SetEvaluator (trino-main 366 API)

java.lang.Object
- io.trino.operator.window.pattern.SetEvaluator

```
public class SetEvaluator
extends Object
```
This class returns a set of positions to aggregate over for an aggregate function in row pattern matching context. Aggregations in row pattern matching context have RUNNING or FINAL semantics, and they apply only to rows matched with certain pattern variables. For example, for a match "A B A A B", the aggregation `sum(B.x)` only applies to the second and the last position.
This evaluator is stateful. It requires a reset for every new match. The method `resolveNewPositions()` returns a portion of positions corresponding to the new portion of the match since the last call. It is thus assumed that a sequence of calls since the instance creation or `reset()` applies to the same match (i.e. the `matchedLabels` passed as an argument to one call is prefix of `matchedLabels` passed in the next call).
Also, a full list of positions for a current match is kept, and it can be obtained via the `getAllPositions()` method. This is for the purpose comparing pattern matching threads in ThreadEquivalence.

Nested Class Summary

Nested Classes
Modifier and Type Class Description

static class SetEvaluator.SetEvaluatorSupplier

Constructor Summary

Constructors
Constructor Description

SetEvaluator(Set<Integer> labels, boolean running)

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`SetEvaluator`	`copy()`
`ArrayView`	`getAllPositions(ArrayView labels)`
`long`	`getAllPositionsSizeInBytes()`
`void`	`reset()`
`ArrayView`	`resolveNewPositions(int currentRow, ArrayView matchedLabels, int partitionStart, int patternStart)`	This method is used for resolving positions for aggregation: - During pattern matching.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
  - SetEvaluator
```
public SetEvaluator(Set<Integer> labels,
                    boolean running)
```
- Method Detail
  - reset
```
public void reset()
```
  - resolveNewPositions
```
public ArrayView resolveNewPositions(int currentRow,
                                     ArrayView matchedLabels,
                                     int partitionStart,
                                     int patternStart)
```
    This method is used for resolving positions for aggregation: - During pattern matching. In this case, the evaluated label has been appended to `matchedLabels` - When computing row pattern measures after a non-empty match is found. Search is limited up to the current row in case of RUNNING semantics and to the entire match in case of FINAL semantics.
    TODO If `evaluated` exceeds `aggregated`, we could reuse the pre-evaluated positions. For that, we need to keep count of all previously returned positions from the `aggregated` prefix.
    
    Returns:
    
    array of new matching positions since the last call, relative to partition start
  - getAllPositions
```
public ArrayView getAllPositions(ArrayView labels)
```
  - copy
```
public SetEvaluator copy()
```
  - getAllPositionsSizeInBytes
```
public long getAllPositionsSizeInBytes()
```