_ptr_cell(x1), list_make_ptr_cell(x2), \
list_make_ptr_cell(x3), list_make_ptr_cell(x4), \
list_make_ptr_cell(x5))
#define list_make1_int(x1) \
list_make1_impl(T_IntList, list_make_int_cell(x1))
#define list_make2_int(x1,x2) \
list_make2_impl(T_IntList, list_make_int_cell(x1), list_make_int_cell(x2))
#define list_make3_int(x1,x2,x3) \
list_make3_impl(T_IntList, list_make_int_cell(x1), list_make_int_cell(x2), \
list_make_int_cell(x3))
#define list_make4_int(x1,x2,x3,x4) \
list_make4_impl(T_IntList, list_make_int_cell(x1), list_make_int_cell(x2), \
list_make_int_cell(x3), list_make_int_cell(x4))
#define list_make5_int(x1,x2,x3,x4,x5) \
list_make5_impl(T_IntList, list_make_int_cell(x1), list_make_int_cell(x2), \
list_make_int_cell(x3), list_make_int_cell(x4), \
list_make_int_cell(x5))
#define list_make1_oid(x1) \
list_make1_impl(T_OidList, list_make_oid_cell(x1))
#define list_make2_oid(x1,x2) \
list_make2_impl(T_OidList, list_make_oid_cell(x1), list_make_oid_cell(x2))
#define list_make3_oid(x1,x2,x3) \
list_make3_impl(T_OidList, list_make_oid_cell(x1), list_make_oid_cell(x2), \
list_make_oid_cell(x3))
#define list_make4_oid(x1,x2,x3,x4) \
list_make4_impl(T_OidList, list_make_oid_cell(x1), list_make_oid_cell(x2), \
list_make_oid_cell(x3), list_make_oid_cell(x4))
#define list_make5_oid(x1,x2,x3,x4,x5) \
list_make5_impl(T_OidList, list_make_oid_cell(x1), list_make_oid_cell(x2), \
list_make_oid_cell(x3), list_make_oid_cell(x4), \
list_make_oid_cell(x5))
#define list_make1_xid(x1) \
list_make1_impl(T_XidList, list_make_xid_cell(x1))
#define list_make2_xid(x1,x2) \
list_make2_impl(T_XidList, list_make_xid_cell(x1), list_make_xid_cell(x2))
#define list_make3_xid(x1,x2,x3) \
list_make3_impl(T_XidList, list_make_xid_cell(x1), list_make_xid_cell(x2), \
list_make_xid_cell(x3))
#define list_make4_xid(x1,x2,x3,x4) \
list_make4_impl(T_XidList, list_make_xid_cell(x1), list_make_xid_cell(x2), \
list_make_xid_cell(x3), list_make_xid_cell(x4))
#define list_make5_xid(x1,x2,x3,x4,x5) \
list_make5_impl(T_XidList, list_make_xid_cell(x1), list_make_xid_cell(x2), \
list_make_xid_cell(x3), list_make_xid_cell(x4), \
list_make_xid_cell(x5))
/*
* Locate the n'th cell (counting from 0) of the list.
* It is an assertion failure if there is no such cell.
*/
static inline ListCell *
list_nth_cell(const List *list, int n)
{
Assert(list != NIL);
Assert(n >= 0 && n < list->length);
return &list->elements[n];
}
/*
* Return the last cell in a non-NIL List.
*/
static inline ListCell *
list_last_cell(const List *list)
{
Assert(list != NIL);
return &list->elements[list->length - 1];
}
/*
* Return the pointer value contained in the n'th element of the
* specified list. (List elements begin at 0.)
*/
static inline void *
list_nth(const List *list, int n)
{
Assert(IsA(list, List));
return lfirst(list_nth_cell(list, n));
}
/*
* Return the integer value contained in the n'th element of the
* specified list.
*/
static inline int
list_nth_int(const List *list, int n)
{
Assert(IsA(list, IntList));
return lfirst_int(list_nth_cell(list, n));
}
/*
* Return the OID value contained in the n'th element of the specified
* list.
*/
static inline Oid
list_nth_oid(const List *list, int n)
{
Assert(IsA(list, OidList));
return lfirst_oid(list_nth_cell(list, n));
}
#define list_nth_node(type,list,n) castNode(type, list_nth(list, n))
/*
* Get the given ListCell's index (from 0) in the given List.
