return error when attempt to read/write more than one root element in document

1 files changed, 33 insertions, 0 deletions

diff --git a/src/endable.rs b/src/endable.rs
new file mode 100644
index 0000000..6006080
--- /dev/null
+++ b/src/endable.rs
@@ -0,0 +1,33 @@
+use crate::Error;
+
+#[derive(Debug)]
+pub struct Endable<T> {
+    inner: T,
+    ended: bool,
+}
+
+impl<T> Endable<T> {
+    pub fn new(inner: T) -> Self {
+        Self {
+            inner,
+            ended: false,
+        }
+    }
+
+    pub fn end(&mut self) {
+        self.ended = true;
+    }
+
+    pub fn into_inner(self) -> T {
+        self.inner
+    }
+
+    #[inline(always)]
+    pub fn try_as_mut(&mut self) -> Result<&mut T, Error> {
+        if self.ended {
+            Err(Error::RootElementEnded)
+        } else {
+            Ok(&mut self.inner)
+        }
+    }
+}