glulx-asm 0.1.1

// SPDX-License-Identifier: Apache-2.0 WITH LLVM-Exception
// Copyright 2024 Daniel Fox Franke.

//! Definition and impls for [`AssemblerError`].

use core::fmt::{Debug, Display};

#[derive(Debug, Copy, Clone)]
/// Errors that can occur during assembly.
pub enum AssemblerError<L> {
    /// Assembly would overflow Glulx's 4 GiB address space.
    Overflow,
    /// An operand referenced a label which was not defined.
    UndefinedLabel(L),
    /// A label was defined in multiple places.
    DuplicateLabel(L),
    /// A label was right-shifted beyond its alignment.
    InsufficientAlignment {
        /// The label that produced the error.
        label: L,
        /// The offset that was applied to the label.
        offset: i32,
        /// The attempted right-shift amount.
        shift: u8,
    },
}

impl<L> Display for AssemblerError<L>
where
    L: Display,
{
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        match self {
            AssemblerError::Overflow => write!(f, "address space overflow"),
            AssemblerError::UndefinedLabel(l) => write!(f, "undefined label {l}"),
            AssemblerError::DuplicateLabel(l) => write!(f, "duplicate label {l}"),
            AssemblerError::InsufficientAlignment {
                label,
                offset,
                shift,
            } => write!(
                f,
                "label {label} + offset {offset} is insufficiently aligned to be shifted by {shift}"
            ),
        }
    }
}

#[cfg(feature = "std")]
impl<L> std::error::Error for AssemblerError<L> where L: Debug + Display {}