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/*-------------------------------------------------------------------------
*
* rbtree.h
* interface for PostgreSQL generic Red-Black binary tree package
*
* Copyright (c) 2009-2017, PostgreSQL Global Development Group
*
* IDENTIFICATION
* src/include/lib/rbtree.h
*
*-------------------------------------------------------------------------
*/
#ifndef RBTREE_H
#define RBTREE_H
/*
* RBNode 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
* rb_create.) RBNode is declared here to support this usage, but
* callers must treat it as an opaque struct.
*/
typedef struct RBNode
{
char color; /* node's current color, red or black */
struct RBNode *left; /* left child, or RBNIL if none */
struct RBNode *right; /* right child, or RBNIL if none */
struct RBNode *parent; /* parent, or NULL (not RBNIL!) if none */
} RBNode;
/* Opaque struct representing a whole tree */
typedef struct RBTree RBTree;
/* Available tree iteration orderings */
typedef enum RBOrderControl
{
LeftRightWalk, /* inorder: left child, node, right child */
RightLeftWalk, /* reverse inorder: right, node, left */
DirectWalk, /* preorder: node, left child, right child */
InvertedWalk /* postorder: left child, right child, node */
} RBOrderControl;
/*
* 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 *rb;
RBNode *(*iterate) (RBTreeIterator *iter);
RBNode *last_visited;
char next_step;
bool is_over;
};
/* Support functions to be provided by caller */
typedef int (*rb_comparator) (const RBNode *a, const RBNode *b, void *arg);
typedef void (*rb_combiner) (RBNode *existing, const RBNode *newdata, void *arg);
typedef RBNode *(*rb_allocfunc) (void *arg);
typedef void (*rb_freefunc) (RBNode *x, void *arg);
extern RBTree *rb_create(Size node_size,
rb_comparator comparator,
rb_combiner combiner,
rb_allocfunc allocfunc,
rb_freefunc freefunc,
void *arg);
extern RBNode *rb_find(RBTree *rb, const RBNode *data);
extern RBNode *rb_leftmost(RBTree *rb);
extern RBNode *rb_insert(RBTree *rb, const RBNode *data, bool *isNew);
extern void rb_delete(RBTree *rb, RBNode *node);
extern void rb_begin_iterate(RBTree *rb, RBOrderControl ctrl,
RBTreeIterator *iter);
extern RBNode *rb_iterate(RBTreeIterator *iter);
#endif /* RBTREE_H */
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