v8
10.1.124 (node 18.2.0)
V8 is Google's open source JavaScript engine
custom-space.h
Go to the documentation of this file.
1
// Copyright 2020 the V8 project authors. All rights reserved.
2
// Use of this source code is governed by a BSD-style license that can be
3
// found in the LICENSE file.
4
5
#
ifndef
INCLUDE_CPPGC_CUSTOM_SPACE_H_
6
#
define
INCLUDE_CPPGC_CUSTOM_SPACE_H_
7
8
#
include
<
stddef
.
h
>
9
10
namespace
cppgc
{
11
12
/**
13
* Index identifying a custom space.
14
*/
15
struct
CustomSpaceIndex
{
16
constexpr
CustomSpaceIndex
(size_t value) :
value
(value) {}
// NOLINT
17
size_t
value
;
18
};
19
20
/**
21
* Top-level base class for custom spaces. Users must inherit from CustomSpace
22
* below.
23
*/
24
class
CustomSpaceBase
{
25
public
:
26
virtual
~
CustomSpaceBase
() =
default
;
27
virtual
CustomSpaceIndex
GetCustomSpaceIndex
()
const
= 0;
28
virtual
bool
IsCompactable
()
const
= 0;
29
};
30
31
/**
32
* Base class custom spaces should directly inherit from. The class inheriting
33
* from `CustomSpace` must define `kSpaceIndex` as unique space index. These
34
* indices need for form a sequence starting at 0.
35
*
36
* Example:
37
* \code
38
* class CustomSpace1 : public CustomSpace<CustomSpace1> {
39
* public:
40
* static constexpr CustomSpaceIndex kSpaceIndex = 0;
41
* };
42
* class CustomSpace2 : public CustomSpace<CustomSpace2> {
43
* public:
44
* static constexpr CustomSpaceIndex kSpaceIndex = 1;
45
* };
46
* \endcode
47
*/
48
template
<
typename
ConcreteCustomSpace>
49
class
CustomSpace
:
public
CustomSpaceBase
{
50
public
:
51
/**
52
* Compaction is only supported on spaces that manually manage slots
53
* recording.
54
*/
55
static
constexpr
bool
kSupportsCompaction
=
false
;
56
57
CustomSpaceIndex
GetCustomSpaceIndex
()
const
final
{
58
return
ConcreteCustomSpace::kSpaceIndex;
59
}
60
bool
IsCompactable
()
const
final
{
61
return
ConcreteCustomSpace::kSupportsCompaction;
62
}
63
};
64
65
/**
66
* User-overridable trait that allows pinning types to custom spaces.
67
*/
68
template
<
typename
T,
typename
=
void
>
69
struct
SpaceTrait
{
70
using
Space =
void
;
71
};
72
73
namespace
internal
{
74
75
template
<
typename
CustomSpace>
76
struct
IsAllocatedOnCompactableSpaceImpl
{
77
static
constexpr
bool
value
= CustomSpace::kSupportsCompaction;
78
};
79
80
template
<>
81
struct
IsAllocatedOnCompactableSpaceImpl
<
void
> {
82
// Non-custom spaces are by default not compactable.
83
static
constexpr
bool
value
=
false
;
84
};
85
86
template
<
typename
T>
87
struct
IsAllocatedOnCompactableSpace
{
88
public
:
89
static
constexpr
bool
value
=
90
IsAllocatedOnCompactableSpaceImpl
<
typename
SpaceTrait
<T>::Space>::value;
91
};
92
93
}
// namespace internal
94
95
}
// namespace cppgc
96
97
#
endif
// INCLUDE_CPPGC_CUSTOM_SPACE_H_
include
cppgc
custom-space.h
Generated on Tue May 24 2022 19:28:51 for v8 by
1.9.1