Indexer (OptaPlanner constraints: Constraint streams 8.22.0-SNAPSHOT API)

Type Parameters:

Tuple_ - For example for from(A).join(B), the tuple is UniTuple<A> xor UniTuple<B>. For example for Bi<A, B>.join(C), the tuple is BiTuple<A, B> xor UniTuple<C>.

Value_ - For example for from(A).join(B), the value is Set<BiTuple<A, B>>. For example for Bi<A, B>.join(C), the value is Set<TriTuple<A, B, C>>.
```
public interface Indexer<Tuple_ extends Tuple,Value_>
```
An indexer for entity or fact X, maps a property or a combination of properties of X, denoted by indexProperties, to all instances of X that match those properties, depending on the the indexer type (equal, lower than, ...). For example for {Lesson(id=1, room=A), Lesson(id=2, room=B), Lesson(id=3, room=A)}, calling get(room=A) would return a map with a keySet of lesson 1 and 3.
It returns a Map<X, V> instead of Set<X> for performance, to avoid doing the same hash lookup twice in the client. For example AbstractJoinNode uses the value to store a set of child tuples justified by the X instance.
The fact X is wrapped in a Tuple, because the BavetTupleState is needed by clients of #visit(IndexProperties, Consumer).

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`boolean`	`isEmpty()`
`void`	`put(IndexProperties indexProperties, Tuple_ tuple, Value_ value)`	Differs from `Map.put(Object, Object)` because it fails if the key already exists.
`Value_`	`remove(IndexProperties indexProperties, Tuple_ tuple)`	Differs from `Map.remove(Object)` because it fails if the key does not exist.
`void`	`visit(IndexProperties indexProperties, BiConsumer<Tuple_,Value_> tupleValueMapEntryVisitor)`

- Method Detail
  - put
```
void put(IndexProperties indexProperties,
         Tuple_ tuple,
         Value_ value)
```
    Differs from Map.put(Object, Object) because it fails if the key already exists.
    
    Parameters:
    
    indexProperties - never null
    
    tuple - never null
    
    value - never null
    
    Throws:
    
    IllegalStateException - if the indexProperties-tuple key already exists
  - remove
```
Value_ remove(IndexProperties indexProperties,
              Tuple_ tuple)
```
    Differs from Map.remove(Object) because it fails if the key does not exist.
    
    Parameters:
    
    indexProperties - never null
    
    tuple - never null
    
    Returns:
    
    never null
    
    Throws:
    
    IllegalStateException - if the indexProperties-tuple key didn't exist
  - visit
```
void visit(IndexProperties indexProperties,
           BiConsumer<Tuple_,Value_> tupleValueMapEntryVisitor)
```
    Parameters:
    
    indexProperties - never null
    
    tupleValueMapEntryVisitor - never null
  - isEmpty
```
boolean isEmpty()
```