css_parse/
bump_box.rs

1use crate::{Cursor, CursorSink, Parse, Parser, Peek, SemanticEq, ToCursors};
2use bumpalo::Bump;
3use css_lexer::{KindSet, Span, ToSpan};
4use std::fmt;
5use std::hash::{Hash, Hasher};
6use std::ops::{Deref, DerefMut};
7
8/// An arena-allocated box that retains a reference to its [`Bump`] allocator, enabling [`Clone`] support.
9///
10/// Unlike [`bumpalo::boxed::Box`], which only stores a mutable reference to the allocated value (and thus cannot
11/// implement [`Clone`] without the allocator), `BumpBox` stores both the allocator reference and the value pointer.
12/// This allows it to allocate a new copy during [`Clone::clone`].
13///
14/// This type is intended for recursive AST nodes (e.g. `color-mix()` containing nested `<color>` values) where
15/// indirection is required to break the cycle, but the allocation should still live in the parsing arena.
16pub struct BumpBox<'a, T> {
17	bump: &'a Bump,
18	ptr: &'a mut T,
19}
20
21impl<'a, T> BumpBox<'a, T> {
22	/// Allocates a new value in the given bump allocator.
23	#[inline]
24	pub fn new_in(bump: &'a Bump, value: T) -> Self {
25		Self { bump, ptr: bump.alloc(value) }
26	}
27}
28
29impl<T> Deref for BumpBox<'_, T> {
30	type Target = T;
31
32	#[inline]
33	fn deref(&self) -> &T {
34		self.ptr
35	}
36}
37
38impl<T> DerefMut for BumpBox<'_, T> {
39	#[inline]
40	fn deref_mut(&mut self) -> &mut T {
41		self.ptr
42	}
43}
44
45impl<T: Clone> Clone for BumpBox<'_, T> {
46	fn clone(&self) -> Self {
47		let cloned = self.ptr.clone();
48		Self { bump: self.bump, ptr: self.bump.alloc(cloned) }
49	}
50}
51
52impl<T: fmt::Debug> fmt::Debug for BumpBox<'_, T> {
53	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
54		fmt::Debug::fmt(&**self, f)
55	}
56}
57
58impl<T: PartialEq> PartialEq for BumpBox<'_, T> {
59	fn eq(&self, other: &Self) -> bool {
60		(**self).eq(&**other)
61	}
62}
63
64impl<T: Eq> Eq for BumpBox<'_, T> {}
65
66impl<T: PartialOrd> PartialOrd for BumpBox<'_, T> {
67	fn partial_cmp(&self, other: &Self) -> Option<std::cmp::Ordering> {
68		(**self).partial_cmp(&**other)
69	}
70}
71
72impl<T: Ord> Ord for BumpBox<'_, T> {
73	fn cmp(&self, other: &Self) -> std::cmp::Ordering {
74		(**self).cmp(&**other)
75	}
76}
77
78impl<T: Hash> Hash for BumpBox<'_, T> {
79	fn hash<H: Hasher>(&self, state: &mut H) {
80		(**self).hash(state)
81	}
82}
83
84impl<T: ToCursors> ToCursors for BumpBox<'_, T> {
85	fn to_cursors(&self, s: &mut impl CursorSink) {
86		(**self).to_cursors(s);
87	}
88}
89
90impl<T: SemanticEq> SemanticEq for BumpBox<'_, T> {
91	fn semantic_eq(&self, other: &Self) -> bool {
92		(**self).semantic_eq(other)
93	}
94}
95
96impl<T: ToSpan> ToSpan for BumpBox<'_, T> {
97	fn to_span(&self) -> Span {
98		(**self).to_span()
99	}
100}
101
102impl<M: crate::NodeMetadata, T: crate::NodeWithMetadata<M>> crate::NodeWithMetadata<M> for BumpBox<'_, T> {
103	fn self_metadata(&self) -> M {
104		(**self).self_metadata()
105	}
106
107	fn metadata(&self) -> M {
108		(**self).metadata()
109	}
110}
111
112impl<'a, T: Peek<'a>> Peek<'a> for BumpBox<'a, T> {
113	const PEEK_KINDSET: KindSet = T::PEEK_KINDSET;
114
115	fn peek<I>(p: &Parser<'a, I>, c: Cursor) -> bool
116	where
117		I: Iterator<Item = Cursor> + Clone,
118	{
119		T::peek(p, c)
120	}
121}
122
123impl<'a, T: Parse<'a>> Parse<'a> for BumpBox<'a, T> {
124	fn parse<I>(p: &mut Parser<'a, I>) -> crate::Result<Self>
125	where
126		I: Iterator<Item = Cursor> + Clone,
127	{
128		let value = T::parse(p)?;
129		Ok(BumpBox::new_in(p.bump(), value))
130	}
131}
132
133#[cfg(feature = "serde")]
134impl<T: serde::Serialize> serde::Serialize for BumpBox<'_, T> {
135	fn serialize<S: serde::Serializer>(&self, serializer: S) -> std::result::Result<S::Ok, S::Error> {
136		(**self).serialize(serializer)
137	}
138}
css_parse/bump_box.rs

css_parse/
bump_box.rs
