src/main/java/com/irtimaled/bbor/client/providers/Iterators.java

   1 package com.irtimaled.bbor.client.providers;
   2
   3 import com.irtimaled.bbor.common.models.AbstractBoundingBox;
   4
   5 import java.util.Iterator;
   6 import java.util.function.Supplier;
   7
   8 class Iterators {
   9     private static class Empty<T> implements Iterable<T> {
  10         @Override
  11         public Iterator<T> iterator() {
  12             return new Iterator<T>() {
  13                 @Override
  14                 public boolean hasNext() {
  15                     return false;
  16                 }
  17
  18                 @Override
  19                 public T next() {
  20                     return null;
  21                 }
  22             };
  23         }
  24     }
  25
  26     static <T extends AbstractBoundingBox> Iterable<T> empty() {
  27         return new Empty<>();
  28     }
  29
  30     private static class SingletonIterable<T> implements Iterable<T> {
  31         private final Supplier<T> supplier;
  32
  33         private SingletonIterable(Supplier<T> supplier) {
  34             this.supplier = supplier;
  35         }
  36
  37         @Override
  38         public Iterator<T> iterator() {
  39             return new Iterator<T>() {
  40                 private boolean hasNext = true;
  41                 @Override
  42                 public boolean hasNext() {
  43                     return hasNext;
  44                 }
  45
  46                 @Override
  47                 public T next() {
  48                     if(!hasNext) return null;
  49
  50                     hasNext = false;
  51                     return supplier.get();
  52                 }
  53             };
  54         }
  55     }
  56
  57     public static <T extends AbstractBoundingBox> Iterable<T> singleton(final Supplier<T> supplier) {
  58         return new SingletonIterable<>(supplier);
  59     }
  60 }