2 files changed, 31 insertions, 0 deletions
diff --git a/yapymake/util/__init__.py b/yapymake/util/__init__.py
new file mode 100644
index 0000000..b26bbcd
--- /dev/null
+++ b/yapymake/util/__init__.py
@@ -0,0 +1 @@
+from .peekable_iterator import PeekableIterator
diff --git a/yapymake/util/peekable_iterator.py b/yapymake/util/peekable_iterator.py
new file mode 100644
index 0000000..67bd59d
--- /dev/null
+++ b/yapymake/util/peekable_iterator.py
@@ -0,0 +1,30 @@
+from typing import Iterator, Optional, TypeVar
+
+__all__ = [
+    'PeekableIterator',
+]
+
+T = TypeVar('T')
+
+class PeekableIterator(Iterator[T]):
+    _inner: Iterator[T]
+    _peeked: Optional[T]
+
+    def __init__(self, inner: Iterator[T]):
+        self._inner = inner
+        self._peeked = None
+
+    def __iter__(self) -> Iterator[T]:
+        return self
+
+    def __next__(self) -> T:
+        if self._peeked is not None:
+            result = self._peeked
+            self._peeked = None
+            return result
+        return next(self._inner)
+
+    def peek(self) -> T:
+        if self._peeked is None:
+            self._peeked = next(self._inner)
+        return self._peeked