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/*-------------------------------------------------------------------------
*
* rbtree.h
* interface for PostgreSQL generic Red-Black binary tree package
*
* Copyright (c) 2009-2023, PostgreSQL Global Development Group
*
* IDENTIFICATION
* src/include/lib/rbtree.h
*
*-------------------------------------------------------------------------
*/
#ifndef RBTREE_H
#define RBTREE_H
/*
* RBTNode is intended to be used as the first field of a larger struct,
* whose additional fields carry whatever payload data the caller needs
* for a tree entry. (The total size of that larger struct is passed to
* rbt_create.) RBTNode is declared here to support this usage, but
* callers must treat it as an opaque struct.
*/
typedef struct RBTNode
{
char color; /* node's current color, red or black */
struct RBTNode *left; /* left child, or RBTNIL if none */
struct RBTNode *right; /* right child, or RBTNIL if none */
struct RBTNode *parent; /* parent, or NULL (not RBTNIL!) if none */
} RBTNode;
/* Opaque struct representing a whole tree */
typedef struct RBTree RBTree;
/* Available tree iteration orderings */
typedef enum RBTOrderControl
{
LeftRightWalk, /* inorder: left child, node, right child */
RightLeftWalk /* reverse inorder: right, node, left */
} RBTOrderControl;
/*
* RBTreeIterator holds state while traversing a tree. This is declared
* here so that callers can stack-allocate this, but must otherwise be
* treated as an opaque struct.
*/
typedef struct RBTreeIterator RBTreeIterator;
struct RBTreeIterator
{
RBTree *rbt;
RBTNode *(*iterate) (RBTreeIterator *iter);
RBTNode *last_visited;
bool is_over;
};
/* Support functions to be provided by caller */
typedef int (*rbt_comparator) (const RBTNode *a, const RBTNode *b, void *arg);
typedef void (*rbt_combiner) (RBTNode *existing, const RBTNode *newdata, void *arg);
typedef RBTNode *(*rbt_allocfunc) (void *arg);
typedef void (*rbt_freefunc) (RBTNode *x, void *arg);
extern RBTree *rbt_create(Size node_size,
rbt_comparator comparator,
rbt_combiner combiner,
rbt_allocfunc allocfunc,
rbt_freefunc freefunc,
void *arg);
extern RBTNode *rbt_find(RBTree *rbt, const RBTNode *data);
extern RBTNode *rbt_find_great(RBTree *rbt, const RBTNode *data, bool equal_match);
extern RBTNode *rbt_find_less(RBTree *rbt, const RBTNode *data, bool equal_match);
extern RBTNode *rbt_leftmost(RBTree *rbt);
extern RBTNode *rbt_insert(RBTree *rbt, const RBTNode *data, bool *isNew);
extern void rbt_delete(RBTree *rbt, RBTNode *node);
extern void rbt_begin_iterate(RBTree *rbt, RBTOrderControl ctrl,
RBTreeIterator *iter);
extern RBTNode *rbt_iterate(RBTreeIterator *iter);
#endif /* RBTREE_H */
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