Support both local installation and hermetic build for Python.

BUILD

@@ -2,7 +2,7 @@ exports_files([
     "._dummy_.py",
     "pywrapper.sh",
     "coverage_report.sh",
-])
+] + glob(["external/*.BUILD"]))
 
 sh_library(
     name = "pywrapper",

bazel_pybind11.bzl

@@ -0,0 +1,138 @@
+
+def bazel_pybind11(
+    name = "pybind11",
+    build_file = "@pybind11_bazel//:pybind11.BUILD",
+    sha256 = "c9375b7453bef1ba0106849c83881e6b6882d892c9fae5b2572a2192100ffb8a",
+    strip_prefix = "pybind11-a54eab92d265337996b8e4b4149d9176c2d428a6",
+    urls = ["https://github.com/pybind/pybind11/archive/a54eab92d265337996b8e4b4149d9176c2d428a6.tar.gz"],
+):
+    native.http_archive(
+        name = name,
+        build_file = build_file,
+        sha256 = sha256,
+        strip_prefix = strip_prefix,
+        urls = urls,
+    )
+
+# https://github.com/pybind/pybind11_bazel/blob/master/build_defs.bzl
+# Copyright (c) 2019 The Pybind Development Team. All rights reserved.
+#
+# All rights reserved. Use of this source code is governed by a
+# BSD-style license that can be found in the LICENSE file.
+
+"""Build rules for pybind11."""
+
+def register_extension_info(**kwargs):
+    pass
+
+PYBIND_COPTS = select({
+    "@pybind11//:msvc_compiler": [],
+    "//conditions:default": [
+        "-fexceptions",
+    ],
+})
+
+PYBIND_FEATURES = [
+    "-use_header_modules",  # Required for pybind11.
+    "-parse_headers",
+]
+
+PYBIND_DEPS = [
+    "@pybind11",
+    # "@local_config_python//:python_headers",
+    # "@python//:python",
+    "@python",
+]
+
+# Builds a Python extension module using pybind11.
+# This can be directly used in python with the import statement.
+# This adds rules for a .so binary file.
+def pybind_extension(
+        name,
+        copts = [],
+        features = [],
+        linkopts = [],
+        tags = [],
+        deps = [],
+        **kwargs):
+    # Mark common dependencies as required for build_cleaner.
+    tags = tags + ["req_dep=%s" % dep for dep in PYBIND_DEPS]
+
+    native.cc_binary(
+        name = name + ".so",
+        copts = copts + PYBIND_COPTS + select({
+            "@pybind11//:msvc_compiler": [],
+            "//conditions:default": [
+                "-fvisibility=hidden",
+            ],
+        }),
+        features = features + PYBIND_FEATURES,
+        linkopts = linkopts + select({
+            "@pybind11//:msvc_compiler": [],
+            "@pybind11//:osx": [],
+            "//conditions:default": ["-Wl,-Bsymbolic"],
+        }),
+        linkshared = 1,
+        tags = tags,
+        deps = deps + PYBIND_DEPS,
+        **kwargs
+    )
+
+# Builds a pybind11 compatible library. This can be linked to a pybind_extension.
+def pybind_library(
+        name,
+        copts = [],
+        features = [],
+        tags = [],
+        deps = [],
+        **kwargs):
+    # Mark common dependencies as required for build_cleaner.
+    tags = tags + ["req_dep=%s" % dep for dep in PYBIND_DEPS]
+
+    native.cc_library(
+        name = name,
+        copts = copts + PYBIND_COPTS,
+        features = features + PYBIND_FEATURES,
+        tags = tags,
+        deps = deps + PYBIND_DEPS,
+        **kwargs
+    )
+
+# # Builds a C++ test for a pybind_library.
+# def pybind_library_test(
+#         name,
+#         copts = [],
+#         features = [],
+#         tags = [],
+#         deps = [],
+#         **kwargs):
+#     # Mark common dependencies as required for build_cleaner.
+#     tags = tags + ["req_dep=%s" % dep for dep in PYBIND_DEPS]
+
+#     native.cc_test(
+#         name = name,
+#         copts = copts + PYBIND_COPTS,
+#         features = features + PYBIND_FEATURES,
+#         tags = tags,
+#         deps = deps + PYBIND_DEPS + [
+#             "//util/python:python_impl",
+#             "//util/python:test_main",
+#         ],
+#         **kwargs
+#     )
+
+# Register extension with build_cleaner.
+register_extension_info(
+    extension = pybind_extension,
+    label_regex_for_dep = "{extension_name}",
+)
+
+register_extension_info(
+    extension = pybind_library,
+    label_regex_for_dep = "{extension_name}",
+)
+
+# register_extension_info(
+#     extension = pybind_library_test,
+#     label_regex_for_dep = "{extension_name}",
+# )