engine error skeleton

src/engine/error.rs

@@ -0,0 +1,74 @@
+// This file is part of rust-web/twig
+//
+// For the copyright and license information, please view the LICENSE
+// file that was distributed with this source code.
+
+//! Typisation of syntax errors.
+
+use std::error::Error;
+use std::fmt::{self, Display};
+use std::convert::From;
+
+pub type LoaderError = Box<Error>; // unimplemented!()
+pub type ParserError = Box<Error>; // unimplemented!()
+pub type LexerError = Box<Error>; // unimplemented!()
+pub type ExtensionRegistryError = Box<Error>; // unimplemented!()
+
+
+#[derive(Debug)]
+pub enum TwigError {
+    Loader(LoaderError),
+    Lexer(LexerError),
+    Parser(ParserError),
+    ExtensionRegistry(ExtensionRegistryError),
+}
+
+impl From<LoaderError> for TwigError {
+    fn from(err: LoaderError) -> TwigError {
+        TwigError::Loader(err)
+    }
+}
+
+// Due to the `dummy` error impls we can not define different From-impls
+//
+// impl From<LexerError> for TwigError {
+//     fn from(err: LexerError) -> TwigError {
+//         TwigError::Lexer(err)
+//     }
+// }
+//
+// impl From<ParserError> for TwigError {
+//     fn from(err: ParserError) -> TwigError {
+//         TwigError::Parser(err)
+//     }
+// }
+//
+// impl From<ExtensionRegistryError> for TwigError {
+//     fn from(err: ExtensionRegistryError) -> TwigError {
+//         TwigError::ExtensionRegistry(err)
+//     }
+// }
+
+impl Error for TwigError {
+    fn description(&self) -> &str {
+        match *self {
+            TwigError::Loader(..) => "Twig loader error.",
+            TwigError::Lexer(..) => "Twig lexer error.",
+            TwigError::Parser(..) => "Twig parser error.",
+            TwigError::ExtensionRegistry(..) => "Twig extension registry error."
+        }
+    }
+}
+
+impl Display for TwigError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        try!(write!(f, "{}", self.description()));
+
+        match *self {
+            TwigError::Loader(ref e) => Display::fmt(e,f),
+            TwigError::Lexer(ref e) => Display::fmt(e,f),
+            TwigError::Parser(ref e) => Display::fmt(e,f),
+            TwigError::ExtensionRegistry(ref e) => Display::fmt(e,f),
+        }
+    }
+}

src/engine/mod.rs

@@ -0,0 +1,11 @@
+// This file is part of rust-web/twig
+//
+// For the copyright and license information, please view the LICENSE
+// file that was distributed with this source code.
+
+//! The Twig Engine.
+
+pub mod error;
+pub use self::error::TwigError;
+
+pub struct Engine; // unimplemented!()

src/lib.rs

@@ -60,3 +60,6 @@
 //! [twigphp]: http://twig.sensiolabs.org/documentation
 
 #[macro_use] pub mod api;
+pub mod engine;
+
+pub use self::engine::Engine;