internal/gazelle_binary.bzl

# Copyright 2018 The Bazel Authors. All rights reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#    http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

load(
    "@io_bazel_rules_go//go:def.bzl",
    "GoArchive",
    "go_context",
    "go_rule",
)
load(
    "@io_bazel_rules_go//go/private:rules/aspect.bzl",
    "go_archive_aspect",
)
load(
    "@io_bazel_rules_go//go/platform:list.bzl",
    "GOARCH",
    "GOOS",
)

def _gazelle_binary_impl(ctx):
    go = go_context(ctx)

    # Generate a source file with a list of languages. This will get compiled
    # with the rest of the sources in the main package.
    langs_file = go.declare_file(go, "langs.go")
    langs_content_tpl = """
package main

import (
	"github.com/bazelbuild/bazel-gazelle/language"

	{lang_imports}
)

var languages = []language.Language{{
	{lang_calls},
}}
"""
    lang_imports = [_format_import(d[GoArchive].data.importpath) for d in ctx.attr.languages]
    lang_calls = [_format_call(d[GoArchive].data.importpath) for d in ctx.attr.languages]
    langs_content = langs_content_tpl.format(
        lang_imports = "\n\t".join(lang_imports),
        lang_calls = ",\n\t".join(lang_calls),
    )
    go.actions.write(langs_file, langs_content)

    # Build the gazelle binary.
    library = go.new_library(go, is_main = True)
    attr = struct(
        srcs = [struct(files = [langs_file])],
        deps = ctx.attr.languages,
        embed = [ctx.attr._srcs],
    )
    source = go.library_to_source(go, attr, library, ctx.coverage_instrumented())

    archive, executable, runfiles = go.binary(
        go,
        name = ctx.label.name,
        source = source,
        version_file = ctx.version_file,
        info_file = ctx.info_file,
    )

    return [
        library,
        source,
        archive,
        OutputGroupInfo(compilation_outputs = [archive.data.file]),
        DefaultInfo(
            files = depset([executable]),
            runfiles = runfiles,
            executable = executable,
        ),
    ]

gazelle_binary = go_rule(
    implementation = _gazelle_binary_impl,
    attrs = {
        "languages": attr.label_list(
            doc = "A list of language extensions the Gazelle binary will use",
            providers = [GoArchive],
            mandatory = True,
            allow_empty = False,
            aspects = [go_archive_aspect],
        ),
        "pure": attr.string(
            values = [
                "on",
                "off",
                "auto",
            ],
            default = "auto",
        ),
        "static": attr.string(
            values = [
                "on",
                "off",
                "auto",
            ],
            default = "auto",
        ),
        "race": attr.string(
            values = [
                "on",
                "off",
                "auto",
            ],
            default = "auto",
        ),
        "msan": attr.string(
            values = [
                "on",
                "off",
                "auto",
            ],
            default = "auto",
        ),
        "goos": attr.string(
            values = GOOS.keys() + ["auto"],
            default = "auto",
        ),
        "goarch": attr.string(
            values = GOARCH.keys() + ["auto"],
            default = "auto",
        ),
        "_srcs": attr.label(
            default = "//cmd/gazelle:go_default_library",
            aspects = [go_archive_aspect],
        ),
    },
    executable = True,
)

def _format_import(importpath):
    _, _, base = importpath.rpartition("/")
    return '{} "{}"'.format(base + "_", importpath)

def _format_call(importpath):
    _, _, base = importpath.rpartition("/")
    return "{}.NewLanguage()".format(base + "_")