extras/embed_data.bzl

# Copyright 2017 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/private:context.bzl", #TODO: This ought to be def
    "go_context",
)

def _go_embed_data_impl(ctx):
  go = go_context(ctx)
  if ctx.attr.src and ctx.attr.srcs:
    fail("%s: src and srcs attributes cannot both be specified" % ctx.label)
  if ctx.attr.src and ctx.attr.flatten:
    fail("%s: src and flatten attributes cannot both be specified" % ctx.label)

  args = ctx.actions.args()
  if ctx.attr.src:
    srcs = [ctx.file.src]
  else:
    srcs = ctx.files.srcs
    args.add("-multi")

  if ctx.attr.package:
    package = ctx.attr.package
  else:
    _, _, package = ctx.label.package.rpartition("/")
    if package == "":
      fail("%s: must provide package attribute for go_embed_data rules in the repository root directory" % ctx.label)

  out = go.declare_file(go, ext=".go")
  args.add([
    "-workspace", ctx.workspace_name,
    "-label", str(ctx.label),
    "-out", out,
    "-package", package,
    "-var", ctx.attr.var,
  ])
  if ctx.attr.flatten:
    args.add("-flatten")
  if ctx.attr.string:
    args.add("-string")
  args.add(srcs)

  library = go.new_library(go, srcs=srcs)
  source = go.library_to_source(go, ctx.attr, library, ctx.coverage_instrumented())

  ctx.actions.run(
      outputs = [out],
      inputs = srcs,
      executable = ctx.executable._embed,
      arguments = [args],
      mnemonic = "GoSourcesData",
  )
  return [
      DefaultInfo(files = depset([out])),
      library, source,
  ]

go_embed_data = rule(
    implementation = _go_embed_data_impl,
    attrs = {
        "package": attr.string(),
        "var": attr.string(default = "Data"),
        "src": attr.label(allow_single_file = True),
        "srcs": attr.label_list(allow_files = True),
        "flatten": attr.bool(),
        "string": attr.bool(),
        "_embed": attr.label(
            default = Label("@io_bazel_rules_go//go/tools/builders:embed"),
            executable = True,
            cfg = "host",
        ),
        "_go_context_data": attr.label(default=Label("@io_bazel_rules_go//:go_context_data")),
    },
    toolchains = ["@io_bazel_rules_go//go:toolchain"],
)
"""See go/extras.rst#go_embed_data for full documentation."""