1# Copyright 2020 The Bazel Authors. All rights reserved. 2# 3# Licensed under the Apache License, Version 2.0 (the "License"); 4# you may not use this file except in compliance with the License. 5# You may obtain a copy of the License at 6# 7# http://www.apache.org/licenses/LICENSE-2.0 8# 9# Unless required by applicable law or agreed to in writing, software 10# distributed under the License is distributed on an "AS IS" BASIS, 11# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12# See the License for the specific language governing permissions and 13# limitations under the License. 14 15""" 16select_file() build rule implementation. 17 18Selects a single file from the outputs of a target by given relative path. 19""" 20 21def _impl(ctx): 22 if ctx.attr.subpath and len(ctx.attr.subpath) == 0: 23 fail("Subpath can not be empty.") 24 25 out = None 26 canonical = ctx.attr.subpath.replace("\\", "/") 27 for file_ in ctx.attr.srcs.files.to_list(): 28 if file_.path.replace("\\", "/").endswith(canonical): 29 out = file_ 30 break 31 if not out: 32 files_str = ",\n".join([ 33 str(f.path) 34 for f in ctx.attr.srcs.files.to_list() 35 ]) 36 fail("Can not find specified file in [%s]" % files_str) 37 return [DefaultInfo(files = depset([out]))] 38 39select_file = rule( 40 implementation = _impl, 41 doc = "Selects a single file from the outputs of a target by given relative path", 42 attrs = { 43 "srcs": attr.label( 44 allow_files = True, 45 mandatory = True, 46 doc = "The target producing the file among other outputs", 47 ), 48 "subpath": attr.string( 49 mandatory = True, 50 doc = "Relative path to the file", 51 ), 52 }, 53) 54