v8 147.3.0

Rust bindings to V8
Documentation 
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
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184

# Copyright 2025 The Chromium Authors
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

import collections
import contextlib
import io
import pathlib

from compiler import Compiler
import config
from graph import IncludeDir
from graph import Target

_HEADER = """# Copyright 2025 The Chromium Authors
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

# AUTOGENERATED FILE. DO NOT EDIT.
# To regenerate, see instructions at build/modules/modularize/README.md

"""
_RULE_MAP = {
    IncludeDir.Builtin: 'builtin_module',
    IncludeDir.Framework: 'framework_module',
    IncludeDir.LibCxx: 'libcxx_module',
    IncludeDir.Sysroot: 'sysroot_module',
    IncludeDir.SysrootModule: 'apple_sysroot_module',
}

_SYSROOT_MODULEMAP = """sysroot_modulemap("sysroot_modulemap") {
  source = "module.modulemap.in"
  out = "${target_gen_dir}/module.modulemap"
}

"""


def _filter_targets(targets: list[Target], compiler: Compiler) -> list[Target]:
  module_to_modulemap = compiler.modulemaps_for_modules()
  modulemap_to_modules = collections.defaultdict(list)
  for k, v in module_to_modulemap.items():
    modulemap_to_modules[v].append(k)

  remaining = [target for target in targets if config.should_compile(target)]
  compiled = set(remaining)
  targets = {target.name: target for target in targets}
  while remaining:
    target = remaining.pop()
    for dep in target.public_deps:
      dep = targets[dep]
      if dep not in compiled:
        compiled.add(dep)
        remaining.append(dep)

    # If we use -fmodule-map-file=c_standard_library.modulemap for one target,
    # all modules in c_standard_library.modulemap need to be precompiled.
    if dep.name not in module_to_modulemap:
      continue
    for module in modulemap_to_modules[module_to_modulemap[dep.name]]:
      if module in targets and targets[module] not in compiled:
        compiled.add(targets[module])
        remaining.append(targets[module])
  return sorted(compiled)


def _update_content(path: pathlib.Path, content: str):
  """Updates the content of a file if changed, thus preventing a siso reload."""
  with contextlib.suppress(FileNotFoundError):
    if path.read_text() == content:
      return
  path.write_text(content)


def render_modulemap(out_dir: pathlib.Path, replacements: dict[pathlib.Path,
                                                               str],
                     targets: list[Target]):
  """Writes a modulemap to {out_dir}"""
  f = io.StringIO()
  f.write(_HEADER.replace('#', '//'))
  for target in targets:
    if target.include_dir != IncludeDir.Sysroot:
      continue
    f.write(f'\nmodule {target.name} [system] {{\n')
    for header in target.headers:
      assert header.include_dir == IncludeDir.Sysroot
      f.write(f'  module {header.submodule_name} {{\n')
      for single in sorted(header.group):
        assert single.abs is not None
        path = str(single.abs)
        for frm, to in replacements.items():
          path = path.replace(str(frm), to)
        # After replacements, all paths should be absolute.
        assert not path.startswith('/'), path
        f.write(f'    header "{path}"\n')
      if not header.exports and header.exports is not None:
        f.write('    export *\n')
      for export in header.exports or []:
        f.write(f'    export {export.submodule_name}\n')

      f.write('  }\n')

    f.write('}\n')
  _update_content(out_dir / 'module.modulemap.in', f.getvalue())


def _render_string_list(f, indent: int, key: str, values: list[str]):
  if not values:
    return
  indent = " " * indent
  f.write(f'{indent}{key} = ')

  if len(values) == 1:
    f.write(f'[ "{values[0]}" ]\n')
  elif len(values) > 1:
    f.write(f'[\n')
    for value in values:
      f.write(f'{indent}  "{value}",\n')
    f.write(f'{indent}]\n')


def render_build_gn(out_dir: pathlib.Path, targets: list[Target],
                    compiler: Compiler):
  """Renders a BUILD.gn file for a specific platform to {out_dir}"""
  targets = _filter_targets(targets, compiler)

  f = io.StringIO()
  f.write(_HEADER)
  f.write('import("//buildtools/third_party/libc++/modules.gni")\n\n')
  all_modulemap_configs = set()
  if compiler.sysroot_dir == IncludeDir.Sysroot:
    all_modulemap_configs.add("sysroot_modulemap")
    f.write(_SYSROOT_MODULEMAP)

  module_to_modulemaps = compiler.modulemaps_for_modules()

  for target in sorted(targets):
    rule = _RULE_MAP[target.include_dir]

    modulemap_target = None
    if target.name in module_to_modulemaps:
      kind, rel = compiler.split_path(module_to_modulemaps[target.name])
      modulemap_target = rel.removesuffix('/module.modulemap').removesuffix(
          '.modulemap').replace('/', '_') + '_modulemap'
      if kind == IncludeDir.Framework and modulemap_target not in all_modulemap_configs:
        f.write(f'framework_modulemap("{modulemap_target}") {{\n')
        f.write(f'  name = "{modulemap_target.removesuffix("_modulemap")}"\n')
        f.write('}\n')
        all_modulemap_configs.add(modulemap_target)
      elif kind == IncludeDir.SysrootModule and modulemap_target not in all_modulemap_configs:
        f.write(f'apple_sysroot_modulemap("{modulemap_target}") {{\n')
        f.write(f'  sysroot_path = "{rel}"\n')
        f.write('}\n')
        all_modulemap_configs.add(modulemap_target)

    f.write(f'{rule}("{target.name}") {{\n')
    if target.include_dir in [IncludeDir.SysrootModule, IncludeDir.Framework
                              ] and modulemap_target is not None:
      f.write(f'  modulemap = ":{modulemap_target}"\n')
      if kind == IncludeDir.SysrootModule:
        f.write(f'  modulemap_path = "{rel}"\n')
    _render_string_list(f, 2, 'public_deps',
                        [f':{dep}' for dep in target.public_deps])
    for k, v in sorted(target.kwargs.items()):
      _render_string_list(f, 2, k, sorted(v))
    f.write('}\n\n')

  f.write('group("all_modules") {\n')
  f.write('  public_deps = [\n')
  for target in sorted(targets):
    f.write(f'    ":{target.name}",\n')
  f.write('  ]\n')
  f.write('}\n\n')

  f.write('config("all_modulemap_configs") {\n')
  f.write('  configs = [\n')
  f.write('    "//buildtools/third_party/libc++:builtin_modulemap",\n')
  f.write('    "//buildtools/third_party/libc++:libcxx_modulemap",\n')
  for target in sorted(all_modulemap_configs):
    f.write(f'    ":{target}",\n')
  f.write('  ]\n')
  f.write('}\n')

  _update_content(out_dir / 'BUILD.gn', f.getvalue())