1 files changed, 132 insertions, 0 deletions
diff --git a/python/pip_install/private/pip_install_utils.bzl b/python/pip_install/private/pip_install_utils.bzl
new file mode 100644
index 0000000..488583d
--- /dev/null
+++ b/python/pip_install/private/pip_install_utils.bzl
@@ -0,0 +1,132 @@
+# Copyright 2023 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.
+
+"""Utilities for `rules_python` pip rules"""
+
+_SRCS_TEMPLATE = """\
+\"\"\"A generated file containing all source files used for `@rules_python//python/pip_install:pip_repository.bzl` rules
+
+This file is auto-generated from the `@rules_python//python/pip_install/private:srcs_module.update` target. Please
+`bazel run` this target to apply any updates. Note that doing so will discard any local modifications.
+"\"\"
+
+# Each source file is tracked as a target so `pip_repository` rules will know to automatically rebuild if any of the
+# sources changed.
+PIP_INSTALL_PY_SRCS = [
+    {srcs}
+]
+"""
+
+def _src_label(file):
+    dir_path, file_name = file.short_path.rsplit("/", 1)
+
+    return "@rules_python//{}:{}".format(
+        dir_path,
+        file_name,
+    )
+
+def _srcs_module_impl(ctx):
+    srcs = [_src_label(src) for src in ctx.files.srcs]
+    if not srcs:
+        fail("`srcs` cannot be empty")
+    output = ctx.actions.declare_file(ctx.label.name)
+
+    ctx.actions.write(
+        output = output,
+        content = _SRCS_TEMPLATE.format(
+            srcs = "\n    ".join(["\"{}\",".format(src) for src in srcs]),
+        ),
+    )
+
+    return DefaultInfo(
+        files = depset([output]),
+    )
+
+_srcs_module = rule(
+    doc = "A rule for writing a list of sources to a templated file",
+    implementation = _srcs_module_impl,
+    attrs = {
+        "srcs": attr.label(
+            doc = "A filegroup of source files",
+            allow_files = True,
+        ),
+    },
+)
+
+_INSTALLER_TEMPLATE = """\
+#!/bin/bash
+set -euo pipefail
+cp -f "{path}" "${{BUILD_WORKSPACE_DIRECTORY}}/{dest}"
+"""
+
+def _srcs_updater_impl(ctx):
+    output = ctx.actions.declare_file(ctx.label.name + ".sh")
+    target_file = ctx.file.input
+    dest = ctx.file.dest.short_path
+
+    ctx.actions.write(
+        output = output,
+        content = _INSTALLER_TEMPLATE.format(
+            path = target_file.short_path,
+            dest = dest,
+        ),
+        is_executable = True,
+    )
+
+    return DefaultInfo(
+        files = depset([output]),
+        runfiles = ctx.runfiles(files = [target_file]),
+        executable = output,
+    )
+
+_srcs_updater = rule(
+    doc = "A rule for writing a `srcs.bzl` file back to the repository",
+    implementation = _srcs_updater_impl,
+    attrs = {
+        "dest": attr.label(
+            doc = "The target file to write the new `input` to.",
+            allow_single_file = ["srcs.bzl"],
+            mandatory = True,
+        ),
+        "input": attr.label(
+            doc = "The file to write back to the repository",
+            allow_single_file = True,
+            mandatory = True,
+        ),
+    },
+    executable = True,
+)
+
+def srcs_module(name, dest, **kwargs):
+    """A helper rule to ensure `pip_repository` rules are always up to date
+
+    Args:
+        name (str): The name of the sources module
+        dest (str): The filename the module should be written as in the current package.
+        **kwargs (dict): Additional keyword arguments
+    """
+    tags = kwargs.pop("tags", [])
+
+    _srcs_module(
+        name = name,
+        tags = tags,
+        **kwargs
+    )
+
+    _srcs_updater(
+        name = name + ".update",
+        input = name,
+        dest = dest,
+        tags = tags,
+    )