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bazel-skylib/rules/write_file_private.bzl
László Csomor 2d1669ed88
write_file: add rule and tests (#122)
This PR adds two new rules: write_file and
write_xfile.

Both rules solve a common problem: to write a text
file with user-defined contents.

The problem is routinely solved using a genrule.
That however requires Bash, since genrules execute
Bash commands.  Requiring Bash is a problem on
Windows.

The new rules do not require any shell.

The only difference between the rules is that
write_xfile creates an executable file while
write_file doesn't.

See https://github.com/bazelbuild/bazel/issues/4319
2019-03-19 07:52:56 +01:00

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# Copyright 2019 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.
"""Implementation of write_file macro and underlying rules.
These rules write a UTF-8 encoded text file, using Bazel's FileWriteAction.
'_write_xfile' marks the resulting file executable, '_write_file' does not.
"""
def _common_impl(ctx, is_executable):
# ctx.actions.write creates a FileWriteAction which uses UTF-8 encoding.
ctx.actions.write(
output = ctx.outputs.out,
content = "\n".join(ctx.attr.content) if ctx.attr.content else "",
is_executable = is_executable,
)
files = depset(direct = [ctx.outputs.out])
runfiles = ctx.runfiles(files = [ctx.outputs.out])
if is_executable:
return [DefaultInfo(files = files, runfiles = runfiles, executable = ctx.outputs.out)]
else:
return [DefaultInfo(files = files, runfiles = runfiles)]
def _impl(ctx):
return _common_impl(ctx, False)
def _ximpl(ctx):
return _common_impl(ctx, True)
_ATTRS = {
"content": attr.string_list(mandatory = False, allow_empty = True),
"out": attr.output(mandatory = True),
}
_write_file = rule(
implementation = _impl,
provides = [DefaultInfo],
attrs = _ATTRS,
)
_write_xfile = rule(
implementation = _ximpl,
executable = True,
provides = [DefaultInfo],
attrs = _ATTRS,
)
def write_file(name, out, content = [], is_executable = False, **kwargs):
"""Creates a UTF-8 encoded text file.
Args:
name: Name of the rule.
out: Path of the output file, relative to this package.
content: A list of strings. Lines of text, the contents of the file.
Newlines are added automatically after every line except the last one.
is_executable: A boolean. Whether to make the output file executable. When
True, the rule's output can be executed using `bazel run` and can be
in the srcs of binary and test rules that require executable sources.
**kwargs: further keyword arguments, e.g. `visibility`
"""
if is_executable:
_write_xfile(
name = name,
content = content,
out = out,
**kwargs
)
else:
_write_file(
name = name,
content = content,
out = out,
**kwargs
)