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//! Basic error handling mechanisms
use std::error::Error;
use std::fmt;

/// The result type for the Parsing
pub type PeelResult<'a, T> = Result<T, PeelError>;

/// Representation for an error of the library
pub struct PeelError {
    /// The error variant
    pub code: ErrorType,

    /// Additional description for the error
    pub description: String,

    /// The cause for this error
    pub cause: Option<Box<Error>>,
}

impl fmt::Display for PeelError {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(f,
               "Code: {:?}, Description: {}",
               self.code,
               self.description)
    }
}

impl fmt::Debug for PeelError {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        fmt::Display::fmt(self, f)
    }
}

impl Error for PeelError {
    fn description(&self) -> &str {
        &self.description
    }
}

#[derive(Debug, PartialEq, Eq)]
/// Error codes as indicator what happened
pub enum ErrorType {
    /// New nodes have to be added before traversing
    NoTreeRoot,

    /// The root parser failed already
    RootParserFailed,
}

/// Throw an internal error
pub fn bail(code: ErrorType, description: &fmt::Display) -> PeelError {
    PeelError {
        code: code,
        description: description.to_string(),
        cause: None,
    }
}

macro_rules! bail {($code:expr, $($fmt:tt)*) => (
    return Err(::error::bail($code, &format_args!($($fmt)*)))
)}