Add error generator macro

libimagerror/src/error_gen.rs

@@ -0,0 +1,113 @@
+#[macro_export]
+macro_rules! generate_error_types {
+    (
+        $name: ident,
+        $kindname: ident,
+        $($kind:ident => $string:expr),*
+    ) => {
+        #[derive(Clone, Copy, Debug, PartialEq)]
+        pub enum $kindname {
+            $( $kind ),*
+        }
+
+        impl Display for $kindname {
+
+            fn fmt(&self, fmt: &mut Formatter) -> Result<(), FmtError> {
+                let s = match *self {
+                    $( $kindname::$kind => $string ),*
+                };
+                try!(write!(fmt, "{}", s));
+                Ok(())
+            }
+
+        }
+
+        #[derive(Debug)]
+        pub struct $name {
+            err_type: $kindname,
+            cause: Option<Box<Error>>,
+        }
+
+        impl $name {
+
+            pub fn new(errtype: $kindname, cause: Option<Box<Error>>) -> $name {
+                $name {
+                    err_type: errtype,
+                    cause: cause,
+                }
+            }
+
+            pub fn err_type(&self) -> $kindname {
+                self.err_type
+            }
+
+        }
+
+        impl Display for $name {
+
+            fn fmt(&self, fmt: &mut Formatter) -> Result<(), FmtError> {
+                try!(write!(fmt, "[{}]", self.err_type));
+                Ok(())
+            }
+
+        }
+
+        impl Error for $name {
+
+            fn description(&self) -> &str {
+                match self.err_type {
+                    $( $kindname::$kind => $string ),*
+                }
+            }
+
+            fn cause(&self) -> Option<&Error> {
+                self.cause.as_ref().map(|e| &**e)
+            }
+
+        }
+
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use std::error::Error;
+    use std::fmt::Error as FmtError;
+    use std::fmt::{Display, Formatter};
+
+    generate_error_types!(TestError, TestErrorKind,
+        TestErrorKindA => "testerrorkind a",
+        TestErrorKindB => "testerrorkind B");
+
+    #[test]
+    fn test_a() {
+        let kind = TestErrorKind::TestErrorKindA;
+        assert_eq!(String::from("testerrorkind a"), format!("{}", kind));
+
+        let e = TestError::new(kind, None);
+        assert_eq!(String::from("[testerrorkind a]"), format!("{}", e));
+    }
+
+    #[test]
+    fn test_b() {
+        let kind = TestErrorKind::TestErrorKindB;
+        assert_eq!(String::from("testerrorkind B"), format!("{}", kind));
+
+        let e = TestError::new(kind, None);
+        assert_eq!(String::from("[testerrorkind B]"), format!("{}", e));
+
+    }
+
+    #[test]
+    fn test_ab() {
+        let kinda = TestErrorKind::TestErrorKindA;
+        let kindb = TestErrorKind::TestErrorKindB;
+        assert_eq!(String::from("testerrorkind a"), format!("{}", kinda));
+        assert_eq!(String::from("testerrorkind B"), format!("{}", kindb));
+
+        let e = TestError::new(kinda, Some(Box::new(TestError::new(kindb, None))));
+        assert_eq!(String::from("[testerrorkind a]"), format!("{}", e));
+        assert_eq!(TestErrorKind::TestErrorKindA, e.err_type());
+        assert_eq!(String::from("[testerrorkind B]"), format!("{}", e.cause().unwrap()));
+    }
+}

libimagerror/src/lib.rs

@@ -1,6 +1 @@
-#[cfg(test)]
+pub mod error_gen;
-mod tests {
-    #[test]
-    fn it_works() {
-    }
-}