Proof of concept: reporting span information to a Spanned<T> type

1 files changed, 49 insertions, 0 deletions

diff --git a/src/spanned.rs b/src/spanned.rs
new file mode 100644
index 0000000..04ec9b8
--- /dev/null
+++ b/src/spanned.rs
@@ -0,0 +1,49 @@
+//! ```
+//! #[macro_use]
+//! extern crate serde_derive;
+//!
+//! extern crate toml;
+//! use toml::spanned::Spanned;
+//!
+//! #[derive(Deserialize)]
+//! struct Udoprog {
+//!     s: Spanned<String>,
+//! }
+//!
+//! fn main() {
+//!     let t = "s = \"udoprog\"\n";
+//!
+//!     let u: Udoprog = toml::from_str(t).unwrap();
+//!
+//!     assert_eq!(u.s.start, 4);
+//!     assert_eq!(u.s.end, 13);
+//! }
+//! ```
+
+use serde::{Serialize, Serializer};
+
+// FIXME: use a more unique name like "toml::Spanned".
+#[doc(hidden)]
+pub const NAME: &str = "Spanned";
+#[doc(hidden)]
+pub const FIELDS: &[&str] = &["value", "start", "end"];
+
+///
+#[derive(Deserialize, Debug)]
+pub struct Spanned<T> {
+    ///
+    pub value: T,
+    ///
+    pub start: usize,
+    ///
+    pub end: usize,
+}
+
+impl<T: Serialize> Serialize for Spanned<T> {
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: Serializer,
+    {
+        self.value.serialize(serializer)
+    }
+}