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+/*-------------------------------------------------------------------------
+ *
+ * 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 three 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
+ *
+ * (At the moment, ints and Oids are the same size, but they may not
+ * always be so; try to be careful to maintain the distinction.)
+ *
+ *
+ * Portions Copyright (c) 1996-2020, 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;
+} ListCell;
+
+typedef struct List
+{
+ NodeTag type; /* T_List, T_IntList, or T_OidList */
+ 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 address of list's third cell, if it has one, else NULL */
+static inline ListCell *
+list_third_cell(const List *l)
+{
+ if (l && l->length >= 3)
+ return &l->elements[2];
+ else
+ return NULL;
+}
+
+/* Fetch address of list's fourth cell, if it has one, else NULL */
+static inline ListCell *
+list_fourth_cell(const List *l)
+{
+ if (l && l->length >= 4)
+ return &l->elements[3];
+ 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_node(type,lc) castNode(type, lfirst(lc))
+
+#define linitial(l) lfirst(list_head(l))
+#define linitial_int(l) lfirst_int(list_head(l))
+#define linitial_oid(l) lfirst_oid(list_head(l))
+#define linitial_node(type,l) castNode(type, linitial(l))
+
+#define lsecond(l) lfirst(list_second_cell(l))
+#define lsecond_int(l) lfirst_int(list_second_cell(l))
+#define lsecond_oid(l) lfirst_oid(list_second_cell(l))
+#define lsecond_node(type,l) castNode(type, lsecond(l))
+
+#define lthird(l) lfirst(list_third_cell(l))
+#define lthird_int(l) lfirst_int(list_third_cell(l))
+#define lthird_oid(l) lfirst_oid(list_third_cell(l))
+#define lthird_node(type,l) castNode(type, lthird(l))
+
+#define lfourth(l) lfirst(list_fourth_cell(l))
+#define lfourth_int(l) lfirst_int(list_fourth_cell(l))
+#define lfourth_oid(l) lfirst_oid(list_fourth_cell(l))
+#define lfourth_node(type,l) castNode(type, lfourth(l))
+
+#define llast(l) lfirst(list_tail(l))
+#define llast_int(l) lfirst_int(list_tail(l))
+#define llast_oid(l) lfirst_oid(list_tail(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_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_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_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))
+
+/*
+ * 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 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 *lappend(List *list, void *datum);
+extern List *lappend_int(List *list, int datum);
+extern List *lappend_oid(List *list, Oid datum);
+
+extern List *list_insert_nth(List *list, int pos, void *datum);
+extern List *list_insert_nth_int(List *list, int pos, int datum);
+extern List *list_insert_nth_oid(List *list, int pos, Oid datum);
+
+extern List *lcons(void *datum, List *list);
+extern List *lcons_int(int datum, List *list);
+extern List *lcons_oid(Oid datum, List *list);
+
+extern List *list_concat(List *list1, const List *list2);
+extern List *list_concat_copy(const List *list1, const List *list2);
+
+extern 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 List *list_delete(List *list, void *datum);
+extern List *list_delete_ptr(List *list, void *datum);
+extern List *list_delete_int(List *list, int datum);
+extern List *list_delete_oid(List *list, Oid datum);
+extern List *list_delete_first(List *list);
+extern List *list_delete_last(List *list);
+extern List *list_delete_nth_cell(List *list, int n);
+extern 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 List *list_append_unique(List *list, void *datum);
+extern List *list_append_unique_ptr(List *list, void *datum);
+extern List *list_append_unique_int(List *list, int datum);
+extern List *list_append_unique_oid(List *list, Oid datum);
+
+extern List *list_concat_unique(List *list1, const List *list2);
+extern List *list_concat_unique_ptr(List *list1, const List *list2);
+extern List *list_concat_unique_int(List *list1, const List *list2);
+extern 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 List *list_copy(const List *list);
+extern List *list_copy_tail(const List *list, int nskip);
+extern 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_oid_cmp(const ListCell *p1, const ListCell *p2);
+
+#endif /* PG_LIST_H */
generated by cgit v1.2.3 (git 2.39.1) at 2024-08-16 20:41:10 +0000