*/
static inline int
list_cell_number(const List *l, const ListCell *c)
{
Assert(c >= &l->elements[0] && c < &l->elements[l->length]);
return c - l->elements;
}
/*
* Get the address of the next cell after "c" within list "l", or NULL if none.
*/
static inline ListCell *
lnext(const List *l, const ListCell *c)
{
Assert(c >= &l->elements[0] && c < &l->elements[l->length]);
c++;
if (c < &l->elements[l->length])
return (ListCell *) c;
else
return NULL;
}
/*
* foreach -
* a convenience macro for looping through a list
*
* "cell" must be the name of a "ListCell *" variable; it's made to point
* to each List element in turn. "cell" will be NULL after normal exit from
* the loop, but an early "break" will leave it pointing at the current
* List element.
*
* Beware of changing the List object while the loop is iterating.
* The current semantics are that we examine successive list indices in
* each iteration, so that insertion or deletion of list elements could
* cause elements to be re-visited or skipped unexpectedly. Previous
* implementations of foreach() behaved differently. However, it's safe
* to append elements to the List (or in general, insert them after the
* current element); such new elements are guaranteed to be visited.
* Also, the current element of the List can be deleted, if you use
* foreach_delete_current() to do so. BUT: either of these actions will
* invalidate the "cell" pointer for the remainder of the current iteration.
*/
#define foreach(cell, lst) \
for (ForEachState cell##__state = {(lst), 0}; \
(cell##__state.l != NIL && \
cell##__state.i < cell##__state.l->length) ? \
(cell = &cell##__state.l->elements[cell##__state.i], true) : \
(cell = NULL, false); \
cell##__state.i++)
/*
* foreach_delete_current -
* delete the current list element from the List associated with a
* surrounding foreach() loop, returning the new List pointer.
*
* This is equivalent to list_delete_cell(), but it also adjusts the foreach
* loop's state so that no list elements will be missed. Do not delete
* elements from an active foreach loop's list in any other way!
*/
#define foreach_delete_current(lst, cell) \
(cell##__state.i--, \
(List *) (cell##__state.l = list_delete_cell(lst, cell)))
/*
* foreach_current_index -
* get the zero-based list index of a surrounding foreach() loop's
* current element; pass the name of the "ListCell *" iterator variable.
*
* Beware of using this after foreach_delete_current(); the value will be
* out of sync for the rest of the current loop iteration. Anyway, since
* you just deleted the current element, the value is pretty meaningless.
*/
#define foreach_current_index(cell) (cell##__state.i)
/*
* for_each_from -
* Like foreach(), but start from the N'th (zero-based) list element,
* not necessarily the first one.
*
* It's okay for N to exceed the list length, but not for it to be negative.
*
* The caveats for foreach() apply equally here.
*/
#define for_each_from(cell, lst, N) \
for (ForEachState cell##__state = for_each_from_setup(lst, N); \
(cell##__state.l != NIL && \
cell##__state.i < cell##__state.l->length) ? \
(cell = &cell##__state.l->elements[cell##__state.i], true) : \
(cell = NULL, false); \
cell##__state.i++)
static inline ForEachState
for_each_from_setup(const List *lst, int N)
{
ForEachState r = {lst, N};
Assert(N >= 0);
return r;
}
/*
* for_each_cell -
* a convenience macro which loops through a list starting from a
* specified cell
*
* The caveats for foreach() apply equally here.
*/
#define for_each_cell(cell, lst, initcell) \
for (ForEachState cell##__state = for_each_cell_setup(lst, initcell); \
(cell##__state.l != NIL && \
cell##__state.i < cell##__state.l->length) ? \
(cell = &cell##__state.l->elements[cell##__state.i], true) : \
(cell = NULL, false); \
cell##__state.i++)
static inline ForEachState
for_each_cell_setup(const List *lst, const ListCell *initcell)
{
ForEachState r = {lst,
initcell ? list_cell_number(lst, initcell) : list_length(lst)};
return r;
}
/*
* forboth -
* a convenience macro for advancing through two linked lists
* simultaneously. This macro loops through both lists at the same
* time, stopping when either list runs out of elements. Depending
* on the requirements of the call site, it may also be wise to
* assert that the lengths of the two lists are equal. (But, if they
* are not, some callers rely on the ending cell values being separately
* NULL or non-NULL as defined here; don't try to optimize that.)
