runmat-vm 0.4.5

use crate::bytecode::Bytecode;
use crate::runtime::call_stack::error_namespace;
use miette::{SourceOffset, SourceSpan};
use runmat_runtime::{build_runtime_error, RuntimeError};
use runmat_thread_local::runmat_thread_local;
use std::cell::Cell;

runmat_thread_local! {
    static CURRENT_PC: Cell<usize> = const { Cell::new(0) };
}

#[inline]
pub fn set_vm_pc(pc: usize) {
    CURRENT_PC.with(|cell| cell.set(pc));
}

#[inline]
pub fn current_vm_pc() -> usize {
    CURRENT_PC.with(|cell| cell.get())
}

pub fn attach_span_at(bytecode: &Bytecode, pc: usize, mut err: RuntimeError) -> RuntimeError {
    if err.span.is_none() {
        if let Some(span) = bytecode.instr_spans.get(pc) {
            let len = span.end.saturating_sub(span.start).max(1);
            err.span = Some(SourceSpan::new(SourceOffset::from(span.start), len));
        }
    }
    err
}

pub fn attach_span_from_pc(bytecode: &Bytecode, err: RuntimeError) -> RuntimeError {
    let pc = current_vm_pc();
    attach_span_at(bytecode, pc, err)
}

#[inline]
pub fn mex(id: &str, msg: &str) -> RuntimeError {
    let suffix = match id.find(':') {
        Some(pos) => &id[pos + 1..],
        None => id,
    };
    let ident = format!("{}:{suffix}", error_namespace());
    build_runtime_error(msg.to_string())
        .with_identifier(ident)
        .build()
}

#[inline]
pub fn ensure_runtime_error_identifier(mut err: RuntimeError) -> RuntimeError {
    if err.identifier.is_none() {
        err.identifier = Some(format!("{}:RuntimeError", error_namespace()));
    }
    err
}