Extract upToAndIncluding iterable

1 files changed, 38 insertions, 0 deletions

diff --git a/src/main/java/org/zwobble/couscous/util/UpToAndIncludingIterable.java b/src/main/java/org/zwobble/couscous/util/UpToAndIncludingIterable.java
new file mode 100644
index 0000000..aef5d06
--- /dev/null
+++ b/src/main/java/org/zwobble/couscous/util/UpToAndIncludingIterable.java
@@ -0,0 +1,38 @@
+package org.zwobble.couscous.util;
+
+import java.util.Iterator;
+import java.util.NoSuchElementException;
+import java.util.function.Predicate;
+
+public class UpToAndIncludingIterable {
+    public static <T> Iterable<T> upToAndIncluding(Iterable<T> iterable, Predicate<T> predicate) {
+        return () -> new UpToIterator<>(iterable.iterator(), predicate);
+    }
+
+    private static class UpToIterator<T> implements Iterator<T> {
+        private final Iterator<T> iterator;
+        private final Predicate<T> predicate;
+        private boolean finished;
+
+        public UpToIterator(Iterator<T> iterator, Predicate<T> predicate) {
+            this.iterator = iterator;
+            this.predicate = predicate;
+        }
+
+        @Override
+        public boolean hasNext() {
+            return !finished && iterator.hasNext();
+        }
+
+        @Override
+        public T next() {
+            if (hasNext()) {
+                T value = iterator.next();
+                finished = predicate.test(value);
+                return value;
+            } else {
+                throw new NoSuchElementException();
+            }
+        }
+    }
+}