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//! Namespace reference type.
#![cfg(not(feature = "no_module"))]
use crate::ast::Ident;
use crate::{Position, StaticVec};
#[cfg(feature = "no_std")]
use std::prelude::v1::*;
use std::{fmt, num::NonZeroUsize};
/// _(internals)_ A chain of [module][crate::Module] names to namespace-qualify a variable or function call.
/// Exported under the `internals` feature only.
///
/// Not available under `no_module`.
///
/// A [`u64`] offset to the current stack of imported [modules][crate::Module] in the
/// [global runtime state][crate::GlobalRuntimeState] is cached for quick search purposes.
///
/// A [`StaticVec`] is used because the vast majority of namespace-qualified access contains only
/// one level, and it is wasteful to always allocate a [`Vec`] with one element.
#[derive(Clone, Eq, PartialEq, Default, Hash)]
#[non_exhaustive]
pub struct Namespace {
/// Path segments.
pub path: StaticVec<Ident>,
/// Cached index into the current stack of imported [modules][crate::Module], if any.
pub index: Option<NonZeroUsize>,
}
impl fmt::Debug for Namespace {
#[cold]
#[inline(never)]
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
if self.is_empty() {
return f.write_str("NONE");
}
if let Some(index) = self.index {
write!(f, "{index} -> ")?;
}
f.write_str(
&self
.path
.iter()
.map(Ident::as_str)
.collect::<StaticVec<_>>()
.join(crate::engine::NAMESPACE_SEPARATOR),
)
}
}
impl fmt::Display for Namespace {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
if self.is_empty() {
return Ok(());
}
f.write_str(
&self
.path
.iter()
.map(Ident::as_str)
.collect::<StaticVec<_>>()
.join(crate::engine::NAMESPACE_SEPARATOR),
)
}
}
impl Namespace {
/// Constant for no namespace.
pub const NONE: Self = Self {
index: None,
path: StaticVec::new_const(),
};
/// Is this [`Namespace`] empty?
#[inline(always)]
#[must_use]
pub fn is_empty(&self) -> bool {
self.path.is_empty()
}
/// Get the [position][Position] of this [`Namespace`].
///
/// # Panics
///
/// Panics if the path is empty.
#[inline(always)]
#[must_use]
pub fn position(&self) -> Position {
self.path[0].pos
}
/// Get the first path segment of this [`Namespace`].
///
/// # Panics
///
/// Panics if the path is empty.
#[inline(always)]
#[must_use]
pub fn root(&self) -> &str {
&self.path[0].name
}
}