Add error module with crate's `Error` type.

Implement `Display`, `Error`, and various `FromError<T>` traits on
`Error`, allowing the use of `try!` on the various `Result` types in the
crate.

Note that currently the only error variants are those thrown from
a lower-level operation.

2 files changed, 49 insertions, 0 deletions

diff --git a/src/error.rs b/src/error.rs
new file mode 100644
index 0000000..57d636a
--- /dev/null
+++ b/src/error.rs
@@ -0,0 +1,47 @@
+use std::{
+    error,
+    fmt,
+    io,
+};
+
+use utils::NotmuchEnum;
+use ffi;
+
+#[derive(Debug)]
+pub enum Error {
+    IoError(io::Error),
+    NotmuchError(ffi::NotmuchStatus),
+}
+
+impl fmt::Display for Error {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "{}", error::Error::description(self))
+    }
+}
+
+impl error::Error for Error {
+    fn description(&self) -> &str {
+        match *self {
+            Error::IoError(ref e) => error::Error::description(e),
+            Error::NotmuchError(ref e) => e.description(),
+        }
+    }
+}
+
+impl error::FromError<io::Error> for Error {
+    fn from_error(err: io::Error) -> Error {
+        Error::IoError(err)
+    }
+}
+
+impl error::FromError<ffi::NotmuchStatus> for Error {
+    fn from_error(err: ffi::NotmuchStatus) -> Error {
+        Error::NotmuchError(err)
+    }
+}
+
+impl error::FromError<ffi::notmuch_status_t> for Error {
+    fn from_error(err: ffi::notmuch_status_t) -> Error {
+        Error::NotmuchError(ffi::NotmuchStatus::from_notmuch_t(err))
+    }
+}
diff --git a/src/lib.rs b/src/lib.rs
index f490df7..f7358b7 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -6,3 +6,5 @@ mod macros;
 
 mod ffi;
 mod utils;
+
+pub mod error;