History

java.lang.Object
- net.sf.saxon.regex.History

```
public class History
extends java.lang.Object
```
The History object is used to avoid backtracking too far. In particular, when a greedy repeat operator allows zero repetitions (something we try to optimize away, but it isn't always possible, then if we backtrack all the way to the start position, we only allow a match at this position if no match at this position is currently recorded in the history.

- Constructor Summary
  
  Constructors
  Constructor Description
  
  History()
- Method Summary
  
  All Methods Instance Methods Concrete Methods
  Modifier and Type Method Description
  
  boolean isDuplicateZeroLengthMatch(Operation op, int position)
  - Methods inherited from class java.lang.Object
    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail
- History
```
public History()
```

Method Detail

isDuplicateZeroLengthMatch

public boolean isDuplicateZeroLengthMatch(Operation op,
                                          int position)