*
* The caveats for foreach() apply equally here.
*/
#define forboth(cell1, list1, cell2, list2) \
for (ForBothState cell1##__state = {(list1), (list2), 0}; \
multi_for_advance_cell(cell1, cell1##__state, l1, i), \
multi_for_advance_cell(cell2, cell1##__state, l2, i), \
(cell1 != NULL && cell2 != NULL); \
cell1##__state.i++)
#define multi_for_advance_cell(cell, state, l, i) \
(cell = (state.l != NIL && state.i < state.l->length) ? \
&state.l->elements[state.i] : NULL)
/*
* for_both_cell -
* a convenience macro which loops through two lists starting from the
* specified cells of each. This macro loops through both lists at the same
* time, stopping when either list runs out of elements. Depending on the
* requirements of the call site, it may also be wise to assert that the
* lengths of the two lists are equal, and initcell1 and initcell2 are at
* the same position in the respective lists.
*
* The caveats for foreach() apply equally here.
*/
#define for_both_cell(cell1, list1, initcell1, cell2, list2, initcell2) \
for (ForBothCellState cell1##__state = \
for_both_cell_setup(list1, initcell1, list2, initcell2); \
multi_for_advance_cell(cell1, cell1##__state, l1, i1), \
multi_for_advance_cell(cell2, cell1##__state, l2, i2), \
(cell1 != NULL && cell2 != NULL); \
cell1##__state.i1++, cell1##__state.i2++)
static inline ForBothCellState
for_both_cell_setup(const List *list1, const ListCell *initcell1,
const List *list2, const ListCell *initcell2)
{
ForBothCellState r = {list1, list2,
initcell1 ? list_cell_number(list1, initcell1) : list_length(list1),
initcell2 ? list_cell_number(list2, initcell2) : list_length(list2)};
return r;
}
/*
* forthree -
* the same for three lists
*/
#define forthree(cell1, list1, cell2, list2, cell3, list3) \
for (ForThreeState cell1##__state = {(list1), (list2), (list3), 0}; \
multi_for_advance_cell(cell1, cell1##__state, l1, i), \
multi_for_advance_cell(cell2, cell1##__state, l2, i), \
multi_for_advance_cell(cell3, cell1##__state, l3, i), \
(cell1 != NULL && cell2 != NULL && cell3 != NULL); \
cell1##__state.i++)
/*
* forfour -
* the same for four lists
*/
#define forfour(cell1, list1, cell2, list2, cell3, list3, cell4, list4) \
for (ForFourState cell1##__state = {(list1), (list2), (list3), (list4), 0}; \
multi_for_advance_cell(cell1, cell1##__state, l1, i), \
multi_for_advance_cell(cell2, cell1##__state, l2, i), \
multi_for_advance_cell(cell3, cell1##__state, l3, i), \
multi_for_advance_cell(cell4, cell1##__state, l4, i), \
(cell1 != NULL && cell2 != NULL && cell3 != NULL && cell4 != NULL); \
cell1##__state.i++)
/*
* forfive -
* the same for five lists
*/
#define forfive(cell1, list1, cell2, list2, cell3, list3, cell4, list4, cell5, list5) \
for (ForFiveState cell1##__state = {(list1), (list2), (list3), (list4), (list5), 0}; \
multi_for_advance_cell(cell1, cell1##__state, l1, i), \
multi_for_advance_cell(cell2, cell1##__state, l2, i), \
multi_for_advance_cell(cell3, cell1##__state, l3, i), \
multi_for_advance_cell(cell4, cell1##__state, l4, i), \
multi_for_advance_cell(cell5, cell1##__state, l5, i), \
(cell1 != NULL && cell2 != NULL && cell3 != NULL && \
cell4 != NULL && cell5 != NULL); \
cell1##__state.i++)
/* Functions in src/backend/nodes/list.c */
extern List *list_make1_impl(NodeTag t, ListCell datum1);
extern List *list_make2_impl(NodeTag t, ListCell datum1, ListCell datum2);
extern List *list_make3_impl(NodeTag t, ListCell datum1, ListCell datum2,
ListCell datum3);
extern List *list_make4_impl(NodeTag t, ListCell datum1, ListCell datum2,
ListCell datum3, ListCell datum4);
extern List *list_make5_impl(NodeTag t, ListCell datum1, ListCell datum2,
ListCell datum3, ListCell datum4,
ListCell datum5);
extern pg_nodiscard List *lappend(List *list, void *datum);
extern pg_nodiscard List *lappend_int(List *list, int datum);
