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
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
|
"""BUILD rules for generating flatbuffer files."""
flatc_path = "@flatbuffers//:flatc"
DEFAULT_FLATC_ARGS = [
"--no-union-value-namespacing",
"--gen-object-api",
]
def flatbuffer_library_public(
name,
srcs,
outs,
language_flag,
out_prefix = "",
includes = [],
include_paths = [],
flatc_args = DEFAULT_FLATC_ARGS,
reflection_name = "",
reflection_visiblity = None,
output_to_bindir = False):
"""Generates code files for reading/writing the given flatbuffers in the requested language using the public compiler.
Outs:
filegroup(name): all generated source files.
Fileset([reflection_name]): (Optional) all generated reflection binaries.
Args:
name: Rule name.
srcs: Source .fbs files. Sent in order to the compiler.
outs: Output files from flatc.
language_flag: Target language flag. One of [-c, -j, -js].
out_prefix: Prepend this path to the front of all generated files except on
single source targets. Usually is a directory name.
includes: Optional, list of filegroups of schemas that the srcs depend on.
include_paths: Optional, list of paths the includes files can be found in.
flatc_args: Optional, list of additional arguments to pass to flatc.
reflection_name: Optional, if set this will generate the flatbuffer
reflection binaries for the schemas.
reflection_visiblity: The visibility of the generated reflection Fileset.
output_to_bindir: Passed to genrule for output to bin directory.
"""
include_paths_cmd = ["-I %s" % (s) for s in include_paths]
# '$(@D)' when given a single source target will give the appropriate
# directory. Appending 'out_prefix' is only necessary when given a build
# target with multiple sources.
output_directory = (
("-o $(@D)/%s" % (out_prefix)) if len(srcs) > 1 else ("-o $(@D)")
)
genrule_cmd = " ".join([
"for f in $(SRCS); do",
"$(location %s)" % (flatc_path),
" ".join(flatc_args),
" ".join(include_paths_cmd),
language_flag,
output_directory,
"$$f;",
"done",
])
native.genrule(
name = name,
srcs = srcs,
outs = outs,
output_to_bindir = output_to_bindir,
tools = includes + [flatc_path],
cmd = genrule_cmd,
message = "Generating flatbuffer files for %s:" % (name),
)
if reflection_name:
reflection_genrule_cmd = " ".join([
"for f in $(SRCS); do",
"$(location %s)" % (flatc_path),
"-b --schema",
" ".join(flatc_args),
" ".join(include_paths_cmd),
language_flag,
output_directory,
"$$f;",
"done",
])
reflection_outs = [
(out_prefix + "%s.bfbs") % (s.replace(".fbs", "").split("/")[-1])
for s in srcs
]
native.genrule(
name = "%s_srcs" % reflection_name,
srcs = srcs,
outs = reflection_outs,
output_to_bindir = output_to_bindir,
tools = includes + [flatc_path],
cmd = reflection_genrule_cmd,
message = "Generating flatbuffer reflection binary for %s:" % (name),
)
native.Fileset(
name = reflection_name,
out = "%s_out" % reflection_name,
entries = [
native.FilesetEntry(files = reflection_outs),
],
visibility = reflection_visiblity,
)
def flatbuffer_cc_library(
name,
srcs,
srcs_filegroup_name = "",
out_prefix = "",
includes = [],
include_paths = [],
flatc_args = DEFAULT_FLATC_ARGS,
visibility = None,
srcs_filegroup_visibility = None,
gen_reflections = False):
'''A cc_library with the generated reader/writers for the given flatbuffer definitions.
Outs:
filegroup([name]_srcs): all generated .h files.
filegroup(srcs_filegroup_name if specified, or [name]_includes if not):
Other flatbuffer_cc_library's can pass this in for their `includes`
parameter, if they depend on the schemas in this library.
Fileset([name]_reflection): (Optional) all generated reflection binaries.
cc_library([name]): library with sources and flatbuffers deps.
Remarks:
** Because the genrule used to call flatc does not have any trivial way of
computing the output list of files transitively generated by includes and
--gen-includes (the default) being defined for flatc, the --gen-includes
flag will not work as expected. The way around this is to add a dependency
to the flatbuffer_cc_library defined alongside the flatc included Fileset.
For example you might define:
flatbuffer_cc_library(
name = "my_fbs",
srcs = [ "schemas/foo.fbs" ],
includes = [ "//third_party/bazz:bazz_fbs_includes" ],
)
In which foo.fbs includes a few files from the Fileset defined at
//third_party/bazz:bazz_fbs_includes. When compiling the library that
includes foo_generated.h, and therefore has my_fbs as a dependency, it
will fail to find any of the bazz *_generated.h files unless you also
add bazz's flatbuffer_cc_library to your own dependency list, e.g.:
cc_library(
name = "my_lib",
deps = [
":my_fbs",
"//third_party/bazz:bazz_fbs"
],
)
Happy dependent Flatbuffering!
Args:
name: Rule name.
srcs: Source .fbs files. Sent in order to the compiler.
srcs_filegroup_name: Name of the output filegroup that holds srcs. Pass this
filegroup into the `includes` parameter of any other
flatbuffer_cc_library that depends on this one's schemas.
out_prefix: Prepend this path to the front of all generated files. Usually
is a directory name.
includes: Optional, list of filegroups of schemas that the srcs depend on.
** SEE REMARKS BELOW **
include_paths: Optional, list of paths the includes files can be found in.
flatc_args: Optional list of additional arguments to pass to flatc
(e.g. --gen-mutable).
visibility: The visibility of the generated cc_library. By default, use the
default visibility of the project.
srcs_filegroup_visibility: The visibility of the generated srcs filegroup.
By default, use the value of the visibility parameter above.
gen_reflections: Optional, if true this will generate the flatbuffer
reflection binaries for the schemas.
'''
output_headers = [
(out_prefix + "%s_generated.h") % (s.replace(".fbs", "").split("/")[-1])
for s in srcs
]
reflection_name = "%s_reflection" % name if gen_reflections else ""
flatbuffer_library_public(
name = "%s_srcs" % (name),
srcs = srcs,
outs = output_headers,
language_flag = "-c",
out_prefix = out_prefix,
includes = includes,
include_paths = include_paths,
flatc_args = flatc_args,
reflection_name = reflection_name,
reflection_visiblity = visibility,
)
native.cc_library(
name = name,
hdrs = output_headers,
srcs = output_headers,
features = [
"-parse_headers",
],
deps = [
"@flatbuffers//:runtime_cc",
],
includes = ["."],
linkstatic = 1,
visibility = visibility,
)
# A filegroup for the `srcs`. That is, all the schema files for this
# Flatbuffer set.
native.filegroup(
name = srcs_filegroup_name if srcs_filegroup_name else "%s_includes" % (name),
srcs = srcs,
visibility = srcs_filegroup_visibility if srcs_filegroup_visibility != None else visibility,
)
|
