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Support multiple iterators in the Red-Black Tree implementation.

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While we don't need multiple iterators at the moment, the interface is
nicer and less dangerous this way.

Aleksander Alekseev, with some changes by me.
This commit is contained in:
Heikki Linnakangas
2016-09-02 08:39:39 +03:00
parent 76f9dd4fa8
commit 9f85784cae
4 changed files with 209 additions and 175 deletions
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22
src/include/lib/rbtree.h
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@@ -22,7 +22,6 @@
*/
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 */
@@ -41,6 +40,22 @@ typedef enum RBOrderControl
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);
@@ -60,7 +75,8 @@ 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);
extern void rb_begin_iterate(RBTree *rb, RBOrderControl ctrl,
RBTreeIterator *iter);
extern RBNode *rb_iterate(RBTreeIterator *iter);
#endif /* RBTREE_H */