1 files changed, 48 insertions, 0 deletions
diff --git a/third_party/rust/quick-error/examples/context.rs b/third_party/rust/quick-error/examples/context.rs
new file mode 100644
index 0000000000..334700a03f
--- /dev/null
+++ b/third_party/rust/quick-error/examples/context.rs
@@ -0,0 +1,48 @@
+#[macro_use(quick_error)] extern crate quick_error;
+
+use std::io::{self, stderr, Read, Write};
+use std::fs::File;
+use std::env;
+use std::num::ParseIntError;
+use std::path::{Path, PathBuf};
+
+use quick_error::ResultExt;
+
+quick_error! {
+    #[derive(Debug)]
+    pub enum Error {
+        NoFileName {
+            description("no file name specified")
+        }
+        Io(err: io::Error, path: PathBuf) {
+            display("could not read file {:?}: {}", path, err)
+            context(path: &'a Path, err: io::Error)
+                -> (err, path.to_path_buf())
+        }
+        Parse(err: ParseIntError, path: PathBuf) {
+            display("could not parse file {:?}: {}", path, err)
+            context(path: &'a Path, err: ParseIntError)
+                -> (err, path.to_path_buf())
+        }
+    }
+}
+
+fn parse_file() -> Result<u64, Error> {
+    let fname = try!(env::args().skip(1).next().ok_or(Error::NoFileName));
+    let fname = Path::new(&fname);
+    let mut file = try!(File::open(fname).context(fname));
+    let mut buf = String::new();
+    try!(file.read_to_string(&mut buf).context(fname));
+    Ok(try!(buf.parse().context(fname)))
+}
+
+fn main() {
+    match parse_file() {
+        Ok(val) => {
+            println!("Read: {}", val);
+        }
+        Err(e) => {
+            writeln!(&mut stderr(), "Error: {}", e).ok();
+        }
+    }
+}