extern pg_nodiscard List *lappend_oid(List *list, Oid datum);
extern pg_nodiscard List *lappend_xid(List *list, TransactionId datum);
extern pg_nodiscard List *list_insert_nth(List *list, int pos, void *datum);
extern pg_nodiscard List *list_insert_nth_int(List *list, int pos, int datum);
extern pg_nodiscard List *list_insert_nth_oid(List *list, int pos, Oid datum);
extern pg_nodiscard List *lcons(void *datum, List *list);
extern pg_nodiscard List *lcons_int(int datum, List *list);
extern pg_nodiscard List *lcons_oid(Oid datum, List *list);
extern pg_nodiscard List *list_concat(List *list1, const List *list2);
extern pg_nodiscard List *list_concat_copy(const List *list1, const List *list2);
extern pg_nodiscard List *list_truncate(List *list, int new_size);
extern bool list_member(const List *list, const void *datum);
extern bool list_member_ptr(const List *list, const void *datum);
extern bool list_member_int(const List *list, int datum);
extern bool list_member_oid(const List *list, Oid datum);
extern bool list_member_xid(const List *list, TransactionId datum);
extern pg_nodiscard List *list_delete(List *list, void *datum);
extern pg_nodiscard List *list_delete_ptr(List *list, void *datum);
extern pg_nodiscard List *list_delete_int(List *list, int datum);
extern pg_nodiscard List *list_delete_oid(List *list, Oid datum);
extern pg_nodiscard List *list_delete_first(List *list);
extern pg_nodiscard List *list_delete_last(List *list);
extern pg_nodiscard List *list_delete_first_n(List *list, int n);
extern pg_nodiscard List *list_delete_nth_cell(List *list, int n);
extern pg_nodiscard List *list_delete_cell(List *list, ListCell *cell);
extern List *list_union(const List *list1, const List *list2);
extern List *list_union_ptr(const List *list1, const List *list2);
extern List *list_union_int(const List *list1, const List *list2);
extern List *list_union_oid(const List *list1, const List *list2);
extern List *list_intersection(const List *list1, const List *list2);
extern List *list_intersection_int(const List *list1, const List *list2);
/* currently, there's no need for list_intersection_ptr etc */
extern List *list_difference(const List *list1, const List *list2);
extern List *list_difference_ptr(const List *list1, const List *list2);
extern List *list_difference_int(const List *list1, const List *list2);
extern List *list_difference_oid(const List *list1, const List *list2);
extern pg_nodiscard List *list_append_unique(List *list, void *datum);
extern pg_nodiscard List *list_append_unique_ptr(List *list, void *datum);
extern pg_nodiscard List *list_append_unique_int(List *list, int datum);
extern pg_nodiscard List *list_append_unique_oid(List *list, Oid datum);
extern pg_nodiscard List *list_concat_unique(List *list1, const List *list2);
extern pg_nodiscard List *list_concat_unique_ptr(List *list1, const List *list2);
extern pg_nodiscard List *list_concat_unique_int(List *list1, const List *list2);
extern pg_nodiscard List *list_concat_unique_oid(List *list1, const List *list2);
extern void list_deduplicate_oid(List *list);
extern void list_free(List *list);
extern void list_free_deep(List *list);
extern pg_nodiscard List *list_copy(const List *oldlist);
extern pg_nodiscard List *list_copy_head(const List *oldlist, int len);
extern pg_nodiscard List *list_copy_tail(const List *oldlist, int nskip);
extern pg_nodiscard List *list_copy_deep(const List *oldlist);
typedef int (*list_sort_comparator) (const ListCell *a, const ListCell *b);
extern void list_sort(List *list, list_sort_comparator cmp);
extern int list_int_cmp(const ListCell *p1, const ListCell *p2);
extern int list_oid_cmp(const ListCell *p1, const ListCell *p2);
#endif /* PG_LIST_H */
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