chore: import upstream snapshot with attribution

cmake/external/python.cmake

@@ -0,0 +1,87 @@
+# Copyright (c) 2016 PaddlePaddle 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.
+
+include(python_module)
+
+check_py_version(${PY_VERSION})
+
+# Find Python with minimum PY_VERSION specified or will raise error!
+find_package(PythonInterp ${PY_VERSION} REQUIRED)
+find_package(PythonLibs ${PY_VERSION} REQUIRED)
+
+if(WIN32)
+  execute_process(
+    COMMAND
+      "${PYTHON_EXECUTABLE}" "-c"
+      "from distutils import sysconfig as s;import sys;import struct;
+print(sys.prefix);
+print(s.get_config_var('LDVERSION') or s.get_config_var('VERSION'));
+"
+    RESULT_VARIABLE _PYTHON_SUCCESS
+    OUTPUT_VARIABLE _PYTHON_VALUES
+    ERROR_VARIABLE _PYTHON_ERROR_VALUE)
+
+  if(NOT _PYTHON_SUCCESS EQUAL 0)
+    set(PYTHONLIBS_FOUND FALSE)
+    return()
+  endif()
+
+  # Convert the process output into a list
+  string(REGEX REPLACE ";" "\\\\;" _PYTHON_VALUES ${_PYTHON_VALUES})
+  string(REGEX REPLACE "\n" ";" _PYTHON_VALUES ${_PYTHON_VALUES})
+  list(GET _PYTHON_VALUES 0 PYTHON_PREFIX)
+  list(GET _PYTHON_VALUES 1 PYTHON_LIBRARY_SUFFIX)
+
+  # Make sure all directory separators are '/'
+  string(REGEX REPLACE "\\\\" "/" PYTHON_PREFIX ${PYTHON_PREFIX})
+
+  set(PYTHON_LIBRARY "${PYTHON_PREFIX}/libs/Python${PYTHON_LIBRARY_SUFFIX}.lib")
+
+  # when run in a venv, PYTHON_PREFIX points to it. But the libraries remain in the
+  # original python installation. They may be found relative to PYTHON_INCLUDE_DIR.
+  if(NOT EXISTS "${PYTHON_LIBRARY}")
+    get_filename_component(_PYTHON_ROOT ${PYTHON_INCLUDE_DIR} DIRECTORY)
+    set(PYTHON_LIBRARY
+        "${_PYTHON_ROOT}/libs/Python${PYTHON_LIBRARY_SUFFIX}.lib")
+  endif()
+
+  # raise an error if the python libs are still not found.
+  if(NOT EXISTS "${PYTHON_LIBRARY}")
+    message(FATAL_ERROR "Python libraries not found")
+  endif()
+  set(PYTHON_LIBRARIES "${PYTHON_LIBRARY}")
+endif(WIN32)
+
+# Fixme: Maybe find a static library. Get SHARED/STATIC by FIND_PACKAGE.
+add_library(python SHARED IMPORTED GLOBAL)
+set_property(TARGET python PROPERTY IMPORTED_LOCATION ${PYTHON_LIBRARIES})
+
+set(py_env "")
+if(PYTHONINTERP_FOUND)
+  find_python_module(pip REQUIRED)
+  find_python_module(numpy REQUIRED)
+  find_python_module(wheel REQUIRED)
+  find_python_module(google.protobuf REQUIRED)
+  find_package(NumPy REQUIRED)
+  if(${PY_GOOGLE.PROTOBUF_VERSION} AND ${PY_GOOGLE.PROTOBUF_VERSION}
+                                       VERSION_LESS "3.0.0")
+    message(
+      FATAL_ERROR
+        "Found Python Protobuf ${PY_GOOGLE.PROTOBUF_VERSION} < 3.0.0, "
+        "please use pip to upgrade protobuf. pip install -U protobuf")
+  endif()
+endif(PYTHONINTERP_FOUND)
+
+include_directories(${PYTHON_INCLUDE_DIR})
+include_directories(${PYTHON_NUMPY_INCLUDE_DIR})