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/*
IXBTreeCursor.h
Copyright 1991, NeXT, Inc.
*/
#import "IXBTree.h"
#ifdef NX_COMPILER_RELEASE_3_0
@interface IXBTreeCursor : Object <IXCursorPositioning>
#else
@interface IXBTreeCursor : Object
#endif
{
struct BTree *btree;
void *keyBuffer;
unsigned keyLength;
unsigned bufferSize;
unsigned storeVersion;
unsigned keyLimit;
unsigned traceHint;
unsigned cursorVersion;
unsigned cursorDepth;
NXZone *cursorZone;
struct BTreeTraceRecord *cursorTrace;
struct {
unsigned isSpanning:1;
unsigned rightRotation:1;
unsigned leftRotation:1;
unsigned traceNeeded:1;
unsigned traceOpened:1;
unsigned zeroPosition:1;
unsigned lastPosition:1;
} cursorStatus;
}
- (IXBTree *)btree;
- initWithBTree:(IXBTree *)aBTree;
/* these methods provided for subclasses. isSynchronized returns FALSE when */
/* the btree has been modified by another cursor, or the last change to the */
/* btree destroyed the synchronization. use setKey:andLength: to synchronize*/
/* or isMatch or getKey:andLength: if still using the same key. changeCount */
/* returns the btree's notion of the store's change count. If this is stale, */
/* synchronization is necessary.*/
- (BOOL)isSynchronized;
- (unsigned)changeCount;
/* the value is a pointer to a buffer. if zero, a buffer will be allocated. */
/* if non- zero, it will be interpreted as a buffer pointer. do not pass an*/
/* uninitialized pointer.*/
- (unsigned)readValue:(void **)value; /* reads the value and returns length*/
- (unsigned)readRange:(void **)value /* reads part of the value*/
ofLength:(unsigned)length atOffset:(unsigned)offset;
- removeValue; /* removes the key/value pair from the B* tree*/
- (BOOL)writeValue:(const void *)value /* replaces if key exists, else inserts*/
andLength:(unsigned)length;
- writeRange:(const void *)value
ofLength:(unsigned)length atOffset:(unsigned)offset;
/* these interpret the value at the cursor location as a typed stream archive.*/
- readObject;
- readObjectFromZone:(NXZone *)zone;
- (BOOL)writeObject:anObject;
/* returns a pointer to a potentially write mapped page. use at your own risk.*/
/* it is fast, since it saves copying, but if you modify the value incorrectly, */
/* you may damage the btree.*/
- (unsigned)openRange:(void **)value
ofLength:(unsigned)length atOffset:(unsigned)offset
forWriting:(BOOL)writing;
/* store hints in secondary btrees to locate primary keys quickly for read */
/* only or read mostly btrees. hints may actually diminish performance when */
/* use with frequently modified btrees.*/
- (BOOL)getKey:(void **)key /* returns hint for cursor position*/
andLength:(unsigned *)length withHint:(unsigned *)hint;
- (BOOL)setKey:(const void *)key /* sets key with hint returned by preceding*/
andLength:(unsigned)length withHint:(unsigned)hint;
@end
These are the contents of the former NiCE NeXT User Group NeXTSTEP/OpenStep software archive, currently hosted by Netfuture.ch.