1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152

//! 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,
    ops::{Deref, DerefMut},
};

/// _(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)]
pub struct Namespace {
    path: StaticVec<Ident>,
    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 Deref for Namespace {
    type Target = StaticVec<Ident>;

    #[inline(always)]
    fn deref(&self) -> &Self::Target {
        &self.path
    }
}

impl DerefMut for Namespace {
    #[inline(always)]
    fn deref_mut(&mut self) -> &mut Self::Target {
        &mut self.path
    }
}

impl From<Vec<Ident>> for Namespace {
    #[inline]
    fn from(mut path: Vec<Ident>) -> Self {
        path.shrink_to_fit();
        Self {
            index: None,
            path: path.into(),
        }
    }
}

impl From<StaticVec<Ident>> for Namespace {
    #[inline]
    fn from(mut path: StaticVec<Ident>) -> Self {
        path.shrink_to_fit();
        Self { index: None, path }
    }
}

impl Namespace {
    /// Constant for no namespace.
    pub const NONE: Self = Self {
        index: None,
        path: StaticVec::new_const(),
    };

    /// Create a new [`Namespace`].
    #[inline(always)]
    #[must_use]
    pub fn new(root: impl Into<Ident>) -> Self {
        let mut path = StaticVec::new_const();
        path.push(root.into());

        Self { index: None, path }
    }
    /// Get the [`Scope`][crate::Scope] index offset.
    #[inline(always)]
    #[must_use]
    pub(crate) const fn index(&self) -> Option<NonZeroUsize> {
        self.index
    }
    /// Set the [`Scope`][crate::Scope] index offset.
    #[inline(always)]
    pub(crate) fn set_index(&mut self, index: Option<NonZeroUsize>) {
        self.index = index;
    }
    /// 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
    }
}