Initial

advent/common/char_provider.py

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+from typing import Iterable, Iterator
+
+from .provider import EofException, Provider
+
+
+class CharProvider(Provider[str]):
+    data: Iterator[str]
+
+    def __init__(self, data: Iterator[str] | Iterable[str]) -> None:
+        if isinstance(data, Iterator):
+            self.data = data
+        else:
+            self.data = iter(data)
+        self.peeked: list[str] = []
+
+    def _ensure_next(self) -> str:
+        if not self.peeked:
+            try:
+                self.peeked = [next(self.data)]
+            except StopIteration:
+                raise EofException() from None
+        return self.peeked[0]
+
+    def peek(self) -> str:
+        return self._ensure_next()
+
+    def get(self) -> str:
+        result = self._ensure_next()
+        self.peeked = self.peeked[1:]
+        return result
+
+    def finished(self) -> bool:
+        try:
+            self._ensure_next()
+            return False
+        except EofException:
+            return True