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
|
use std::fmt::{self, Debug, Display, Formatter};
use std::num::NonZeroU64;
use std::ops::Range;
use crate::syntax::SourceId;
/// A value with the span it corresponds to in the source code.
#[derive(Copy, Clone, Eq, PartialEq, Hash)]
pub struct Spanned<T> {
/// The spanned value.
pub v: T,
/// The location in source code of the value.
pub span: Span,
}
impl<T> Spanned<T> {
/// Create a new instance from a value and its span.
pub fn new(v: T, span: impl Into<Span>) -> Self {
Self { v, span: span.into() }
}
/// Convert from `&Spanned<T>` to `Spanned<&T>`
pub fn as_ref(&self) -> Spanned<&T> {
Spanned { v: &self.v, span: self.span }
}
/// Map the value using a function keeping the span.
pub fn map<F, U>(self, f: F) -> Spanned<U>
where
F: FnOnce(T) -> U,
{
Spanned { v: f(self.v), span: self.span }
}
}
impl<T: Debug> Debug for Spanned<T> {
fn fmt(&self, f: &mut Formatter) -> fmt::Result {
self.v.fmt(f)
}
}
/// A unique identifier for a syntax node.
///
/// This is used throughout the compiler to track which source section an error
/// or element stems from. Can be [mapped back](crate::source::SourceStore::range)
/// to a source id + byte range for user facing display.
///
/// Span ids are ordered in the tree to enable quickly finding the node with
/// some id:
/// - The id of a parent is always smaller than the ids of any of its children.
/// - The id of a node is always greater than any id in the subtrees of any left
/// sibling and smaller than any id in the subtrees of any right sibling.
///
/// The internal ids of spans stay mostly stable, even for nodes behind an
/// insertion. This is not true for simple ranges as they shift. Spans can be
/// used as inputs to memoized functions without hurting cache performance when
/// text is inserted somewhere in the document other than the end.
///
/// This type takes 8 bytes and is null-optimized (i.e. `Option<Span>` also
/// takes 8 bytes).
#[derive(Debug, Copy, Clone, Eq, PartialEq, Hash)]
pub struct Span(NonZeroU64);
impl Span {
// Number of bits for and minimum and maximum numbers assignable to spans.
const BITS: usize = 48;
const DETACHED: u64 = 1;
const MIN: u64 = 2;
const MAX: u64 = (1 << Self::BITS) - 1;
/// The full range of numbers available to spans.
pub const FULL: Range<u64> = Self::MIN .. Self::MAX + 1;
/// Create a new span from a source id and a unique number.
///
/// Panics if the `number` is not contained in `FULL`.
pub const fn new(id: SourceId, number: u64) -> Self {
assert!(number >= Self::MIN && number <= Self::MAX);
let bits = ((id.into_raw() as u64) << Self::BITS) | number;
Self(to_non_zero(bits))
}
/// A span that does not point into any source file.
pub const fn detached() -> Self {
Self(to_non_zero(Self::DETACHED))
}
/// The id of the source file the span points into.
pub const fn source(self) -> SourceId {
SourceId::from_raw((self.0.get() >> Self::BITS) as u16)
}
/// The unique number of the span within the source file.
pub const fn number(self) -> u64 {
self.0.get() & ((1 << Self::BITS) - 1)
}
}
/// Convert to a non zero u64.
const fn to_non_zero(v: u64) -> NonZeroU64 {
match NonZeroU64::new(v) {
Some(v) => v,
None => unreachable!(),
}
}
/// Result of numbering a node within an interval.
pub type NumberingResult = Result<(), Unnumberable>;
/// Indicates that a node cannot be numbered within a given interval.
#[derive(Debug, Copy, Clone, Eq, PartialEq)]
pub struct Unnumberable;
impl Display for Unnumberable {
fn fmt(&self, f: &mut Formatter) -> fmt::Result {
f.pad("cannot number within this interval")
}
}
impl std::error::Error for Unnumberable {}
|
