Generalize plugin support in Bazel Skylark rule
It helps users to support their own plugins in a manner consistent to
cc_proto_library and py_proto_libary in their skylark rules
diff --git a/protobuf.bzl b/protobuf.bzl
index c5555fd..0b8f5e7 100644
--- a/protobuf.bzl
+++ b/protobuf.bzl
@@ -62,9 +62,19 @@
if ctx.attr.gen_py:
args += ["--python_out=" + ctx.var["GENDIR"] + "/" + gen_dir]
- if ctx.executable.grpc_cpp_plugin:
- args += ["--plugin=protoc-gen-grpc=" + ctx.executable.grpc_cpp_plugin.path]
- args += ["--grpc_out=" + ctx.var["GENDIR"] + "/" + gen_dir]
+ if ctx.executable.plugin:
+ plugin = ctx.executable.plugin
+ lang = ctx.attr.plugin_language
+ if not lang and plugin.basename.startswith('protoc-gen-'):
+ lang = plugin.basename[len('protoc-gen-'):]
+ if not lang:
+ fail("cannot infer the target language of plugin", "plugin_language")
+
+ outdir = ctx.var["GENDIR"] + "/" + gen_dir
+ if ctx.attr.plugin_options:
+ outdir = ",".join(ctx.attr.plugin_options) + ":" + outdir
+ args += ["--plugin=protoc-gen-%s=%s" % (lang, plugin.path)]
+ args += ["--%s_out=%s" % (lang, outdir)]
if args:
ctx.action(
@@ -72,6 +82,7 @@
outputs=ctx.outputs.outs,
arguments=args + import_flags + [s.path for s in srcs],
executable=ctx.executable.protoc,
+ mnemonic="ProtoCompile",
)
return struct(
@@ -82,7 +93,7 @@
),
)
-_proto_gen = rule(
+proto_gen = rule(
attrs = {
"srcs": attr.label_list(allow_files = True),
"deps": attr.label_list(providers = ["proto"]),
@@ -93,11 +104,13 @@
single_file = True,
mandatory = True,
),
- "grpc_cpp_plugin": attr.label(
+ "plugin": attr.label(
cfg = HOST_CFG,
+ allow_files = True,
executable = True,
- single_file = True,
),
+ "plugin_language": attr.string(),
+ "plugin_options": attr.string_list(),
"gen_cc": attr.bool(),
"gen_py": attr.bool(),
"outs": attr.output_list(),
@@ -105,6 +118,26 @@
output_to_genfiles = True,
implementation = _proto_gen_impl,
)
+"""Generates codes from Protocol Buffers definitions.
+
+This rule helps you to implement Skylark macros specific to the target
+language. You should prefer more specific `cc_proto_library `,
+`py_proto_library` and others unless you are adding such wrapper macros.
+
+Args:
+ srcs: Protocol Buffers definition files (.proto) to run the protocol compiler
+ against.
+ deps: a list of dependency labels; must be other proto libraries.
+ includes: a list of include paths to .proto files.
+ protoc: the label of the protocol compiler to generate the sources.
+ plugin: the label of the protocol compiler plugin to be passed to the protocol
+ compiler.
+ plugin_language: the language of the generated sources
+ plugin_options: a list of options to be passed to the plugin
+ gen_cc: generates C++ sources in addition to the ones from the plugin.
+ gen_py: generates Python sources in addition to the ones from the plugin.
+ outs: a list of labels of the expected outputs from the protocol compiler.
+"""
def cc_proto_library(
name,
@@ -150,7 +183,7 @@
if internal_bootstrap_hack:
# For pre-checked-in generated files, we add the internal_bootstrap_hack
# which will skip the codegen action.
- _proto_gen(
+ proto_gen(
name=name + "_genproto",
srcs=srcs,
deps=[s + "_genproto" for s in deps],
@@ -170,13 +203,14 @@
outs = _CcOuts(srcs, use_grpc_plugin)
- _proto_gen(
+ proto_gen(
name=name + "_genproto",
srcs=srcs,
deps=[s + "_genproto" for s in deps],
includes=includes,
protoc=protoc,
- grpc_cpp_plugin=grpc_cpp_plugin,
+ plugin=grpc_cpp_plugin,
+ plugin_language="grpc",
gen_cc=1,
outs=outs,
visibility=["//visibility:public"],
@@ -286,7 +320,7 @@
if include != None:
includes = [include]
- _proto_gen(
+ proto_gen(
name=name + "_genproto",
srcs=srcs,
deps=[s + "_genproto" for s in deps],
