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//! Sailfish runtime

#[macro_use]
mod utils;

mod buffer;
pub mod escape;
pub mod filter;
mod macros;
mod render;
mod size_hint;

pub use buffer::*;
pub use render::*;
pub use size_hint::*;

use std::fmt;

#[doc(hidden)]
pub use crate::{render, render_escaped, render_noop, render_text};

#[derive(Clone, Debug)]
enum RenderErrorKind {
    Msg(String),
    Fmt(fmt::Error),
}

/// The error type which is returned from template function
#[derive(Clone, Debug)]
pub struct RenderError {
    // currently RenderError simply wraps the fmt::Error
    kind: RenderErrorKind,
}

impl RenderError {
    /// Construct a new error with custom message
    pub fn new(msg: &str) -> Self {
        Self {
            kind: RenderErrorKind::Msg(msg.to_owned()),
        }
    }
}

impl fmt::Display for RenderError {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        match self.kind {
            RenderErrorKind::Msg(ref s) => f.write_str(&**s),
            RenderErrorKind::Fmt(ref e) => fmt::Display::fmt(e, f),
        }
    }
}

impl std::error::Error for RenderError {
    fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
        match self.kind {
            RenderErrorKind::Msg(_) => None,
            RenderErrorKind::Fmt(ref e) => Some(e),
        }
    }
}

impl From<fmt::Error> for RenderError {
    #[inline]
    fn from(other: fmt::Error) -> Self {
        Self {
            kind: RenderErrorKind::Fmt(other),
        }
    }
}

pub type RenderResult = Result<String, RenderError>;

#[cfg(test)]
mod tests {
    use super::*;
    use std::error::Error;

    #[test]
    fn render_error() {
        let err = RenderError::new("custom error");
        assert!(err.source().is_none());
        assert_eq!(format!("{}", err), "custom error");

        let err = RenderError::from(std::fmt::Error::default());
        assert!(err.source().is_some());
    }
}