neovm-core 0.0.1

Core runtime structures for NeoVM
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//! Bootstrap-facing subset of GNU Emacs's `alloc.c`.
//!
//! GNU exposes several GC / memory-management variables from C before Lisp
//! startup runs.  Keep those defaults here so Lisp like `jit-lock.el` can rely
//! on the same low-level variables during runtime and bootstrap.

use crate::emacs_core::symbol::Obarray;
use crate::emacs_core::value::{Value, list_to_vec, next_float_id};

/// Register bootstrap variables owned by the allocation / GC subsystem.
pub fn register_bootstrap_vars(obarray: &mut Obarray) {
    obarray.set_symbol_value("gc-cons-threshold", Value::fixnum(800_000));
    obarray.set_symbol_value("gc-cons-percentage", Value::make_float(0.1));
    obarray.set_symbol_value("garbage-collection-messages", Value::NIL);
    obarray.set_symbol_value("post-gc-hook", Value::NIL);
    obarray.set_symbol_value(
        "memory-signal-data",
        Value::list(vec![
            Value::symbol("error"),
            Value::string(
                "Memory exhausted--use M-x save-some-buffers then exit and restart Emacs",
            ),
        ]),
    );
    obarray.set_symbol_value("memory-full", Value::NIL);
    obarray.set_symbol_value("gc-elapsed", Value::make_float(0.0));
    obarray.set_symbol_value("gcs-done", Value::fixnum(0));
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::emacs_core::eval::Context;

    #[test]
    fn register_bootstrap_vars_matches_gnu_alloc_defaults() {
        crate::test_utils::init_test_tracing();
        let mut obarray = Obarray::new();
        register_bootstrap_vars(&mut obarray);

        assert_eq!(
            obarray.symbol_value("gc-cons-threshold").copied(),
            Some(Value::fixnum(800_000))
        );
        assert_eq!(
            obarray.symbol_value("garbage-collection-messages").copied(),
            Some(Value::NIL)
        );
        assert_eq!(
            obarray.symbol_value("post-gc-hook").copied(),
            Some(Value::NIL)
        );
        assert_eq!(
            obarray.symbol_value("memory-full").copied(),
            Some(Value::NIL)
        );
        assert_eq!(
            obarray.symbol_value("gcs-done").copied(),
            Some(Value::fixnum(0))
        );

        let signal_data = obarray
            .symbol_value("memory-signal-data")
            .copied()
            .expect("memory-signal-data");
        let items = list_to_vec(&signal_data).expect("memory-signal-data list");
        assert_eq!(items.len(), 2);
        assert_eq!(items[0], Value::symbol("error"));
        assert_eq!(
            items[1],
            Value::string(
                "Memory exhausted--use M-x save-some-buffers then exit and restart Emacs"
            )
        );
    }

    #[test]
    fn evaluator_binds_alloc_bootstrap_vars() {
        crate::test_utils::init_test_tracing();
        let eval = Context::new();
        let obarray = eval.obarray();

        assert_eq!(
            obarray.symbol_value("memory-full").copied(),
            Some(Value::NIL)
        );
        assert_eq!(
            obarray.symbol_value("post-gc-hook").copied(),
            Some(Value::NIL)
        );

        let signal_data = obarray
            .symbol_value("memory-signal-data")
            .copied()
            .expect("memory-signal-data");
        let items = list_to_vec(&signal_data).expect("memory-signal-data list");
        assert_eq!(items[0], Value::symbol("error"));
    }
}