rbtree.h

Go to the documentation of this file.

/*-------------------------------------------------------------------------
 *
 * rbtree.h
 *    interface for PostgreSQL generic Red-Black binary tree package
 *
 * Copyright (c) 2009-2013, PostgreSQL Global Development Group
 *
 * IDENTIFICATION
 *      src/include/utils/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        iteratorState;  /* workspace for iterating through tree */
    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;

/* 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);
extern RBNode *rb_iterate(RBTree *rb);

#endif   /* RBTREE_H */