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use super::{Scopes, Value};
use crate::diag::TypError;
use crate::syntax::Span;
use crate::Context;
/// A virtual machine.
pub struct Machine<'a> {
/// The core context.
pub ctx: &'a mut Context,
/// The stack of scopes.
pub scopes: Scopes<'a>,
/// A control flow event that is currently happening.
pub flow: Option<Flow>,
}
impl<'a> Machine<'a> {
/// Create a new virtual machine.
pub fn new(ctx: &'a mut Context, scopes: Scopes<'a>) -> Self {
Self { ctx, scopes, flow: None }
}
}
/// A control flow event that occurred during evaluation.
#[derive(Debug, Clone, PartialEq)]
pub enum Flow {
/// Stop iteration in a loop.
Break(Span),
/// Skip the remainder of the current iteration in a loop.
Continue(Span),
/// Stop execution of a function early, optionally returning an explicit
/// value.
Return(Span, Option<Value>),
}
impl Flow {
/// Return an error stating that this control flow is forbidden.
pub fn forbidden(&self) -> TypError {
match *self {
Self::Break(span) => {
error!(span, "cannot break outside of loop")
}
Self::Continue(span) => {
error!(span, "cannot continue outside of loop")
}
Self::Return(span, _) => {
error!(span, "cannot return outside of function")
}
}
}
}
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